Single-ended triode amps

[manisandher]

I suspect this post will ruffle a few feathers, but here goes anyway...

I bought a new (actually used, but new to me) pair of single-ended mono valve amps (a pair of Consonance 211S monos). They were virtually brand new and going for just a 1/3 of (not off!) their original retail price. And their reviews were very interesting. So I bought them, with no real idea of what I was going to do with them. (Not the first time this has happened...)

The seller suggested that I get hold of a pair of new Elrog 211 valves for them if possible and I managed to do this.

The amps are rated at around 15W into 8 Ohms. The speakers in my office are rated at 96dB/W@1m, although I suspect this is a little bit optimistic. In any event, I attached the amps and was literally blown away with the sound. And this only a few days after the Mach II was installed here. I could have lived with this sound forever. Really.

But then I thought... I wonder how they'd sound driving the 118dB/W@1m Orelo speakers. I knew they'd be too noisy for a permanent setup, but wanted to try temporarily anyway. So I connected them and switched them on. Immediately there was way more background noise than normal, to the point where I could actually hear the audio PC electrical noise coming through the horns - lots of clicking and swirling going on. And there was quite a bit of noise coming through the LF drivers too. At the listening position the noise remained easily audible and way more than would be ordinarily acceptable. I was going to simply disconnect the amps, but thought I'd try them anyway. I set XX to -30dB and pressed play, and...

... I was presented with simply the best sound I've ever had in my listening room. The sound easily bettered the speakers' built-in amps in every way imaginable. The only area that sounded pretty similar was the relatively lean and a bit dull/flat bass - totally different to when the amps were in my office. (But this isn't so surprising, as the bass amps in the speakers take the signal and amplify it to match the sensitivity of the mid/high horn. If they weren't there, I suspect the bass would have been a lot better.)

Reverting back to the regular all active set up, the sound is as flat as a pancake in comparison. All the magic has gone.

So, what to conclude? A few things:

1. Ambient noise makes no difference to the SQ. I know Peter will hate this statement. It's been my 'dogma' (and many others here too, I know) for many, many years. But this experience tells me otherwise. Maybe the type of ambient noise is more important than the amount. The relatively high noise coming through the Orelos from the SETs would not have been correlated with any signal. I wonder if this makes a difference?

2. The SET crowd really aren't mad. I suspect they've known all along that they have the best sound, and laugh at the rest of us. Unfortunately, most of the SET crowd use turntables (I certainly have nothing against that) and have never heard anything approaching the quality of the XX/MachII/NOS1a combination. For me, this digital chain and a SET driving a good high-efficiency horn is a match made in heaven.

3. I remember reading a paper by Nelson Pass, talking about the monotonicity of air, and how single-ended amplification is the only type that can ever truly sound 'natural' to the human ear. Maybe he's on to something?

4. I remember reading a paper by Thorsten Loesch talking about the harmonic distortion produced by a single-ended amp being benign to the human ear. Maybe he's onto something?

5. I remember reading a paper by Eduardo B. E. de Lima talking about how the distortion spectrum of a single-ended amp could actually be used to reduce the distortion inherent in speaker drivers. Maybe he's onto something?

5. With the SET in place, even with all that background noise, I could easily hear minute differences in SFS, etc. Actually, such differences were easier to hear with the SET in place. And the amount of inner detail coming from the music was nothing like I'd ever heard in my room before. The difference between the Mach II and my previous audio PC was much greater with the SET in place than with the active amps.

*********************
As a result of this little impulsive buy, I've had to reset my whole audio thinking. These amps are gems. But I suspect all decent SETs are, because of the physics of sound and the way the ear hears it...

Anyway, no going back for me! There will be a permanent SET setup in my office and in my main room by the end of the year. I cannot listen to anything else now.

Mani.

[fralippo]

SET DHT amps are the best. But good luck finding a really top quality one ;-)

[manisandher]

I know a guy who's got a massive Kondo collection. Maybe I can persuade him to sell me a pair of his cheaper monos. Would still be too expensive for me 

No, I know exactly where a pair of SETs for my main system are coming from. I've been in touch with the manufacturer and he's looking to get me a pair by the end of November. Of course I'll post all the details in due course.

Mani.

[PeterSt]

1. Ambient noise makes no difference to the SQ. I know Peter will hate this statement.

Haha, first is correct, latter is wrong.
I don't care a hoot about ambient noise and thinking twice you'll know about my kitchen endeavours.
Point is : what you call ambient noise was electrical noise first.

So what you're saying is that this noise at 60dB down (or maybe a bit more down) and which eats half of your digital bits, sounds better to you. Well, this is fine of course.
But best would be really when we could figure out that those eaten bits better be chopped off in the first place; only then it is really justified (read : at this moment they are harmful so they better not be there).
Of course it is allowed to claim that the amp still sounds better, despite that noise (so it is overly good). No problems with that one.

Regards,
Peter

PS: Just saying () : flat as a pancake is 10586.0. I (re)tried it yesterday and couldn't listen to it for exactly that reason. I can also tell you that some like 10586.0 explicitly for that so YMMV; it could give a kind of accuracy because of undecompressed depth (same as too wide and then getting inaccurate).

[manisandher]

So what you're saying is that this noise at 60dB down (or maybe a bit more down) and which eats half of your digital bits, sounds better to you.

Yes! And that even with this noise, I can hear minute differences in SFS. I didn't realise these SFS differences sat between the MSB and LSB 

Mani.

[PeterSt]

I didn't realise these SFS differences sat between the MSB and LSB 

Is there more outside of this universe ?
(I really don't understand)

[Nick]

Mani hi,

Interesting, I do like the sound of SETs so I can understand what your describing Mani.

Just a thought. Looking on line the Consonance 211 it has an input impedance of 100k, a typically high for valve input stage.

Peter is getting great sound with the NOS1 => B'ASS line buffer. => Orelos. Might some of the magic you are hearing be down to the Consonance presenting a relatively easily driven load to the NOS1 output stage ?

I don't know the input impedance of the Orelos and how they compare in this respect to the 100k input of the Consonance amps but could be using a B'ASS might make the Orelos amps closer to the Consonance, that is if NOS1 to amp matching is a factor.

I know I really need a B'ASS to help drive the eight gainclone inputs in my amp. Maybe I should get out the audio note 300b SETs that have been under the my stairs for the last 6 years, just to see how they sound compared to the gainclone setup ...... :-)

Nick.

[Scroobius]

Interesting  -  Mani you will remember my Audio Note AN speakers you heard them here and very much liked the sound of them IIRC. When you heard them they were being driven by the Gainclone amp that I built and that is featured elsewhere on this forum.

What you did not hear was the system that used to drive the AN's prior to the GC's. It featured AN DAC an AN pre amp driving two AN mono block SET valve amps.  I had made many (very expensive) changes to the DAC, pre amp and the SET's. The mono block SET's had high spec AN output transformers, matched high spec triodes and WKZ blackgate ps caps. along with other tweaks.

I only built the Gainclone amp because I saw them discussed on this forum and did not know anything about them. When I put the completed GC amp into service I was astonished with what I heard - they were much better than the SET's (in this room). The mid range was surprisingly similar to the SET's but the top end, bass and control over the speaker was in a different class to the SET's. However I do remember the SET's having a very beguiling sound.

It was then that I invested in the NOS to drive the GC amp and never looked back.

Of course life is not that simple and it would have been interesting to hear the SET's driven by the NOS1 but that was not possible as I had to sell the SET's not least because they were freaking big and I had no where to put them. Certainly my SET's just did not have the umph to deliver sensible power and dynamics in this large room even though they were driving efficient speakers. The mid range was excellent but I have to say the GC's matched them in that respect. I have heard many SET based systems but I have to say I could not be tempted back from my experience anyway.  I would love to hear your SET amps though maybe you can change my mind!!

Cheers

Paul

[manisandher]

Hey Nick, good to hear from you after such a long time!

Might some of the magic you are hearing be down to the Consonance presenting a relatively easily driven load to the NOS1 output stage ?

Certainly a possibility. However, as I said earlier:

The only area that sounded pretty similar was the relatively lean and a bit dull/flat bass - totally different to when the amps were in my office. (But this isn't so surprising, as the bass amps in the speakers take the signal and amplify it to match the sensitivity of the mid/high horn. If they weren't there, I suspect the bass would have been a lot better.)

If the improved sound was down to the SETs providing an easier load for the NOS1a, I'd expect the LF to be massively improved too. And it just wasn't. In my office, driving the 96dB/W@1m Impulse H2 speakers, the bass is simply tremendous with the SETs. Driving the Orelos, it hardly changed at all, and certainly didn't match the improvements in the rest of the sound.

Whenever I've heard Paul's Orelino speakers, I've always said there is something wrong with the LF in my speakers. The DSP adjustments sounded impressive when I first did them, but reverting back to the original filters showed me how much better they (the originals) actually were.

Right now, I'm still inclined to think the improvement in SQ is down to the phenomenal performance of these 211 SET amps. Oh, and the >$1.5k (for a pair) Elrog 211 valves - simply stunning, compared to the Psvane 211 valves that came with the amps when I bought them.

