advertisement


Microphony III

That would depend upon a number of factors, how large the amplitude, the medium , air, or structural borne and how the object is connected to the structure.
Keith.
 
BE718, could you tell us please, in layman's terms, what sort of distance a 10Hz, or 30Hz (in other words low or very low) frequency would oscillate? A rumble from a lorry for example if it drove close to a house.

Not sure why you want to know this? depending on the size of the lorry and its load, and the nature of the ground, and the level of oscillation and its frequency you are interested in, then anything from zero to about 300 mtres. Yes, it is a very rough guess. Just think of earthquakes, depending on the seismic force the ground wave can travel miles, easily multiples of 10
 
Convenient excuse for what exactly? While we're at it where in my post did I refer to the need for a zen like state?

To not consider that there may be familiarisation/normalisation issues with unfamiliar systems/environments, which is what my post was pointing out, seems a very strange scientific outlook.

My point was obvious, the differences, if they exist, must be vanishingly small if you need to do that to stand a chance of hearing them.
 
Boarding an aeroplane is potentially a life-and-death situation.

Audio nirvana or lack thereof isn't.

The point was you trust science, lets say measurement science, to ensure that your plane stays in the air (remember I was a measurement engineer at Rolls Royce aero engines) but as soon as it comes near your hifi you go all apoplectic.

I have effectively been a precision recording engineer, both analogue and digital for many years. Aero engine design and performance is verified with measurement. Design changes are made due to the measurements. This includes vibration, noise, stress, pressure, temperature, speeds, thrust, clearances etc, etc.......The signals are more often than not conditioned by instrumentation amplifiers very similar to audio amplifiers.

So you trust it with your life but not with your hifi.........OK :)
 
BE I'm really grateful for your input. I'd honestly advise though that you give up trying to persuade people to see sense. To be brutally honest lots of people aren't interested in reading anything that doesn't match their preconceptions. The whole function of sciencey sounding stuff is simply to validate the hobby experience. Eventually you will burst a bloodvessel if you assume that you will eventually get through to someone who is talking round in a circle throwing up daft points which indicate that they haven't listened or understood more of less anything you have said. If someone asks a question and then proceeds to post on ignoring your answer it's a giveaway.

I say this not to dissuade you from posting but in order to preserve your sanity and to discourage you from giving up altogether.


There is very little coming up that has not been covered by the following, which I think follows from what you have said [do correct me if I have misunderstood]

1) most vibration coming from sound playing in a room comes through the air. if I have understood correctly, you can't stop that vibration using any stand.

2) You can't effectively stop vibration coming from the floor using a rigid stand.

3) you can't, using a rigid stand, drain from a component the vibration coming though the air or coming from the component itself .

4) solid state components are not really affected by vibration anyway, if they were it would be common knowledge in the design of pretty much all sensitive electronic equipment not just the ones with moving parts.

5) if they were affected in this way, and for other things which really are affected, like turntables and maybe valves, in order to isolate or reduce the effect of vibration you need a specific design strategy based on compliant coupling , damping and/or changes to the effective mass of the thing you are protecting which will have to be based on specific properties of the thing you are protecting and the frequencies of concern

6) stands which are not designed in this way can only have either no effect or at best a random effect as they might change the amount or quality of vibration coming through the floor, but not eliminate or probably reduce it. Most of the time they probably have little effect. However, even then, let's not forget 1)

And here's one of my own. if points 1) to 6) are correct then it seems to me that if you identify a particular stand (and certainly one not not designed as per 5)) having a particular sound with pretty much all equipment (perhaps to a greater of lesser extent) then your identification is unlikely to result from a genuine physically generated effect.

Thats pretty much spot on, thank you for the concise summary.
 
Not sure why you want to know this? depending on the size of the lorry and its load, and the nature of the ground, and the level of oscillation and its frequency you are interested in, then anything from zero to about 300 mtres. Yes, it is a very rough guess. Just think of earthquakes, depending on the seismic force the ground wave can travel miles, easily multiples of 10

I am sure I remember reading that in one high amplitude ocean test the sound was heard twelve thousand miles away, an the sound had taken several hours
to reach that spot.
Keith.
 
This thread has been interesting, and thanks to BE for all the food for thought. I have a few, probably not particularly helpful, comments.

Firstly, with regard to Keith’s perennial remarks about something not being properly designed. I realise this is normally trotted out without a moment’s thought mainly to get a rise out of somebody, but it does seem to me that he may be making assumptions about the design criteria which he might not be entitled to make.

Not being an electronics designer (no, really), I’m not qualified to comment, but ISTR John W and others, who are, have said that, for example, power supplies can be susceptible to electrical noise, and/or that if you apply too much regulation to a power supply, sound quality suffers.

