[Steve Eddy]

Not irrelevant.  They may convince him that he didn't hear a difference.

And if a frog had wings it wouldn't bump its ass hopping.

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[bigshot]

That's what's so frustrating for me. KeithEmo is throwing up smoke screens and everyone else is running around in circles instead of keeping focus and simply put the onus on KeithEmo to substantiate his claim.

 
I've personally done very careful tests, and I haven't found ANYTHING that sounds different than anything else. That goes from the Oppo HA-1 all the way down to a Coby DVD player that cost under $40.

 

[Steve Eddy]

I've personally done very careful tests, and I haven't found ANYTHING that sounds different than anything else. That goes from the Oppo HA-1 all the way down to a Coby DVD player that cost under $40.

Great. But KeithEmo says that he has. So again, the focus should be on his substantiating that claim.

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[Steve Eddy]

While we're waiting for the next installment of War and Peace, here's a thread I came across over in the cables etc. forum that probably should have been posted over here. It resulted in my doing a little experiment last night that might be of interest.

http://www.head-fi.org/t/767362/symmetrical-audio-cable-over-single-wire-cable#post_11611386

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[StanD]

While we're waiting for the next installment of War and Peace, here's a thread I came across over in the cables etc. forum that probably should have been posted over here. It resulted in my doing a little experiment last night that might be of interest.

http://www.head-fi.org/t/767362/symmetrical-audio-cable-over-single-wire-cable#post_11611386

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How would the resistance of a single common ground wire in the cable affect crosstalk when using a low impedance headphone? I would think that a high impedance headphone would be able to tolerate a higher single ground lead resistance. In this case, not thinking about any capacitance.

 

[Steve Eddy]

How would the resistance of a single common ground wire in the cable affect crosstalk when using a low impedance headphone? I would think that a high impedance headphone would be able to tolerate a higher single ground lead resistance. In this case, not thinking about any capacitance.

Hmmm... The answer to that would have to take other things into consideration like the voltage sensitivities of the headphones.

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[StanD]

Hmmm... The answer to that would have to take other things into consideration like the voltage sensitivities of the headphones.

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Also the voltage drops (audio) due to the common lead. I think that might be more inportant than capactitance, unless it's severe capacitance. Depending on the headphones I would think that the crosstalk might be affected more by the impedance curve of the headphones affecting the FR of the crosstalk. Some like planars are resistive and some dynamics are relatively flat which mitigates the FR of the crosstalk.

 

[Steve Eddy]

Also the voltage drops (audio) due to the common lead.

That's a given. But the voltage drop is going to be a function of current, and current, if we're going to use some reference SPL, is going to depend on sensitivity. See what I'm saying?

I think that might be more inportant than capactitance, unless it's severe capacitance. Depending on the headphones I would think that the crosstalk might be affected more by the impedance curve of the headphones affecting the FR of the crosstalk. Some like planers are resistive and some dynamics are relatively flat which mitigates the FR of the crosstalk.

It would depend on the resistance of that common resistance. Just take some simple math to work it out.

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[StanD]

That's a given. But the voltage drop is going to be a function of current, and current, if we're going to use some reference SPL, is going to depend on sensitivity. See what I'm saying?

It would depend on the resistance of that common resistance. Just take some simple math to work it out.

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As a simple model, if one thinks at a particular frequency, the voltage drop would be as a resistive voltage divider network, both channels. Sensitivity would be how it manifests in SPL.
The common resistance in addition to the rest forms a resistve mixer manifesting in crosstalk. Assuming one doesn't get into the reactances and impedance curves. I doubt that this is much of a problem with 300 Ohm cans.

 

[Steve Eddy]

As a simple model, if one thinks at a particular frequency, the voltage drop would be as a resistive voltage divider network, both channels. Sensitivity would be how it manifests in SPL.
The common resistance in addition to the rest forms a resistve mixer manifesting in crosstalk. Assuming one doesn't get into the reactances and impedance curves. I doubt that this is much of a problem with 300 Ohm cans.

Or the 60 ohm cans I was using.

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[KeithEmo]

Here on the west coast, Turner Classic Movies is airing The Subject Was Roses. So how 'bout we get back to The Subject Was Actual Audibility.

Before the smoke machines were dragged out, we had two empty-handed claims of actual audibility on the table made by KeithEmo, one concerning digital filters and the other concerning two different Schiit amps.

KeithEmo seems to want to start out assuming the differences are actually audible.

I say the most reasonable thing to do is not make such assumptions and establish whether there are any actual audible differences in the first place and if so, we can move on to figuring out the cause.

KeithEmo doesn't want to bother with the mess of controlled listening tests.

Ok.

So can anyone tell my why a relatively simple null test wouldn't resolve this for both claims?

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Yes.
 
The reason "a simple null test" won't resolve these questions is that we're talking about whether something is audible or not.
 
