[bwaslo]

>Can we take two identical cables,break one in on a break in device for 200 HRs and then measure any difference between the two?

I've made a (freeware) software program you can use to do this yourself.

http://libinst.com/Audio%20DiffMaker.htm

You use it with a good quality soundcard to digitally record your choice of music.  Use a track that sounds different to you through the cables, and record a sample of the same music playing through each cable. 

The program then takes the two recordings and fine adjusts the time difference and any slight level changes between the two recorded tracks.  And then it SUBTRACTS one from the other.  (Digital recordings, being essentially sequences of numbers, can be subtracted sample by sample using simple arithmetic).  The result is a listenable track that contains only what is different between the two tracks.  If you can hear sound in the "difference" track, something changed.  If you can't hear anything in the difference track, well, then there is ...no difference.  Even if the sound card is not perfect, had distortion or frequency response irregularities, the result the program gets will still be valid.  Unless of course the effect is something that manages to be totally silent when recorded with a soundcard. 

Download the program and try it yourself, if interested.  It also has some features to make it easy to share recording sets (originals and difference recordings made with the program) with others, so experiment results can be shared and each person can hear for himself whether the cable burn-in (or any other tweak) does something he can hear.

This test doesn't give you a graph or a numerical test result. It gives you sound (or not) you can listen to, so there is no expectation that you need to ignore your ears and what thay hear.  It just makes it so what you hear is only any changes that may have occurred.

Have fun.

[avahifi]

Darn, you don't know of a MAC version of this difference detector program do you?

Here I simply use a white noise CD track (stereo - both channels identical) and invert and sum the results at the output of the amp or preamp under test (or wires, cables, or whatever) with the scope.  If you see any resulting difference at all, something is wrong.

Regards,

Frank Van Alstine

[bwaslo]

Hi Frank,

Sorry, it was done for Windows but not for MAC. I don't have programming tools for Mac. Also, doing this was a reasonable effort only because a lot of the code used in this was adapted from code already done for our PRAXIS program (for Windows). Rewriting it for Mac would be more work than I would want to take on.

This Audio DiffMaker program has been around for a few months or so, but I've gotten surprisingly little response from audiophiles.  I sometimes wonder if it might just be more fun for people to argue about audibility of differences made by tweaks than to actually find out about it.

The white noise test will do the trick too, though its result might be less easy to evaluate for a listener than doing it with a music track he had been using to evaluate with in an "auditioning" test.  White noise also leaves the door open for the "but that's different than music!" argument.   But white noise is probably a more demanding test than music, I'd think.

One advantage of doing it with recordings is that the two cases being compared need not be done at the same time.  You could use the same CD, for instance, to compare before and after applying some treatment.  You could do the recordings with a white noise track, if you wanted to keep the WN stimulus and also be able to time shift.

Not that I'd want to push the Windows OS on a Mac user, but you could probably pick up a cheap Win desktop (like one of the under $400 Dells) to use just for this test.

Bill

[bpape]

My question has to do with level.  Everyone argues that we can hear fractions of a db difference so things need to be exact when level matching to compare.  Can one hear a difference signal that is only a fraction of a db or even 1-2db if that's the whole signal?  My guess is no.  Can the scope see a fraction of a db? 

Bryan

[bwaslo]

>Can one hear a difference signal that is only a fraction of a db or even 1-2db if that's the whole signal?  My guess is no. 

Probably not.

>Can the scope see a fraction of a db?

Sure it can, easy.  And a voltmeter or response measurement device can too.

But for the program mentioned above, the level difference is critical for a completely different reason.  It operates by subtracting signals, which makes any resulting difference much more likely to be audible.  A dB difference is another form of a fractional difference. You can't tell a 1V tone from a 1.001V tone playing into your power amplifier. But that doesn't mean you couldn't hear the result of coherently subtracting those two -- after subtraction it would be a 0.001V signal, well above the noise floor.

A 1.001V signal is only 0.009dB above a 1V signal:

20*log(1.01/1) = 0.009dB.

I doubt anyone could tell those apart.

