Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
It's as much a hovercraft as a pancake is a waffle.

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


               

Sphereverb

  (+4, -1)
(+4, -1)
  [vote for,
against]

A plate reverb consists of a steel plate attached to a frame, under tension. The sound travels along the surface from and to transducers placed on the plate. They're quite heavy: the EMT140 (an industry standard) weighs almost 600 lbs, most of which is the framework that keeps the tension on the plate.

So, and I think you can tell from the Title where I'm going with this, if we make a sphere of the same material then pressurize it to give the proper tension, we have a device with, as far as I can imagine, superior qualities, for a very small fraction of both size and weight.

Math:

The plate in the EMT140 is 1m x 2m x 0.5mm.
The material it's made of (cold-rolled steel) weighs 7,850kg per cubic metre.

Therefore the actual plate weighs only 7.85kg/17.3lbs
2 square metres is the surface area of a sphere of .39m radius

Our Sphereverb will be about 2'7" in diameter and weigh less than 20 pounds.

(I haven't been able to dig up tension specs yet, so I have no data on the amount of compression, thus none on the possibility of using ovoid, ellipsoid, x-oid shapes which would give much more variety).

FlyingToaster, Jun 26 2011


Please log in.
If you're not logged in, you can see what this page looks like, but you will not be able to add anything.



Annotation:







       Simple geometry is the enemy of good-sounding reverb.   

       I'ts important that the "tail" or decay of the reverb be fairly uniform at all frequencies. It's unlikely that a simple shape would show these characteristics.
csea, Jun 26 2011
  

       //simple geometry// but if I said "x-oid" then I couldn't make the semi-pun sphe-reverb.   

       Easily solved by either manufacturing it with an irregularly shaped "cork(s)" of a different substance for the reflections to bounce off of, or to make it not-quite-a-sphere.   

       I can't help thinking there's a perfect mathematical shape which would result in a perfect wash.   

       A cylinder would be functionally the same, as far as reflections are concerned, as a plate, but there's gotta be something better.
FlyingToaster, Jun 26 2011
  

       Just to rereiterate, this idea is the opposite of the one that doesn't work (and got all the buns) :D   

       The sound travels across the surface of the tank, and the inside pressure keeps the surface taut and has no aural purpose.   

       Like [csea] says, a simple sphere is much less than optimal (sorta crappy in fact). However a round-ended enclosed cylinder (ie: two halves of a sphere and a tube) gives the same overall acoustic results as a real plate, and there's probably even better shapes.
FlyingToaster, Jun 26 2011
  

       Have a pressurised, reverberating bun.
pocmloc, Jun 26 2011
  

       + for effort.
sqeaketh the wheel, Jun 28 2011
  

       A high internal pressure would damp reverberation.
MechE, Jun 28 2011
  

       I doubt it would be high pressure. I haven't found how much tension they put on plates but a modern grand piano has 20 tons. A plate reverb wouldn't come even close to that, but even if it's 10 tons on a 3x6' plate, that's only equivalent to an extra half atmosphere in a pressure-vessel with equal surface area.
FlyingToaster, Jun 28 2011
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle