Testing a few amps

[manisandher]

I had a couple of friends over yesterday (what my wife refers to as my 'hifi geeks') and we went to work comparing a few amps driving my electrostatic speakers. Without going into details, we compared an OTL 300B SET (5W), a SS single-ended class-A (100W), a SS class-AB (200W) and a class-D (400W)*.

These guys have seriously high-end systems. And they were blown away by the... class-D amp!!!

BUT... I've heard many class-D amps, and can tell you that they are not all made equal. There is one make that stands head and shoulders above all the others I've heard. And that is Hypex, designed by Bruno Putzeys and made in Holland (does anyone get the feeling, like me, that the Dutch are taking over?).

The amp we heard was one that I put together using two Hypex UcD700HG modules with their recommended voltage regulators and massively over-specified linear PSs.

I just wanted to share this, as I believe you can now buy a serious power amplifier for very reasonable money.

Mani.

(* All power ratings into 8 Ohms.)

[PeterSt]

Somehow I have the feeling that you're leaving out something of the story. I mean, since the Hypexes are yours and they were catching dust in your garage, what is the real message ? hehe

Peter

[manisandher]

Haha,

The real message is that the Hypexes are no longer for sale... but the others may well be!!!

No, that really wasn't the point. I'm notoriously bad at selling gear - all that packaging up and shipping is just more hassle than it's worth. And as a result, I've got a whole basement full of stuff gathering dust. Hey Peter, we do have something in common after all

No, the point was that I really think these amps are good, and wanted to share this with others. Nothing more, nothing less.

Mani.

[Marcin_gps]

Very interesting. I considered Icepower amplifier from Polish manufacturer Audiomatus. A fellow at hi-fi forum says that Audiomatus humiliated his Bel Canto eVo 4 mk II monoblocks. Here's the review of those audiomatus - http://www.highfidelity.pl/artykuly/0603/audiomatus.html (the editor's reviews are now available on 6moons.)

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

[earflappin]

Mani, what is the nominal impedance and impedance curve of your electrostatics? 

[Telstar]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

No tripath chip is able to power his electrostatics.

[Telstar]

BUT... I've heard many class-D amps, and can tell you that they are not all made equal. There is one make that stands head and shoulders above all the others I've heard. And that is Hypex, designed by Bruno Putzeys and made in Holland (does anyone get the feeling, like me, that the Dutch are taking over?).

The amp we heard was one that I put together using two Hypex UcD700HG modules with their recommended voltage regulators and massively over-specified linear PSs.

Good to know. I'll use hypex modules for my subs

[manisandher]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

Hi Marcin,

No, I've never heard a Tripath, and as Telstar's pointed out, there'd probably be no point with the Quads. But I've owned ICE-powered amps before and actually still have a PS Audio somewhere - it's OK, but the Hypex UcDs are in another league altogether.

Mani.

[manisandher]

Mani, what is the nominal impedance and impedance curve of your electrostatics?

Hi earflappin,

You know, I shouldn't be talking to a 'sinner'. Now if you could find a way to get your MH working with XX, then all will be forgiven...

I can't find any impedance curves for the 2805s. One of the guys who was over at my place (very knowledgeable) doesn't believe they have the same sub-1ohm of earlier ESLs at high frequencies. Powerful as they are, I don't think the Hypex UcD700HG amps are very happy at sub-4ohm impedances.

Mani.

[manisandher]

Good to know. I'll use hypex modules for my subs

Before I got the Quads, I was multi-amping a pair of Wilson-Benesch Chimera speakers (yes, also gathering dust in my basement!) with a total of eight UcD700HG amps. Of course, you'd think that 700W into 4ohms for tweeter is total overkill. Yes, but boy did they sing with this sort of power on tap. In any event, the Hypex amps are mighty fine up top as well as down below.

Mani.

[Marcin_gps]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

No tripath chip is able to power his electrostatics.

Hmm, even Virtue Sensation? (65W per channel) I guess you know better, I haven't got any contact with electrostatics so far.
I wonder though, how come you prefer the old Pass integrated amp considering what you wrote about Hypex Just curious..

[manisandher]

The Pass amp was the '100W SS single-ended class-A amp' that I mentioned in the first post of this thread. It's not an integrated though - it's a 50Kg stereo power amp.

