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Microphony III

You are of course correct. That should be the number one consideration after buying the gear, and before checking out cabling and other peripherals.

After buying equipment, I advocate the following:

1. Find the best location for speakers and ears (listening chair). The best way is to use frequency response (FR) measurements from say 0-500Hz using something like REW software.

2. Room treatment, particular bass traps. The FR software will tell you the sort of problems you have.

3. Complete the speaker/room corrections with an equaliser (it works for me anyway, before the naysayers jump in).

4. Consider cables, anti-vibration, power products. The last two won't change the FR but offer other qualities as described on this thread.

5. Consider CD cleaning and other CD treatment.

Up to number three I completely agree with you, under a turntable ,isolation can be extremely useful, maybe even under loudspeakers.
Your equipment should already have good internal power regulation.
This thread has shown that vibration/ Microphony is a non issue for solid state electronics.
Keith.
 
Thanks for trying to explain. However this is all clearly beyond my knowledge of digital audio, and I don't wish to spend further time

That is perfectly fine. Suffice to know that digital audio is that non-intuitive (and often taught incompletely or even erroneously) that even physics or electronics professionals and academics get it wrong at a fundamental level.

In the module itself the ground of each socket is connected to a feed wire which enters the acoustic labyrinth, providing a low impedance acoustic route into an advanced labyrinth structure.

V-AQ are convinced, or try to convince you, that one of the major bugbears in audio are the vibrations picked up by all cables. These vibrations have to be kept from entering the gear. Obviously. Hence the decoupling 'labyrinths'.
 
That is perfectly fine. Suffice to know that digital audio is that non-intuitive (and often taught incompletely or even erroneously) that even physics or electronics professionals and academics get it wrong at a fundamental level.



V-AQ are convinced, or try to convince you, that one of the major bugbears in audio are the vibrations picked up by all cables. These vibrations have to be kept from entering the gear. Obviously. Hence the decoupling 'labyrinths'.

:) ....and whats that got to do with the ground/RF issues they talk about the block curing????????

Foo plain and simple.
 
What I've now done is downloaded a few vibration detecting apps onto my phone, and I'm wandering around looking at vibrations! Wife is convinced I've finally lost it. However, my room has solid floors (2" of slate on the soil) and my rack is a solid oak post waith cantilevered 20mm perspex shelves. Listening at truly insane levels shows no more vibration of the shelves than absolute silence, and likewise my TT on its perspex table is collecting almost no sound vibration at all, except if you place the phone in the centre of the closed lid. There is some vibration in the plinth when the motor is running. My EAR890 has a slight vibration (which is audible, just) at 50Hz due to the transformer. My sofa picks up quite a lot from the speakers, and my downstairs loo door peaks at 60Hz quite notably.
I'm convinced no vibration is entering the system via the cables.
So, do you think I'll get away with mass damping the loo door?
 
Going back to the unexpected speaker measurements and weirdness, I have set one speaker up being driven by my little Raspberry PI Volumio/HiFi Berry class D amp. A project that will be stuffed inside a speaker at some point.

The other speaker connected to the TAG power amp. The channels input is terminated. The output is teed off (at the amp output terminals) to the B&K measurement system.

Mains pick up is far higher than I expected, but somewhat inevitable with the unscreened speaker cable connected. There is nothing else connected to the amp. Difficult to see how any cross talk can happen.

So music played on RPi about 75-85 dB(A) in the room. It appears in the noise floor on the amp with the speaker connected. It doesn't with it not connected. Same result as previously, same on all 5 TAG amp channels. It isnt microphony in the amp, it also almost disappears when you put a cushion over the woofer, so it is coming from the speaker.

I'm uploading videos to youtube, but they are taking some time. I will slot the links into this post when finished.

Vid 1
https://youtu.be/lYcDS52_-Ok

Vid 2
https://youtu.be/rvToS3tLGso

So this really isnt expected, as mentioned elsewhere, I would expect the amps low output impedance to kill this.

Confused:confused: going to have to try this on another amp.
 
Replace the amp with an 0.1R-0.5R resistor and see what happens? Try it with the amp powered off. Try another amp.

The mains pickup is also bothersome, you should be measuring the voltage developed across a very low impedance at these low frequencies, it's surprising to see any more than a little hiss coming from the amp. FWIW I just stuck a multimeter across the speaker terminals of one of the channels of a cheap Yamaha AV amp. 3.5R, speaker was connected, so this is the cable and speaker in parallel with the amp. At the tiny voltage of a digital multi-meter. Possibly something to investigate, because I don't believe that is the output impedance when the amp channel is driving some signal.

This is all way off the topic, no vibration here... More interesting though.

