Serious Question: How can DAC's have a SOUND SIGNATURE if they measure as transparent? Are that many confused?

[pma]

So as a designer what aspect do you pay attention to in order to create spaciousness in your amps?

Pass has said negative phase 2nd harmonic distortion enhances space at low levels. Is that what you have in mind.

Space is “enhanced” by some added noise and modulated noise. You need to make it adequately bad to get those audiophile attributes .

 

[Roland]

Testing dacs results in some measurements which can be ranked, but the link to the sound that comes out has not been established. The presumption is that two dacs measuring the same will sound identical, but this hasn’t been tested or proven.

 

[Blumlein 88]

Here is a stereophile graph of a 20 watt rated Lamm amp at 1 khz vs power output. That sort of rising distortion was intentional.

 

[HarmonicTHD]

Testing dacs results in some measurements which can be ranked, but the link to the sound that comes out has not been established. The presumption is that two dacs measuring the same will sound identical, but this hasn’t been tested or proven.

And neither has the opposite. Now what?

 

[SIY]

Of course. You have to know what creates spaciousness to understand how it works. Nelson Pass has written on this topic but I'm assuming his works are not considered 'citations'. I suspect this is something designers know and haven't bothered to get some sort of independent testing done. To us its just engineering.

I'll bite. At what level would this be perceptible in any way?

 

[Blumlein 88]

Also, with levels of 2nd and 3rd harmonics of something like the Lamm they swamp any harmonics in a clean SS amp. Which is why if you fed such an amp into a powerful SS amp you get the Lamm sound. A more cost effective design would create the Lamm output say for headphone levels and allow use of it as a preamp for SS power amps. Or alternatively a soft ware plug in.

@pkane could you create this profile in your Distort software? One that does vary the distortion at various output levels. I think you indicated you had done such a thing or similar, but had not released it to anyone else.

 

[pma]

Here is a stereophile graph of a 20 watt rated Lamm amp at 1 khz vs power output. That sort of rising distortion was intentional.

View attachment 261372

I have personal experience with some of those cult amplifiers - Pass Aleph 3, Ayre V3, not speakIng about Pass Zen - which is rather a toy and is really horrible. I have to say I have never found Aleph or Ayre to give some great spaciousness. I have also built a copy of Ayre V3 and it was one of the worst amps I ever had here. I should add that I subjectively evaluate amplifiers by listening to classical music, large philharmonic orchestra. I do not believe in any magic of added H2 or H3 at all.

 

[atmasphere]

So as a designer what aspect do you pay attention to in order to create spaciousness in your amps?

Pass has said negative phase 2nd harmonic distortion enhances space at low levels. Is that what you have in mind.

The deisgner of LAMM amps has a similar idea. That 2nd and 3rd harmonic distortion should rise more or less linearly with power and be the same across the audible band in order to get space and dynamics and a non-sterile sound.

Correct. And similarly, the phase of the 3rd harmonic can affect what is perceived as 'impact'. More impact being a positive phase. You can see how this affects the waveform easily enough through superposition.
As a designer while I'm aware of these things, traditionally (since for the last 50 years or so my designs have been triode OTLs) I've been more concerned about linearity and bandwidth. The ear uses phase relationships as part of its mechanism to locate sounds in space. Since our OTLs are zero feedback they could not rely on phase correction to get that bit right, so we went for wide bandwidth which is easy to do with an OTL.
Since our OTLs are fully differential and balanced, naturally this meant that the 3rd would be the dominant harmonic. So I've always aimed to get the most symmetrical clipping out of the amp as this minimizes distortion. Its possible to 'tune' the circuit a bit in this regard by adjusting the operating point of the differential amplifiers so I took to minimizing the distortion on an empirical basis with an analyzer after doing the math to arrive at initial values in the circuit. That operating point usually turned out to be very near the maximum gain available from the circuit, suggesting maximum differential effect. To that end I've found that in any amplifier using differential amplifiers, performance is left on the table if the CCS doesn't employ at least 2 stages to regulate current. Of course in solid state amplifiers using differential amplifiers, you have a different problem that usually prevents the differential amplifiers from using all the differential effect available so gain is often degenerated. You don't run into that with tube circuits.
I've always felt that rising distortion with frequency is a bad thing. Our OTLs don't do that. When I saw that a class D amp doesn't have to do that either (usually this means its of the self-oscillating variety) then we started developing our own class D circuit.

 

[Blumlein 88]

I have personal experience with some of those cult amplifiers - Pass Aleph 3, Ayre V3, not speakIng about Pass Zen - which is rather a toy and is really horrible. I have to say I have never found Aleph or Ayre to give some great spaciousness. I have also built a copy of Ayre V3 and it was one of the worst amps I ever had here. I should add that I subjectively evaluate amplifiers by listening to classical music, large philharmonic orchestra. I do not believe in any magic of added H2 or H3 at all.