It's a laid back amp, and sounds very nice when matched with the right speakers. I've managed to get very good sound using it to drive a pair of Celestion SL600 speakers. But with the electrostatics, the Hypex is better. The reason why I'd never mentioned the Hypex before was simply because up until that point I'd never tried it with the Quads.

Incidentally, one of the guys who was over at my place has dropped me an email. He says about the Quad 2805 speakers, "Hi-Fi World's measurements show a 6ohm average with a low of 3.2 ohms and a high of 12 ohms."

Mani.

[Telstar]

Before I got the Quads, I was multi-amping a pair of Wilson-Benesch Chimera speakers (yes, also gathering dust in my basement!) with a total of eight UcD700HG amps. Of course, you'd think that 700W into 4ohms for tweeter is total overkill. Yes, but boy did they sing with this sort of power on tap. In any event, the Hypex amps are mighty fine up top as well as down below.

Mani.

Personally, I would never use a class-d or any amp with global feedback for the tweeters.
But I think the ucd2k are just what my subs will need

[Telstar]

Incidentally, one of the guys who was over at my place has dropped me an email. He says about the Quad 2805 speakers, "Hi-Fi World's measurements show a 6ohm average with a low of 3.2 ohms and a high of 12 ohms."

Mani.

I think that the hypex modules provide lots of current that the ESL likes. Some other current monster SS may likely provide an overall better sound but at a cost several times higher (also a faster amp than Pass designs is needed to keep up with the Quads). Something along the lines of Viola and Mark Levinson.

[pedal]

The first generation ICE power amplifiers from B&O are seriously flawed. They mute the micro dynamics and rob the sparkle and life out of the music. You get a lot of watt, but no soul. Kind of a “stupid blond”. They are not to consider as high end.

If you want to do something serious with Class D, then the first thing is to get rid of the integrated cheap switching power supply. They really suck.  Building a huge oversized linear PSU “by the book” is mandatory. (Because Class D is so efficient, the PSU still can be smaller/cheaper than with an A/AB/Tube amplifier). I have also heard that the Hypex modules are better sounding than ICE.

I believe in Manisandher observations. Class D has potential if done right. But remember that all Class D is like an open loop circuit. Noise can enter from anywhere and will be included in the music signal. The chassis, the interconnect cables, the mains cable, the loudspeaker cables, –all these works like an antenna for unwanted noise. So Class D will always be troublesome. And that’s why there must be a coil on the output loudspeaker terminal. The coil acts like a low pass filter preventing noise being picked up by the speaker cables and entered into the circuit. But a coil is a coil. It decreases bandwidth and it reduces the amplifiers performance with high frequency square tones. Especially with high-rez music, like SACD/Blu-Ray/DVD-A @ 24/192, I think you will hear the shortcomings of the limited bandwidth. In this regard, you might say that Class D is reducing what XX HighEnd software and (future) filter less DAC is trying to improve…

Also, there is so much global feedback in Class D. With traditional amplifier design, we have learn that the less feedback, the better sound. But with Class D it's "all feedback" as far as I have understood. I would guess this also puts its signature on the sound. But, I have not heard the Hypex modules, so it's only a speculation by me. But I have heard the B&O ICE modules in my system, and they are cr*p sounding in a highend perspective. (But OK for mid-fi/consumer sound systems).

[manisandher]

But with the electrostatics, the Hypex is better [than the Pass Aleph 4].

I'd like to retract this statement.

I didn't feel like working today and have spent the whole day reading (currently getting through 'Fooled by Randomness' by Nassim Taleb) and listening to music.

I've also been comparing amplifiers again. The main reason for this is that I've had a couple of offers for my Pass Aleph 4 power amp and X1 preamp (around a third of what I paid for them new 9-10 years ago). Before saying 'yes', I just wanted to make sure that I was doing the right thing. And boy am I glad I did! The Aleph 4 is MUCH better than the Hypex amp. The Hypex amp sounds ultra, ultra smooth... but pretty dead and boring in comparison to the Aleph. It also has much lower resolution - it sounds smeared in comparison. The Aleph is SO musical - it sings. Its top end is WAY more extended than the Hypex. But across the range, it's just better in every respect.

Indeed, I concure with everything that Pedal and Telstar have said - I'd now only recommend the Hypex modules for bass and not for full range duties.

