Microphony III

[BE718]

QUOTE To return to the OP, I’d still like to know what is going on. If it isn’t microphony (at least in the terms investigated here, and I did suggest some enquiries which haven’t taken place and no doubt there are others) then what is it? Psychoacoustic suggestibility is, of course, one possibility, but you won’t prove it by a process of elimination. Nor will you eliminate it by making people doubt the evidence of their ears.

The best I can offer is the possibility of Resonance, there is some evidence of this in the nature of the material and structure of the stand in Steven’s photograph, and the fact that he hears an improvement or change when damping is added (an assumption on my part). The load of 40kg is probably quite high for the structure (stand) and the subsequent deflections and strain energies make it a possibility. I get a sense of similar thoughts from Tony L’s comments. In Be718’s very useful work, his own stand is very rigid – both the structure and the glass shelves, so not particularly prone to resonances which would impact on solid state, or even valve kit. The impulses from the 300hz load from is amp are extremely low, so the two cases are quite different. Again noting Tony L’s comments valve equipment is a little more sensitive to its environment than solid state, although the fact that Westlakes dac ‘sound’s’ better without the case is a puzzle that requires some sort of explanation. BE could probably do some bump tests on Steven’s stands to confirm the validity of this theory, but I guess that’s not possible. or even practical

Like you I think it unkind to insinuate that people are not hearing differences, and certainly to imply madness is out of order (although to be fair I did not see this in a quick scan of the posts). Our brains try to make sense of our world, and use past experience and acquired knowledge to do so – and we all get it wrong or different, occasionally, perhaps without exception.

Have a look over the past few pages I have made a response regarding resonances. I would love to test Stevens stand but I am about 10000 miles away !
There's no doubt his stand will have different natural frequencies to mine however, a less rigid stand will probably have lower natural frequencies. We have seen that lower frequency vibration will result in greater displacement.............interesting isn't it,

I do have an mdac I might play with it. If it's used with headphones and there's a difference without the case then acoustically induced vibration obviously isn't the answer. More likely internal rf.

Just because my stand is rigid doesn't mean it is not prone to resonances. One doesn't follow the other. I'll bump test it again tonight to demonstrate. A wine glass is pretty rigid, rings like a bell!

 

[cooky1257]

I blame the top-notch Manchester ales consumed afterwards meself!

The discoveries of which materials work better (or even worse against expectation) have been accidental on a few occasions.

PEEK was an accidental discovery as it was chosen as a tougher material to replace acrylic screws that kept splitting under stress from the stand flexing front-to-back. It was then discovered that as well as being stronger, it sounded better too.

My own experimentation with PEEK has confirmed this to my own satisfaction.

PEEK has a variety of applications-the surrounds of my Beryllium diaphragms are made of it. I have no doubt it's robust enough to hold stuff together. It's interesting that you attribute the change in sound to the change in material rather than the change in the level of torque you can apply to hold the stand together.

 

[Steven Toy]

No. Never said that. You know I haven't. Straw man anyone?

My input thus far has been to demonstrate the mechanism you think is happening (Your stand isolating vibration) almost certainly isn't.

I have also demonstrated that any effect on my ss amp due to acoustically induced vibration from a 90dB(A) pink noise and sine source-is below its noise floor of -125 dB ref 1volt, which is below the threshold of hearing. The effect, if there is one, is more akin to invisible than your terminology of subtle. Draw your own conclusions if you like.

It is of course entirely possible that you valve amp is grossly microphonic. If it is then I'll remain happy with my ss amp

The stand supports all of my equipment (except two PSUs and the mains block that have their own stands) not just the amplifier.

The amplifier is more microphonic than a solid state amp but sounds better to my ears despite this. It sounds better still for sitting on a ReVo stand.

Good designers come upon trade-offs and the need to make compromises. The skill lies in the choices they make.

 

[Steven Toy]

PEEK has a variety of applications-the surrounds of my Beryllium diaphragms are made of it. I have no doubt it's robust enough to hold stuff together. It's interesting that you attribute the change in sound to the change in material rather than the change in the level of torque you can apply to hold the stand together.

The level of torque seems to matter too. There seems to be a fairly broad optimum level and too tight may be sonically deleterious.

The cause of the screws splitting was not too much torque applied to them but the flexing of the upright sections when equipment was being placed upon or removed from the stand. The screws are also designed so that they can only be turned with the thumb and finger.

 

[Hipper]

Again, I'm afraid you are asking impossible questions. Define significant? Significant wrt what?

low frequency at a low amplitude won't cause a building to vibrate. An earthquake however.....

There is no absolute. The relationship between a,v and d is relative, it doesn't mean that at a low enough frequency displacement suddenly becomes a problem....whatever you define problem aS

Sorry

'Significant' means to me something that concerns our discussions here, namely that it might have an effect on our audio equipment.

