Do vibrations have an impact on solid-state amplifiers' sound quality?

[solderdude]

In the days of tubes and analog gear (vinyl, tape) vibrations were certainly an issue.
Most certainly when used on wooden floors (vinyl).

Today... tubes, vinyl, analog tapes, some tuners even are still equally susceptible to vibrations. This stuff is what audiophiles love. I can see those folks might benefit from using feet.
I can also see benefits of putting speakers on damping feet, if only for the neighbors.

Some components that one taps on could cause audible issues. Usually they are mechanical components like crystals (these are mechanical components but not all of them are created equal), relay contacts, switch contacts, volume controls and in a far lesser degree (ceramic) capacitors.
You would have to tap on it though, which means a lot of G's usually. And when you tap on components you are also tapping on the PCB creating movement to components around it too.

The thing in practice is that G-forces induced by music is usually very low and mainly very low frequency only.
And even when this happens the speakers are very likely playing very loud and there will be a ton of distortion anyway.

So yes, there can be measurable and even audible effects even on SS gear but in everyday use there won't be a real difference unless one of the mechanical components in it is (going) faulty.

To the OP question:

Do vibrations have an impact on solid-state amplifiers' sound quality?​

The answer is: it might and it depends on how much vibration we are talking about.
When those vibrations are caused by reproduced music that would have to be really loud in very close proximity. The speakers would be distorting a LOT more than any vibrations could be causing.
Non-issue but tapping on components inside an amp (or perhaps even on the chassis) could be audible when there is silence in the room.
When blasting music through speakers those sounds will be overpowering any small measurable effects that might occur.
All of this assuming the amp in question does not have any 'mechanical components' in there that are (getting) faulty.

 

[MAB]

Thanks for doing this! This makes complete sense, too. Given how capacitors work it's not hard to believe thumping one might affect it, but that does not translate into a generalized "microphonics" from any and all vibration. So much audio woo comes from starting from a genuine effect and exaggerating it past all reason, especially if you can claim to ward off something unseen.

Yes, agree with your assessment. If I squint, I may see the beginning of noise in the Genelec and JBL full-power measurements... the hash in the Genelec loopback trace at about 2.5 kHz, and similar crud in the JBL woofer loopback just under 2 kHz. Which makes sense, we know every component and trace in the analyzer will have electrical artifacts if vibrated enough or put under sufficient pressure. 5 cm from either of those speakers at full volume is completely bonkers. I'm actually surprised it's so clean since the QA403 has a bunch of relays, and my experience is those are often very sensitive to vibration. But that might be from finding so many degraded relays making odd sounds and noise in old gear.

Like you say, the effects are real. Even strain is used to enhance the mobility of carriers in semiconductors, in the case of PMOS and NMOS mobility enhancement the changes under tensile and compressive strain are huge. For instance, Mark Bohr's discussion of the trials and tribulations of integrating strained NMOS and PMOS devices into a controllable and manufacturable process. But the strain is many orders of magnitude greater than clamping a PCB in a vice, and has nothing to do with audio.

 

[Holmz]

I couldn't agree more. Tapping until you get an audible response is completely unrepresentative of actual use.

When I do that on my TT, I can tap it so hard that my finger nail hurts and it does not come through the speakers with the needle down on a non-spinning vinyl, all while the volume railed.
Other’s have their TTs thumping

If “it” doesn’t make sound with a nail thump, then it will not likely do so when the music is playing, unless there is some specific high-Q resonate freq.

I can envision some tube equipment being microphonic, but I was somewhat surprised about those capacitors.

 

[DSJR]

One UK manufacturer made a huge thing about suspending the preamp boards, attaching them to plates hanging on a spring suspension. Their godawful speakers of the period had decoupled connection sockets which were ridiculous as the cables touched the frame the sockets were fitted in. they even did it with the three prong 13A mains connectors we use (maybe the latter made a bit of sense as the prongs may just sit in the receptacles better?)

All this firm needed to so was improve their designs, which at a humongous price, I think they have done. their 'godawful' speakers have thankfully been confined to history, the amps look like complex modern builds now and distortion is something like 15 - 20dB lower than in 'my' day, the preamps are streaming based it appears and all this anal 'tweakery' seems to have quietly dissipated, apart from ludicrous pricing on their interconnects and speaker wires.

I do however remember the original Arcam FMJ models from ~2000 or so, responding well to an isolated-shelf racking system that 'Something Solid' used to make before the man retired. Their solid-box CD player definitely appearing to 'improve.' I'm a confirmed 'tune dem' bod of old (melody and harmony before pr@t) and felt I could 'follow the tune' better with this gear when it was set up on said rack, which used balsa shelves sitting on pre-tensioned nylon? rope as used in sail lines I recall. I'd love it for a proper null test to be done to see if there really *was* a difference here...