I really don't know what happened when my friends were around a few weeks ago. We all agreed that the Hypex sounded better then. There must have been something seriously wrong with the way I set things up... that's all I can think of.

... a faster amp than Pass designs is needed to keep up with the Quads.

I’ve mentioned before that the Pass has a slew rate of 30 volts/microsecond – in Nelson Pass’s own words: “... which is about 30 times faster than the fastest signal you will ever see, and about 100 times faster than what you will be listening to.”

So how ‘fast’ is fast enough?

Mani.

[Telstar]

I’ve mentioned before that the Pass has a slew rate of 30 volts/microsecond – in Nelson Pass’s own words: “... which is about 30 times faster than the fastest signal you will ever see, and about 100 times faster than what you will be listening to.”

So how ‘fast’ is fast enough?

Mani.

I know Nelson's quote (it's also in a book that i have), but I think much more is needed, something like 1v/us per Watt.

And especially one thing: current slew rate, not voltage slew rate.
One day i'll find a mean to measure it

[PeterSt]

I didn't calculate it, but I'm sure Telstar is right although I again look at it from another angle. I think mr. Pass didn't incorporate the possible transients from digital, and then I mean *after* good filtering. This is ns level ...

Btw, I had over a fine engineer, who was the most sure nothing like a GainClone (which I use) could ever produce good sound. He tried in the past with many attempts, so he was the most sceptical I could have anything like good sound, let alone something coming close to "reality" - and which I dared promising him in advance;
First he had to withdraw the latter, but next he (thus !) couldn't find anything wrong with the GainClones. What in the world could he have done wrong at his attempts in the past ?

I only want to say : there is so much more involved. All has to match, and in order to get there you have to understand all elements and how they influence.
It can be done ...

Peter

[manisandher]

I’ll begin by apologising for this post from the outset – it’s probably of absolutely no interest to any of you...

Speed, speed, speed. This is what people seem to be saying really matters. OK, I’ll buy into this. So, I’ve been looking into an ultra-fast and reasonably powerful amplifier to drive my Quad electrostatics. ‘Spectral’ amplifiers seem an obvious choice, to try at least.

So, I called a Spectral dealer in the UK called Steven Harper (of ‘The Audio Consultants’) to have a chat. His first question was, “What are you using as a source?” This kind of surprised me because I would have thought that the obvious first question to ask when you’re considering an amplifier is, “What are your speakers?”... but there you go. I explained that I have a PC/DAC as my main source and before I could go on to give any details, he scowled at me. I then had a 30 minute lecture (really, a one-way lecture) on how a CD played back on a £20K Spectral or a £10K Nagra CD player (both of which he sells) will beat any other digital source. During these 30 minutes, I listened as politely as I could muster while he recounted all the occasions where he had demonstrated the superiority of these CD players to his customers over their “terrible-sounding USB DACs”, and where he also made some pretty dodgy statements about digital audio in general (he obviously didn’t know what ‘bit depth’ and ‘sample rate’ meant). I did actually agree with some of the points he made - he believed that the best sounding labels on CD are ECM and Reference Recordings – I think they sound great too.

So, 30 minutes into the ‘conversation’, once I could get a word in, I mentioned that my PC wasn’t actually connected to my DAC via USB. He was taken aback. “So how else can it be connected?” he asked. After I’d explained how my PC and DAC were connected, the ‘conversation’ then went on to why I would want to use a PC/DAC anyway, as opposed to a good CD player. I mentioned that one of the advantages is that I can play back hires material. As an example, I cited the Reference Recording 24/176.4 hires files. According to RR, these are direct copies of the digital masters which have been derived by digitising the analogue master tapes. But he believed that his CDs had a higher native resolution that my 24/176.4 files. His reasoning was that these hires files contain higher jitter than the CDs because jitter is introduced when files are downloaded from online (???). I mentioned that my files were not actually downloaded at all, but were copies of the digital masters put onto DVD-Rs and sent to me via the post (I don’t think he believed me). In a really condescending manner, he implied that I was mistaken if I thought that my PC/DAC combo playing any files could even come close to his Spectral CD player. At this point, I pretty much had enough and let him know that actually my DAC was an ADC also, and actually the very machine that was used to create the RR CDs that he thinks sound so wonderful. Oh and that the £20K Spectral CD player’s output stage is based on the DAC section of my machine.