Mani.

[manisandher]

When I put the completed GC amp into service I was astonished with what I heard - they were much better than the SET's (in this room). The mid range was surprisingly similar to the SET's but the top end, bass and control over the speaker was in a different class to the SET's. However I do remember the SET's having a very beguiling sound.

My 211 SETs actually have a very mediocre sound with the cheap Chinese valves that come standard with the amps. Most customers upgrade to the very good Chinese Psvane 211 valves, which really improve the sound of the amps. I didn't try these valves when the SETs were connected to the Orelos, but suspect there wouldn't have been such a massive improvement in SQ. There really is a quantum leap in SQ going from the Psvanes to the German Elrog 211 valves. I suspect most of the magic is happening within these valves.

Certainly my SET's just did not have the umph to deliver sensible power and dynamics in this large room even though they were driving efficient speakers. The mid range was excellent but I have to say the GC's matched them in that respect. I have heard many SET based systems but I have to say I could not be tempted back from my experience anyway.  I would love to hear your SET amps though maybe you can change my mind!!

The dynamics that I'm getting with these amps, driving either of my speakers, is simply stunning. I'm sure they'd run out of steam with the Impulses at some point, but in my main room with the Orelos, I never dared taking them louder than -21dB.

Of course, you're welcome to come and listen for yourself whenever you like!

Mani.

[CoenP]

Hoorah for the SET resurrection!

The GC amp I build long ago sounded tonally fine and precise, but could not match the sheer musicality of my ultra low power pedestrian SET amps (that is a SESPPaT: a Single Ended Small Power Pentode as Triode). As a matter of fact the SET sounded more dynamic and live (compression?).

I heard noises in the Altecs too, but most of it was in retrospect the result of an insufficiently shielded interconnect.

PS: Just saying () : flat as a pancake is 10586.0. I (re)tried it yesterday and couldn't listen to it for exactly that reason. I can also tell you that some like 10586.0 explicitly for that so YMMV; it could give a kind of accuracy because of undecompressed depth (same as too wide and then getting inaccurate).

Aha, I think I encountered this flatness the past days, I already wondered if something was wrong with my ears or setup. Dynamics and balance are ok though a bit dry. It plays tunes too.

regards, Coen

[acg]

Hi Mani,

I can confirm that it is possible for SET amps to have zero noise on high efficiency horns.  I am talking put your head in the horns and hear not  whisper.

The beauty of SET's is that their level of distortion decreases as their output decreases, so with 118dB sensitivity horns such as the Orelos will be using a tiny fraction of a watt for sane listening levels and their distortion profile may be absolutely minimal.  On the other hand SS amps can really have some problems at under 0.1W output (not saying that this is the case with Peters gainclones but making a crude generalisation).

You will probably find that a lower voltage tube than the 211 will give you even better results...in my limited experience the lower voltage tubes have more balance and nuance and are able to shift dynamically with more composure.  Tubes like the 6C33C have a low plate resistance (and 200V B+) and can consequently be made with a much lower output impedance (around 0.1R-0.2R depending on loading) and in this situation where you may end up trying to directly amplify the BD15 drivers in Peters speakers the low output impedance will certainly help.

For the horn you may even be able to run a single stage SET which is as simple an amplifier as you can build.    

Cheers,

Anthony

[manisandher]

Hoorah for the SET resurrection!

 

You will probably find that a lower voltage tube than the 211 will give you even better results...in my limited experience the lower voltage tubes have more balance and nuance and are able to shift dynamically with more composure.  Tubes like the 6C33C have a low plate resistance (and 200V B+) and can consequently be made with a much lower output impedance (around 0.1R-0.2R depending on loading) and in this situation where you may end up trying to directly amplify the BD15 drivers in Peters speakers the low output impedance will certainly help.

Thanks Anthony. I'll be exploring different options going forward, and this is really helpful. Lamm uses the 6C33C, right?

Mani.

[CoenP]

You will probably find that a lower voltage tube than the 211 will give you even better results...in my limited experience the lower voltage tubes have more balance and nuance and are able to shift dynamically with more composure.  Tubes like the 6C33C have a low plate resistance (and 200V B+) and can consequently be made with a much lower output impedance (around 0.1R-0.2R depending on loading) and in this situation where you may end up trying to directly amplify the BD15 drivers in Peters speakers the low output impedance will certainly help.

Well, kind off. I do not think the low plate impedance (= usually lower plate voltages) is key here per sé, but that this provides for a better starting point for winding the output transformer. The winding ratio for a 6c33c can be much lower than ie a 211, hence better coupling and thus a wider frequency range (more high and more low). Of cource there is more to good sound than this.

Regards, Coen

[acg]

Well, kind off. I do not think the low plate impedance (= usually lower plate voltages) is key here per sé, but that this provides for a better starting point for winding the output transformer. The winding ratio for a 6c33c can be much lower than ie a 211, hence better coupling and thus a wider frequency range (more high and more low). Of cource there is more to good sound than this.

Regards, Coen

I suggested that tube and its very low plate resistance because Mani is talking about integrating it into an existing speaker system.  I suggested bi-amping, with the 6C33C specifically for the bass channel if he did wish to go that way.  The Orelo's have been designed with a very low output impedance amplifier in mind (the gainclones), and although the DSP for the low end does muddy the waters a little in suggesting the best way forward, changing amps to a high output impedance DHT or IDHT is unlikely to get a good result in the bass in this situation because those high plate resistance tubes simply cannot be have an OPT wound for low output impedance.  Higher amplifier output impedance = more SPL output at woofer resonance which is probably going to be counter-productive in this situation.

As an example, I am about to take delivery of a custom OPT for a bass SET amplifier to drive the woofer towers that I am building.  These towers have 8 x 10" drivers per side, are wired in parallel and present a load to the amplifier of 1R.  The OPT for this channel will load the 6C33C tube to 1000R which will give me about 10watts and an amplifier output impedance of about 0.2R which results in a speaker damping factor of 5 or so, which is quite high considering this is a zero feedback single ended triode.  The Bass OPT is flat (at full power) from about 4Hz to 5kHz.

In Mani's situation I predict that the important thing metric will be the speaker damping factor and the number of watts he has to play with.  Is 10 watts enough?  I don't know...it depends on a lot of things...but if it is then a low output impedance is likely to be an important factor in SQ especially if no feedback is involved.

Regarding the low voltage tubes vs high voltage tubes...this is simply my opinion and personal preference...and is influenced by what I have heard with 211's and 845's and the like.  SET amps are so difficult to integrate perfectly into a speaker system...you need high sensitivity speakers, loads of dynamic headroom and a willingness to call the results for what they are regardless of expenditure or expectations.  Because of the well documented technical limitations in SET amps they need to be carefully paired to the speakers...most hifi systems (read low sensitivity with varying impedance loads) perhaps will sound better in some areas with a SET amp, but overall the result will probably be worse than a good SS amp.  There is a LOT more to it than being able to get enough SPL.  Find that symbiotic pairing and wow, SS does not get close (in my opinion of course).

So Mani, regarding amplifying the woofers in your speakers, whether you can go SET will depend on many things, but most importantly the power response of those BD15 drivers.  Do you know how much DSP boost is required to get that system flat to 20Hz?  That number right there will be the most important thing to consider which way forward.

Cheers,

Anthony

PS: Mani, yes I have heard the early LAMM's with the 6C33C and they did sound very pleasing in that system.  The best 6C33C that I have heard though is diy.  I am copying them myself.

[manisandher]

Hey Anthony, thanks for the insights - very interesting.

But I don't think I'll be messing around with the Orelo speakers. The DSP and servo-assisted bass is an integral part of the design and can work incredibly well - anyone interested should just take a visit to Paul's place to hear this, with his slightly smaller Orelino speakers (if Paul's willing, of course). The 211 SET amps totally transformed the sound of my Orelos overall, but had little affect on the bass, which suggests to me that the 'quality' of the bass is being determined by the DSP and the servo-assistance. No matter what I try, I can't seem to get the low end right in my room with the Orelos.

Mani.

[PeterSt]

No matter what I try, I can't seem to get the low end right in my room with the Orelos.

Of course you will.
All it needs is a bit of "complaint" so we can work on it. Only the other day I had an idea but it appeared practically difficult (so I didn't announce myself while you don't even complain ).

Peter

[PeterSt]

I can confirm that it is possible for SET amps to have zero noise on high efficiency horns.  I am talking put your head in the horns and hear not  whisper.

Hi there Anthony,

If you know the efficiency of your horns (I'm sure you are referring to those ... what is it ?

The beauty of SET's is that their level of distortion decreases as their output decreases,

Isn't it so that you bring this a bit the other way around : these amps (means of amplification) are full with distortion but with some lower load they are fine ("better" would be more realistic).

THD ?
I'd be careful, because the THD could be higher than even a speaker (I am not sure any more, but I recall something like 0.02% THD from the (Orelo) mid/1KHz at 120dBSPL - maybe it was 0.2% but it doesn't matter really when we start out with tubes. Or ?)

Anyway, it is difficult for me to be part of the discussion, especially when noise is so high that it can only be destructive while people claim it sounds better.
Well, I don't need to say what's next, right ?

