Blind Listening Tests & Amplifiers

[SY]

Controlled testing is the single most powerful tool in all of perceptual research; why throw it away or dismiss what it tells you?

 

[fdegrove]

ASSUMPTIONS.

Hi,

Geez, I'm having a field day...

you would be unable to tell with better than chance probability whether the two amps sounded identical or not, assuming the resistors had the same value and similarly low C and L parasitic impedances.

Assuming that those are the only factors...in real life more is at work here...

Fred, it seems you're right, we really have to put in one little detail after the other...

Within a few months I hope to discuss quantum physics/mechanics and see how far we can push that...
In the mean time we all have to live with a null.

Cheers,

 

[nw_avphile]

Re: Re: Re: Re: Re: Re: Re: VIBERATIONSSSS

One possible answer could be that measurements are done in two dimentional environment and we perceive music in three dimentional environment so it doesn't correlate well (if I can say so)

It is actually better to do resistors test in one amp, because you can never position two amps in the same space in exactly same way. Both may be affected by different resonant modes and this cause the test to be invalid. Having two different amps involves two different sets of wiring and this is an additional variable.

Sorry, but electrical signals are electrical signals. They don't care if we live in seven dimensions. The electrons pumped from your amp to your speakers are all those resistors have a chance to influence in this world.

As for your other concern, if both amps sounded the same would you be happy the resistors sounded the same? Or are you suggesting that somehow the resonances from mechanical vibration will, against all imaginable odds, exactly cancel out the electrical changes made by the resistors?

 

[SY]

that measurements are done in two dimentional environment and we perceive music in three dimentional environment so it doesn't correlate well

I'm not quite sure what the mantra part means (measurements are done in however many dimensions an experiment calls for), but as to correlation, quite the opposite is true. If a box of gain has an output that's a scalar multiple of the input for any given test signal to within 16 bits over the audio band, that measurement will near-guarantee you that you won't be able to distinguish one from the other in a blind listening test, short term or long.

 

[Peter Daniel]

Controlled testing is the single most powerful tool in all of perceptual research; why throw it away or dismiss what it tells you?

I'm not dismissing it and I would be really interested to see how it goes since I never took part in one.

I can only rely on my own experiments so far, yet not being completely retarted I cannot put away everything I learned and experienced so far and throw myself into realms of new religion.
I'm too old for that, but not scheptical yet. It's quite possible that I might take different POV if it would make sense. Things would be much simpler too, no $28 resistors to buy (I didn't tell you, but I'm getting them at substantial discount)

 

[SY]

I hope to discuss quantum physics/mechanics

There ought to be a corollary to Godwin's Law.

 

[fdegrove]

Catch 22

Hi,

Sorry, but electrical signals are electrical signals. They don't care if we live in seven dimensions. The electrons pumped from your amp to your speakers are all those resistors have a chance to influence in this world.

Not true.

And maybe one day I'll explain...

Under attack I'm worse than Fred....Can't stand ignorance...

Do your homework. I won't be smiling for too long.

 

[Peter Daniel]

I'm not quite sure what the mantra part means (measurements are done in however many dimensions an experiment calls for

The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility?

 

[nw_avphile]

I'm not dismissing it and I would be really interested to see how it goes since I never took part in one.

I can only rely on my own experiments so far, yet not being completely retarted I cannot put away everything I learned and experienced so far and throw myself into realms of new religion.
I'm too old for that, but not scheptical yet. It's quite possible that I might take different POV if it would make sense. Things would be much simpler too, no $28 resistors to buy (I didn't tell you, but I'm getting them at substantial discount)

I stand corrected... you might be more open minded than I originally gave you credit for

Have you ever done any measuring on your gainclone (frequency response, power output, distortion, etc)? What other amps do you have available to you? Apparently some Aleph clones? Any commercial amps?

 

[nw_avphile]

The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility?

Well there's always some remote possibility of most anything. But in this case, Out - In = Distortion seems pretty darn hard to refute--especially when the input signal is limited to the audio band (which pretty much anything from CD is).

 

[Peter Daniel]

If a box of gain has an output that's a scalar multiple of the input for any given test signal to within 16 bits over the audio band, that measurement will near-guarantee you that you won't be able to distinguish one from the other in a blind listening test, short term or long.

You are not advocating here the term: 'perfect sound forever 'and claiming that all CDP sound the same?