Perhaps you could offer a comment on Keith's example:

One of the engineers from Speirs & Robertson told me that they encountered a particular problem at a research institute which was set in a secluded area, at certain times of the day, the ESMs would be affected by vibration.
Eventually they tracked the issue down to a railway line some ten miles away, the vibration coincided with the goods train passing.

(I don't know what 'ESMs' are)

 

[Purité Audio]

Electron Scanning Microscopes, that particular problem would not be an issue for us.
They are an interesting company , their isolation platforms and tables are used under ,NFM's ESMs and incredibly accurate balances, in laboratories and research institutes all over the world.
They use a rolling air diaphragm ,which isolates in three plains, it works effectively from a few Hz upwards, I use one of their active air designs under my GPA Monaco turntable.
If you really want to isolate something then they are the people to go to.
Keith.

 

[westsea]

Have a look over the past few pages I have made a response regarding resonances. I would love to test Stevens stand but I am about 10000 miles away !
There's no doubt his stand will have different natural frequencies to mine however, a less rigid stand will probably have lower natural frequencies. We have seen that lower frequency vibration will result in greater displacement.............interesting isn't it,

I do have an mdac I might play with it. If it's used with headphones and there's a difference without the case then acoustically induced vibration obviously isn't the answer. More likely internal rf.

Just because my stand is rigid doesn't mean it is not prone to resonances. One doesn't follow the other. I'll bump test it again tonight to demonstrate. A wine glass is pretty rigid, rings like a bell!

Thanks
It is interesting, relationship between rigidity, displacement, mass etc. I would like to have a handle on these, from your bump test note I looked at this https://www.ctconline.com/pdf/pubTechPapers/13-Bump Testing.pdf

I found it very useful (forgive me if I am teaching you to suck eggs) I have designed structures where the natural frequency was critical - in the late 50's; no calculators, it took nearly a month of hard solid work - so I would like to get a handle on the key factors, I doubt I could come to an in depth understanding as the number of variables is uncommonly high
PS the wine glass is in effect a bell ( i used to ring them a few years ago, will have a think - are they a special case? they are designed to resonate a specific frequency's with an obvious relationship to mass and frequency

 

[ultrawomble]

PEEK was an accidental discovery as it was chosen as a tougher material to replace acrylic screws that kept splitting under stress from the stand flexing front-to-back.

Is that a scientific term for wobbling?

 

[BE718]

Thanks
It is interesting, relationship between rigidity, displacement, mass etc. I would like to have a handle on these, from your bump test note I looked at this https://www.ctconline.com/pdf/pubTechPapers/13-Bump Testing.pdf

I found it very useful (forgive me if I am teaching you to suck eggs) I have designed structures where the natural frequency was critical - in the late 50's; no calculators, it took nearly a month of hard solid work - so I would like to get a handle on the key factors, I doubt I could come to an in depth understanding as the number of variables is uncommonly high
PS the wine glass is in effect a bell ( i used to ring them a few years ago, will have a think - are they a special case? they are designed to resonate a specific frequency's with an obvious relationship to mass and frequency

Yep, the CTCs article covers the basics. We do use CTC accelerometers, however they aren't the highest quality. Far prefer the wilcoxons. Just as a note the accel manufacturers websites are usually a good technical resource.

One of the big problems I have with these stands is that they are essentially generic. Let's Assume for one moment that resonance of the stand is an issue and vibration being transferred into the equipment at those natural frequencies and causing problems.

If you change your amp for example for a different one, the change in mass will change the stands natural frequencies. The result is therefore random depending on your kit.

Jo punter has absolutely no idea if he has improved the vibration or actually made it worse!

What are the natural frequencies of the amp? Does it coincide with the stand? What frequencies cause issues? The tube natural frequencies? Some other component? Again all this is going to be different with every piece of equipment.

Joe average has no capability to make any judgement on this, which is I cheekily (yet seriously) suggested to Steven that his improvements may not be, he may just like the sound of the additional distortion his stand creates ..........waits for the reaction

I'm off to get my rubber hammer out!

 

[BE718]

Bump test

OK, as an example, here is the stand natural frequencies with and without my MDAC sat on the top shelf.

without mdac

with mdac

 

[adamdea]

Like you I think it unkind to insinuate that people are not hearing differences, and certainly to imply madness is out of order (although to be fair I did not see this in a quick scan of the posts). Our brains try to make sense of our world, and use past experience and acquired knowledge to do so – and we all get it wrong or different, occasionally, perhaps without exception.

I'm not sure where you are going here, but

-it is not unkind to suggest that different hearing experiences may ensue for reasons other than a difference in the sound pressure waves reaching the ear.