I suspect this post will ruffle a few feathers,

True.

haha

[acg]

Hi there Anthony,

If you know the efficiency of your horns (I'm sure you are referring to those ... what is it ?

113dB one watt one metre [EDIT: and with AC filaments which are generally considered noisier than DC]

The beauty of SET's is that their level of distortion decreases as their output decreases,

Isn't it so that you bring this a bit the other way around : these amps (means of amplification) are full with distortion but with some lower load they are fine ("better" would be more realistic).

THD ?
I'd be careful, because the THD could be higher than even a speaker (I am not sure any more, but I recall something like 0.02% THD from the (Orelo) mid/1KHz at 120dBSPL - maybe it was 0.2% but it doesn't matter really when we start out with tubes. Or ?)

Yes, some SET's have quite large 'distortion', pretty much all second order, but it seems to fit with our physiology somehow and sound fine/not there.  I have seen SET measurements at speaker loads (ie. not running flat out) where the distortion is less than good SS at the same levels, but the key is high sensitivity and matching the amplifier to drivers that are not impacted by the shortcomings of the topology.  It sounds like the horn on the Orelos is a good match.

If low distortion was the sole metric by which to measure amplifier performance we have been at the pinnacle of audio amplification for a quarter century...haha...not true...but it certainly low distortion is very important.

Cheers,

Anthony

[acg]

No matter what I try, I can't seem to get the low end right in my room with the Orelos.

Mani.

As you are no doubt aware Mani, good low end is mostly about positioning.  Positioning of the speakers and positioning of the listening chair...both should be positioned with consideration of measured SPL for frequencies below the rooms Schroeder Frequency, usually somewhere near 250Hz.  Walking around with an RTA finding the room nulls and peaks for various frequencies is probably the best place to start...shift the speaker...get out the RTA...and iterate.  Once the speakers and chair are placed for best bass response then fine-tune the positioning to get the sound and imaging you want in the higher frequencies.

It takes a lot of effort to get right.  Have you read Jim Smiths book?  That is a good place to start.

[manisandher]

As you are no doubt aware Mani, good low end is mostly about positioning...

... It takes a lot of effort to get right.

Yeah, sure Anthony. In the old days, I used to spend hours/days with 'golden ratios', etc. My Orelos, with their currently sand-filled wings, weigh in at about 150kg each. Also, they're quite big in comparison to my [approx.] 6x5x4m room. So by necessity, they have remained sitting relatively close to the corners of the room since I received them.

In any event, I'm not sure if OB speakers can be treated in the same way as IBs, ported, etc.

Mani.

[acg]

In any event, I'm not sure if OB speakers can be treated in the same way as IBs, ported, etc.

Mani.

Where the wavelength is longer than any room dimension, the room is the instrument, not so much the speaker.  IB has to obey the same rules of physics as any other topology.  My horn stacks when they are finished will be about 500kg each...I still plan to move them around to find where they best 'play the room'.

[PeterSt]

But Anthony, you are out of space anyway !

[manisandher]

There will be a permanent SET setup in my office and in my main room by the end of the year. I cannot listen to anything else now.

Done!

Mani.

[acg]

wow!

[manisandher]

wow!

Yeah, and to my ears, they sound as good as they look. They certainly seem to match the room (sonically and aesthetically) better than any other speakers I've ever had in it.

And now to that NOS1 upgrade we've all been hearing about... 

Mani.

[briefremarks]

Mani,

I saw these Tune Audio "reproducing machines" as they call them when I was researching speakers.  As I understand there is a downward firing bass horn, and the mid and hi horns.

These seem to be in the same spot as the Orelo's were.  How do they compare?  The reviews on the website are in Greek and French, so not accessible to me.

I am, of course, awaiting the arrival of the Orelos.

Ramesh

[manisandher]

How do they compare?

Hi Ramesh, there's no question in my mind that the Animas are better suited to my reasonably small listening room (~6x5x4m) than the Orelos. The Animas respond well to being placed pretty close to the corners, and I think this is where they differ mainly - I am now convinced that the Orelos need a couple of meters of breathing space behind them to perform well in the LF. Paul has a lot of breathing space behind his Orelinos, and they sound superb.

Certainly, I have absolutely no issues with bass in my room with the Animas. I'm getting a beautifully balanced sound, which I never achieved with the Orelos without some serious DSP in the LF, which brought along a whole new host of problems, as I discovered over time.

If I were typing this a few hours ago, I would have said that the Animas are way more laid back and less dynamic than the Orelos. But I've just connected my BD-Design mono amps to the Animas to give the speakers a bit of a continuous thrashing (get them loosened up a bit) and I'm hearing quite a few similarities now. I still doubt that any amp on the planet would get as much drive out of the Animas as you can get with the Orelos with their built-in amps.

If you can get a sound even half-way approaching that of Paul's set up, you'll be in for a real treat. If I could have gotten the Orelos to work in my room, I absolutely would have kept them. But I have to say, I am really enjoying the SET sound with the Animas. I just know this SET/speaker set up is the end game for me.

HTH.

Mani.

[PeterSt]

Hi Mani,

Very nice looking ! really so.

I am now convinced that the Orelos need a couple of meters of breathing space behind them to perform well in the LF.

Allow me to tell you "better not be", because how else is it working out elsewhere, including my own room (say 80cm from the wall behind them). If only we would have worked this out then we would have know (and solved it), but we did not ...
The above is only the necessary lead-in to an observation :

As you know, the Orelo's explicitly fire less backward than forward because of the wave guide set up. This is also the reason they are allowed to be very close to the wall behind them. They just are and they are everywhere where I listened to them myself. Now :

The Animas have a downfiring woofer. So, not even forward firing (say without port) but explicitly downfiring, which means thay radiate 360 degrees and thus also right into the corners. And now something else happens (outside of phase stuff which I wouldn't like for theories, but that's me ...

So as we both know you suffer from these room modes. I forgot by now how or what, but together with your "odd" high ceiling, that did not work out as you would have wanted. But what is a room mode ?
Well, let's say it is a tight/small area where waves meet and cancel (your situation) or add. Why is that area tight ? well, WHEN the beaming as such is that in the first place. So as we know the bass from the Orelo design is the most directive but which means that it comes to you without too many (early) reflections, especially not from the back. And this now is crucial ...

Let's assume that your speaker is 1 meter from the corner. Or that the middle of the bass driver / opening is. This means that before the wave hits the corner (or wall) it has travelled 1 meter. Next it travels one meter back to the speaker opening where it meets with the next cycle without phase difference. Well, this is idle hope of course (is that Dutch ?), but let's say it works out. If it does ... same problem as with the Orelo ! haha. Well, some time smear, but that is all.
The idle hope though predicts that this is not going to happen at all, and most certainly not for all frequencies at the same time. And most of all not for the wavelengths longer than 2 meters, which are about all of them coming from there (I'd say, without doing any math). So ...

What you nicely created is some heavy smear for that tight area from before. That tight area is not that at all now and it allows the waves which met not to meet at all (read : they still do, but 15cm away they do not and the next effect is not a full cancellation).
That meanwhile it is quite messy is something else (you should be able to hear that by means of a lower bass (say more dark) but not as tight. Btw this could be harder to experience because the bass doesn't go as low as the Orelo to begin with, so even for me it is hard to predict in comparison.

But see ? now your problem of the cancellation is solved.
And when I am right on this, you could have solved the issue by means of moving one of the speakers a bit forward or backward (let the top horn stay in position). Well, sort of, for proof. It is not a real solution of course.

What's for sure is that they look seriously nice ! (thanks to that great finish I'd say ?)

Best regards,
Peter

[manisandher]

Very nice looking ! really so.

Thanks Peter.

If only we would have worked this out then we would have know (and solved it), but we did not ...

[snip]

And when I am right on this, you could have solved the issue by means of moving one of the speakers a bit forward or backward (let the top horn stay in position).

Over the two and half years I had the Orelos here, I tried a lot of different things, including different positions. I actually had them 1m from the rear wall in the beginning, and only moved them closer over time. Going from 1m to nearer the rear wall really didn't seem to change much here. Filling the wings with 240kg of sand didn't help the sound (nor my back!). The only thing that 'worked' was using severe DSP, but that turned out to be too much of a 'sledge hammer' approach and introduced other issues that I discovered later.

In any event, the ultimate test is using your own ears. And my ears are clearly telling me that whatever the issue was with the Orelos in my room, I don't have it with the Animas. To my ears, the bass sounds as clean as it did with the Orelos... just way more of it! What's not to like?

Edit: I want to make it absolutely clear that I'm talking about the performance of the Orelos in my specific room, with a 4m ceiling.

Mani.

[acg]

Mani,

Lovely looking speakers and I think there is a lot to like about the design of them also.  I would be so tempted to go active with them, but to each their own of course.  Are you planning a sub at all?  You get so much "presence" with the lowest octave...personally I would try to integrate a lower channel (says he not having heard them - sorry!)

Cheers,

Anthony

[manisandher]

Hi Anthony, no... no changes planned whatsoever.

