Vibration, isolation and electronics...

Phelonious Ponk

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Continued from Jeff's WBAS thread, from here, where Jack said:

That's not entirely true Tim and you're using the same logic as Micro when you invoke the Pro world. There are many vibration isolation products for speakers and equipment for pros and they are gaining in popularity. Auralex makes the MoPad, Adam ships with their own set of pads, potting is common for quite a few onboard components. New potting agents for high temperature instrumentation are popping up regularly and can be bought in bulk. What one has to take into account with pro gear is that electronics are usually rackmounted and these enclosures help protect the chassis of the equipment and the mounting couples the equipment (the heavy faceplates do have a reason for being there. Meanwhile, soffit monitors are decoupled and near field monitors are now getting either pads or joint and elbow devices. They know the problems exist and they are addressing them. That the domestic market beat the pro world to the punch is more a function of the domestic market simply needing it more. $40 Tim, give them a shot with your monitors if you aren't using any yet and let us know if they work or if the Pro world is just trying to carpet bag the pro market. :)

Two different conversations, Jack. What you're talking about is isolating the monitors from the console desk in the case of near fields and from coupling with the walls in the case of soffit-mounts. The point there is to keep architectural and furniture resonances from buggering the frequency response of the monitors. What micro and Frank are talking about is the common audiophile belief in ground vibrations that cause audible (but oddly immeasurable) distortion in electronics. It is not totally unfounded, but like many audiophile myths, while the problem exists in the extreme (a turntable sitting on a subwoofer comes to mind), it is, according to the data, a non-issue in common practice. The fact that amps work so weill, mounted directly inside active monitor speakers effectively debunks the myth in my view. YMMV.

Regarding the kind of monitor isolation you're referring to, I've already gone way beyond pads. My monitors are isolated, I'm sure, to a degree that is absolutely unnecessary. But it makes me feel better. :)

By the way, the pro world is not a completely myth-free zone. There are audiophile/engineers. They're pretty rare, but they do exist, and I've found more than a couple of them that believe, as many audiophiles do, in ghosts in the machines that cannot be quantified yet still manage to be very, very scary. Steve Hoffman is one of the best-known of the breed, and I've found some of his mastering work that seemed dulled in an attempt to make it sound more analog. Yesterday, however, I acquired his re-master of Bill Evans' "Explorations." Absolutely gorgeous.

Tim
 

Jeff Fritz

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JackD201

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I really don't know what you expect from me Tim. Microphonics wasn't completely banished by solid state. You don't need me to prove that.

All I said is that Pro and High End designers know it exists and do what they have to do to keep it from being a problem. I never said your amps were microphonic or that amps or passive circuitry couldn't be put in loudspeaker enclosures but since somebody did all I can say is that it doesn't mean it can't be addressed.
 

FrantzM

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Have a look at the Magico QPod, screen 3 (scroll over for the measurements):

http://magico.net/Product/QPOD/QPOD_03.php

Interesting but how does this translate into the electric signal. Does the electrical impulse response change with the use of the Q-pods? The chassis could well ring like a bell while the electrical characteristics remain unchanged.
 

Phelonious Ponk

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I really don't know what you expect from me Tim. Microphonics wasn't completely banished by solid state. You don't need me to prove that.

All I said is that Pro and High End designers know it exists and do what they have to do to keep it from being a problem. I never said your amps were microphonic or that amps or passive circuitry couldn't be put in loudspeaker enclosures but since somebody did all I can say is that it doesn't mean it can't be addressed.

I know it wasn't you who said that, Jack, and I understand that good active monitors are designed with the circuitry anchored firmly enough not to rattle about. I don't want anything from you, my friend, but the conversation I was in with Frank and micro was about how active speakers must have problems from internal vibrations, and your examples were mostly about external, airborne vibrations.

Tim
 

Phelonious Ponk

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Interesting but how does this translate into the electric signal. Does the electrical impulse response change with the use of the Q-pods? The chassis could well ring like a bell while the electrical characteristics remain unchanged.

