Plate reverb idea/questions

I have been a fan of plate reverb for many years but I have never made one. The space and brightness it can add to vocals and solo sounds is unique and distinctive.
I understand the mechanism but the physics escapes me. Can a plate be too thin, thick, soft or hard? Is there a formula or am I in suckitandsee territory?

The back of a Kosmo rack seems like a natural place to fit up something like this; a largish rectangle.

Using multiple drivers, and dampers (my word for ‘tuning’ harmonic shiz from a plate reverb - aka blu tak or a blob or two of glue) to add (or remove) qualities of the sound much like a filter is something I’d like to play with.

I know we have some physicists here and wondered if anyone can point me to some laymans reference material so I can better plan an experimental muck about this summer.

There are things I want to know like what would a hole or holes in the plate do? Distortion, some weird 2d lens effect, nothing at all? Does it need to be flat? Could I spiral up a sheet (rolled up but not touching) and make a tube plate reverb or take an old pipe and make one cut lengthways to make it a curved plate?
What part does the environment play? What would a pressurised space or vacuum add or remove?

Too many unknowns for me so any steer to good info, algorithm, physical laws would be great.

Ok I’ve used up my daily quota of question marks…
Cheers

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This has been on my list of projects to do for a long time, but no space for it right now…

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This is a good read (most of the valhalla dsp pages are if you’re into that kind of thing):

Cheers

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Thanks, I saw this when it came out. Looks like a fun project but a lot of time seems to be spent on making it ‘like’ a traditional big plate rather than explore the quality of the smaller design. I wondered how small is too small? Is the big heavy frame needed? What happens if you put a sheet under tension like a drum skin? A good reference though.

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What a brilliant paper. It’s a great start. Many thanks.

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My approach would probably - get all the electronics/mics, then start attaching them to things and seeing what happens. What happens with a pipe? A radiator? etc…

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Yes that’s my usual approach too. When I first got a copy of Nicholas Collins’ book Handmade Electronic Music I made a bunch of drivers and contact mics and stuck them to many things; bowls, cymbals, toy cars, even my kitchen window (on a stormy day it was like a jazz drum solo).
I’d like to see if the huge plate size is as important as the structure of the plate material, could a simple steel ruler provide a useable effect for example.
A fun summer of Gin and tin snips awaits!
Has anyone else had a go or read anything else I might find useful?

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Okay - so that’s a real nice video - not just the reverb part, but the bit about failure and satisfaction and building stuff yourself - hits on a lot of the reason’s that this whole DIY electronic music instrument hackery is such a great hobby.

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If you think about rolling up a sheet of paper into a tube, or even bending it into a U shape, that makes it stiff against flexing in ways a flat sheet isn’t. So a tube or a curved plate is going to have very different vibrational characteristics than a flat one.

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Cymbals seems to be interresting (more small too :slight_smile: )

different but interresting too

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Agreed but I wonder if the steel were treated, like aneiling or pressed/rolled/beaten or put under tension … Sorry, rambling.
In my 20’s I added a DIY resonator to a ukulele and spent ages beating the metal cone with a panel hammer to put the surface under tension the sound and volume difference was amazing. It might be fun to mic up my dobro and put a driver on the bridge to make a cone reverb… Ok, really rambling!
Evening All

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Hi Farabide,
I actually built 2 plate reverb units a few years ago, one of them still placed right next to my modular. I am an acoustic engineer, hence I might be able to answer some of your questions, so feel free to ask :slight_smile:
Here are some thoughts:

  • regarding the general physics in a plate: the plate may be regarded as a 2D room, hence it will have a 2D wave that travels across its area. At the edges of the plate, the sound is reflected (due to the change of impedance). Hence, any hole within the plate will act similar to e.g. a pillar in a 3D room: it additionally reflects the wave when it comes by the hole. But: the hole will also change the global structural behaviour of the plate, hence the wobly behaviour of the plate might be enhanced in a not so pleasant way.
  • wobbliness: this is a plate characteristic that the real 3D room doesn’t have. It stems from the whole plate oscillating. It may be avoided/attenuated/frequency-shifted by applying pre-tensioning. Hence, a strong pre-tensioning is really important for a good plate reverb.
  • the frame that holds the plate: a stiff frame is essential because it enables you to apply a good amoint of tension without having to fear the whole thing to break apart. I welded a stainless steel frame for that.
    Regarding the electronic side of plate reverb: I use cheap piezos, they are definitely sufficient for my needs. As exciters, I use surface transducers by Visaton, definitely recommend them. For amplification, I did try several solutions. I started valve-based, (both amplifier for the exciter and high-impedance preamp for the piezos based on Merlin Blencowes designs), bbut I must say: transistor wins for me. The cleaner the better, as this tranports the transients nice and it doesn’t get muddy etc.
  • placement: I would not place the plate too near to power supplies etc since especially the piezos might catch quite some noise/hum. This is a similar pain in the butt as the spring reverb pan placement…
  • size: size matters, at least for standard steel material (and thickness). I would not go below 1.5m at least for the longer side of the plate…

Any more questions? Looking forward to your build!

Best wishes,
Alex

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@CC-TOP !
Welcome back and thank you for the assist.
Lot of information and I’m looking forward to experimenting.

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