I've totally fallen in love with the SET sound, top to bottom, and going fully active would mean 3-4 SET monos on each channel. I'm simply not going to do this. And I'm not in the least bit interested in any other type of amplification now, so no mixing class-D (or whatever) for the bass, and SETs above. For me, it's got to be SET all the way.

I now hear a 'glare' / a 'sheen' that all the PP amps I have here seem to add to the sound. It sounds really impressive for a few minutes, and then fatiguing. The sound is too 'tight', too controlled almost. Actually, I'd say that the only PP amps I've ever heard that don't have this were the Sauermann monos I owned. I don't regret selling them though, because as good as they were, I still prefer the sound of my current (cheaper) SETs.

I reckon I'm getting a good response down beyond 40Hz (with a big dip at 50Hz still). That's good enough for me.

Mani.

[Scroobius]

I just wanted to give my impressions of Mani's sound with Orelo's as I have heard his system many times.  The sound of Mani's Orelo system was almost diametrically opposite to mine (essentially the same system as Mani's). In fact if blind folded anyone listening would have said they were totally different systems with maybe some very small similarities. Not only was the bass completely and totally different (that has been discussed many times) but just about every other aspect was different. The dynamics and "alive" quality of the sound here is similar to a live performance. Bass is simply amazing on live recordings, you can "feel" the stage moving on some recordings (Brubeck Time Further Out for example). From bass through mid range to top end totally different sound. It is inconceivable that it would have been possible to have made tweaks or even radical changes to Mani's system to have made the sound anything like mine.

This is absolutely not a boast, it is simply an observation and I regularly thank the almighty for gifting me the acoustics in my room. BUT I am sure that it was an accident and I am equally sure the almighty did not intend to do any such thing. That is because my room is an ABSOLUTE DOG and would be written off by any self respecting sound engineer as a ridiculous place to even attempt to reproduce music.

As an example with music playing walk the length of my room away from speakers toward the listening position and you will hear cancellations and reinforcements in the bass as you walk. Not just trivial small changes but wapping great big changes.

I have also heard Peter's system and it just does not happen at his which is in a very big room with lots of space between the outer edges of the speakers and the side walls. No such luck here there are lots of side wall reflections because so close.

So here are some quotes from Mani's and Peter's posts above: -

Orelos need a couple of meters of breathing space......

.....how else is it working out elsewhere, including my own room (say 80cm from the wall behind them)

........but which means that it comes to you without too many (early) reflections, especially not from the back.

Peter is (of course) absolutely right the Orelo's reduce rear firing bass. And I have measured that here - over much of the bass frequencies. But certainly not all. Lets take 50hz, in this room a very strange thing happens. Measured inside the throat close to the speakers of the Orelino's the response is very even measured 20 to 200 Hz. But move the microphone out of the throat of the speaker to the interface where the sound leaves the speaker and hits the room and a very strange thing happens. There is an almost total cancellation at 50hz. In the measured response there is a deep notch at 50Hz all around the listening space. If I play a test tone of 50hz and then walk all the way to the listening position you virtually cannot hear it at all. So where does the 50hz go? well the answer is that because it is not being cancelled by the forward going 50hz wave it travels backwards into the conservatory that is behind my speakers. If you stand in the conservatory right at the back whilst the speakers are playing you will find it almost painful to hear. You would not guess it by listening but it does appear to be a small range around 50hz.  There is a lot of sound energy travelling backwards from my speakers IN THIS PARTICULAR ROOM and that is proved by measurement and from the fact no one wants to sit in the conservatory while the speakers are playing  .

So the acoustics in my room are very far from ideal but you would never think it when you listen. The sound quality according to every one who has listened to them is simply astonishing. I really cannot imagine what it will sound like when the B'ASS and Phisolator mods are applied - my mouth waters in anticipation.

But no matter how good my system sounds at the end of the day the room acoustics have a massive impact on sound quality. And that applies even when the speakers minimise those problems as the Orelo's are designed to do.


Paul

[acg]

I have also heard Peter's system and it just does not happen at his which is in a very big room with lots of space between the outer edges of the speakers and the side walls. No such luck here there are lots of side wall reflections because so close.

The larger the room the lower the Schroeder frequency and the fewer room nodes...that is simple physics.  I would love a big room for audio, but that is not going to happen anytime soon.

[arvind]

Hi Mani,

Sorry to hear about the problems faced by you with the Orelo in your set up. My room size (8.5x5.6x2.7) is pretty similar to yours, except for the height.

The Orelo is placed 70cm from the back wall & 50cm from the side wall. About 4.0m between speakers (centre to centre). Practically negligible toe in. Listening position is 5m from the speakers.The low end is one of the best I have heard & mind you I have done no dsp settings.

As a matter of fact with my previous speakers, I was facing an issue of standing waves at 60/63Hz & to eliminate that I had bass traps installed. The first thing I threw out of my room, were these traps & now no standing waves.

Currently my only disappointment with the Orelo in my set up, are the upper mids, they are a bit harsh & smeared. Bert is working to find a way to solve this. At this point I would say that the tube amps work better in this area. More musical & involving.

However if your issue is related to room modes it's unlikely that it would differ from one speaker to another. I would think so.

Best regards,

Arvind

[manisandher]

I just wanted to give my impressions of Mani's sound with Orelo's as I have heard his system many times.

Thanks Paul, that puts a lot of things into perspective. Yes, I could have persevered with the Orelos, but I suspect it would have taken a suspended ceiling to really make progress, and I'm not about to ruin the great job the Victorian builders did 130 years ago (when British engineering led the way... how times have changed!).

My system will never sound like yours - yours assaults the senses (in the best possible way - the visceral impact really has to be heard to be believed), whereas mine massages them (but only when using a SET).

Mani.

[manisandher]

The low end is one of the best I have heard & mind you I have done no dsp settings.

Hi Arvind, that's really good to hear. Anyone looking for end-game speakers with decent bass should have the Orelos right up there on their list.

Currently my only disappointment with the Orelo in my set up, are the upper mids, they are a bit harsh & smeared.

I don't think I ever came across this issue with mine - perhaps with certain XX settings. Have you tried playing around with SFS and Q settings to see if you can tame this? Otherwise, I'm sure Bert will come up with something.

Mani.

[PeterSt]

Hi Mani, thank you for your help.

Although anything might be helpful to Arvind's situation, the problem is partially psychological because we (Arvind, Bert and me) know that something went wrong in there during production of this particular set.

Best regards,
Peter

[PeterSt]

If I play a test tone of 50hz and then walk all the way to the listening position you virtually cannot hear it at all. So where does the 50hz go?

Hi Paul,

Of course with the remainder of your long post as context :

I think you should run such a room mode calculator for the two parts of your room and most probably you will see that no voodoo is going on (I know you did not state that, but as long as we don't understand it often ends up as that ).
So what I dare predict is that all the longitudinal way the 50Hz is cancelled out because of the height of your room and then combined with the width. This makes shifting the back or forward the listening position not a solution. Btw, the same was going on with Mani's although I recall something else as 50Hz for that, but never mind.

Now run the same calculator through your conservatory of which you already know that at least the width is very different. With a bit of luck in there the 50Hz rules the other way around and instead of a notch because of cancelation you have a peak because of addition. It would be very coincidental, but it can happen.

Btw initially - when I read your post - I had the idea that the 50Hz would bounce back from the wall behind you and work out in the conservatory. But I don't think I can justify that together with the cancellation in that part of the room where also the bouncing back should occur.  A bit of a far sought option would be that the wave travels along e.g. the ceiling (or any of the other 3 surfaces) which you did not observe (measure) and works out to normal listening height in the conservatory. If you use a tool which can visualise where the wave of interest is audible, you will see it in there. So *if* you can see that the 50Hz is somewhere still for sure, it would be my bet that it works out in the conservatory. Thus not of what the back of the speaker is doing, but what bouncing back from the wall behind you implies.

This stuff is not to be underestimated. For example, Bert has had his large Orelo's in the middle of his room (similar to you, Paul). Well, if you did not first go to the normal listening position (with a nice flat / straight wall behind it and even corners) and listened from behind the speakers (face to the listening position), you would buy the speaker, so normally is that sounding all over. And mind you, that is in the face of the back of the (open) woofers !!
It is only that when later listening from the normal listening position you'll easily hear more highs. But actually you had no idea that they lacked and more importantly, all was in proper balance (distance from behind the speaker to the opposite wall is about 6 meters).

Regards,
Peter

[Scroobius]

Hey Mani

the visceral impact really has to be heard to be believed), whereas mine massages

So is what we are aiming for is a system that provides a "Visceral Massage" well maybe but I suspect that the two are mutually exclusive  .

It would be easy to get the impression that I only ever listen to music at silly high levels - that is not the case - my listening is mostly at very modest levels (really......... !!)

P

[arvind]

Hi Mani,

Thanks for the suggestion, although I have exhausted all permutation combinations of sfs, Q & filter to no avail.

Finally the only thing that partially works is reducing the slope & dip on the Orelo, though it's not the ideal method.

Hopefully Bert will fix the problem soon which could lead to solving this issue too.

Best regards,

Arvind

[manisandher]

... [my system] massages [the senses] (but only when using a SET).