Paul
 
Oh yes, best thing I ever did.

I've seen pictures of your setup... oh dear, oh dear, oh dear.

;-)

P.S If your syatem sounds so good, why are you constantly tinkering with it?

There is nothing 'constant' about it.

In the black-and-white world things are either perfect or broken. My system is neither, just bloody good to my ears and many of those who have visited, all of whom have stated that the "oh dear, oh dear, oh dear" sofa that you are undoubtedly referring to is a non-issue. In fact, it's beneficial in deadening the room; I've heard the system without it. Those of an objectivist persuasion tend to listen with their eyes, as you have been doing but to a mere photo of my system.

If my system is neither perfect nor broken, just merely good, this means that it can be improved by giving me even more of the same. This isn't an upgrade treadmill, as with constant speaker changes that aren't really an upgrade at all, just a change of flavour that may or may not reveal even more the shortcomings of the system upstream. This is progress. I'm enjoying what I have now but at the same time I look forward to the next unlocking of even more info on recordings in a few weeks' time.
 
Replace the amp with an 0.1R-0.5R resistor and see what happens? Try it with the amp powered off. Try another amp.

The mains pickup is also bothersome, you should be measuring the voltage developed across a very low impedance at these low frequencies, it's surprising to see any more than a little hiss coming from the amp. FWIW I just stuck a multimeter across the speaker terminals of one of the channels of a cheap Yamaha AV amp. 3.5R, speaker was connected, so this is the cable and speaker in parallel with the amp. At the tiny voltage of a digital multi-meter. Possibly something to investigate, because I don't believe that is the output impedance when the amp channel is driving some signal.

This is all way off the topic, no vibration here... More interesting though.

Paul

Yes, somewhat off topic, just one of those odd things discovered during the vibration investigation. I'm not going to publish more about it in this thread. I will continue to investigate offline.
 
Thanks very much for posting these - for anyone who has not looked, the second video shows the pink noise test in action.

I know it's more work, but is there any chance of you repeating the second video, but with the bottom right plot expanded to fill the whole computer screen and the camera fixed on this (possibly with the aide of a tripod) throughout so it's easier to see what's going on. If you could turn the noise on and off a few times, allowing the exponential averaging time to do its stuff before each switch over, that would be great. If you could also do something similar with the swept sine wave and music noise signals that would also be great!

My guess is that if we are going to see anything, then it's not going to be immediately obvious - if it was, there wouldn't be so much back and forward debate.

(I've got a bit of background that's relevant, about 30 years ago used to work on research, development and trials of speech recognition in military fast jets - we're talking really significant noise, along with tons of vibration and other issues!)

Thanks again for all your efforts.

Cheers. Bill


Hi BE, do you think you'll get time to generate these videos? I think they would show the conclusion of your work so far in the frequency domain before looking more closely at the time domain which I think you were considering.

Thanks again.

Cheers. Bill
 
I'm going to try to, the kit has to go back to the office to do some paying work tomorrow :) so it might take a few days
 
Steven,

It's not the sofa I'm objecting to, it's the rats nest of wire, it's the nasty plastic eyesore in the room. And yes, I know beauty is in the eye of the beholder, but seriously dude... oh dear, oh dear, oh dear.
 
Steven,

It's not the sofa I'm objecting to, it's the rats nest of wire, it's the nasty plastic eyesore in the room. And yes, I know beauty is in the eye of the beholder, but seriously dude... oh dear, oh dear, oh dear.

The stand passes the WAF test here.

Everyone's a winner!
 
Thanks very much for posting these - for anyone who has not looked, the second video shows the pink noise test in action.

I know it's more work, but is there any chance of you repeating the second video, but with the bottom right plot expanded to fill the whole computer screen and the camera fixed on this (possibly with the aide of a tripod) throughout so it's easier to see what's going on. If you could turn the noise on and off a few times, allowing the exponential averaging time to do its stuff before each switch over, that would be great. If you could also do something similar with the swept sine wave and music noise signals that would also be great!

My guess is that if we are going to see anything, then it's not going to be immediately obvious - if it was, there wouldn't be so much back and forward debate.

(I've got a bit of background that's relevant, about 30 years ago used to work on research, development and trials of speech recognition in military fast jets - we're talking really significant noise, along with tons of vibration and other issues!)

Thanks again for all your efforts.

Cheers. Bill

Hello BE

In post #612, I think, you said that you were going to try and post these additional videos - did you manage to get them done?

Thanks. Bill
 
Hi

I'm afraid not, the B&K pulse kit has been snaffled by work to do paying jobs. I think this is very inconsiderate of my employer to take my tools away :)
 


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