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

[fpitas]

If I was designing a super amp using compound semiconductors, I think I'd try silicon carbide. Silicon carbide devices have become reasonably common for high performance power switching.

 

[SIY]

Thor, do you by chance know any audio equipment makers using GAN? I'm not up on it enough to know any companies using this.

I’ve reviewed several amplifiers using GaN in AudioXpress. Orchard participates here.

 

[Spkrdctr]

The burden of proof is the other way around. The null hypothesis is that there is no difference. Insisting on "proof" of a lack of difference is doubly poor thinking. We measure things that are known, scientifically, to be audible (and to much greater sensitivity than even the exceptional human ear). If you assert they sound different, and hope to advertise, sell, or recommend equipment based on that idea, you need to show it.

Fortunately, there have been lots of controlled trials that are consistent with this null hypothesis, and providing zero evidence of an audible difference.

Great post. To put it in my "man on the street" terms. Any idiot can make up ideas and present them as facts. It takes the listener ten times the effort to disprove the idiots ideas. But, when you are done, the idiot refuses to believe the science and says you and your facts are just wrong. No proof they are wrong, just the idiot not agreeing with your two hour explanation using science and prior testing data. It all then comes down to the old but 100% accurate Biblical statement "Don't cast your pearls before Swine". Lots of Swine visit ASR and then get beaten down and leave. The fun for ASR members is giving out the beat down. But, the swine ask for it when they try to present made up opinions as facts. Oh well, the circle of life continues.

 

[Spkrdctr]

I’ve reviewed several amplifiers using GaN in AudioXpress. Orchard participates here.

SIY, thanks for your lightning fast response! I will check out AudioXpress. The wave of the future is happening now.

 

[pma]

Thor, do you by chance know any audio equipment makers using GAN? I'm not up on it enough to know any companies using this.

I think in this:

 

[atmasphere]

With a "500W" amp we have more headroom, clipping should normally not happen, so we can relax requirements.

In a self oscillating amplifier, the issue is finding one oscillation solution during overload recovery.

So, change the devices? After all we are designers here. GAN is quite interesting.

It is. The issue you run into with them is that they won't turn off when told to, without a bit of a kick. That is provided by the output filter choke. Were this not the issue, the deadtime could be quite a bit less than you see in GaNFET amps right now.

The HF side of SET is generally not a problem. Winding transformers with enough sections to have ~ 100kHz -3dB is not in itself difficult.

If at the power levels of the Lamm, getting power response that high is not trivial. If the amp really did have that kind of HF bandwidth then its distortion is likely higher than suggested by Vlad... This based on my surmise of why it sounded the way it did, but I really didn't care why enough to put it through the full barrage to find out. All that was important there was that the amp didn't have to be shipped out of state so the customer was happy.

 

[Thorsten Loesch]

Fortunately, there have been lots of controlled trials that are consistent with this null hypothesis,

There have been lot's of Audio ABX tests that are consistent with the null hypothesis because of statistical and procedural features that promote such results dramatically over correctly rejecting the null hypothesis in the presence of modest and small audible differences. And that is only unfortunate if you prefer comforting lies (everything sounds the same) to the unpleasant truth.

Thor

 

[Thorsten Loesch]

Thor, do you by chance know any audio equipment makers using GAN? I'm not up on it enough to know any companies using this.

I am not really up to speed. I know some people I occasionally chat to use GAN and I have been looking at a lot at the use of GAN in power supplies and in Motor Controllers.

As said, there is no real difference between a step down DC-DC converter and a Class D Amplifier.

Thor

 

[FlyingFreak]

This is a class of amp thread now? What is going on? Have mods learn to consider threads with such a name 'trash thread' and avoid them while letting them run?

 

[fpitas]

As said, there is no real difference between a step down DC-DC converter and a Class D Amplifier.

Thor

Well, sort of. And there's no real difference between an AB amp and a linear regulator. I'm not sure any of that tells us much.