I think for the first time ever, I've got a system that actually helps me to relax. Personally, I now think single-ended amplification is necessary to achieve this. I'm sure most people here would disagree, and I could certainly be wrong. But let me just quote something that Nelson Pass has written about this:

Given the assumption that every process that we perform on the signal will be heard, the finest amplifiers must employ those processes which are most natural.

There is one element in the chain which we cannot alter or improve upon, and that is the air. Air defines sound, and serves as a natural benchmark.

Virtually all the amplifiers on the market are based on a push-pull symmetry model. The push-pull symmetry topology has no particular basis in nature.

Is it valid to use air's characteristic as a model for designing an amplifier? If you accept that all processing leaves its signature on the music, the answer is yes.

One of the most interesting characteristics of air is its single-ended nature. Sound traveling through air is the result of the gas equation:

PV1.4 = 1.26 X 104

where P is pressure and V is volume. The small nonlinearity which is the result of air's characteristic is not generally judged to be significant at normal sound levels, and is comparable to the distortion numbers of fine amplifiers. This distortion generally only becomes a concern in the throats of horns, where the intense pressure levels are many times those at the mouth, and where the harmonic component can reach several per cent.

We can push on air and raise the pressure an arbitrary amount, but we cannot pull on it. We can only let it relax and fill a space as it will, and the pressure will never go below "0". As we push on air, the increase in pressure is greater than the corresponding decrease when we allow air to expand. This means that for a given motion of a diaphragm acting on air, the positive pressure perturbations will be slightly greater than the negative. From this we see that air is phase sensitive.

As a result of its single-ended nature, the harmonic content of air is primarily 2nd order, and most of the distortion of a single tone is second harmonic. Air's distortion characteristic is monotonic, which is to say its distortion products decrease smoothly as the acoustic level decreases. This is an important element which has often been overlooked in audio design and is reflected in the poor quality of early solid state amplifiers and D/A and A/D converters. They are not monotonic: the distortion increases as the level decreases.

Mani.

[Scroobius]

I've got a system that actually helps me to relax. Personally, I now think single-ended amplification is necessary to achieve this.

I have been there and spent a serious amount of time and money to get what I thought a SET system could deliver but ultimately it just didn't. Having said that I remain completely open minded and look forward to hearing your system.

Paul

[manisandher]

I have been there and spent a serious amount of time and money to get what I thought a SET system could deliver but ultimately it just didn't.

Hey Paul, you never used a full horn system with SETs though, did you? High efficiency (>105dB/W@1m) is a must to get the best out of a SET, I think.

Having said that I remain completely open minded and look forward to hearing your system.

Well, be prepared to be underwhelmed. It doesn't sound particularly impressive to my ears, mainly because it doesn't bring any part of the sound to attention. I haven't thought, "amazing bass", or "amazing dynamics", or anything like that. But what I have noticed is that I sit through whole albums just listening (no playing on the laptop) and am surprised when the album finishes.

And I can't even suggest that it sounds 'real'...

Mani.

[briefremarks]

Mani,

I've had the same experience as you in the past about being more "relaxed" listening to the radio, or even my in-wall speakers, than to "hi-fi" systems.  Once one reaches a certain level of quality, however--and this has been the case for me only recently with Stealth, RAM-OS, XXHE and Phasure--I find myself listening as if at a concert, not necessarily critically, and music is music again, without worry about the "system."  There is an unexpected quality to this experience, just as when one hears an unexpected sound in real life, a sudden "what was that?" feeling.  So the music does draw attention to itself, but not to marvel at the "system" but to be immersed in the piece itself and the performance.

Ramesh

[vrao]

My understanding about amplifiers

1. Current vs voltage school of thought - effects the speakers differently.

2. Power - a dark kept secret. Power rating are for a single signal. And power response drops with a complex signal. Power reserve can be "relatively" addressed for amplifiers with less than 60W, without affecting the outgoing signal. Add a power robbing crossover and more variables in the mixture.

Relax response: a very primitive description .... when the necessary parameters are met by the human auditory complex, brain will relax. Most will go to sleep ....

Because most are sleep deprived .... and once the brain feels safe, it will proceed to the next important thing on the list!

Best,
VJ

[manisandher]

Relax response: a very primitive description .... when the necessary parameters are met by the human auditory complex, brain will relax. Most will go to sleep ....

Because most are sleep deprived .... and once the brain feels safe, it will proceed to the next important thing on the list!

Ah, so it's not that the music is boring! Thanks.

Mani.

[vrao]

Mani,

Try comparing MP3 and hirez files. It may answer your question 

Best,
VJ

[vrao]

Mani,

Also look into this if not already done so!

http://www.crownaudio.com/en/tools/calculators

"Amplifier Power Required"

http://www.crownaudio.com/how-much-amplifier-power

"Peak headroom

Because music has transient peaks that are 6 to 25 dB above the average level, the power amplifier needs to produce enough power to handle those peaks without distortion.

For example, if you need 100 watts continuous power to achieve the desired average SPL, you need 1,000 watts continuous to handle 10 dB peaks, 3,162 watts to handle 15 dB peaks, and 10,000 watts to handle 20 dB peaks. Clearly, the peaks require far more power than the average levels. In the calculator's Peak Headroom field, enter 6 dB for rock music that is compressed or limited, or enter 20 to 25 dB for uncompressed live music. If you can live with some short-term clipping which may be inaudible, enter 10 to 15 dB.
 

[manisandher]

VJ, a few really dumb questions (and a lot of dodgy maths, I'm sure - a few edits already!):

1. Why would I need such high ratings of continuous power for momentary peaks in the music? Edit: Ha, I should have read the article more carefully. "According to Crown's chief amplifier engineer, Gerald Stanley, amplifier continuous power and amplifier peak power are nearly the same. Typically, peak power is only 1 dB higher than continuous power, and depends on peak duration."

2. My new SET amp will be only 5W pc. So in order to achieve 20dB peaks, the continuous power will be only 0.05W. But, my new speakers are 109dB/W@1m (across the full range). With only 0.05W, I can still achieve an SPL of 96dB @1m (109dB-13dB) - is this correct?

3. Let's consider the Orelo speakers now. We've got something like 60W of power going into the bass unit. So, for the same 20dB peaks, we have only 0.6W of continuous power. I'm assuming that the 'true' sensitivity of the bass unit is around 100dB/W@1m (it's just 'servo-assisted' to match the mid/high unit). So what does the SPL work out to with only 0.6W? 96dB (or so) @1m? In any event, around the same SPL as my Animas with only 0.05W of continuous power going to the bass unit.

4. It seems to me that the sensitivity of the speaker (across the full range, not just the mid and high) is way more important than amplifier power, because 10,000W+ amps just aren't a realistic proposition for home audio use.  In which case, 99.9% of audiophiles are 'stuffed' as they use woefully insensitive speakers. Is this correct?

I'm sure you're busy, so if anyone else would like to chime in, I'd appreciate it.

Mani.

[vrao]

Hi Mani,

I'm no expert with electronics.

In one of the links there is a program to add your desired listing level, distance, speaker sensitivity etc with head room to estimate power requirements. With a high sensitivity speaker I believe you will not have any issues within the normal listening levels. I've seen over 20dB peaks with Phasure DAC.

In which case, 99.9% of audiophiles are 'stuffed' as they use woefully insensitive speakers. Is this correct?

Most likely .... so.   

Best,
VJ

[manisandher]

VJ, I found the 'Amplifier Required Power' calculator thanks. With a 20dB headroom, it looks like I'm good for 86dBSPL at my listening position with my 5W amps and 109dB/W@1m speakers. Good enough for me.

It's all very well talking about the need for high powered amps to cope with headroom, but I think there is another potentially very important consideration: the effect these high-powered (non-class A) amps have on the AC mains. My feeling is that they might 'modulate' the mains with their current drain as the music plays, which may affect the source components adversely. Pure speculation on my part, but it was part of my reasoning to go the high-efficiency fully horn-loaded route, without servo-assisted bass.

Mani.

[manisandher]

Also look into this if not already done so!

http://www.crownaudio.com/en/tools/calculators

This gives a whole new perspective to the 'loudness wars'. It's just as well that much rock/pop music only requires 6-10dB of headroom as the majority of 'systems' out there would start clipping with more. You're sitting at home with your 50W amp thinking all is good. Well, for a 10dB headroom you're going to need a 500W amp! With a typical pair of 87dB/W@1m sensitivity speakers you'd get 84dBSPL in a listening room like mine. With 'better' mastered music requiring a 20dB headroom, you'd get just 74dBSPL at the listening position before clipping.

Really interesting stuff...

Mani.

[acg]

And valve clipping is soooo much nicer to listen to than SS...as a generalisation...that is if you must listen to something clip.

That is the beauty of an active system when using low powered amplifiers, they do not have to drive the passive crossover components.  Mani, you have passive crossovers which also have to be driven by the amplifier, so your 0.05W calculation is likely to be quite underestimated, it is likely to be quite a bit higher.  Then there is the unknown impedance behaviour of the speaker and crossovers which will affect the power that the amplifier is able to deliver.