What this tells me is that ‘proper design’ takes into account measures to reduce susceptibility to external influences but also notices if those measures themselves adversely affect the overall performance of the unit in terms of the overall design aims (eg best SQ for the cost), and adjusts the compromises accordingly. Keith’s rather blunt assertions make no allowances for such things.

So, if the designer observes that his unit works better with decent mains, or sounds different on different surfaces, he might be able to design-out that susceptibility but if doing so results in a unit that sounds like it is playing underwater, then it’s perhaps preferable to accept the quirks. Depending on your budget, you may have more or less scope to work on solutions. That's different to 'correctly' and 'incorrectly' designed, which does sound a bit Soviet in its unequivocality. Are we to expect 'an amp designer's response to just criticism' at any point, perhaps?

Just saying.

And my second point is that while BE has been careful to argue that ‘you imagined it’ is simply a possibility which shouldn’t be ignored (on which he is undoubtedly correct), others have taken the ‘it’s not shown up in the vibration measurements’ to be tantamount to saying ‘it’s not been measured, therefore you imagined it’.

Let’s just say that that conclusion does not follow from the evidence. Unless and until you can dismiss every other possibility, AND can show that the conclusion is one you have evidence to support, it's just a different sort of unsubstantiated supposition. Like, oh I don't know, like the ones about microphony are now slated as being. It is, I think, quite rare for anybody on here to be sufficiently educated and experienced in both electronics AND human perception, so that they would be qualified to make these definitive statements.

In short, if you want to rely on a claim that those reporting changes to the sound have imagined those changes, then under the usual rules we’re entitled to ask for your evidence and supporting arguments. Otherwise, it is only your opinion, just as ‘I heard it, and can’t explain it, but don’t think it is all psychoacoustic trickery’ is only my opinion. So please stop using 'you must have imagined it' as an argument unless you have the knowledge and facts to be sure of your ground. It’s only what you ask of others, after all.

Bear in mind also that, certainly the way it is expressed by some, ‘…therefore you imagined it’ can be a highly pejorative comment. Basically, the way some posters deploy it, they are accusing somebody of hearing things, and we all know that hearing things that aren’t there is what mad people do. They are, in effect, accusing somebody of being crazy. They never come out and actually accuse people of being mad, but you’d have to be pretty dumb not to be able to read between the lines to what they are implying.

That’s the bit that generates the heat in these threads, because the targets of the argument are quite reasonably annoyed at being told they are mental –the poster might try to deny that that was what they meant, but it’s a bit lame. So even if it is the accused who raises the temperature of the debate in retort, the provocation has come from elsewhere (hint: and not from the intellectual or moral high ground).

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.

A couple of points, a well regulated and good performing (sounding) power supply are not mutually exclusive. I think you are making many assumptions in your statements there to justify a product which doesnt perform as well as it should (in whatever regard).

Secondly, I have never said that people imagine things. That has a negative connotation which is unhelpful and an inaccurate description of what I am referring to.

People most definitely do get psychologically influenced. They are more likely to perceive what they want to. There is no escaping that That includes me with my scepticism. Perceiving something due to an influence of whatever nature is real, it's not imaginary. However, that doesnt mean the perception is accurate.

This is precisely why I measure to establish facts. These facts may not be the whole picture, but the more informed you are the better judgements you can make.

This is also why I want to perform blind tests.


As far as I'm concerned this is a far more open minded approach than people seem to be implying. Far better than belligerently saying "I hear it therefore it is" and proceeding to stick your head in the sand.

I am open to suggestions as to what the cause of peoples perceptions are. I would also like to know why I cant hear the difference if it is real.
 
If you are out and about in a park today theres a little exercise I used to give art students to do with colour. Usually set in the autumn for browns but it should work with green. the task was to collect as many different shades of leaf you could find in one hour to produce a colour chart(of leaves). After completing the exercise, for a good day or so the world looks different, you are far more attuned to the variety and intensity of colours. The same thing happens after spending time in a colour/grading suite in film and tv.
You are seeing more, it was always there. Had i administered 'Nikon opticron 4000 Eyedrops' before the exercise i bet some would attribute this new awareness to them.
 
BE718, could you tell us please, in layman's terms, what sort of distance a 10Hz, or 30Hz (in other words low or very low) frequency would oscillate? A rumble from a lorry for example if it drove close to a house.

Im not entirely clear what you are asking, but if its what displacement may be measured, I'm afraid its not possible to answer. Every situation might be different, the ground conditions, the frequency and amplitude of vibration from the lorry etc etc.
 
OK, the final measurements that include velocity and displacement. The graphs are of the same data, but re-arranged vertically. Accel, velocity, displacement. Sorry I didnt update the labels.

