Do you isolate your gear?

Mark C Flick

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Would be interesting. I do not disbelieve there is an improvement, just does not seem plausible to me. Then again, I'm happy to be proven wrong and learn something new.
 

mike w

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I can understand isolation for source components and maybe speakers but not isolation for electronics. All those data centers that make this forum conversation even possible might want to rethink how they cool their web-servers. (The internal fans they currently use to cool the compute boards add significant vibration to the electronics). Not to mention all those active speakers makers that have their amps strapped to a thumping electro-mechanical device.

I would like to add a couple things that I think are missing from the explanation of experimental practice.
The onus is on the designer/ manufacturer making the device to substantiate their claims of how their product has better performance or value, not the other way around. But they never do. They rely on anecdotal evidence. (Hey, I saw David Copperfield make the Statue of Liberty disappear. Are you going to tell me that wasn’t real??). They hide behind the null hypothesis and say the 3rd party experimenter didn’t prove that their device was better because of the following reasons.....blah blah blah. So, nothing is decided by the test they say, please refer to our marketing material. Actually, what was decided was that the difference was so small as to be insignificant under those test conditions.

There is a distinction between statistical difference and technical difference. Given unlimited budget, a large enough sample size and and a capable metrology, we could detect very small differences with statistical significance. As a practical matter, no one does this. (Matt mentions this.)

The Benchmark DAC3 has benchmark measurements. Certainly, there is no reason to buy anything more expensive, although there are many options available, since it is unlikely to have better performance - no practical technical difference. Any differences are way below the audible threshold. Actually, you can go the other direction cost-wise and buy a less capable product because you can’t hear the difference anyway. http://archimago.blogspot.com/

Why bring this up? Because real products with real value get buried in the sea of marketing hype. So, how do you sort thru the to find value? The Audio Media doesn’t help much. Maybe I’m just lazy. I could get the Isoacoustic GAIA with the 30 day trial and judge for myself. But I don’t see a reasonable explanation as to why this should make a difference. Inertia wins out. I’ll keep with my focus on room acoustics.
 

Matthew J Poes

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I can understand isolation for source components and maybe speakers but not isolation for electronics. All those data centers that make this forum conversation even possible might want to rethink how they cool their web-servers. (The internal fans they currently use to cool the compute boards add significant vibration to the electronics). Not to mention all those active speakers makers that have their amps strapped to a thumping electro-mechanical device.

I would like to add a couple things that I think are missing from the explanation of experimental practice.
The onus is on the designer/ manufacturer making the device to substantiate their claims of how their product has better performance or value, not the other way around. But they never do. They rely on anecdotal evidence. (Hey, I saw David Copperfield make the Statue of Liberty disappear. Are you going to tell me that wasn’t real??). They hide behind the null hypothesis and say the 3rd party experimenter didn’t prove that their device was better because of the following reasons.....blah blah blah. So, nothing is decided by the test they say, please refer to our marketing material. Actually, what was decided was that the difference was so small as to be insignificant under those test conditions.

There is a distinction between statistical difference and technical difference. Given unlimited budget, a large enough sample size and and a capable metrology, we could detect very small differences with statistical significance. As a practical matter, no one does this. (Matt mentions this.)

The Benchmark DAC3 has benchmark measurements. Certainly, there is no reason to buy anything more expensive, although there are many options available, since it is unlikely to have better performance - no practical technical difference. Any differences are way below the audible threshold. Actually, you can go the other direction cost-wise and buy a less capable product because you can’t hear the difference anyway. http://archimago.blogspot.com/

Why bring this up? Because real products with real value get buried in the sea of marketing hype. So, how do you sort thru the to find value? The Audio Media doesn’t help much. Maybe I’m just lazy. I could get the Isoacoustic GAIA with the 30 day trial and judge for myself. But I don’t see a reasonable explanation as to why this should make a difference. Inertia wins out. I’ll keep with my focus on room acoustics.
While I agree with some of the things you are saying, I want to be very careful with our language. We can hold any opinion we want, but we must be very careful that we don’t try to shield our opinion from scrutiny through a misuse of the scientific method.

Both statistically and conceptually we cannot accept the null hypothesis ever. Science, by nature, does not allow us to do that. To go back to a fundamental philosophical issue, we cannot ever prove that god does not exist. We can prove that god does exist. The same holds true in all of science. We cannot prove that something isn’t true, only that it is true.

