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Old 14th February 2012, 05:13 PM   #2351
SY is offline SY  United States
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Originally Posted by dvv View Post
RAAL, huh? So you know Aleksandar Radosavljevic, aka "Aca", aka "Aca Ribon"?
Yes, we had dinner, drinks, and a lot of conversation at one of the Burning Amp festivals in San Francisco. Good guy, doing some impressive work.
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Old 14th February 2012, 05:25 PM   #2352
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There are 2 big differences: to evaluate thoroughly if change of a part of a wire can be used by a customer to claim that the device sold is not as as advertised, and the real difference when it is clearly audible that it is a breakthrough, and it sounds like a real band in your room. When water running on record caused my subconscious reaction of jumping and turning around; when my guest said that he wants too a house near a creek because he likes how frogs sing; when my father in law insisted tat somebody played piano in our house; when my guests were scared by roaring lion; all this and other things happened when I did not use special cables, capacitors, triple-more-blind tests. All bits added to reproduction quality are valid, but the end result is always the same: the better is the system, the less it is heard itself.
However, we can use thermometer, X-rays, to check what is broken in human body. Like, designing equipment I always measure how big are things that are heard as unnatural additions, in order to minimize their effects. But such measurements are useless if we want to check how well the person is prepared to perform on Olympic games. The only measurement is, the real competition.
The same with sound system: if it is sick, we must measure certain things, sometimes working as a detective to find what is wrong. But we can't use the same measurements to tell how inaudible will be the whole system.
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Old 14th February 2012, 05:35 PM   #2353
dvv is online now dvv  Serbia
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Originally Posted by john curl View Post
Dvv, I hope that I am allowed to tell you what I think.
I have done comparative tests over the years, and I have heard differences in materials, even when the measurement similarity implies that it should not be there.
Over 30 years ago in an LTE in 'TAA', I wrote about this comparison in response to Dr. Lipshitz, one of the champions of ABX testing, comparing the very new (at the time) 5534 IC and one of my studio board quality discrete circuit boards. I heard the difference and reported it, and of course, as I had not followed ABX protocol, it was dismissed by Dr. L. However, IF I was really prejudiced in the comparison, I would have heard NO DIFFERENCE, because that would have been the cheaper and easier way to build future products. However, with some individuals, you can never get past the opinion that there are few important differences, and therefore you must be imagining things.
Secondly, when it came to differences between silver and copper hookup wire, I made a comparison test of that as well with the Blowtorch preamp.
You see, my business partner died, unexpectedly, leaving me to finish 5 units that were already paid for, for someone in Japan.
Unfortunately, somebody ran off with the spool of silver wire that he used as hookup wire for the previous 40 units, and it was almost impossible to replace, so I looked for the highest quality copper hookup wire that I could find, and we built a unit with it, instead of the silver wire that was traditionally used. Then I had to listen carefully to the final result, and there WAS a difference, but it was small enough to get away with to individual customers, so long as they did not have an original to directly compare to. In fact, it was easier to listen to the copper wire version than the silver wire equivalent. We proceeded to make the next 5 units in this way, and now they are in Japan.
Still, it always nags me that the difference was there. So be it.
In reality, you can never prove your position to someone who simply does not believe that differences of this kind exist. Tests will be demanded, parsing of protocol procedure will ensue, and nobody will be satisfied.
First, let's be done with the protocol - John, you are welcome to offer your views, whatever they may be, to me at any time. Agree or disagree as you see fit, because even if you disagree, and say why, I am still learning - rest assured that I will at least seriously review my own opinion. I have followed your work for over 35 years, since the early days of Mark Levinson, on to the Parasound, which remains one of my (as yet) unfulfilled wishes. As far as I am concerned, you have "made your bones" several times over and that means I can only benefit from your knowledge. I am Old School, a definitely dying breed in these fast strike, fast buck days of whizz kids, and have been taught to respect solid work.

As for your above text, this is EXACTLY the same situation, just the background is different, and I am one up on you here, because I keep the silver wire under lock and key.

As you said, the difference is small, but it's there. If we used the much cheaper but still excellent copper wire, nobody but us would even know, until some DIYer changed the wire and reported the difference, or some such.