[PeterSt]

VJ and others,

I am going to read into those links you handed, later. For now I can only contribute by saying that the bass drivers of the Orelo MKII are 101dB (1W/@1m) sensitive natively and that something like 9dB can be added because of the "horn loading". Tbh that was so for the Orelo MKI, the MKII should be a bit better on it.

Btw, generally, the power of an amplifier is determined by its possibility to deliver the current needed over the period of time the music depcits. So might an amplifier be able to deliver 20 Watts continuously then it may well be that it can do 200W as well (depending on the power supply). The question though is : for how long. Is that 0.1 second ? is it 2 second ? or can it handle 200W for 3 seconds before it melts down. Because it is about that : the heat (I'm thinking Solid State - Tubes are a different matter I think).
In the same realm we need to think about the impedance. The lower the impedance (and again it is the music which depicts that), the more current will (need to) flow, the shorter the "peak" is allowed to last. This obviously depends on the speaker too; can it go to 1 Ohm ? does it never drop under 4 Ohm at any frequency ?

Something else is that I learnt that the power music requires can not be calculated really, because it is too complex.

Regards,
Peter

[manisandher]

... something like 9dB can be added because of the "horn loading".

Peter, my understanding was/is that the Orelo wings are not there for horn-loading - they are simply way too small to achieve this at such frequencies. True horn-loaded bass units look more like below, no? The second pic gives an idea of the length required for true horn loading at low frequencies.

Mani.

[manisandher]

Mani, you have passive crossovers which also have to be driven by the amplifier, so your 0.05W calculation is likely to be quite underestimated, it is likely to be quite a bit higher.

Hey Anthony, the sensitivity of my speakers was measured at the output of the speakers, so I'm assuming it included the 1st order crossover components.

But I totally agree that running speakers actively is the best way. I've been there and done that (but not with horns), see attached. 4x Hypex HG700 amps per speaker, so plenty of power. And yes, the results were much better than with the passive crossover. But the gear takes over the room and I'm just not prepared to go there now. That's the beauty of the Orelo speakers -it's all packaged beautifully together.

Mani.

[PeterSt]

Hi Mani,

Peter, my understanding was/is that the Orelo wings are not there for horn-loading

That is why I put that "horn loading" in between quotes. Still it is to some degree because of the compressed and accelerated air the lot as a whole implies. Otherwise it is sufficient to measure the difference (SPL) between the back and the front. The "phase plug" is there for a reason too. The partial covering of the woofers, same.

And ... would you call the bass section of the Anima a horn ? Edit : with loading as such, I mean.
So let's say that loudspeaker designers are always bound to space constraints, and that compromises lure from many angles.

Best regards,
Peter

[acg]

And ... would you call the bass section of the Anima a horn ? Edit : with loading as such, I mean.

Yes, it is a horn.  The backchamber adds compression to the woofer as does a horn throat smaller than the size of the woofer cone.  The height  that the downfiring horn is set above the floor dictates the horn mouth area into the room.  I assume the height from the floor can be adjusted.

[manisandher]

Yeah, I don't know how else you'd get a 109dB/W@1m efficiency from a single 12" driver if it wasn't horn-loaded.

Listening to sine tones at my seating position, I'm getting useful output to about 40Hz, after which it drops fairly quickly. Interestingly, I'm getting very good output at 50Hz with the Animas - there was almost zero output with the Orelos at 50Hz... in the same room and at the same seating position. Weird...

Mani.

[PeterSt]

Mani, not weird. The source of the sound is from 3 dimensions or so different (height, direction, reflections).
A 4th dimension would be how clean that sound/sine is. For example, put up a square and see how "useful" that output is. And before you try for real, I don't think you can measure the native sine as such from the speaker. So this starts right in front of the speaker itself, but you won't get any nice sine. No promise, but that's what I think and expect.
So you will get more than 50Hz and you won't be able to tell what you hear.

This story is not so much different from "spreadening" the wave because of the reflections from the wall behind the speaker. And why do I have the hunch that you don't want to believe that.

Anyway, nothing weird. Just as could be expected.

Regards,
Peter

[manisandher]

So you will get more than 50Hz and you won't be able to tell what you hear.

I'll take some measurements next week - pure 50Hz sine wave fed to speakers, recorded at seating position with measurement mic, and analyzed on Audacity. Should tell exactly what's happening.

And why do I have the hunch that you don't want to believe that.

Peter, what do you want me to say? I haven't expressed to anyone my real level of disappointment in the Orelos not working out for me. I know they're great speakers, but they way they sounded in my room...  It's a shame you never managed to make it over and take a listen for yourself. Actually, Paul's earlier account says most of it. The only thing it doesn't (can't) convey is my often deep exasperation over the last two and a half years of not enjoying music in my main room. My office  and portable systems have been my saviours in this time. I now have a system that I love the sound of in my main room. Quite frankly, I don't care if it's distortion all over the place - I'll take it in a heartbeat over the sound I had before.

Mani.

[CoenP]

I think this thread is causing confusion, at least to me so hereunder an attempt to clarify my view on power a little.  

Peak sinus power and average RMS power have physical definitions.

Rated amplifier power is always rated at a certain (restive) impedance.

This has a lot of implications.

————— tutorial break “understanding power”—————

Delivered Power is defined as (Applied Voltage)x(Required Current).

The amount of current required for a certain applied voltage is determined by Ohm's law: Required Current (Ampere) = Applied Voltage (Volt) / Impedance (Ohm).
In loudspeakers this impedance is frequency dependent and as such has a "phase angle" that defines the lag between the current and applied voltage. This last complication is not needed to understand power delivery.

Say the impedance at a certain frequency is 8 ohm (no phase angle). If we have a signal that peaks at say 40 Volts than the required peak current would be 40V / 8Ohm = 5 Amperes, hence the required peak power would be 40Vx5Amp = 200 Watts.
A sinusoidal signal averages out on the 'Root of the Mean of the Squares' aka RMS value which is root(1/2) x Max voltage. At root(1/2) x Max voltage, the required average current current would be: root(1/2) xMax Voltage / impedance = root(1/2) x Required Current. The Average Power in RMS will now be the product of those two values hence root(1/2) x root (1/2) x peak Voltage x peak Current = 1/2 x  Peak Power (sinusoidal).

Halving the impedance to 4 ohms would double the required current for a given max voltage In the case of 40V this will be required peak current of 10 Amps in stead of 5 Amps, so double the power would be required by the loudspeaker :10Amps x 40V = 400 Watt peak. Doubling the impedance to ie 16 ohms wil consequently half the required power.

The above stated ‘phase angle” makes these precise calculations of the ‘current - voltage relation’ harder and more abstract, but what happens in practice is that there can be (far) more or (far) less current required by the loudspeaker (“load”) than the resistor would predict. In other words there may be more (or less) power required than in the resistor case. The amplifiers design has to be able to cope with this.

—————— end of tutorial break — — — — — — — -

Now a power amplifier specification measurement is usually performed with a resistive (no phase angle) load of a standardized value (to be able to compare). Mostly this will be 8 ohm. Power amplifiers however have two physical constraints that determine the maximum power that it can deliver into other loads than that value; ones that are greater or smaller than 8 ohms (and/or when the phase angle requires more or less current).
One is the maximum available voltage, the other the maximum available current.

Typically transistor power amplifiers operate at voltages that are close to the voltage that is required for the 8 ohm power specification. Our 100W RMS (hence 200W sinus peak into 8 ohms) amplifier wil likely operate at 50V-60V tension. This causes an available power reduction for a 16ohm load (2,5Amp needed for 40Volts or 100W peak or 50W RMS), yet the amplifier may be able to supply the 10 amps necessary for a 4 ohm load and as such provide more power when more amps are needed. Eventually the amplifiers power supply is not able to provide any more amps before blowing the fuse or significantly degrading the supply tension.
So this amp’s real maximum delivered power will be determined by how much current it is able to supply for the maximum voltage (about 40 V). This can be much more than the rated 100Watt.

 Amplifiers with a typical current constraint are OTL designs. The tubes operate at very high voltages (150-200V), but cannot source more than the tubes allow for the 8 ohm per specification (like 1 amp per tube max). That is that a 100Watt RMS (40V, 5 Amps at 8 ohm) rated OTL amp will not be able to deliver the 10 Amps required for 4 ohms, but it is able to deliver 5 Amps into 16 ohm. That is 5 amps at 80 Volt or 400Watt peak or 200Watt RMS. This amplifier real maximum power is limited by how much voltage it is able to generate for a 5 amp load. Also this can be much more than the rated 100Watt.

Usually -Single Ended- Tube amplifiers are designed to optimally couple the tube to to the load. In such a case the maximum Voltage and maximum current occur both at the rated impedance.
So our example amplifier of 100 Watt would not be able to supply more than 5 amps and more than 40 Volts which occurs precisely at 8 ohm. Both maxed out at the same time, so theoretically one point with maximum power.
Well those are the ratings. In reality the tube amp can deliver more than 5 amps or more than 40 Volts but not at the rated impedance. This flattens the ‘peak available power’ curve somewhat. Please note that this maximum power is more like a real ‘peak/RMS power’ unlike the two examples above.