We can’t prove that isolation devices make no audible difference. We can simply fail to support the notion that they do. We can hold the opinion that they make no difference. We can even say that science has so far failed to prove they make a difference.

It is not ok to use that science to suggest something is true. You can’t say that isolation makes a difference because science hasn’t proven that it does. That makes no sense. But you are welcome to hold the opinion that it does or does not make a difference. The counter remains equally true. You can’t say that because science has failed to show that it makes a difference, it must not.

In addition, it is to fair to say that tests which fail to find audible differences prove it doesn’t because whatever difference is does make is so small as to be impossible to readily detect. That makes a major inaccurate assumption about the study. That you have accounted for all alternative explanations. Andrew Gelman talks a lot about this in his explanation of the problems with P values. The null hypothesis is actually one of many alternative hypothesis. We work to control for the others but we can never control for all others. Studies always have some noise as a result of that.

Let’s take online double blind studies like Archimago did. Is that scientifically rigorous? It sure looks it. It used statistics, it controlled for some sources of bias, etc. It is not a high quality scientific study and I’m sure he knows it. It’s good blog fodder and that is all. He can’t and doesn’t control for the listener or listening conditions. He assumes people use high resolution listening gear and take the test seriously. A huge assumption to make and one that a century of research suggests is unlikely to be true.

If someone believes that all playback systems sound the same that there are three potential paths (or more) someone might take. 1) they take the test seriously and listen for differences but don’t expect to find them, 2) they strongly believe no such differences exist and do not seriously listen for them, 3) they intentionally sabotage the test, essentially trolling it.

I’ve also witnessed people take a listening test like this in a manner that clearly would obfuscate any differences. Listening through laptop speakers, on cheap headphones, or in a noisy environment.

Having done human subject research including preference testing, i have seen all of this happen. It is always standard practice in rigorous research to build in protections and to clean the data of responses which clearly are not in line with the testing assumptions. For example when assessing the validity of a new achievement test, we use a pattern recognition algo to detect people who answered with a pattern. They clearly weren’t even trying and their results would screw up the norm reference calculation.

You might say that it is unlikely that someone would troll an online blind listening test, but I’ve had people do it to me in person. I am sure it happens online. With ABx testing, there is no easy way to detect that and remove those answers. It’s one of many reasons why ABx is less favored today, MUSHRA being a better alternative. You can include questions that help you detect people who aren’t trying or are intentionally trying to mess up the test.

A lot in sound quality research is far more nuanced and less certain than most realize. I’m doing a bunch of work now related to the sound quality of low frequencies. I presented on my work in developing an alignment technique using wavelets and pointed out that this also allows someone to zero out group delay at low frequencies. That led to my looking into research on the audibility of group-delay at low frequencies. The commonly held belief is that it simply doesn’t matter. Some go so far as to say it only matters if it exceeds 1 or 2 cycles. Yet the research suggests something else all together. In fact it’s shockingly audible if the research is to be believed (it is so shockingly detectable at low levels that many, myself included, feel more replication is needed to accept such results). Distortion is another one, the research is mixed here but basically there is some research (not nearly enough) that suggests that extremely low levels of IMD or harmonic distortion are audible at low frequencies outside the masking zone. In other words, higher order distortions. Again, if we accept the handful of studies on this topic, it would suggest most of our assumptions and beliefs are wrong and we’ve been designing speakers all wrong.

Notice that I’m hedging my bets here. I’m not accepting the alternative hypothesis or fully rejecting the null. I’m saying we have evidence that suggests we need to do more research. We need to explain away bias, statistical forking paths, any alternative explanations. But just because I find them hard to believe doesn’t mean I’m rejecting them either. It points me In a direction where I want to do or see more research.

One problem with much of the audiophile soundquality Research is that academic researchers could care less. Those without a dog in the race aren’t doing this work. We have research that suggests HD audio is audible over SD audio, and other research that suggests MP3’s can’t be distinguished from SD audio or HD Audio. Which is it? My read is that it’s all very nuanced. Most recordings are so poor that the audible differences that can exist are obscured by the technique. As such, MP3’s are I distinguishable from better formats in many cases. However, it isn’t true to say they are always the equal in all music. Music can and does contain information that is audibly reproduced in a superior manner by these better formats. Even with high sampling rate, we have a bunch of new research that suggests that the differences are audible and it has nothing to do with hearing ultrasonics. I’m aware of a new study in review that may change our view of the nyquist frequency and provides a scientific basis for the potential audibility of high sampling rate music. I found it because I found huge differences in an analysis or HD vs SD vs MP3 audio streams in the audible range from 10khz on up. Further investigation found these issues to be robust using different analysis and different means of manipulating the tracks (I.e. just examining the HD sources and down-converting them myself). I assumed the mistake was mine and sent the results to a digital signals expert who told me his work into nyquist theorem actually explains this and did his own investigation. A small team of digital experts eventually looked into it and walked away certain the results are real but explainable by existing research adopted in DSP for radar. Basically that you actually need 4 times (or more) the bandwidth digitally to fully reconstruct the audible bandwidth without any errors.