But a 0.001V signal is 60dB below a 1V signal

20*log(0.001/1) = -60dB.

If a 1V signal makes a loud sound, you could certainly hear something just 60dB lower than that if it were the only sound being played.

[aerius]

Some time in the spring of 2006, HiFi News & Reviews did a cable break-in test.  They looped a test track about 20 times or something like that to account for statistical anomalies caused by sound card or computer PSU noise, first they did it with a fresh cable, then they broke it in for a bunch of hours and then repeated the test.  The results for both runs were different, but the differences were quite small and they decided that further tests were needed before they could draw a clear-cut conclusion.  They said more tests would be done in a future issue but I haven't had a chance to see if they did any.

[Ethan Winer]

A few months back i switched amps, upgrading from a '92 Muse Model 100 to an '02 Belles 150A Hot Rod.   musicans now appear to the outer left and right of my speakes

I'm at a loss, but it's either comb filtering, your imagination, or the previous amp was incredibly lame.  Again, there's nothing an amplifier can do that will affect spatial imaging etc. Maybe if the crosstalk was really bad (30 dB or less) it would compromise imaging. It would have to be a truly crappy design to be that bad though. Do either of those amps happen to use tubes?

> since i'm bald i'm not sure if comb filtering affects my room <

Wow, I'd never guess from your avatar photo!

--Ethan

[bpape]

Maybe I misunderstand the program then.  IF we're subtracting two signals and they're say .1db apart, then if you're really subtracting the whole signal, then the result should be - 0.1db - correct?  Should matter not what the output level was before.  If it was 90db and you subtract 89.9db - you get 0.1 db.  Start with 70 and subtract 69.9 you get 0.1db.  Am I missing something here or is it just time for a beer?


Bryan

[Dan Banquer]

A few months back i switched amps, upgrading from a '92 Muse Model 100 to an '02 Belles 150A Hot Rod.   musicans now appear to the outer left and right of my speakes

I'm at a loss, but it's either comb filtering, your imagination, or the previous amp was incredibly lame.  Again, there's nothing an amplifier can do that will affect spatial imaging etc. Maybe if the crosstalk was really bad (30 dB or less) it would compromise imaging. It would have to be a truly crappy design to be that bad though. Do either of those amps happen to use tubes?

> since i'm bald i'm not sure if comb filtering affects my room <

Wow, I'd never guess from your avatar photo!

--Ethan

One of things I have observed is that if the electronics put out enough noise into a speaker that has good dispersion then the effect can seem more like "better imaging" as the noise is dispersed along with the music. I consider this a false effect but pleasureable to some. These are my observations only.
                   d.b.

[Ethan Winer]

Steve,

> absence of proof is not proof of absence. So best we can say is that there is currently an abesnce of proof. <

Okay, let's take that to the absurd extreme.

I posit that the moon is made of green cheese. You cannot prove it's not made of green cheese! Sure, we've sent astronauts to the moon, and they even brought back soil samples. But three feet below the surface is where the green cheese layer starts. And you can't prove otherwise.

So all we can go by is common sense, and what is currently known. From all that is known, the four parameters I detail in THIS article from Skeptic magazine comprise everything that matters about audio.

BTW, skeptic James Randi uses a similar argument, though I thought up the green cheese first as far as I know. Randi tells people they can't prove there's no Easter Bunny. And they really can't! But that doesn't mean the Easter Bunny is really possible. This is where the common sense part comes in.

--Ethan

[Ethan Winer]

Pez,

> I have heard numerous speakers with horrible off axis meausurements have a wonderful soundstage. I've heard speakers with pretty much ruler flat response that sounded horrible and have all kinds of sonic abberations off-axis. And yes I have heard an amp image poorly that measures well. <

Normally at this point in the conversation I'd ask if you have any acoustic treatment in your room, especially absorption at the first reflection points. But I want to avoid appearing as a shill for the acoustic treatment industry so I won't ask you that.

