Amplifiers and vibration - AVS Forum
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post #1 of 2 Old 07-03-2014, 02:29 PM - Thread Starter
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Amplifiers and vibration

I could recall nothing from the last time I looked into this, so did some googling for what little info is out there

It seems not all capacitors are microphonic. So I wonder, what the concern with vibration and amplifiers?

The manufacturer should be securing microphonic caps as much as possible such that they are minimally effected by vibration or use caps that don't have microphonics ( at least those that are in the signal path.)

I read where inductors could also be microphonic. I don't know if it's common to have inductors in the audio signal path, but I would expect some in the tuner. I think they are usually pretty well secured in circuits I have seen, but I suppose it could be a concern, not sure.

Heat seems to be a much bigger concern, hence the reason for mounting certain components to the same heat sink, and possible compensation circuitry. Yet people don't worry about heat except as a general thing to avoid.

Modern electronics seem to cover this stuff well - back in the early days of analog synths, they would go out of tune all the time. Maybe some of their non linear behavior was part of their charm.

I am not saying vibration can't be a factor, but it seems rather isolated to a few components and correctable as part of the amplifier design.

"But this one goes up to 11"
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post #2 of 2 Old 07-03-2014, 02:57 PM
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Quote:
Originally Posted by MichaelJHuman View Post
I could recall nothing from the last time I looked into this, so did some googling for what little info is out there

It seems not all capacitors are microphonic. So I wonder, what the concern with vibration and amplifiers?
At some microscopic level all parts are microphonic, but the parts used in quality SS audio gear (e.g. typical mi-fi and up) has no audible microphony. They aren't like tubes, and even tubes aren't that bad unless they are loose internally.

Tying parts down doesn't reduce internal vibration that much because the circuit cards you tie them down to are also vibrating. Usually, the purpose of tying parts down is to reduce stress on leads.

Modern surface mount parts are glued to the circuit cards to hold them in place during the soldering step because there are no leads to hold them in place.

I've put audio gear right in front of a big woofer that I drove the ^%$$!! out of. In some very sensitive measurements I could actually measure traces of the sine wave that was driving the speaker, but it was down in the noise. Just a testimonial to how sensitive modern measurements can be.
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