C'mon Peter, the post is not ridiculous at all, and you know it.  Last time Rob sent his dac across for upgrade it returned with the power transformers banging around loose inside the dac case.  Not your fault for sure but instead of going through the insurance rubbish it was me that repaired it.  Those two transformers are still only attached to the frame where I used epoxy to repair the broken weld, so I can for sure understand why Rob is reluctant to send his dac back for more of the same postal treatment...that joint will most likely break again in transit and the transformers will go banging into the power supplies.



Peter, at the cost of freight for the NOS1a from here to there and back again, those prices on the front page are closer to what we will be paying.  My NOS1 is coming to you regardless, but the "I can't be bothered claiming back EU55 so you'll have to pay it" attitude is a bit rich on top of EU400-500 freight for an EU580 upgrade.  Plus you have not responded to my email as to whether we can claim the tax back from our end.

Anyway, as I have just reminded you Rob is reluctant to send back his DAC.  Even small overseas audio companies make arrangements for local techs in Australia to perform the upgrades/repairs on their behalf.  That is what Rob is hoping for. 

Written in the best spirit as the sandwich between the rock and the hard place.

Regards,

Anthony

The difference could be in the Tascam unit as well...but I prefer the original CD rip.

So, I have listened.

The original CD Rip is clearly the best sounding here, reasonably closely followed by the third through the Mach II where there is some loss of clarity and perhaps a touch of dynamics.  The second file through the Microrendu is flat, thick and unresolved.  The transients are flattened, the soundstage is less deep and it is what I would call a large departure from the CD rip. 

Most notable is the piano rendition of the Microrendu: the touch of the hammer is muted and dull compared to the other two versions, and the notes are quickly truncated and fail to hang due to the lower resolution and smearing of other instruments and notes.

Saying that, I don't think the Mach II is perfect either, but it is much, much closer to the original CD rip, and remember that I am not playing back using a Mach II.

I've been asleep.  Just downloaded the new files and started the system, so I will play one album for warmup and then get into the test.

Hi Mani,

For what it is worth given the conversation that has followed since I downloaded and listened to those three files, I can certainly hear what yourself and Peter are talking about.  The latter two files are quite different dynamically to the original file, and second in particular is very flat and fuzzy, the kind of fuzzy that I would expect from a cheap dac.  Anyway, the conversation in this thread has moved on but I am still interested to see where this all leads.

Cheers,

Anthony

 

No problem with HT disabled.

Hi Robert,

I've just built my new AudioPC and expanded the RAM-OS's to about 25GB and just started playing with 14393.  It sounds different to 10586 for sure, but I am not yet convinced it is entirely for the better.  Time will tell.

Anthony

Hi Peter,

A while back I had a problem playing FLACs (but not WAVs)...

http://www.phasure.com/index.php?topic=2895.0



...if I remember correctly this was because I had 16 cores and XXHE supported 12 (at that time).  You did something to XXHE and the problem went away.

As you know I now have my new AudioPC up and running with a 20 core E5-2698 V4 hyperthreaded to 40 cores.  I am getting the same problems as I had in the above thread when playing FLAC files, so it sounds like this is the same issue, I have 40 cores and XXHE supports fewer than that.

Anyway, WAV's play well and the sound is pretty decent too, so this topic is just a reminder to please enable more cores to the next iteration of XXHE so I can play my FLAC albums.

Regards,

Anthony 

I have had this issue, and still have it in fact.  I just assumed it was a W10 issue.  It seems to happen less often to me when the RAM-OS disk is NOT ejected, but that could be coincidence.

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'.

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.

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


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

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.

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