With these three amplifiers you can understand that they favor different loudspeakers. The transistor amp theoretically matches well with a loudspeaker that has a low impedance  (<8 ohm)or impedance dips, the OTL favors high impedance ones (>16 ohms) and can handle impedance peaks well and the the transformer coupled tube amp is best served with a constant impedance at the rated value.

For sure there is much more to amplifiers than maximum deliverable power , but my experience is that this rule is implicitly followed by many ’system builders’.

Lastly I wanted to observe that an increase in power does translate into an equal amount of increase in sound pressure. Most amplifiers act as voltage amplifiers so the current follows the applied voltage. As the voice coils heat up and become more resistive, less power is absorbed for that voltage. Also speakers' excursion does not follow the power (and certainly not voltage) in a linear relationship extra power is less extra excursion than you expect.

This power transfer thing is where horns have big advantages. The compression drivers provide a very resistive load to the amplifier and they use low power, hence little heating of the voicemail occurs. And lastly excursion of the compression driver is extremely small and thus very linear. They are ideal candidates for transformer coupled tube amps, especially of the DHT variety that exhibit extremely low distortions at low signal levels.

I hope this helps somewhat to be more specific in what we try to say.

regards, Coen

[PeterSt]

It's a shame you never managed to make it over and take a listen for yourself.

Hey Mani,

Can you please rephrase with proper context ?
I am sure that in English it can read positively, but I am more sure it can read negatively all the more, and I am dead sure that Dutch and maybe others *will* read this as a pure negative.

I have my response ready, but so far I feel this is not for the public. A few words to make it look more positive seems to be sufficient.

Outside of this, I fully agree (I stay neutral for now).

Peter

[manisandher]

It's a shame you never managed to make it over and take a listen for yourself.

Hey Mani,

Can you please rephrase with proper context ?

Well, I meant this quite literally. If you or Bert had heard the Orelos as they sounded in my room, I don't think you would have recognized them at all. And I think it would have required this first hand experience to really get a grasp of what might be going on.

This is in no way a criticism of you or Bert for not coming over. All your other Orelo/Orelino customers seem perfectly happy and you can't go flying around the world when something doesn't work out for one person.

Is this clearer?

Mani.

[PeterSt]

I think this thread is causing confusion, at least to me so hereunder an attempt to clarify my view on power a little.

Thank you very much Coen.

N.b.: I largely repeat myself with the text below, so maybe skip. Better read Coen't post again.

Maybe I should have added the Voltage factor, which I didn't because of simplification but also because it seems too obvious ... to me. But even with your great post we can explicitly add some text about that :

So the volume we apply, is the Voltage we apply. Very low volume is e.g. 5V, high volume could be 40V.
However, this relates to the last part of Coen's post, where high sensitive horns already play massively loud with 5V. Or if you like ... at 1W (when sufficiently efficient). So it always comes down to this one :

Required Current (Ampere) = Applied Voltage (Volt) / Impedance (Ohm).

and Ohms law is indeed everywhere. What is not in this equation is how much power the loudspeaker driver needs to move. Now though we have the eg. 109dB sensitivity "by means of a power of 1 Watt at 1 meter distance". Somehow this 1 Watt translates to 2.83 Volts.  So ... P(ower) = U (Voltage) x I (Amperes).
P = U x I is the same as I = P / U. Thus, 1 / 2.83 = 0.353 Ampere.
Aha, so 0.353 Ampere is needed to blast 109dBSPL from a 109dB sensitive speaker.

I think the larger deal of Coen's post is about that this is not realistic because of several reasons. The foremost one (I think) is the required current which is invisible to us and can be the limiting factor like Coen told (side note : this is the different approach from taking care of infinite current supply and next see your amplifer melt down because of insufficient heat dissipation - those Watts need to dissipate and fast).
More indirectly the impedance is even more invisible and as we know the less impedance the more current required. Lastly - but I repeat myself - the music itself (the frequencies) determine the level of the impedance. Thus, also when a speaker is rated at 8 Ohms, it can be so that it most often plays with 12 Ohms or more, now consuming less current than when frequencies pass by which go all the way down to the rated 8 Ohm and which is thus more difficult for the amplifier (it requires more current).

Let me lastly add that clipping of an amplifier should not happen and *if* it happens, the design is not correct.
On the other hand (big fun) if you allow for infinite current and ratings are exceeded (for example you buy a new loudspeaker and you didn't think of the fact it can go down to 1 Ohm), the melt down is underway.
Also good to see through is that while the current can be virtually infinite (just by means of the design and all), the allowed Voltage explicitly is not. Thus, when I would design an amplifier then the voltage is always limited because the parts used are voltage limited. And this limits the current required  (Ohm's law : I = U / R) ? No not really, because the R is there. That bloody impedance. So if I would design an amplifier for my high sensitivity horns with sufficient current supply, will it melt down on a 85dB inefficient speaker ? No. There will just be no sound (it now requires 40V instead of e.g. 5V).

Thank you Coen.
Regards,
Peter

[PeterSt]

This is in no way a criticism of you or Bert for not coming over. All your other Orelo/Orelino customers seem perfectly happy and you can't go flying around the world when something doesn't work out for one person.

Okay Mani. Thanks.
Btw, I would - that flying. The sad thing of this case is that it literally didn't happen, while it was surely planned. It was even planned for a second time, or at least something of that order. Ask Paul for fun, what I wrote him after your last visit. And not because you complained (heck, you should have, am I right ?).
Anyway, it is good as it is as long as you have found some peace. If you only notice that this is not per se my own situation. That this is coincidentally related to that "shame that it did not happen" could be just a bit too sensitive for me. What you don't tell, you don't tell.
Mind you, you actually once again imply that someone should have come over. I am starting to think that someone may have missed an email (to read or to write).
I suggest that if we need more of this, someone starts writing an email instead of having it on a forum.

Thanks,
Peter

[CoenP]

Hi Peter,

Thanks for the additions!

let me push yours a little further:

There is the efficiency of the loudspeaker that tells us about the amount sound pressure we get from 1 watt of power and the sensitivity that tells us about the amount of sound pressure we get from 2,83V RMS (which is of course 1 watt @ 8 Ohms, apply the math!). They are related via the impedance.

The sensitivity tells us about how much voltage the amplifier must deliver to play at a certain loudness, the efficiency purely how electrical power translates into sound pressure power.

Simply put the efficiency does not take the impedance into account, but the sensitivity does. A 100dB/watt efficient loudspeaker can have an impedance of any ohm. I have Philips 9710 AM that are 800ohms rated impedance and about 100dB efficiency, contrary to Peter's 8 ohm horns (2,83 volt) you will need a truckload of voltage (28,3V) to get a watt into them.

It takes some effort to estimate the amount of SPLs in your listening chair. As old fashioned dual channel listeners we have actually two amplifiers and two loudspeakers generating a signal. This potentially adds 3dB to the maximum attainable sound pressure.

Yet our chairs and couches are some meters from the speakers, we are usually not at the specificatied 1 meter away from them. Depending on the radiation pattern (directivity versus frequency) the sound pressure lowers with increasing distance from the loudspeaker. As a rule we may assume that the radiated surface increases with distance and as such decrease between 3 and 6dB every doubling away. So if the output is at 1m 100dB it is at 2m: 97-94 dB and at 4m 95 -88dB.  This suggests that we need more than 120dB (minus 3 ....) at the loudspeakers to get 120dB at our chairs.

But the room is not an infinite space, that is waves reflect on all boundaries: the floor, ceiling, sidewalls, but also tables closets etc. Especially the side and behind walls are acoustically close to the loudspeaker and as such are the reflections are significant. Well that is for those frequencies that the loudspeaker has a wide dispersion. Anyway a lot of energy is confined in and and interacts with the room. Signals with low directivity (lower notes) interact the most. This accounts for extra decibels for many frequencies.

In the end I do not think we need 120dB+ capable loudspeakers and amplifiers in our rooms. My 103dB Altec VOTT was intended to operate with a 15 watt amplifier. Originally they were designed for intelligible sound in a 400 seat movie theatre. I already got loudness complaints with my 2x0,8watt tube amp so in practice the "120 dB calculations"  do not really make sense.
Unlike the image industry there are little generally accepted and implemented references for sound. If this were the case we would be able listen to realistic sound levels, at least how they were recorded or intended by the engineer. Imho the 120dB case (a full-out orchestra: Mahler/ R. Strauss) can only apply with such a reference. In all other cases we would have changed the volume (=power) with the crescendo to something we can bear in our rooms.

regards, Coen

[vrao]

It is my understanding that high powered amplifiers could not be "reliably" made back in the day. Therefore an elegant solution, hand in hand with the horns.

Amplifier (also the speaker) should have enough power reserve to handle transients ... if the distortion/clipping happens, then its almost always noticed, hence the "sound signature" discussion of the equipment ... Here its mostly the high efficiency crowd, and not much of an issue. but elsewhere its another story. For example my prior Omnis were 84 dB sensitive. I would play it at nominal 78-80 dB. I don't even want to extrapolate the power requirements for lets say 20 dB headroom, with room loading included. It could not handle more than 500W for more than 3sec. Something had to give, with that low-efficiency, heat I suppose ...