Well hush my mouth. I've never seen that before. I still can't imagine it is a serious problem that can't be addressed in design or there wouldn't be a worldfull of active monitors with electronics right inside the cabinet without any QPods in there.

Tim
 

Jeff Fritz

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Well hush my mouth. I've never seen that before. I still can't imagine it is a serious problem that can't be addressed in design or there wouldn't be a worldfull of active monitors with electronics right inside the cabinet without any QPods in there.

Tim

Well, some can't imagine that there are a whole lot of speakers claimed to be SOTA that have tweeters that go all earthquake before they reach 20kHz. But it happens everyday.
 

Phelonious Ponk

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Well, some can't imagine that there are a whole lot of speakers claimed to be SOTA that have tweeters that go all earthquake before they reach 20kHz. But it happens everyday.

Imagine or no, there are a whole lot of engineers whose hearing is highly trained for detail, and whose active systems have extremely high resolution and low noise floor. And instead of running back to passive systems, they're running away from them. Clearly they don't hear this problem.

All earthquake?

Tim
 

microstrip

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Tim,

Any decent text book in low level instrumentation will extensively refer to noise, including microphony effects and many others. Designers know how to deal with with them it in their projects and many excellent instrumentation systems have been built using these principles. Some will even advertise it. But if you look for the public tests you are asking or academic publications with results and conclusions you will not find them. May be they carried them and consider them classed information they do not want to release. Can you conclude they are deceiving you and participating in the big microphony conspiration ? Are you expecting that Nordost will release the DIY guide to manufacture ODIN cables in your garage? :eek:

BTW, we should not forget that audio professionals or engineers needs are different from audio consumers or audiophiles as we often call them in this forum. Sometimes you seem to forget that there are "audiophile/engineers" and "engineer/audiophiles". Do you know the difference between them?
 

Jeff Fritz

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Imagine or no, there are a whole lot of engineers whose hearing is highly trained for detail, and whose active systems have extremely high resolution and low noise floor. And instead of running back to passive systems, they're running away from them. Clearly they don't hear this problem.

All earthquake?

Tim

Yes . . . as in Richter Scale . . . OK, bad joke. To pick on a speaker that I know won't get me in trouble (because the company is long out of business), you can clearly see where this soft dome breaks up:
http://www.soundstagemagazine.com/measurements/soliloquy_65/

The speaker measures very nicely otherwise. Do you think this would be a problem in the right room with, say, hi-rez source material? Look off axis . . .

The point is that this is an area that has been solved with the best designs. Some of the worst metal domes look much worse.
 

Phelonious Ponk

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I'd like to see the signal leaving the preamp before and after the isolation. I'll go out on a limb and suggest that there is no change. The chassis vibration differences are interesting, but the question remains does isolation contribute to fidelity?

Exactly. And regarding micro's question above about Nordost releasing a DIY guide to their products, nobody is asking for anything of the kind. Some data supporting the notion that there is an audible effect, however, is not too much to ask of expensive products with great claims.

Tim
 

microstrip

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Exactly. And regarding micro's question above about Nordost releasing a DIY guide to their products, nobody is asking for anything of the kind. Some data supporting the notion that there is an audible effect, however, is not too much to ask of expensive products with great claims.

Tim

As you probably know, most of the existing data was obtained in tests "carried by skilled ears, one of the most powerful existing instruments" ( I am quoting the Burmester site). Something that I am 100% sure it is not enough to please you, as it was not carried in your system and in your presence :( .
 

Phelonious Ponk

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As you probably know, most of the existing data was obtained in tests "carried by skilled ears, one of the most powerful existing instruments" ( I am quoting the Burmester site). Something that I am 100% sure it is not enough to please you, as it was not carried in your system and in your presence :( .

