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Superdad

Amir misses the point again: Looks for the music in the noise.

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zerung   

The design of the Iso Regen is amazing in that the Designer did not hear the unit, nor test this Himself ..... Designed mostly based on his theoretical, practical and innovative knowledge.

Those of us who dont rely on datas found the unit to be unsurpassed based on their own sonic tests.

Those of us who cannot see or hear, do need charts to prove the veracity of the product. When the chart proves nothing, the ears also hears nothing. 

See no Evil. Hear No Evil. Do evil

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All of the tests done by Amir seem to be very competent. Recall that he was technical editor for a video magazine.

Three minor points:

1] The tested components are often on loan, so he can't go back months later and retest.

2] Some questions as to the best audio test frequencies.

3] In the case of the Iso Regen, not testing it connected to poorly designed components.

 

So what were your problems and did you share them on the original thread?

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10 minutes ago, zerung said:

 When the chart proves nothing, the ears also hears nothing. 

 

Why would you think that biases work only one way? If you don't expect to hear a difference, you don't. If you expect to hear a difference, you do. Works both ways.

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Cxp   

I don't dispute that the tests were done competently. 

 

But... how do the tests he conducted convey spatial imaging or instrument separation?

 

I don't believe a low end DAC is really necessary, heck PS Audio has their own LANRover designed because they didn't like USB over their own Directstream. 

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1 minute ago, Cxp said:

I don't dispute that the tests were done competently.

But... how do the tests he conducted convey spatial imaging or instrument separation?

So exactly what tests would you use to measure spatial imaging or instrument separation?

 

I believe that a newer Audio Precision instrument can do about 200 different tests. I don't think any of them test for the above.

 

Did you suggest addition tests on the original thread?

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Spatial imaging or instrument separation are not the real differences, they are how humans perceive or describe the differences. So for the electronics part of the system, if those heard differences are measured, it will come down to distortion, noise and frequency response. Lets add Left to Right channel differences.

 

* * * * * * * * * * * * * * *

add level differences to the list.

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Cxp   
5 minutes ago, Speedskater said:

Spatial imaging or instrument separation are not the real differences, they are how humans perceive or describe the differences. So for the electronics part of the system, if those heard differences are measured, it will come down to distortion, noise and frequency response. Lets add Left to Right channel differences.

 And timing! 

Honest question, how do we measure timing coming out of a DAC...  The ideal test to me would be to identify bit signatures of individual instruments in the data and analyze the timing of those bits going into the DAC and out of the DAC and see if there are changes. Just spit-balling here. 

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Superdad   

It is really quite amazing just how much they are still stumbling around in the dark in that thread.  Despite our spelling some things out (here, on our web site, and in our white paper), they really do not understand either our tech or USB DAC input design.  So much misinformation.

I would post over there to explain and clear up some misconceptions, but there are some extremely hostile individuals there (and I am not referring to Amir or Dennis), and their overall agenda is completely biased against concepts which do not fit their limited view of audio engineering.  I simply don't have the bandwidth or the stomach to engage with the likes of Sal, DallasJustice, Jinjuku (plissken), etc.

 

By the way, someone mentioned the CoolGear unit, which also uses the Silanna isolator--but no hub chip for regenerating a new signal and jitter removal.  It measures and sounds terrible--and barely works for isochronous audio.  It is a wonderful demonstration tool for what added jitter in a USB signal sounds like.  And that is leaving aside the rest of its technical deficiencies (in voltage regulation, impedance, etc.).

I actually encourage people to take a listen to what the Silanna chip on its own sounds like.  So yes, galvanic isolation is worthwhile, but it comes with a high penalty if not done right.  And even then, I'd say that it represents only about 20% of the benefit of the ISO REGEN.

 

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mansr   
10 hours ago, The Computer Audiophile said:

@mansr The objective information you asked for is here - 

 

Yes, some DACs suffer from ground loop issues, and these can benefit from an isolation device. I've said as much many times. It's the "regeneration" aspect I have doubts about.