-that possibility would be immediately apparent to any researcher in any of the various scientific disciplines in which it is necessary to consider the cause of such an experience and would likely to be one of the first things one anyone would seek to establish or reject in the course of an experiment.

-it does not equate to saying that someone is hallucinating, but is a consequence of the way our perceptual systems work. It is not reducible to concepts like expectation bias. It is not particularly intuitive nor is it amenable to self diagnosis either.

That's it really. It's not rude and it's not remote. I'm afraid most people on a hifi forum are inclined to approach this problem arsy versy for the very reason that it's not intuitive, as well of course as the obvious selection effect of membership of the cohort. There is however no excuse for persistently and wilfully not getting it.

 

[Steven Toy]

Joe average has no capability to make any judgement on this, which is I cheekily suggested to Steven that his improvements may not be, he may just like the sound of the additional distortion his stand creates ..........waits for the reaction 

Although this is a self-confessed troll I shall respond.

I think it is very unlikely that all of the following improvements are the result of added distortion:

● Improved transient response.

● More depth to soundstage.

● A more precise and focussed image.

● Improved perceived dynamic range and contrast.

● Better resolution of high-frequency information like harmonics and decay.

● Better perception of changes in pitch, ie. melody.

● Improved perception of the separation of different musical strands (voices or instruments) producing harmony.

● Greater ease in following individual rhythmic patterns and the interplay between them in recordings.

● A greater sense of the acoustic space (either artificial effects or real) in which the recording was made, especially decay and reverb.

● Improved perception of instrumental tone and 'texture' across the entire frequency range.

● A reduction in perceived 'glare' that can make busy recordings sound a little muddled.

Read each one above one more time. I think you'll agree that it's a bit more than "Steven likes the effect" or Orwellian Newspeak "double plus good."

I can understand the resistance from the naysayers. Nobody would want to believe that they were missing out on the improvements that I've outlined above, would they?

If (and it's a big if..) these improvements were as a result of added distortion, you'd be able to measure it, wouldn't you?

 

[adamdea]

Bump test

OK, as an example, here is the stand natural frequencies with and without my MDAC sat on the top shelf.

without mdac

with mdac

So the M-dac is quite good at damping the stand's resonance at 100, 200 and 400Hz?

 

[Steven Toy]

Bump test

OK, as an example, here is the stand natural frequencies with and without my MDAC sat on the top shelf.

I used to have a stand similar to this. Moving to a Quadraspire Reference stand was quite a big upgrade back in 2001.

Those uprights are made from some kind of alloy or stainless steel and they are hollow. The shelves are made from glass and are not damped sufficiently. With a pen, tap one of the uprights and a shelf.

I bet they ring like the proverbial bell. That ringing is singing along with your music.

Your kit will sound better plonked on the floor, especially if you moved that stand to another room.

 

[Steven Toy]

Is that a scientific term for wobbling?

The wobbling of the uprights causes the acrylic screws to flex and split.

Semantics?

 

[Michael J]

The wobbling of the uprights causes the acrylic screws to flex and split.

Semantics?

A design issue, perhaps?

 

[Purité Audio]

I used to have a stand similar to this. Moving to a Quadraspire Reference stand was quite a big upgrade back in 2001.

Those uprights are made from some kind of alloy or stainless steel and they are hollow. The shelves are made from glass and are not damped sufficiently. With a pen, tap one of the uprights and a shelf.

I bet they ring like the proverbial bell. That ringing is singing along with your music.

Your kit will sound better plonked on the floor, especially if you moved that stand to another room.

Have you looked at any of Alan's previous measurements carried out on that very rack?
Keith.

 

[Steven Toy]

Have you looked at any of Alan's previous measurements carried out on that very rack?
Keith.

Just tap it with a bloody pen!

 

[Steven Toy]

A design issue, perhaps?

Design is a balance of compromises.

 

[Hipper]

Electron Scanning Microscopes, that particular problem would not be an issue for us.
They are an interesting company , their isolation platforms and tables are used under ,NFM's ESMs and incredibly accurate balances, in laboratories and research institutes all over the world.
They use a rolling air diaphragm ,which isolates in three plains, it works effectively from a few Hz upwards, I use one of their active air designs under my GPA Monaco turntable.
If you really want to isolate something then they are the people to go to.
Keith.

I looked at their site.

Interestingly I couldn't find any scientific reports on the effectiveness of their products!

There must be something they are trying to isolate from. They mention airborne vibrations without saying where they come from and also mention buildings without going into detail.

In my travels I came across this:

http://www.strattontechnologies.co.uk/active-vibration-isolation/silencer/

http://www.audiotechnique.com/reference/accurion/364_accurion_eng.pdf