EMT Plate Reverb Tech Support and Audio Samples
updated 10th November 2012 by Eddie Ciletti

Over the past year, I have been helping a client get his EMT 140 Plate Reveb online.  It started back in August 2011 with an amplifier overhaul.  I added a few EQ trim mods in anticipation of instaling new piezo pickups that will have higher output and much more low frequency response.  The new pickups were installed a few months later by my assistant at the time, John Kargol.  In October 2012, the plate was tuned (re-tensioned) as per Jim Cunningham's specs and 'calibration' tools.  Then, the driver magnet assemble was repositioned because EITHER the plate had been mistuned for a long time OR the frame had been bent, because the voice coil was runbbing agains the magnet assembly.

The first week of Novemebr 2012, I added a 12 dB / octave high pass filter to eliminate sub sonic interference.  While it was a bit difficult to predict how the passive filter would affect the piezo - the filter itself reduce the level at 160Hz by 6db.  It's a little more complicated than that and I will share the details ina fture update.   I think you will find that the initial listening tests confirm that my educated guess was in the ballpark. 

AUDIO SAMPLES
Thanks to Zach Hollander at THE PEARL RECORDING STUDIO in NE Minneapolis for sending these sound samples...
 

Click
 Drums
Piano
Guitar

TIPS

  • You'll want to purchase Jim Cunningham's tuning kit.  Jim worked with Bill Putnam at Universal - the Studios and the Audio company - and, when the EMT plate patent expired, he created his own Echoplate Versions.  He is knowledgeable, helpful and has an extensive audio history. 
  • Folow Jim's instructions and do not overtighten.  The plate may seem 'loose,' especially across its length.
PARTS
  • Amplifier upgrade include replacing interstage and power supply capacitors and upgrading plate and grid resistors to metal film.  I also replaced the filament hum balance pots.
It may be hard to believe, but on a whim, I had instructed the client  to purchass a few of these very affordable piezo pickups from All Electronics, a surplus store in California.

These are glued to the plate using the 'rear-view mirror to glass adhesive.'