 

[Peter Daniel]

Well there's always some remote possibility of most anything. But in this case, Out - In = Distortion seems pretty darn hard to refute--especially when the input signal is limited to the audio band (which pretty much anything from CD is).

You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations?

 

[fdegrove]

PLAYING THE DEVILS ADVOCATE.

Hi,

You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations?

Peter, with al due respect, I am sure you can figure that out for yourself.

Think along source isolation and amp isolation the viberations, , then diff it , something must show up...

Ciao,

 

[SY]

You are not advocating here the term: 'perfect sound forever 'and claiming that all CDP sound the same?

I specifically said "box of gain."

The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility?

Speaking STRICTLY in the realm of boxes of gain, I think it's highly unlikely. If someone shows in a controlled test that a box of gain with the usual measurable criteria in these arguments (flat response, high input Z, low output Z, low offset, no overloading, etc, etc, etc) can be audibly distinguished, I'd certainly change my opinion. I'm someone who used to regularly hear all kinds of wonderful things, suddenly going (apparently) deaf the day I started putting my beliefs to a valid test. It's commendable that you're open-minded enough and curious enough (very important, that!) to try to do the same thing.

 

[Peter Daniel]

I don't have an opinion on that. I just wanted to hear how they can comment this.

 

[Peter Daniel]

I'm someone who used to regularly hear all kinds of wonderful things, suddenly going (apparently) deaf the day I started putting my beliefs to a valid test. It's commendable that you're open-minded enough and curious enough (very important, that!) to try to do the same thing.

Does that mean that you don't have a preference for any particular equipment (beside the convenience aspect only )?

Is it possible that after going through such test it is psychological now that suddenly you stopped hearing those things? Doesn't it bother you now that you possibly lost some of your previous abilities??

 

[nw_avphile]

You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations?

Well... this is sort off topic, but you asked so I'll answer.

Microphonics are a known issue with tubes. Tube phono (and mic) pre-amps, especially, are prone to picking up vibrations. The elements delicately suspended in some tubes are prone to moving around, and because of the very high gain in those circuits, their tiny modulations get amplified to an audible level.

I'm open minded enough to think vibrations can possibly have an effect on other components as well, but I've never encountered it that I'm aware of. The amount of overall gain in a power amp is roughly 2 orders of magnitude less than in a phono pre-amp. So any tiny effects from microphonics would be much less likely to have an audible effect.

Now if you're talking about mechanical things, like a CD transport (or, obviously, a turntable) vibrations can play a BIG role in the sound.

Looking at the pics of your amp, I can see you've put a ton of effort into turning it into a very non-resonant block. Your craftsmanship is very admirable! But as I pointed out earlier, null testing might be a really good guide as to just how much of that sort of thing is necessary on future projects. That way you might decide you can focus more of your efforts on the outside of the enclosure where they can be more readily appreciated by others (compared to the inside).

Regardless of the sonic benefits of the construction methods you used, the "cool factor" remains very high! It reminds me of elaborate inlaid wood projects that defy description.

 

[SY]

Does that mean that you don't have a preference for any particular equipment (beside the convenience aspect only )?

Quite the opposite. I build tube stuff.

Is it possible that after going through such test it is psychological now that suddenly you stopped hearing those things? Doesn't it bother you now that you possibly lost some of your previous abilities??

In the sense that I lost my ability to believe in the tooth fairy when I caught my mom slipping a quarter under my pillow.

 

[Peter Daniel]

Tubes, turnables and CD players have moving parts and resonance issues can be simply explained there. My main concern however is the influence of vibrations on static active and not active parts (ICs, resisstors, caps etc). I just noticed that using different insulating pad on my gainclone chip, changes the tonal character of the amp. And it is only my observation but a friend was surprised when I told him it's the same amp. So somehow the pad was acting as a barrier between chip and chassis and Kapton provided more damping than aluminum oxide which is more brittle. I still didn't figure out how vibrations affect the chip inside to change its sound. Do they modulate it somehow, if yes, what exactly and can it be measured? And this is still on topic.

 

[SY]

I'd expect that differences in bolt torque will be more imortant to the resonant signature. But since it's the power amp part, it's an easy thing to check. With your ear near the speaker, tap on the IC with a hard, light object. Hear anything from the speaker? Repeat the test with soft music or test tones running through. Hear anything?