And that is all very interesting but it’s a purely mathematical analysis. No listening tests and that remains the gold standard for making sense of this. I could share these tracks with everyone and do blondes testing. It would prove nothing useful. You really need to do controlled listening tests under blind conditions using MUSHRA. Nobody with the technology and budget to do that cares. The most I got was an offer to help with the analysis if I’m willing to collect the data. The hardest and most expensive part.
 

mike w

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Your research sounds interesting and challenging. To me, that’s the making of a fun job.

I don’t agree with your statements about the null hypothesis. I’ll comment more on that later. Your challenge to the atheist - to prove God does not exist has some broken logic in it. One cannot disprove a negative but you know that already.

I have run many, many DOE’s. Some with spectacular results, others not so much. In all cases, none of these tests were perfectly designed or executed. In the real world, nothing is perfect. Enter the hired statistician to review any audio test that I have ever read about on-line. Not surprisingly, this academic finds fault with the experimental design. And, like a lawyer, argues because of this fault we must reject all the findings (and preserve the financial well being of the cable purveyors, fusers, isolation scheme makers and other dubious audio product sellers.)

Archimago’s test was primarily for the individual test taker to determine if they could hear a difference and secondarily to understand how they compared to the population of test takers as a whole. This is not the making of a journal paper, nor was it positioned to be. I think even Archimago would agree that he has a ways to go to get to the academic rigor of say Robert Harley’s AES paper on the problems with ABX testing ;-)

Shewhart of Bell labs made it clear many years ago that everything has variation. Any thing made by man or nature has variation and follows a statistical distribution. Two Benchmark DAC3’s manufactured on the same day are not exactly the same. They may meet the same specifications but are not the same in every parameter. We say they are close enough. If not, end of line testing at Benchmark would have screened out the non-conforming product.

The question regarding the null hypothesis is whether the units under test are “significantly” different from one another. We define significant in this case by the success criteria i.e., tensile strength >10 psi, wear cycles >10K, noise floor lowered by 20dB, etc. We already know that they are different base on Shewhart but that is not what we are testing. It is easy to say whether the population of the test groups are “significantly” different after the test by the success criteria and confidence level that we chose before the test. Nothing is 100% certain but if we achieve results with 99% confidence, I’ll go with it.

If people cannot hear a difference between audio products unsighted, then there isn’t a significant difference. I accept the null hypothesis because I couldn’t demonstrate a difference. Full stop.

I wonder why after > 75 blind listening tests (primarily for speakers), Floyd Toole thought all good electronics sounded the same? I am weary of subjective reviews on questionable audio products. Where do you draw the line? Do you think magic dots on windows influence the acoustic properties of the room or that crystals attached to the back of audio gear improve the sound? If you cannot call this out for what it is, then all the products reviewed are tainted by this craziness and a huge discount factor needs to apply to everything reviewed. That is unfair to manufacturers with legitimate product.
 

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It seems strange to me that very minor vibrations would have an effect on sound stage. Perhaps it could somehow introduce some noise.... dunno... but sound stage?

Several of us visited the Isoacoustic room a few years ago at Axpona or RMAF... can't remember which... and we all thought we heard differences. I ended up getting a set of the feet, but sold my heavy 13A's before I could try them out... and what I have now is not as heavy. They look really nice ... so I may trade them in on the lighter model... just forgot all about them. Then we could do some testing on our next Cedar Creek Cinema GTG.
 

Matthew J Poes

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It seems strange to me that very minor vibrations would have an effect on sound stage. Perhaps it could somehow introduce some noise.... dunno... but sound stage?

Several of us visited the Isoacoustic room a few years ago at Axpona or RMAF... can't remember which... and we all thought we heard differences. I ended up getting a set of the feet, but sold my heavy 13A's before I could try them out... and what I have now is not as heavy. They look really nice ... so I may trade them in on the lighter model... just forgot all about them. Then we could do some testing on our next Cedar Creek Cinema GTG.
I’ve always been skeptical that they could make much difference. I’d be interested in what you guys find.