Anyway, it was 45 minutes into our ‘conversation’ by now and I’d had enough. I had called as a genuine buyer for an amp. True, I wasn’t going to buy the top-end Spectral amp, but the one that I was considering was still £10K! And rather than trying to understand what I was trying to achieve, he went off lecturing me about how cr*p computer audio is – something that he patently knows very little about. So, I said that I’d buy the Spectral amp from someone else and I put the phone down on him...

What a strange interaction.

Mani.

[Per]

I’ll begin by apologising for this post from the outset – it’s probably of absolutely no interest to any of you...

On the contrary, Mani. I always enjoy reading your posts and this too was a VERY interesting read - to me at least.

Thanks for sharing. I fully understand your frustration.

Per

[Telstar]

I enjoy them too. There is just so much of bulls*t in the audio market today, that along with crazy pricetags.

[Gerard]

I put the phone down on him...

 

Ps:Very nice story! 

[DannyD]

Mani,

After A/B’ing my current model Spectral 4000 CD player to several generations of XXHE (and Berkeley Alpha) over more than a year, I finally sold the Spectral.  I felt that Peter’s good work finally pretty much caught up to the Spectral, and by getting rid of the Spectral I was also able to get rid of c-j pre-amp by which I improved the sound considerably more than the Spectral ever did.   Granted, I don’t have Spectral amps but current model VTL 450 tube monoblocks which are undoubtedly a lot slower but still quite nice in their own right.  As you rightly pointed out to the dimwitted Spectral rep, high rez material is a completely different ball game.  Spectral is known to very arrogant.  Good for you hanging up on them!

[PeterSt]

I like long-threaded posts with ambience and the real story in it.
Ah, you know.

[Telstar]

Granted, I don’t have Spectral amps but current model VTL 450 tube monoblocks which are undoubtedly a lot slower but still quite nice in their own right. 

Don't be so sure of the slowness of tubes.

[Calibrator]

... while he recounted all the occasions where he had demonstrated the superiority of these CD players to his customers over their “terrible-sounding USB DACs”, and where he also made some pretty dodgy statements about digital audio in general ...

Hi Mani,

it's reassuring to read that dickheaditis (tm) is not confined to the southern oceans and has proliferated worldwide .. haha. Seems like that company needs to change their name to "The Audio Insulters". Your patience exceeds mine by a long margin, as I would have hung up after a couple of minutes. I enjoyed the read

Cheers,

Russ 

[manisandher]

For anyone who's interested, I've ordered a 'Sanders Sound Systems' Magtech amplifier: http://www.sanderssoundsystems.com/products/amplifiers/magtech-amp. I think this should be a pretty good substitute for a Spectral amp. And you know the great thing? I don't have to deal with any hifi dealers or distributors. Joy!

Mani.

[christoffe]

For anyone who's interested, I've ordered ................. .

Hi Mani,

highend is a long journey and it will never end.

If you have a chance you should listen to a Dartzeel NHB-108B (www.dartzeel.com). This is one of the best amps in musicality terms and can drive your speakers easily.


Joachim

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Windows VISTA SP2> XXHE 09z-2 - Adaptive mode -  Q1/2/3/4/5 = 1/0/0/0/0 / No Invert / Playerprio = Low / ThreadPrio = RealTime / Scheme = 3 @ UnAttended / Arc Prediction * > Acer , Intel i750>|- Weiss Minerva -|- Dartzeel NHB-108B > speakers: Anat Referenz II Studio>

[PeterSt]

Looks great and fresh. But maybe it's a current (driven) amp ? I'm not sure how that would work out with "regulators", but it could be something like "the current is not derouted but the voltage is".

I would look for the most not-obvious anomalies. Not that I can think of any !
Specs sure look good to me ...

Keep us informed !
Peter

[Telstar]

For anyone who's interested, I've ordered a 'Sanders Sound Systems' Magtech amplifier: http://www.sanderssoundsystems.com/products/amplifiers/magtech-amp. I think this should be a pretty good substitute for a Spectral amp. And you know the great thing? I don't have to deal with any hifi dealers or distributors. Joy!

Mani.

That should be fast
Let us know how it sounds.

[manisandher]

highend is a long journey and it will never end.