But I would know, and it would nag me to hell and back because I would always think I had not quite done the job, when I so easily could have. And that's something I don't want to live with.

I quite agree with your view that some things you cannot prove even if you yourself are aware that they are there, but even so, it's healthy to get one's *** kicked here and there by even some total sceptic because I think we all tend to drift away a bit, sort of shut ourselves into our own views more than is good for us. Sometimes, this can lead us into very much dead end streets without us even noticing it.
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Old 14th February 2012, 05:41 PM   #2354
dvv is online now dvv  Serbia
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Originally Posted by SY View Post
Yes, we had dinner, drinks, and a lot of conversation at one of the Burning Amp festivals in San Francisco. Good guy, doing some impressive work.
Yes, he is guilty on both counts. A man well worth knowing.

You should meet his dad, whom he takes after - just as impressive. Strong willed, opinionated, overt, but you get the feeling that if he's got your back, you're safe as houses.

If you liked Aca, I suspect you'd love Milan Karan (Karan Acoustics | Manufacturer of High-End Audio ). All 6'6'', 260 lbs of him, if there was a real life Gentle Giant, that would be him. He makes some awesome audio products.
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Old 14th February 2012, 05:49 PM   #2355
dvv is online now dvv  Serbia
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Originally Posted by Wavebourn View Post
There are 2 big differences: to evaluate thoroughly if change of a part of a wire can be used by a customer to claim that the device sold is not as as advertised, and the real difference when it is clearly audible that it is a breakthrough, and it sounds like a real band in your room. When water running on record caused my subconscious reaction of jumping and turning around; when my guest said that he wants too a house near a creek because he likes how frogs sing; when my father in law insisted tat somebody played piano in our house; when my guests were scared by roaring lion; all this and other things happened when I did not use special cables, capacitors, triple-more-blind tests. All bits added to reproduction quality are valid, but the end result is always the same: the better is the system, the less it is heard itself.
However, we can use thermometer, X-rays, to check what is broken in human body. Like, designing equipment I always measure how big are things that are heard as unnatural additions, in order to minimize their effects. But such measurements are useless if we want to check how well the person is prepared to perform on Olympic games. The only measurement is, the real competition.
The same with sound system: if it is sick, we must measure certain things, sometimes working as a detective to find what is wrong. But we can't use the same measurements to tell how inaudible will be the whole system.
Agreed.

Only in this case, we were not dealing with anything as big as a revelation or some such, simply an improvement. And small as it may be, it gets the device nearer to disappearing.

Anyway, I don't believe in revelations, perhaps because I've never witnessed one and because I don't write for magazines. I believe in slow, steady work, and improvement in small steps, I believe that a working project is never finished, because I think everything can be improved, even if by only a little.
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Old 14th February 2012, 06:03 PM   #2356
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Originally Posted by dvv View Post
Agreed.

Only in this case, we were not dealing with anything as big as a revelation or some such, simply an improvement. And small as it may be, it gets the device nearer to disappearing.

Anyway, I don't believe in revelations, perhaps because I've never witnessed one and because I don't write for magazines. I believe in slow, steady work, and improvement in small steps, I believe that a working project is never finished, because I think everything can be improved, even if by only a little.
Me too! But if each step does not lead to break-through heard as disappearing of equipment they are wrong steps.
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Old 14th February 2012, 06:12 PM   #2357
jcx is offline jcx  United States
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Default random observations - not specific criticisms

even 0.5% resistor tolerance may not be enough - the worst "worse case" for 2 gain setting networks with 0.5% R is a 2% level mismatch which can be "clearly audible" as a difference but not percieved as a loudness change

level, frequency response matching to better than Clark's ABX threshold curves are considered an absolute necessary condition for anyone from the psychoacoustic science camp to credit subjective discrimination as possibly "interesting"

ABX Amplitude vs. Frequency Matching Criteria

with only 20 dB negative feedback the open loop gain match needs to be better than 10% to even get to the 1%, 0.1 dB level - people seldom match semis for all gain limiting "parasitics" like output conductance

the level, frequency response matching should be verified at the final, post switch electro-acoustic transducer terminals – I assume many won’t have the mics and room/couplers to do actual listening position SPL measurements with good repeatability

better consumer/prosumer soundcards have the resolution, repeatability, if not absolute accuracy or channel matching

it could be illuminating to see if the difference is robust enough to survive hi res digital encoding - maybe Audio DiffMaker can find the difference in the amp’s outputs

