yet another diy plate reverb

[Whoops]

Something that seems to be important with the Piezo element for plate reverbs is the resonant frequency of the piezo.
There used to be a website www.platereverb.com/ from Jim Cunningham (Echoplate) with some good info on building your own plate. Jim also sold there some parts, like the piezo elements.

the website went down sometime around 2015, here is the page from wayback machine:
https://web.archive.org/web/20150409235759/http://www.platereverb.com/

Here is some notes I have from Jim Cunningham:

"The pickups are piezo elements but it is important to choose one that has it's resonant frequency well outside the audio range. All piezo devices have a screaming resonance so this is very important. Also they must be mounted with a special conducting cement (to avoid ground loops) which we supply with our pickups."

From another source:

"Jim Cunningham also sells some piezo pickups.  These pickups just look like the standard piezo transducers that are maybe 20mm in diameter.
They get glued on to the plate with a fast bonding adhesive"

________

I didn't find any source for Piezo elements with the resonant frequency outside the audio range, if someone can find them or have a source please let us know

thank you so much

 

[CJ]

would be interested to know if temperature of the plate affects the delay time,

 

[Whoops]

would be interested to know if temperature of the plate affects the delay time,

Well sound travels faster in harder surfaces. So I guess if the plate gets really hot the metal will be less hard so the delay time will be longer. But we are talking about a really really small increase and the plate had to be really hot also.

I'm guessing, but I think with normal temperature variations the delay time will (approximately) not be affected

 

[Rob Flinn]

I did a Jim Cunningham piezo upgrade to an EMT for someone.  It lowers the noise a significant amount compared to the original paickups.  He supplied some adhesive that was what you use to stick a rearview mirror on a car windscreen(shield).

 

[Whoops]

I did a Jim Cunningham piezo upgrade to an EMT for someone.  It lowers the noise a significant amount compared to the original paickups.  He supplied some adhesive that was what you use to stick a rearview mirror on a car windscreen(shield).

Just the piezo or you replaced also the electronics?

 

[Rob Flinn]

You had to replace 1 or 2 caps and maybe a couple of resistors to account for the very high impedance of the piezo pick up.  This was to a valve version, but I did it more than 10 years ago so my memory is a bit fuzzy on the specific details.

 

[DerEber]

would be interested to know if temperature of the plate affects the delay time,

It definitely changes the sound. My Plate is in an not heated room and the plate changes the sound through the year.
Someday it sounds uneven and I feel like "damn I should tune the plate soon".
Two weeks later it push up the faders and be like "wow..... too good! "
But I do not think the delay time changes too much if anyhow.

 

[kooma]

little more progress on my reverb.
I tested tda2030 chipamp as a driver and small lm386 amps as a preamp for piezos.

Here is audio on differend plate tensions;
-first dry
-then really sloppy tension(bolts so loose, that you can twist them bare hands)
-mid tension
-tight as I could twist it ( I need to get bigger wrench btw..)
-and last same tightnes, but transducer is placed better.
https://soundcloud.com/anodivirta/plate-tightnesss
piezos and transducer were in same places in all takes( except slight movement during tightening)
the annoying resonances comes mostly from transducer that isnt glued into the plate(I'm going to change plate and them glue piezos and transducer into final postions..)