I wouldn't mind if I thought I was actually moving forward, rather than going around in circles all the time. I mean, am I really deriving more pleasure from my music today than I did say 20 years ago? I'm not sure that I am. Of course, a lot of this has to do with what's going on in our own heads... Maybe I need to start taking some 'substances' rather than getting new kit... it'd probably work out a lot cheaper!

Back OT, I really hope I've found a good amp with which to drive my electrostatics. If not, I will certainly look into the Dartzeel NHB-108B. Another amp that I have my eyes on (but can't really afford, unless I sell my car, my wife's jewellery, and hell, probably my wife as well) is the Berning Quadrature Z. If it's a high-powered version of my Berning Siegfried 300B, it should be very good indeed.

But I'd rather not spend too much money on an amp right now beacuse I have a feeling that ultimately, I'll end up with low-powered amps driving ultra-high efficiency speakers with active line-level crossovers.

We'll see...

Mani.

[Telstar]

But I'd rather not spend too much money on an amp right now beacuse I have a feeling that ultimately, I'll end up with low-powered amps driving ultra-high efficiency speakers with active line-level crossovers.

[christoffe]

highend is a long journey and it will never end.

But I'd rather not spend too much money on an amp right now beacuse I have a feeling that ultimately, I'll end up with low-powered amps driving ultra-high efficiency speakers with active line-level crossovers.

Hi Mani,

I do believe that there is a false interpretation of my post.
I recommended "to listen" to a Dartzeel amp and not to buy one. Tastes are different.
I buy most of the audio equipment second hand only. This is a reason that I did not have to sell my wife and the life insurance until now (maybe in the future).
The prices of audio equip. are not calculated on earth nowadays. You see it on the price tag of the Berning Quadrature Z.
The cheapest and major improvement of the SQ is an investment in the acoustic of the listening room. (the priorities are: acoustic first, acoustic second, speaker positioning third)


You wrote on July 28th, that speed is essential, and the Dartzeel (second hand: EUROS 7.000,00 - and I'm driving now a 6 year old Polo) is the fastest amp I ever listened to, and the amp has ULTRA strong 100watts/8 Ohms down to 1,6 Ohms.
Ken Kessler was driving the Quad ESL 2905 with a McIntosh 2102 / (http://www.quad-hifi.co.uk/downloads/HFN%20ESL%20review%2006.pdf)

We are eager waiting for your comments  / praise of your new Magtech Amplifier (the power of this amp is unbelievable, amazing).

kind regards

Joachim

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Windows VISTA SP2> XXHE 09z-2 - Adaptive mode -  Q1/2/3/4/5 = 1/0/0/0/0 / No Invert / Playerprio = Low / ThreadPrio = RealTime / Scheme = 3 @ UnAttended / Arc Prediction * > Acer , Intel i750>|- Weiss Minerva -|- Dartzeel NHB-108B > speakers: Anat Referenz II Studio>

[earflappin]

I owned the darTZeel amp and pre-amp for awhile.  Great products and fantastic customer support. 

I've also heard the best Boulder, Spectral, Halcro and Pass Labs SS amps in my system and a very special custom made hybrid (tube gain / SS output) amp.  IMVHO, the Atma-Sphere OTL (output transformerless) amps are a very audible cut above all of these amplifiers.  However, to use the lower powered S30 and M60 Atma-Sphere's you really need a high efficiency, 8 ohm nominal speaker with flattish impedance curve.  Personally, after having owned and auditioned many speakers, I  think high efficiency is the way to go anyway if your goal is to as closely reproduce the sound of live music as possible. 

So, if you have speakers which fit the profile I summarized above I would strongly recommend you audition the Atma-Sphere S30 (single chassis stereo amp with 30 watts Class A power) or the M60's (monoblocks with 60 watts Class A power).  They are reasonably priced used (at least here in the USA) and make every other amp I've listened to sound colored.  They do run hot, however.

[manisandher]

Yes, I've heard good things about the Atma-Sphere amps (OTLs, like the Bernings). I can imagine they sound great driving the Geddes Speakers...

They do run hot, however.

And that's the problem - I'd really like an amp that runs cool. This is the main reason I let the Pass Aleph 4 go - beautifully natural sound, but way too hot. Now, the Sanders Magtech amp runs totally cool. If it sounds half as good as its specs look on paper, I should be happy. I'll know for sure tomorrow...