I would certainly try it to characterize, eliminate any measurable differences before even considering subjective evaluation

Last edited by jcx; 14th February 2012 at 06:18 PM.
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Old 14th February 2012, 06:34 PM   #2358
dvv is online now dvv  Serbia
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Originally Posted by jcx View Post
even 0.5% resistor tolerance may not be enough - the worst "worse case" for 2 gain setting networks with 0.5% R is a 2% level mismatch

level, frequency response matching to better than Clark's ABX threshold curves are considered an absolute necessary condition for anyone from the psychoacoustic science camp to credit subjective discrimination as possibly "interesting"

ABX Amplitude vs. Frequency Matching Criteria

with only 20 dB negative feedback the open loop gain match needs to be better than 10% to even get to the 1%, 0.1 dB level - people seldom match semis for all gain limiting "parasitics" like output conductance

the level, frequency response matching should be verified at the final, post switch electro-acoustic transducer terminals Ė I assume many wonít have the mics and room/couplers to do actual listening position SPL measurements with good repeatability

better consumer/prosumer soundcards have the resolution, repeatability, if not absolute accuracy or channel matching

it could be illuminating to see if the difference is robust enough to survive hi res digital encoding - maybe Audio DiffMaker can find the difference in the ampís outputs

I would certainly try it to characterize, eliminate any measurable differences before even considering subjective evaluation
Odd that you should say the above.

For decades, I maintained that gain inbalance in a stereo amp will null an awful lot of spatial information in the signal (assuming it's there, of course). I've been called names not to be mentioned in polite company. Some people are just born naturally stupid, I guess, and there is no cure.

Once, for the hell of it, I installed trimmers as pots on the input of a lowly, some would say Zero Fi, Technics integrated amp, one of those using chip amps. After some fiddling to adjust the output level to within 1 mV of the target signal (thank God it was a multiturn trimmer!), which was 17.9 Vrms into 8 Ohms, or 40 Watts, we (the owner and I) did hear more detail in the same system, under the same conditions as before "the mod", with the "Tone defeat" switch ON, which incidentally bypasses the balance pot as well.

I think a designer is faced with a choice here. One, he can use 0.1% metal film resistors, which are kinda hard to come by and are by no means cheap, but the worst is that in my admittedly limited experience, they deviate from nominal values by a lot more than 0.1%, I've seen even 0.3%. Two, he can just take his chances and use standard 1% resistors, perhaps checking them out by measurement before installatio. And three, he can install a 25 turn trimmer and go for precision adjumstment.

Logically, the third option is the best, but it does have the one obvious caveat - it puts that trimmer slap bang in the middle of the signal path, and multiturn trimmers are not known for their sound quality. But, if you're on a tight budget, I'd go for that option as the most cost-conscious.

Regarding semis, you're quite right in stating people do not match them for anything else but sheer gain. I suppose that's better than nothing, but on the other hand, real transistor analyzers are rather expensive and are simply not readily available to most of us. In other words, I can't afford one, much as I'd love to have it.

If I'm wrong, please, PLEASE let me know.
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Old 14th February 2012, 06:38 PM   #2359
dvv is online now dvv  Serbia
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Originally Posted by Wavebourn View Post
Me too! But if each step does not lead to break-through heard as disappearing of equipment they are wrong steps.
Obviously, why bother with a mod which does nothing worth mentioning otherwise?

But then, none of us knows how many small steps it will take for the equipemtn to sonically disappear, do we? So we work on, step by step, hoping to reach it relatively soon.

But admit it - it's FUN! Every little step brings its own rewards.
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Old 14th February 2012, 10:13 PM   #2360
tvrgeek is offline tvrgeek  United States
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How much factor can you give that if a change makes an audible difference by reasonable test methods, and you have invested considerable intellectual capital, that the change will be presumed positive when it may not be?

I would think that conformation of an audible difference is the invitation to find an objective measure of the difference. Without objective measurements, we are reduced to art. Not knocking art, but I like engineering too.
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