--Ethan

[Ethan Winer]

Dan,

> if the electronics put out enough noise into a speaker that has good dispersion then the effect can seem more like "better imaging" as the noise is dispersed along with the music. <

That'd have to be one might noisy amplifier!

--Ethan

[bpape]

OK.  And SS measures better than tubes so it must be better.  CD measures better than vinyl so it must be better.  If they measure the same they must be the same.  IMO all bad assumptions.

If I take 2 cars and say all that matters for perfomance is braking distance, top speed, and acceleration.  If they both perform the exact same, then just buy the cheaper one - right?  Wrong. 

How does one measure a car's comfort?  How do you measure the 'feel' of the road?  How do you measure how a seat fits?  The last is particularly telling.  Those things are all personal preference.  Everyone will have the same seat that measures the same fit differently.  While it doesn't impact the function of the seat, it may impact the comfort or the feel you get when you throw it into the corner. 

The article you quoted Ethan is fair enough - but you totally dismiss basically all measurable characteristics of wire as unimportant at audio frequencies.  So then even the things that ARE measurable don't matter?

Bryan

[bpape]

Dan,

> if the electronics put out enough noise into a speaker that has good dispersion then the effect can seem more like "better imaging" as the noise is dispersed along with the music. <

That'd have to be one might noisy amplifier!

--Ethan

Not if we can hear and measure 0.1db - right?   Can't have it both ways.

Bryan

[Steve Eddy]

Okay, let's take that to the absurd extreme.

No, let's not. You can take most anything to an absurd extreme, and taking something to an absurd extreme is absurd in itself.

se

[Dan Banquer]

Dan,

> if the electronics put out enough noise into a speaker that has good dispersion then the effect can seem more like "better imaging" as the noise is dispersed along with the music. <

That'd have to be one might noisy amplifier!

--Ethan

Given the near total lack of grounding standards in consumer audio, and really questionable grounding schemes inside these units, noisy electronics is more the norm. As I am fond of saying "Audio: The bastard child of electronics"
                            d.b.

[bwaslo]

>Maybe I misunderstand the program then.  IF we're subtracting two signals and they're say .1db apart, then if you're really subtracting the whole signal, then the result should be - 0.1db - correct? 

Nope.  If you subtract signals, you don't subtract the dBs.  You subtract the relative voltage values they represent, each of which would be 10^([dB_Value]/20).  Subtracting dBs gives you another dB value, but that equates to effectively *dividing* the signal amplitudes (assuming they are same frequency and in phase...another complication, being glossed over here).  If I wanted to divide one signal by another, I could subtract their related dB values.  But I needed to subtract one signal from another, so I subtract their *voltage* values, not their dB values.

>Should matter not what the output level was before.  If it was 90db and you subtract 89.9db - you get 0.1 db.  Start with 70 and subtract 69.9 you get 0.1db.  Am I missing something here or is it just time for a beer?

No, the misunderstanding is just about how dBs and logarithms work.  (But a beer might be a good idea, still.)

Don't know if you've been around long enough to remember slide rules, but they basically were able to do multiplication by adding logarithms of numbers.  When you add quantities expressed using dB, you are actually in effect multiplying the relative scalar quantities they represent. 

As a crude example, say you limited discussion to powers of ten.  You could represent the number 100 by counting the zeroes to the left of the decimal-- use "2" to represent the number 100.  The number 10,000 would be represented as "4" because there are 4 zeroes.  To find what 10x10,000 is, you can then just add the "2" to the "4", getting "6" -- 100x10,000=1 million, which is 1,000,000, which has "6" zeroes. That's essentially how dB and logarithms work. 

A voltage that is 6dB higher than another has twice the voltage  - it is the same as multiplying by 2.  If you add 6dB more to it, you are really doubling the previous voltage again, so while the addition gets you (in dBs) 12dB,you've actually quadrupled the original voltage. Adding 6dB to a dB value doubles the voltage it represents (when you convert from dB back to volts).  Decibel notation is a trick used by engineers who have to multiply and divide numbers all over the place and need to be able to do it in their heads when handling complicated systems.  Multiplying or dividing in your head is difficult, adding or subtracting are relatively easy.