A manufacturer's own subjective opinion of their own products shouldn't be enough for anybody. We all need to listen first, and when we're talking about something as questionable as this, I personally require some objective confirmation of audibility before I'll even seek the product out for an audition. Clearly your mileage varies.

Tim
 

fas42

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We're bogging down yet again in this subjective vs. objective quarrel, and really, it is a red herring. There is many areas of life where it is impossible or very difficult to get objective "proof" that something is superior in some area of behaviour, yet we still go forward and make good decisions based on "seat of the pants" appraisals. When was the last time you purchased a vehicle on basis that technical tests "proved" that the vehicle could perform at some level? What if suddenly dealers said you couldn't take a vehicle on a test drive before purchase; they would just shove a heap of paperwork in your hands that "proved" that their car or SUV did what they claimed and you had to be satisfied with that?

Frank
 

Phelonious Ponk

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In this particular case, Frank, I'm not looking for technical proof of performance. I'm just looking for evidence of audibility. I have every theoretical and practical reason to believe it is not, right up to and including hearing great clarity and resolution in systems that have the amps literally inside the speakers while people are selling schemes to isolate components in a separate chassis from vibrations that come up through the floor and the rack. I'm tired and this is probably going to be a clumsy extension of your analogy, but this is more like you're trying to sell me an upgrade to the SUV that isolates the cab from the tinniest flaws in the pavement. Meanwhile, I'm driving down a pothole-laden dirt road in the un-upgraded model and the ride is smooth as silk.

At that point you're going to have to come up with a bit more than "the vibrations exist."

Tim
 

fas42

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I'm just looking for evidence of audibility
My evidence, is that for many systems the SQ changes as you up the volume. Perhaps you, but certainly others, would state that this is due to driver distortion or room acoustics messing things up. But my own experiments with my own gear, have demonstrated that vibration, along with power supply quality and other things, are the culprit here, able to create that "ball of mess" sound that has been mentioned elsewhere. I've been able to run symphonic works, Deep Purple, Led Zeppelin, and similar at maximum volume without those problems, because I have worked hard to eliminate these causes of bad sound -- if I didn't worry about vibration issues my sound would be as mucked up as anyone else's here.

Of course, if you are able to run your setup flat out without any degradation then obviously it's all been sorted out and vibration and everything else has been properly engineered out of the equation ...

Finally, the vibrations always "exist", the key thing is to stop them getting to places where they could do bad things.

Frank
 

Orb

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Tim,
I do not think there can be a satisfactory answer either way, because I am not sure there is enough detail or studies done to look at the real world and specific to audio products.
Furthermore this discussion would be compounded with the same issues surrounding other threads such as are we measuring the right parameter with enough detail and how does this apply to being audible - bit like jitter discussions or even the measurement thread.
In summary that leads us to there being no conclusive answer that can satisfy most.

One practical example of microphonics being audible is that of the more recent Conrad Johnson tube preamp (below the reference product) that suffers from this and also is audible.
But then some will counter that this level of microphonics is only applicable to tubes and how much is too much in solid state (to me this cannot be answered), the only point that can be made from is that there it is a real world example but its architecture-topology does not reflect all product sold.

Cheers
Orb
 

Phelonious Ponk

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Furthermore this discussion would be compounded with the same issues surrounding other threads such as are we measuring the right parameter with enough detail and how does this apply to being audible - bit like jitter discussions or even the measurement thread.
In summary that leads us to there being no conclusive answer that can satisfy most.

Agreed. This also functions as an answer to Frank's post above regarding distortion increasing with volume. That could be anything, and even if it is vibration, it is most likely to be airborne. None of it is sufficient to support micro's original post, the one that started all of this, which implied that active speakers were inherently and severely compromised by vibrations because the amps are inside the speaker cabinets. I still contend that the opposite is true; that the clarity and precision of good active studio monitors is the best evidence that the whole vibration theory is flawed. Again, I don't doubt that the vibrations are there. I'm absolutely convinced they are inaudible in most systems.

Tim
 

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