In the specific case of DAC filters, we already know the results of an electrical null test.... the outputs of the filters are quite obviously electrically different, which is easily seen on an oscilloscope trace, so those differences will show up on a null test. I don't think it takes a huge leap of faith to assume that, if you subtract two different electrical signals that look different on an oscilloscope trace, you will end up with some sort of difference (they won't null to zero). The only way that could fail to be true would be if all the chip vendors who make DACs with multiple filter choices (like Texas Instruments and Wolfson), and all the vendors who sell audio technology that offers multiple filters (like Dolby Labs), were deliberately publishing falsified graphs in their data sheets - which seems rather doubtful. (Find yourself a copy of the Texas Instruments PCM5102a DAC chip data sheet, and compare the Interpolation Filter Impulse Response graphs of the various filters; it's pretty obvious that they are quite different. Of course, since we're talking about impulse response, which only affects signals containing transient (non-steady-state) content, a pure sine wave should be identical when played through the various filters, but non-steady-state signals will not be.)

 

[Head Injury]

   
Yes.
 
The reason "a simple null test" won't resolve these questions is that we're talking about whether something is audible or not.
 
In the specific case of DAC filters, we already know the results of an electrical null test.... the outputs of the filters are quite obviously electrically different, which is easily seen on an oscilloscope trace, so those differences will show up on a null test. I don't think it takes a huge leap of faith to assume that, if you subtract two different electrical signals that look different on an oscilloscope trace, you will end up with some sort of difference (they won't null to zero). The only way that could fail to be true would be if all the chip vendors who make DACs with multiple filter choices (like Texas Instruments and Wolfson), and all the vendors who sell audio technology that offers multiple filters (like Dolby Labs), were deliberately publishing falsified graphs in their data sheets - which seems rather doubtful. (Find yourself a copy of the Texas Instruments PCM5102a DAC chip data sheet, and compare the Interpolation Filter Impulse Response graphs of the various filters; it's pretty obvious that they are quite different. Of course, since we're talking about impulse response, which only affects signals containing transient (non-steady-state) content, a pure sine wave should be identical when played through the various filters, but non-steady-state signals will not be.)

But you can listen to the non-zero results of the null test between two different DACs or filters to roughly judge whether the differences would be audible in the real world, without a controlled listening test.

 

[KeithEmo]

  While I am generally inclined to believe that as long as there's no clipping and no unique interactions with the speakers, there are still many who don't.  I don't suppose it's our role in life to enlighten them.  Unfortunately there have been many critics of the study, including small sample size etc.  And the study really doesn't respond to @Keith Emo's claim that the two amps sound different.  I guess we have to ask him if he'll accept the studies you and other have cited. 
 
It seems pretty clear several of us here accept that amps sound pretty much alike when they are just loafing along on normal source material. 

 
Really simple answer.
 
I agree entirely that, under certain circumstances, most amplifiers will sound quite similar.
 
However, take two amplifiers, similar in THD and noise specs, but one with a damping factor of 10 (typical of most tube amps), and one with a damping factor of 500 (typical of most solid state amps), and connect both to a speaker with a moderately reactive impedance, and the interactions between the amplifiers and that speaker will cause the frequency response of the speaker to vary by as much as several dB, which even most folks here agree is clearly audible - so, in that situation, those two amplifiers will in fact sound very different. (And we haven't even mentioned things like distortion spectra yet...)
 
Therefore, I don't doubt at all that you could find plenty of situations, using any number of specific speakers and source material, where none of a good sized sample of test subjects could tell the difference between any of several amplifiers.... but that doesn't prove the general case of "all amplifiers" and "all conditions".
 
(If you want to claim that "all amplifiers that measure the same sound the same" you will first have to find two amplifiers that measure the same in every measurable way. If you ever do, let me know. The actual fact is that most tube amps measure very different from most solid state amps in all sorts of ways - which is probably why they usually sound different 

)

 

[Steve Eddy]

Yes.

The reason "a simple null test" won't resolve these questions is that we're talking about whether something is audible or not.

How so? If the residual isn't audible, how can there be an audible difference?

In the specific case of DAC filters, we already know the results of an electrical null test.... the outputs of the filters are quite obviously electrically different, which is easily seen on an oscilloscope trace, so those differences will show up on a null test. I don't think it takes a huge leap of faith to assume that, if you subtract two different electrical signals that look different on an oscilloscope trace, you will end up with some sort of difference (they won't null to zero).

Never said there would be a zero null. It's whether or not the residual is audible. If the residual isn't audible, how can there be an audible difference?

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[Steve Eddy]

But you can listen to the non-zero results of the null test between two different DACs or filters to roughly judge whether the differences would be audible in the real world, without a controlled listening test.

I guess he doesn't have much familiarity with null testing with respect to establishing audible differences.

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