If you have a voltage that is 0.1dB higher than another you are comparing to (the original value), that really just means that it is about 1.012 times the other, if we talk in voltage ratios instead of in dBs.  If I subtract the original relative VOLTAGE value (1 times the original) from the new relative VOLTAGE value (1.012 times the original), then the difference is 0.012, which back again in dB is -38dB, compared to the original voltage value of 1. The 1, in dB, is "0dB".  If I just subtract 0dB from 0.1dB, that's just means not changing the 0.1dB (same thing as multiplying by 1 =0dB).

So, "0dB" doesn't mean "nothing" -- it means no change in level from what you compare to.   BTW, There is no way to express "nothing" in dB -- it would have to be -infinity dBs.
 
(Sorry for hitting you with the math lecture, I just find that most audiophiles don't really "get" decibels, which makes discussions about signals like this difficult)
--
People aren't generally assumed to be able to identify sound level changes of around a dB as being a change in volume.  Meaning, they could not likely adjust by ear one volume, to match another, within a dB.  But they might experience such a small volume difference as a change in clarity or sound character.

[bpape]

Makes sense.  I understand the doubling of power vs db gain.  That's still only a pc of the story.

Now, let's assume that at a particular frequency, I see a .1db gain (bear with me here).  At another frequency I see a .1db loss.  No matter how you do the math, assuming all other frequencies are exactly equal, the signal voltages will cancel (+.012V on one and -.012V according to your math - but the signals themselves are different.  With a white noise signal, I'm sure there are multiple cases where this happens. 

Only measuring one voltage for the whole signal is no different than setting channel levels using white noise.  It's balancing the total energy at all frequencies - doesn't mean the individual frequencies are the same level between the different speakers. Same with this is my guess.  It's the best that can be done but doesn't tell the whole story IMO.

I'm not trying to minimize what you've done - it's a shot at quantifying what some people claim can be heard but not measured.  I'll likely download it at some point and give it a shot - should be interesting.

Bryan

[bwaslo]

>Only measuring one voltage for the whole signal is no different than setting channel levels using white noise.  It's balancing the total energy at all frequencies - doesn't mean the individual frequencies are the same level between the different speakers

I have to agree on that.  Different speakers with different responses can't be level matched within 0.1dB because their frequency curves are more different than that, if they get matched at one freq they'll be mismatched at another.  Not many people claim that differences between speakers are immeasurable or inaudible, though.

There are other things over which 'philes argue whether (1) a difference is measurable, (2) a difference is audible, and/or (3) whether there is any difference to even be measurable or audible.  The ones for which response differences aren't measurable (i.e., that have the same frequency response shape) or with response curves within less than "X" dB, can be level matched to within "X" dB, though.  Most CD players, cables, cd treatments, vibration absorbers, line conditioners, etc., etc.   The third category above are the kind of things that I'm going after with DiffMaker.

Heck, even when using the SAME loudspeaker in a room, the DiffMaker hasn't shown "no difference" in an acoustical test -- just the changing air currents or any tiny movements of the microphone (I think these are why) will make some differences in the recorded tracks at high frequencies.  Different speakers, even of the same model wouldn't stand a chance of giving playback that could cancel to inaudibility.

If you get the program going, let me know.  I'm looking for some example recordings from use of it to post on my web site.  I'd prefer to just provide the software and get others to do the actual comparison recordings with it, to post so anyone can listen to them.  That way no one can accuse me of having any particular agenda on the subject, if the results that are posted come from others.  I did one example run comparing a Polypropylene film capacitor to a high-K ceramic disk capacitor (something that most will already agree can make a difference).   If test results expose differences happening with tweaks, great, that gives something to look into.  If they show no difference, great too.

Thanks

[Scotty]

Ethan, in your experience what electronic components in a stereo system have
altered the sound staging or imaging when they were exchanged for component
that had the same function within the context of the system? Or more simply, what electronic components in the stereo system matter when it comes to sound staging or imaging.
Scotty