I owned a Pass Aleph 0 way back when it was fairly new. I didn't find it to do 3D space or dynamics like triode amps. It could sound good if you were careful feeding it. It didn't like reactive loads unless they were rather high impedance. It worked surprisingly well on Quads. On Thiels it was a hopelessly over-burdened amp.

 

[Geert]

Pass has said negative phase 2nd harmonic distortion enhances space at low levels. Is that what you have in mind. The designer of LAMM amps(Vladimir Lamm) has a similar idea. That 2nd and 3rd harmonic distortion should rise more or less linearly with power and be the same across the audible band at a given power level in order to get space and dynamics and a non-sterile sound.

If this is how amplifiers are being 'tuned' (and I recall the Pass statement) then the argument that "all competent amplifiers, played at the same volume level in the same equipment/room setting, should sound identical" needs some refinement. Or we conclude that all amplifiers showing audible distortion are incompetent, which is a bit dubious if the distortion behaviour is designed deliberately.

 

[Blumlein 88]

If this is how amplifiers are being 'tuned' (and I recall the Pass statement) then the argument that "all competent amplifiers, played at the same volume level in the same equipment/room setting, should sound identical" needs some refinement. Or we conclude that all amplifiers showing audible distortion are incompetent, which is a bit dubious if the distortion behaviour is designed deliberately.

No it actually needs no refinement. You have to keep in mind preference and fidelity are not the same thing. Perhaps 90% of the world would prefer an amp with the Lamm distortion profile. Those amps are still of lower fidelity and are preferred because of a preferred coloration. I'd venture feeding the output of Lamm amps into a quality class D amp will give you the same sound as a Lamm amp.

Now a Lamm sound profile may not be incompetent, it is of lower fidelity, too low to be transparent and on purpose. So it is tuned, or has a boutique sound. It isn't transparent.

Whether the Lamm amp is truly discernible in general and preferable in general has not really been determined in a rigorous manner.

 

[Geert]

No it actually needs no refinement. You have to keep in mind preference and fidelity are not the same thing. Perhaps 90% of the world would prefer an amp with the Lamm distortion profile.

That's my point exactly. If you take that stance then you say all colouration is bad, while 90% wouldn't agree because they actually prefer it and the designer did a very good job catering for that. A lot of people would call that a competent design. Competent is a term that's to subjective.

Now whether the Lamm amp is truly discernible in general and preferable in general has not really been determined in a rigorous manner.

Indeed, that's why included the conditional statement. A while back I review the distortion behaviour of a lot of amp's measured by Stereophile.com and a lot of the typical audiophile brands like Pass and Gryphon have that rising distortion with increasing power profile, while HiFi brands like Cambridge Audio and Rotel have decreasing distortion with increasing power (and lower distortion in general). So if designers themselves claim this is deliberate there might be some truth in it.

 

[SIY]

If this is how amplifiers are being 'tuned' (and I recall the Pass statement) then the argument that "all competent amplifiers, played at the same volume level in the same equipment/room setting, should sound identical" needs some refinement. Or we conclude that all amplifiers showing audible distortion are incompetent, which is a bit dubious if the distortion behaviour is designed deliberately.

Or we conclude that the advertising claims and the "story" aren't backed up by reality. We're just not that sensitive to realistic distortion, so any of these claims for equipment need actual listening tests to show that they're anything but marketing.

 

[Mr. Widget]

Speaking of Pass Labs, here is John Atkinson's measurement of the XA25. Doesn't look too "Audiophile" for a 25wpc rating.

 

[Mr. Widget]

Or we conclude that the advertising claims and the "story" aren't backed up by reality. We're just not that sensitive to realistic distortion, so any of these claims for equipment need actual listening tests to show that they're anything but marketing.

+1

 

[Blumlein 88]

Cary single ended 300sei amp as measured by Stereophile.

CAD single ended 805RS

VTL large triode amp in push-pull.

 

[pkane]

Cary single ended 300sei amp as measured by Stereophile.
View attachment 261387

CAD single ended 805RS

View attachment 261388

VTL large triode amp in push-pull.
View attachment 261389

My amp, my measurement Pass Aleph 1.2:

 

[Geert]

Or we conclude that the advertising claims and the "story" aren't backed up by reality. We're just not that sensitive to realistic distortion, so any of these claims for equipment need actual listening tests to show that they're anything but marketing.

Yes, but take the Pass Labs INT60 for example. 1kHz 2nd and 3th harmonic at about -65dB, but THD rising a lot with frequency and rising with power. Conclusion?

 

[pma]

Cary single ended 300sei amp as measured by Stereophile

Better to show frequency response modulation by speaker complex impedance with this Cary SE nonsense.

 

[SIY]

Yes, but take the Pass Labs INT60 for example. 1kHz 2nd and 3th harmonic at about -65dB, but THD rising a lot with frequency and rising with power. Conclusion?

Conclusion: Any claims about its "sound" are worthless without some actual listening test data.