Mani.

[manisandher]

If it sounds half as good as its specs look on paper, I should be happy.

Let's just say I'm NOT happy... I'm close on ecstatic!

Using XX's vol control (with QAP) and feeding my DAC (with massively fast output stage) straight into the Magtech amp, my Quads have suddenly come alive and are dynamic as hell... and yet totally natural-sounding. An acoustic guitar (I have a couple) really sounds like one... finally. You wouldn't believe this - I hardly can.

Roger Sanders gives a 30-day money-back guarantee, paying for shipping both ways if necessary. But let me tell you, he ain't getting this amp back... This was €3500 very well spent.

I'd like to thank Peter and Telstar for pointing me in the right direction - it is because of my search for speed that I stumbled upon this amp.

Mani.

[PeterSt]

Hey hey, good !!
And your Quads should be fast, out of anything ...

But please be VERY careful without the preamps. Your Quads me not survive it when something goes wrong. Actually, I think they just won't.
Only do this when you are very very sure all is right on the playback side (that would be me) and for the material you use. And, when there's a new version, thouroughly test all your material and "stuff" (like VolUp, Next) again. Maybe switch Off "Allow Format Changes" to avoid infite combinations. HDCD is part of it.

Good you are happy now !!
Peter

[Gerard]

But please be VERY careful without the preamps. Your Quads me not survive it when something goes wrong. Actually, I think they just won't.
Only do this when you are very very sure all is right on the playback side (that would be me) and for the material you use. And, when there's a new version, thouroughly test all your material and "stuff" (like VolUp, Next) again. Maybe switch Off "Allow Format Changes" to avoid infite combinations. HDCD is part of it.
Peter

Does this count for my ESl elements aswell Peter 

I was planning to do when NOS1 is ready.

 

[PeterSt]

Generally this counts for everything which isn't ready for a burst of the highest transients (static) in the more middle region. I count electrostats amongst that. A ribbon would be prone to break too, but it depends on the frequency they deal with. So a tweeter ? I don't think so.

But actually no one should have this through his/her speakers.

Maybe I overdo things with these warnings, but I just don't want to be responseable. I think I didn't encounter such a blast for over 18 months now, but we all know that some of you had it sometimes. If I only could guarantee it not happening ...

Peter

[manisandher]

Thanks for the warning.

For now, 0.9z-2 seems pretty stable to me. But I tend to load a whole album, set the correct volume at the outset and listen all the way through. Not a lot to go wrong really. But I will use a preamp before trying any new versions of XX.

Mani.

[manisandher]

Once I get my new 'white sheep' NOS1 for my office system, I think I will want to use my Sanders Magtech amp in my office driving my 'small' Quad 2805 speakers. I will then need a new amp in my main room with which to drive my 'big' Quad 2905 speakers. The obvious answer would be to order another Magtech amp. But I have one here already, and so it may be a good opportunity to test a few other amps against it before I make a decision.

I've recently been drawn to Soulution amplifiers - really too expensive for me, but still, I'm interested in learning more about them. I've attached the specs for their stereo power amp, the 710. They quote the slew rate as '330 nano seconds'. This means nothing to me... could someone help me out with understanding this figure (I'm sure it's very simple).

Does anyone have any experience with Soulution amps?

Mani.

[manisandher]

Once I get my new 'white sheep' NOS1 for my office system, I think I will want to use my Sanders Magtech amp in my office driving my 'small' Quad 2805 speakers.

I've currently got my 'Subaru' NOS1 in my office and have just replaced my old Rotel RHB-10 amp with the Magtech. I'm sure the Rotel was very good in its day, but let's just say that I'll definitely want the Magtech in my office when the new NOS1 arrives. I've said it before when I first bought the Magtech, the Quads just come alive with it. They now have real bass. And the sound is super, super smooth.

I'm happy to try a few others amps, but I really can't imagine any bettering the Sanders Magtech with either of my Quad electrostatics.

Mani.

[christoffe]

They quote the slew rate as '330 nano seconds'. This means nothing to me... could someone help me out with understanding this figure (I'm sure it's very simple).

http://en.wikipedia.org/wiki/Slew_rate

[manisandher]

"The unit of slew rate is V/µs."

Hence my confusion...

Mani.

