Miniature plate reverb with *thin* steel

[madact]

Reading around on plate reverbs, I have seen it mentioned in several places that smaller plates can be built using thinner material -this would seem to make sense if the speed of sound (specifically, lateral vibrations) were slower...

The speed of sound in the plate should be related to the density, stiffness and tension of the plate - unfortunately I've been unable to find any references to calculating this on the net.. plenty on radiated energy, little on propagation speed.

I've been able to find the following sheet sizes for reasonable cost on ebay:
.002" x 12" x 30" Stainless Steel foil
.004" x 6" x 36" 1095 Blue tempered Spring Steel
and I was thinking of giving them a shot, but I'm not sure how they would go yet (and tensioning is going to be fun S).

Just for comparison, the JCC & Assoc 'eco plate' reverb unit is 0.024" x 79" 39.5".

(From the EMT240 manual) "The EMT 240 Reverb Foil an electroplated gold foil of great purity (24 “coin gold”) with a thickness of only 18j.jm) and 270x290 mm (10.6”xl 1.4”) size." - but I'm not sure figures translate over with different materials like that...

The steel foil above is 1/12th the thickness of the 'eco plate', and the spring steel 1/6th of the thickness - if someone could help me work out how this relates to tension and sound propagation speed? I'm tempted to try the spring steel just for the easier handling & working, but a 6" x 12" plate seems ambitiously small...

 

[PRR]

The physics, I can't handle.

In water, i think surface waves speed-up as water thickness gets smaller (shallower). That's not really the same thing.

But if a foot of steel could work OK, why did EMT use a yard of Gold?

> reasonable cost on ebay

Brain-Work has cost. Time, coffee, pain.

If you can get a sheet cheap, tie two car-speakers to it, and test, you may have some kind of subjective answer long before some abstract analysis could be formulated and computed.

 

[abbey road d enfer]

The physics, I can't handle.

Neither can I, but just like the propagation speed in a transmission line is way slower than c, I think the soundwave propagation in an acoustic transmision line is way slower than sound speed in steel (about 1500m/sec). Tension does not really change the propagation speed, it changes the boundary behaviour, juste like the load at the ends of a transmission line affects SWR.

But if a foot of steel could work OK, why did EMT use a yard of Gold?

The EMT 240 plate is actually less than a foot-square. The big selling point was the much smaller format. I think if they had found a way of making it out of steel, they would...
Anyway, information on the gold foil is somewhat perplexing. Sometimes they mention solid gold and sometimes they hint at it's a plating on whatever substrate they came up with.