Question, tubes amp placed over a speaker?

I was watching a movie about Mamoru Oshhii* and next to him was a speaker with an amp placed on it. The conversations switched from him to his speaker. I suspect it is just a set for the documentary but wanted to ask the more knowledgeable roon users if the tube amp can be placed on the speaker.
Tried to find the speaker and the ones on the wall, but ended up only with a discontinued LW 6009 or other variants of the LW (also I assume same for the ones on the wall)

*Mamoru Oshhii is the creator or Ghost in the Shell
Thanks
Traian

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I think in audiophileland this would be considered a very bad idea and I cringed when I saw it.
A lot of effort and expense is spent on isolating components from vibrations.
Tubes are particularly microphonic.

Then it occurred to me that my bass guitar rig is tube amp based, as are many guitar player’s rigs, and those amps are almost always placed on top of speakers - usually playing at extremely high volume - and no one thinks twice about it.

So my take is: Bad in theory. No real problem in practice.

Edit - Thinking about this some more I realized my bass amp and speakers are in cabinets roughly 2cm thick with huge rubber feet. Far more than home audio components. So maybe by design there is less vibration transmission.
I really don’t know.
Now I’m curious what others think as well.

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Thank you for the reply

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I edited to add another thought.

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I would instinctively also worry about the castors underneath the speaker cab as well, to me it would be a way of doubling the potential for “theoretical” disturbance in the force; but may be absolutely fine in practice.

My first Fender tube amp weighed only a little less than the AlfaSud that i transported it in, so i think that you are correct Jeff in thinking that they are more rigid/isolated in their construction in comparison to audio components. The keyboard player had a Leslie Cabinet that we all hated having to manhandle, it was both fragile and built like a tank and he would always protest that he had to manage it’s movement rather than help carry the thing!

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I would think this would not be a good idea. The casters, the lack of good isolation between the speaker and the amp. It could work if there was an isolation platform and you never played the music very loud??? I suspect (hope) this is a set-up for the picture. Especially if that speaker is functioning as a Sub.

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Surely if the speakers do their job correctly, they shouldn’t transfer much, i.e., very little, mechanical energy through the enclosure?

But then, audiophiles spend money on isolation, e.g., spikes, when studies suggest that this method transmits more vibrations than something like Blu Tack (which, incidentally, is what my speaker manufacturer recommends.)

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The worst idea to place a tube I’ve ever seen is in the reflex tunnel of Rethm’s active speaker AArka

Actually, too many audiophiles overdo or even misapply component isolation, especially with solid state electronics (I hear you @Martin_Webster!)

With mechanically sensitive devices, like most tubed and vinyl pickup systems, vibration isolation, air and/or structure-borne, does make sense.
Just tap these components lightly to find out about their susceptibility - I’ve seen too many turntable setups having their raised dust covers mounted during playback, acting as perfect resonant pickups!

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I don’t think it matters, so long as the tube amp isn’t connected to anything. :rofl: Which would be the way to go. :wink:

Might rattle a bit on top of the speaker, though.

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It must be a non vibrating speaker. Look at the inside of a valve its all very fragile looking . I am sure the THUMP of a decent woofer would rattle a valve to shreds in no time.

Same goes for any circuitry. A number of times I have taken a pc in for repair, the vibration of the journey fixed it !! :sunglasses:

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But that’s completely different because the amp and cabinet are part of the instrument. Along with the guitar and the pedals it creates the sound to begin with. All the guitarist cares about is the combined sound and most likely microphony plays a part in creating it.

In the same way as you may want electrical distortion as well as mechanical distortion (cone breakup - guitar amps have larger speaker cones than audio speakers have for the same frequencies, and they break up into partial movement) in a guitar rig.

A hifi system, however, should reproduce the sounds without changes, not create sounds on its own. And just like you do not want Marshall distortion in your hifi amps or speakers, you don’t want microphony either

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Excellent answer! Dave Davis took razor blades to his Vox to get the sound that he wanted and then took it back to Vox and said “make me an amp that sounds like this out of the box please”.

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Agree 100%

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I doubt in a blind test anyone would tell the difference. If we haven’t got something to worry about as audiophiles we generally find something.
generalising

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Microphony is real, certainly in tubes, and in small amounts may well be in transistor setups too. The Naim designer said that they developed their spring suspensions after playing around with an oscilloscope and seeing the distortion caused by pointing a speaker onto an amp’s circuit board.

The special output transistors Naim had designed for their power amps have non-magnetic board connectors for the same reason.

Everything can be attributed to marketing speak but he’s an engineer and I have no special reason to think he was lying.

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I understand that. I have had ear890s in mono. They were on a glass Hi-Fi rack, then wood, then granite and squash balls etc etc. all this should be transported to the speaker inputs from microphone/vibration. Never made a difference. I also played with tube dampers, no difference. Maybe I should have bought some russ andrews speaker damper thingies and really gone for it?
Perhaps I’m not gifted enough to appreciate minutiae.

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I don’t really want to go into how relevant it is what the stand is, but tube microphonics were once a practical and real design problem

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Again I understand yet all those fighter jets and their vibrations etc still flew.

Probably because they took the necessary counter measures

Or it wasn’t the problem audiophiles like to make it.