EA Tremolo modifications
Modifications to JD Sleep's version are:
- Input buffer and main gain stage have been combined into a single MOSFET stage designed by Gez Paton.
- The "pulsing LED" by Darren Inwood and Rob Strand.
- Depth and Speed controls have been adjusted to my preferences. The first 25% of the original 1M Depth pot rotation resulted in no audible tremolo effect to allow use as a pre-amp. The Depth pot has been decreased in value with carefully chosen resistor values added before and after. The Rate pot value has been increased and a reverse-log taper offers a better feel. However, a linear or audio taper pot can be used for the Rate control with no ill effects. The 2k2 resistor which precedes the Speed control has been reduced for a faster maximum oscillation rate.
"marrstians" reports that the pulsing LED can also serve as a status indicator when using a 3PDT bypass switch. Simply use the third pole of the switch to break the connection between the LED and the collector of Q3 when bypassed.
Listen to it!
Pablo De Luca (aka Gringo) contributed a PCB layout for the modified EA Tremolo (PDF, 220k)