I will put this across, most tweeters are actually distorting at normal listening levels.

[acg]

Mani, here is a link to the Nelson Pass stuff you mentioned in your first post.  At least I think it is that to which you were referring.

vrao, as the resident expert, what do you make of Mr Pass' writing?  I would like to agree with him because I have skin in the game (am current building my SET amplifiers), but I have never heard anything as "real" as SET amps matched to appropriate speakers.

[briefremarks]

Adding one link to contribute to the discussion.  A good discussion (with tests) of the distortion behavior of chip amps

http://www.customanalogue.com/diytubegainclone/gainclonesound.htm

[PeterSt]

I only had time for 10 seconds to look at that discussion (really not more) but with a noise line at around -90dB, forget everyting (including the discussions I suppose - but again, I did not read anything).

We are looking at -120dB after a gain of 20 (via NOS1a with a noise line a bit better than -140dB).

Peter

[vrao]

Acg:

I had a response I was working on, and ran out of time, and lost it all being logged out

I don't have any more time

But all in all I agree with NP...

Best,
VJ

Edit: Amp/speaker distortions are like Hydra .... you enderstand one and conquer it, few more arise, that didn't didn't exist before .....
 

[acg]

Thanks VJ

[manisandher]

Mani, here is a link to the Nelson Pass stuff you mentioned in your first post.

Anthony, here's the correct link: https://passlabs.com/press/single-ended-class.

Many years ago, I owned a Pass Labs Aleph 4 amp - 100Wpc solid-state single-ended. It was a very smooth-sounding amp, but didn't have enough 'kick' with the Quads electrostatics that I was using at the time, for my liking. I remember when I sold it on eBay. The buyer came over with his girlfriend to collect it and obviously wanted to listen to it first. I put on a track with female vocals and I could see massive smiles immediately on both their faces as soon as the track started. He looked at me and asked me why I was selling such a great-sounding amp.

Back to NP's article... I wonder if his thoughts are only really valid when considering a truly mass-less speaker cone. And perhaps this is why PP amps just tend to sound so much more dynamic than SE amps? High efficiency horns certainly help...

Mani.

[acg]

Mani, here is a link to the Nelson Pass stuff you mentioned in your first post.

Anthony, here's the correct link: https://passlabs.com/press/single-ended-class.

Many years ago, I owned a Pass Labs Aleph 4 amp - 100Wpc solid-state single-ended. It was a very smooth-sounding amp, but didn't have enough 'kick' with the Quads electrostatics that I was using at the time, for my liking. I remember when I sold it on eBay. The buyer came over with his girlfriend to collect it and obviously wanted to listen to it first. I put on a track with female vocals and I could see massive smiles immediately on both their faces as soon as the track started. He looked at me and asked me why I was selling such a great-sounding amp.

Back to NP's article... I wonder if his thoughts are only really valid when considering a truly mass-less speaker cone. And perhaps this is why PP amps just tend to sound so much more dynamic than SE amps? High efficiency horns certainly help...

Mani.

Thanks for clarifying the link.

That bit of your quote I have put in bold I strongly disagree with...I do not think that dynamics or lack thereof are a particular characteristic of either topology (SE or PP)...it all comes down to implementation...but doesn't everything?

[manisandher]

Yeah, I probably should have added, "... in my experience, using the speakers I have to date."

Here's more from Nelson Pass (from Aleph 4 Manual):

"There has been a failure in the attempt to use specifications to characterize the subtleties of sonic performance.  Amplifiers with similar measurements are not equal, and products with higher power, wider bandwidth, and lower distortion do not necessarily sound better. Historically, that amplifier offering the most power, or the lowest IM distortion, or the lowest THD, or the highest slew rate, or the lowest noise, has not become a classic or even been more than a modest success.

For a long time there has been faith in the technical community that eventually some objective analysis would reconcile critical listener's subjective experience with laboratory measurement. Perhaps this will occur, but in the meantime, audiophiles largely reject bench specifications as an indicator of audio quality.  This is appropriate.  Appreciation of audio is a completely subjective human experience.  We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines.   Measurements can provide a measure of insight, but are no substitute for human judgment.

As in art, classic audio components are the results of individual efforts and reflect a coherent underlying philosophy.  They make a subjective and an objective statement of quality which is meant to be appreciated.  It is essential that the circuitry of an audio component reflects a philosophy which address the subjective nature of its performance first and foremost.

Lacking an ability to completely characterize performance in an objective manner, we should take a step back from the resulting waveform and take into account the process by which it has been achieved.  The history of what has been done to the music is important and must be considered a part of the result. Everything that has been done to the signal is embedded in it, however subtly.
Experience correlating what sounds good to knowledge of component design yields some general guidelines as to what will sound good and what will not:

1)  Simplicity and a minimum number of components is a key element, and is well reflected in the quality of tube designs.  The fewer pieces in series with the signal path, the better.  This often true even if adding just one more gain stage will improve the measured specs.

2)  The characteristic of gain devices and their specific use is important.  Individual variations in performance between like devices is important, as are differences in topological usage.  All signal bearing devices contribute to the degradation, but there are some different characteristics are worth attention.  Low order nonlinearities are largely additive in quality, bringing false warmth and coloration, while abrupt high order nonlinearities are additive and subtractive, adding harshness while losing information.

3)  Maximum intrinsic linearity is desired.  This is the performance of the gain stages before feedback is applied.  Experience suggests that feedback is a subtractive process; it removes information from the signal.  In many older designs, poor intrinsic linearity has been corrected out by large application of feedback, resulting in loss of warmth, space, and detail.

High idle current, or bias, is very desirable as a means of maximizing linearity, and gives an effect which is not only easily measured, but easily demonstrated:  Take a Class A or other high bias amplifier and compare the sound with full bias and with bias reduced.  (Bias adjustment is easily accomplished, as virtually every amplifier has a bias adjustment pot, but it should be done very carefully).  As an experiment it has the virtue of only changing the bias and the expectations of the experimenter.

As the bias is reduced the perception of stage depth and ambiance will generally decrease. This perception of depth is influenced by the raw quantity of bias current.  If you continue to increase the bias current far beyond the operating point, it appears that improvements are made with bias currents which are much greater than the signal level.  Typically the levels involved in most critical listening are only a few watts, but an amplifier biased for ten times that amount will generally sound better than one biased for the few watts.

For this reason, designs which operate in what has been referred to as "pure" Class A are preferred because their bias currents are much larger than the signal most of the time.  As mentioned, preamp gain stages and the front ends of power amplifiers are routinely single ended "pure" Class A, and because the signal levels are at small fractions of a watt, the efficiency of the circuit is not important.

4)  Given the assumption that every process that we perform on the signal will be heard, the finest amplifiers must employ those processes which are most natural.  There is one element in the chain which we cannot alter or improve upon, and that is the air.  Air defines sound, and serves as a natural benchmark."


Mani.

[vrao]

To modify and continue:

"Total system distortion" would be the more appropriate.

Either the "entire system" needs to be under one thought process that takes into account all possible details. Or there needs to be parameters that can be adjusted along the chain, to counteract distortions.

[Jack]

Mani
I presume someone is using the Orelo's....?
With presumably more success?
You must be gutted that the sound was not up to the looks.
Were your current speakers salvaged from the wreck of the Nautilus? Horns can be so beautifully quirky in appearance & for me, so far, sonically superior....
(Still Swingin') Jack

[manisandher]

Hi Jack, I'm waiting to hear back from the new owner of the Orelos - I really hope they're working well in his room. Initially yes, I was gutted that I never got them to work in my room. But I'm so content now with my Anima speakers, that that is no longer an issue. The amount of money I lost in selling the Orelos is still hard to stomach though (no different to any other piece of hifi bought from new for the full retail retail price, of course). Oh well, that's life - live and learn...

Mani.

[Robert]

Mani,
       Cars, boats and Hi-Fi are not investments, but if you have the money it doesn't matter.

A wealthy retired HiFi retailer in NZ bought a 1 of 20 only made F1 McLaren sports car new for 2 million(1994). I thought gosh at last a car that should maintain its value. The guy only drove it twice as we don't have good roads and he was afraid of other drivers.

He sold the car to an American collector 6 years later and got $800,000 dollars. I guess if he kept it for 30 years it may have gone up in value.

Hoping this will help with your grief Mani!!!

Robert

[manisandher]

On one of my recent work trips to Germany, I was talking to a guy there who was telling me of a certain word in German, "schadenfreude", that means taking pleasure out of other people's misfortunes. We don't seem to have an exactly equivalent word in English - the best Google translate can come up with is 'malicious joy', which, from what the guy was telling me, misses the point somewhat. In any event, I'd like to think I don't have much 'schadenfreude' inside me.

Edit: Actually, I think "gloat" is the closest we have.

Of course, if the guy in NZ had kept the F1 it'd be worth many, many millions now. It must be one of the most expensive cars in the world right now. (Perhaps Peter's got one covered up in his garage?) If the opportunity ever arose (haha), it'd be a tough choice between that and an Alfa 33 Stradale, which I consider simply the most beautiful car ever made.

Mani.