First is the pink noise. You will clearly see the point I was making about velocity and displacement decreasing with increasing frequency. The displacement has all but disappeared by 500Hz.

displacement%20pink_zpsdbknybwg.jpg


Then the sine wave at the amps resonant frequency of 306Hz. The actual measurement ended up a bit lower than the previous calculated numbers.

displacement_zpsrl6xub1l.jpg
 
Thanks for providing (again) a voice of reason.

Designs are not necessarily poor, just about compromise.

I don't think Keith has designed anything apart from maybe the name of his business using a non-existent French word.

The real French word meaning 'purity' is Pureté.
 
The point was you trust science, lets say measurement science, to ensure that your plane stays in the air (remember I was a measurement engineer at Rolls Royce aero engines) but as soon as it comes near your hifi you go all apoplectic.

I have effectively been a precision recording engineer, both analogue and digital for many years. Aero engine design and performance is verified with measurement. Design changes are made due to the measurements. This includes vibration, noise, stress, pressure, temperature, speeds, thrust, clearances etc, etc.......The signals are more often than not conditioned by instrumentation amplifiers very similar to audio amplifiers.

So you trust it with your life but not with your hifi.........OK :)

I trust it with medicine to save lives too but once you connect engineering with perception, measured science is found wanting by anyone who is not absolutist in their thinking and who doesn't treat measured scientific knowledge as some kind of religion.
 
My point was obvious, the differences, if they exist, must be vanishingly small if you need to do that to stand a chance of hearing them.

You don't.

What you've effectively done is erect an absolutist straw man.

At the one end (black) we have the zen-like state. At the other extreme (white) we have a full-blown panic attack with hyperventilation, blurred vision, parasthesias etc. Somewhere between these extremes (shades of grey) we have various states of mental arousal to include the usual fairly relaxed state in which we sit down and enjoy listening to music.

You are very good at crunching the numbers but your understanding of perception seems almost willfully ignorant.

When in a normal and fairly relaxed state of mind those subtle differences that make music more enjoyable to listen to are obvious.

There is an experiment I'd like to conduct with control and experimental groups. One group would be given a chance to familiarise themselves with the environment in which they are then subject to blind testing of loudspeakers that are subtly but measurably different.

The other group would face the same test from the off in the way that these tests are conducted when someone is trying to rig a null result in order to 'prove' a point instead of trying to establish whether or not there actually is a perceivable difference.

I'd then like to compare the results of each group.
 
Familiarisation with the room and system seems eminently sensible, Toole/Olive if I recollect correctly allowed their subjects to acclimatise before their unsighted testing.
Keith.
 
Familiarisation with the room and system seems eminently sensible, Toole/Olive if I recollect correctly allowed their subjects to acclimatise before their unsighted testing.
Keith.

Indeed but BE329 is suggesting that this should not be necessary; either a difference is audible or not -- black or white.
......................

"Pureté -- in harmony with truth" sounds so much better, don't you think?
 
Steven, if you really want to come across as a leader/innovator in this stuff rather than just a defensive punter all you need to do is to organise a proper controlled blind test and prove that perfectly ordinary folk with no dog in the race can hear a difference between your favoured bit of plastic being there or not. Once you have done that your work is over. All this jumping around blaming and name-calling those who wish to learn and understand how things work is doing you no favours. Once you have proven there is an effect, and a good blind test is proof (this is how science works!), the ball is then entirely in the measurement camp's court to explain what has occurred.

PS This is how medicine works too, e.g. once an 'old wives tale', 'folk remedy', 'herbal medicine' solution or whatever has been proven to have a beneficial effect under controlled test conditions it just becomes known as medicine!
 
I trust it with medicine to save lives too but once you connect engineering with perception, measured science is found wanting by anyone who is not absolutist in their thinking and who doesn't treat measured scientific knowledge as some kind of religion.

The only one with a religious zeal appears to be your good self steven. I don't have absolutist thinking, but it appears you do.

You talk about your vibration isolating stand, but when science shows you it isn't, you go into denial. That is very much like a religious belief.

Have I said there isn't another explanation for what you hear? Nope. I have just pointed out it doesn't appear to be what you think it is.

There has been nothing esoteric or questionable about the vibration measurements I have made. However you don't want to believe them as it doesn't tally with your beliefs.
 
Indeed but BE329 is suggesting that this should not be necessary; either a difference is audible or not -- black or white.
......................

"Pureté -- in harmony with truth" sounds so much better, don't you think?

No I didn't say that, I said it demonstrates how vanishingly small the differences must be if you need to have special preparation to stand a chance of hearing them. Totally different to your misrepresentation.
 
If you are really suggesting that your dac will sound different on each and every different support, then you can simply erect a cloth in front of the rack, and ask someone to pick the component up whilst music is playing.
The human body is pretty good at decoupling, it should be immediately obvious.
Keith.
 


advertisement


Back
Top