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tmtomh   

The above comment by @mmerrill99 is great and contains a wealth of useful info IMHO.

 

However, the problem as I see it is this: We have a wealth of theoretical claims about what can cause noise, and some great empirical examples of how noise in the digital signal can create problems when analogue playback happens and we hear it. BUT none of this addresses the question of whether spurious noise present at the output of the digital source, or the input of the DAC, actually makes it through the DAC and out into the analogue part of the signal chain. 

 

In other words, mmerrill's example shows what happens if we play back a waveform with that extra noise in it. But unless I'm mistaken, there's no evidence that a standard USB connection to a well-designed DAC actually results in that noise (or similar noise) ever getting to the part of the playback chain where the digital signal gets converted back to analogue.

 

If I'm reading Amir's tests correctly (and maybe I'm not!), a properly functioning or well-designed DAC delivers the identical output regardless of whether or not the input has been "cleaned" by the ISO regen or any similar piece of equipment. To me, that means that while the ISO Regen can change the signal that gets presented to the DAC at the DAC's input, it doesn't seem to change the signal that gets presented to downstream equipment by the DAC's output.

 

Furthermore - and again perhaps I am misunderstanding - Amir's claim, and the claim of those who agree with him, is that if a DAC does output something different with the ISO regen in the chain, then there's something deficient about the design of the DAC. Furthermore, it seems likely that a cheap DAC is more likely to have this problem than a more expensive one, and so Amir is asking why it would make sense to buy a $325 add-on for a cheap/bad DAC when for the same money or less one could just get a DAC that doesn't need the ISO regen in order to cope with USB noise.

 

I stress that I have no interest in taking sides here in a rhetorical or snarky way. The above represents my honest, good-faith understanding of the situation at present. Always happy to read substantive responses, and to learn.

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tmtomh   
Just now, mmerrill99 said:

I think you missed the point of my post - Amir's measurements have absolutely no hope of showing what has always said to be at the heart of operation of the USB cleaning devices - he's showing a test which has nothing to do with how the devices are conjectured to work.


And this is his great misinformation - you are assuming that his test shows all there is on the output of a DAC & many more are also assuming this.

 

I'm not blaming you but I am saying that anybody who claims to be an EE (Amir) should understand that the FFT test he is performing is bogus because it has no hope of measuring the dynamic noise that is conjectured to be at the heart of what's going on

 

Okay, thanks. So what kind of test would in your view show us whether or not a device like the ISO Regen changes the signal that leaves the DAC's analogue outputs? 

 

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lmitche   
16 minutes ago, mmerrill99 said:

I think you missed the point of my post - Amir's measurements have absolutely no hope of showing what has always said to be at the heart of operation of the USB cleaning devices - he's showing a test which has nothing to do with how the devices are conjectured to work.


And this is his great misinformation - you are assuming that his test shows all there is on the output of a DAC & many more are also assuming this.

 

I'm not blaming you but I am saying that anybody who claims to be an EE (Amir) should understand that the FFT test he is performing is bogus because it has no hope of measuring the dynamic noise that is conjectured to be at the heart of what's going on

I remember telling Amir that an FFT wouldn't cut it after his first bogus measurements of the Amber Regen. He either didn't get it or only has a hammer and the whole world looks like a nail.

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1 minute ago, tmtomh said:

 

Okay, thanks. So what kind of test would in your view show us whether or not a device like the ISO Regen changes the signal that leaves the DAC's analogue outputs? 

 

Well that's what we might try to discuss here? I asked for any suggestions in my post

But the first step in trying to find ways of measuring this dynamic noise is to recognize what doesn't work & FFTs like Amir has done don't work for measuring this.

 

It's not going to be easy, I would imagine:

a) Because differentiating signal from noise on a DAC's output is not easy. Diffmaker has been used before to do this input Vs output comparison but I don't know if it's sufficiently sensitive enough - it seems very flaky software to me

b) we don't know at what amplitude this modulating noise will be seen? 

 

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