 

[fpitas]

This is a class of amp thread now? What is going on? Have mods learn to consider threads with such a name 'trash thread' and avoid them while letting them run?

This is the catch-all thread, where the frivolous comments go. I mean c'mon. Look at the thread title.

 

[Roland]

Uh huh. We'll hop right on that.

I fell for the hype and bought a couple of top of the range Topping dacs that measured brilliantly without properly realising that cheap dacs would have sounded just the same. Ditto with Nord Hypex amps, when I could have just bought Yamaha A-S 501s. I guess you live and learn!

 

[bkdc]

There must be a device that will level-match two devices and subtracts the output of one device from another.

If there is audible noise, there is a difference. If you hear silence, there isn’t.

There are subtraction programs that you a use to prove to yourself that some compressed audio is distinguishable/indistinguishable from the uncompressed FLAC as you hear the sweet sound of silence after subtraction. Better than an ABX test.

 

[fpitas]

I fell for the hype and bought a couple of top of the range Topping dacs that measured brilliantly without properly realising that cheap dacs would have sounded just the same. Ditto with Nord Hypex amps, when I could have just bought Yamaha A-S 501s. I guess you live and learn!

I'm glad you lived and learned (?)

 

[Thorsten Loesch]

In a self oscillating amplifier, the issue is finding one oscillation solution during overload recovery.

Yes. Self oscillating Class D amplifiers suffer from a number of drawbacks over those with a fixed frequency, including the lack of ability to reliably synchronise two or more Amplifiers to avoid beat notes, especially with the relatively high level of carrier breakthrough in them.

It is. The issue you run into with them is that they won't turn off when told to, without a bit of a kick. That is provided by the output filter choke. Were this not the issue, the deadtime could be quite a bit less than you see in GaNFET amps right now.

It seems to not be an issue in power supplies...

If at the power levels of the Lamm, getting power response that high is not trivial.

It is trivial. Power levels do not directly come into it. If needed use vertical sections and horizontal sections.

If the amp really did have that kind of HF bandwidth then its distortion is likely higher than suggested by Vlad...

Here the frequency response for one of Vladimir's Tube (not Hybrid) Amplifiers, not sure if that is the one you had at hand.

I see -3dB eyeballed at 70-80kHz.

10kHz squarewave.

And here THD vs. frequency at 0dBW:

And here we see where the problem is, below 100Hz distortion rises a lot. No big issues at high frequencies, though the modest rise in distortion towards high frequency is unnecessary.

Thor

 

[antcollinet]

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.

Since it is not possible to prove the negative here, the requirement is to prove that there is a difference.

This should be easy for somone who is convinced there is a difference. Just get two dacs which measure as transparent, but which you can hear a difference anyway, then prove it with a statistically valid properly controlled blind test.

So - knock your self out...


On the other hand, despite this having been a possiblity for many years, despite the fact you'd expect so many people to have a vested interest in proving it, no-one has yet managed to do so.

 

[fpitas]

I'm totally confused now. That Lamm ML1 amp seems to be triode push-pull. I thought we were talking about a SET?

 

[atmasphere]

I'm totally confused now. That Lamm ML1 amp seems to be triode push-pull. I thought we were talking about a SET?

Yes. And it has the problems I surmised (see Thor's post above) when we auditioned it.

 

[pma]

There must be a device that will level-match two devices and subtracts the output of one device from another.

No. There is not. Smallest inaudible phase shifts between 2 devices make huge difference signal after subtraction. This tells nothing about audible difference. Threads like this would be best closed, they only spread more snake oil and nonsense.

 

[fpitas]

No. There is not. Smallest inaudible phase shifts between 2 devices make huge difference signal after subtraction. This tells nothing about audible difference. Threads like this would be best closed, they only spread more snake oil and nonsense.

Lol! In between the blatant trolling is some discussion useful to noobs, I think.