[PeterSt]

"The unit of slew rate is V/µs."

Think about rise time. Not in general (like how fast to reach your 43.834Vp), but how steep the upgoing (+ down) going line of the square can be. The steeper the better. The more V per us the steeper it will be (per time unit on the x-axis).

That in your case this is given in ns should harm you. That's just a matter of shifting some commas.

[arvind]

Hi Mani,

I have heard the Soulution amps, though not owned them, however recently there was an amp shoot out at Ascendo. The 3 amps used in the shoot out were the Bolder, CAT & Soulution. Mr Jurgen Scheuring of Ascendo e mailed me that the CAT won hands down.

Arvind

[Suteetat]

For what it's worth, I never like Boulder house sound at all. Very detail, but rather thin, brittle sounding, too cool for me. It just does not sound natural to my ear. I heard Soulution, both monoblocks and stereo with Magico Q5 and I like them better than Boulder but still not quite my cup of tea. I run more toward high power tube or solid state with tubey sound, I suppose.

[manisandher]

Thanks Arvind, thanks Suteetat.

You know, I think I'm just going to order another Magtech amp from Roger Sanders. It sounds really nice in my office system right now. My wife popped her head in this morning as I was playing some Satie and said, "That sounds beautiful." I asked whether she meant the music or the sound, and she said that she meant the sound.

I'm not saying that the Magtech is the best amp on the planet, although it may well be for electrostatic speakers, which is Roger Sanders's expertise. If this system (NOS1, Magtech, Quad 2805) were the last one I ever had, I really think I'd be happy with it.

Mani.

[Flecko]

Hi Mani,
I am looking for a new amp too and Magtech seems to fit my "design goals". At the moment I use a 80Wpc Class A fully balanced transistor amp. It has to drive "normal" but low efficency two way speakers. Hence, there is the need of more power. It sounds good to my ears but I think there should be more bass control and a cleaner/faster representation. It sounds a little softened. I have looked at the marked and there are interesting amps from ML, Krell, MBL and so on, that would fit. But they are simply not affordable. The Magtech have nearly perfect specs, even better than the previously mentioned. High power, High damping, very fast and runs cool! Exactly what I was looking for. The price for the Magtech also seems absolutely reasonable.
Do you know if the Magtech is a real balanced design?
Are there any new candidates on your list?
Are you still happy with this amp?
You did not mention explicitly the differences to the Pass Aleph, was the Magtech so much better?
Thank you!

[manisandher]

Hi Flecko, in answer to your Qs:

Are there any new candidates on your list?

I haven't really looked into changing any hardware for a while now. I still love the idea of listening to some Swiss amps though - FM Acoustics, Soulution and Dartzeel. But with the prices that these command, it would be just listening and not buying I think.

Are you still happy with this amp?

Yes, I still very much like the Sanders Magtech amp. It is the smoothest transistor amp I've ever heard and, as I've alluded to before, just works so nicely with the Quad electrostatics. I strongly suspect it would work well with other speaker types too.

You did not mention explicitly the differences to the Pass Aleph, was the Magtech so much better?

I actually never managed to compare them against each other - I sold the Aleph4 a few days before the Magtech arrived. But if I could have only kept one, it would have been the Magtech. The Aleph4 was such an interesting design (100W transistor single-ended class A) and sounded really, really 'nice'. But it was just too much of a heat-generator for me to be using as my main amp day-in, day-out.

In summary, I'm very, very happy with the Magtech.

HTH.

Mani.

EDIT:

Sorry, I forgot one of your Qs:

Do you know if the Magtech is a real balanced design?

You may have to contact Roger Sanders for the official answer, but I don't think it is. I say this because Roger recommends using the single-ended inputs to the amp and not the balanced inputs. If it were a true balanced design, I suspect this recommendation would be reversed. However, in my system, the amp is dead quiet and sounds wonderful via its single-ended inputs.

[Flecko]

Thank you mani for your reply. I guess too, it might be no real balanced design. I contacted Mr. Sanders and asked to be sure. I will report back.

If not, I have an eye on the ML 432. Used it is affordable and it seems to be a well made amp. The 434 and 436 model is even better, if there would be a good offer. But other suggestions are welcome!

PS:
If it doesn't bother you not having a balanced amp, the german company AudioNet also has interesting amps with very good reputation.