I used to have some fancy isolation devices I picked up at Purdue University that we’re used to isolate microscopes and things like that. They used air to adjust the resonant frequency and load tolerance. I found with my turntable it helped reduce some feedback problems I had where the speakers were feeding back vibrational sound into the pickup and causing weird noises. That was a highly unusual situation though. My turntable has no suspension and my speakers and turntable sat in the same platform.

I also used a really big one I had for my subwoofers. At the time I convinced myself it made a difference. Probably because it weighed some 200lbs and so did my subwoofer. After heaving 400lbs into place it sure has better made a difference. For what it’s worth, I couldn’t measure a reliable difference in the time domain, which I would have expected if that were the case.
 

Sonnie

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I could definitely see where isolation could be important for turntables... makes sense.

Danny Ritchie has a good explanation of why limiting subwoofer cabinet resonance is a worthy effort... although I'm still not sure I've ever experienced it.
 

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It seems strange to me that very minor vibrations would have an effect on sound stage. Perhaps it could somehow introduce some noise.... dunno... but sound stage?

Several of us visited the Isoacoustic room a few years ago at Axpona or RMAF... can't remember which... and we all thought we heard differences. I ended up getting a set of the feet, but sold my heavy 13A's before I could try them out... and what I have now is not as heavy. They look really nice ... so I may trade them in on the lighter model... just forgot all about them. Then we could do some testing on our next Cedar Creek Cinema GTG.
I'm generally very skeptical about all of this stuff. Obviously, I started this thread with a statement that I heard a difference in a show room (with isolation pucks). And I've heard the IsoAcoustics in action (you guys know that ;-). Sonnie, I experienced what you did with IsoAcoustics. I'm totally open, though, to there being some kind of placebo going on? Don't know. To be honest, it's really not something that I spend much time mulling over when it comes to systems.
 

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Nope, not needed in my case.

I don't believe isolation is beneficial with most well-designed gear. There are exceptions.
 

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When I had my old Audible illusions setup.... I tried various supports. The one I can still remember was Navcom pucks, and they def made a difference. I also made a custom steel rack that I filled with sand, and used marble shelves, and they also affected the sound. My experience with that preamp was almost anything you did would affect the sound. When I switched over to the Classe DR6 preamp, I was unable to hear any differences at all between various supports, and cables. Since then I still use spikes, tip toes, and pucks, but now I just do it because I like the way they look as I do not hear any differences at all between them.
 

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I’ll start out by saying I’m not a skeptical person. Rather, I’m a little more than gullible. Most if not all advertising for isolation products seems logical on the surface. Converting advertised results into practice is another story.

I tried Bright Star products and thought my system was pumped up a few notches. I put them under tubed electronics to alleviate microphonics caused by floor-borne vibration. Mechanical devices such as CD transports and hard drives also received treatment. Again, I perceived improvement, but I now realize that was probably due to expectation bias and buyer’s justification.

EDIT: In my usual haste, I forgot to say that Bright Star’s approach takes the shape of a mass loaded, RF shielded sandwich. An air bladder platform at the bottom serves as the isolation base for the audio component. Then there’s a ~30lb slab of material treated to reject RF noise which rests on top to load the mechanical system. IIRC, you were only supposed to pump in enough air to get a low oscillation of 2-3 Hz when pressing on one of the sandwich’s corners. Bright Star also encouraged the use of their sandbox-type isolators, which were intended for use under the sandwich.
 
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Negatron

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I’ll start out by saying I’m not a skeptical person. Rather, I’m a little more than gullible. Most if not all advertising for isolation products seems logical on the surface. Converting advertised results into practice is another story.

I tried Bright Star products and thought my system was pumped up a few notches. I put them under tubed electronics to alleviate microphonics caused by floor-borne vibration. Mechanical devices such as CD transports and hard drives also received treatment. Again, I perceived improvement, but I now realize that was probably due to expectation bias and buyer’s justification.
On your tube equipment it may actually have made a difference...it was 100% repeatable in my experience with a Audible illusions 3a tube preamp. We also were abke to hear a diffence when we moved to a custom welded steel rack vs a so so wooden rack, and with cables. The cables I believe now were noticable because of the output Impedance of the preamp not being low enough, and hence not matching. The input impedance of the amps. When I switched to the Classe DR6 preamp we could hear zero difference with the cables (Classe had less than 1ohm output impedance).
 
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