2deaf's 12dw7 transformerless reverb driver on the breadboard

[pullshocks]

In another thread, 2deaf posted a transformerless reverb driver circuit to use with a 4FB type reverb tank that I had bought off craigslist and never got around to using.


I now have this circuit up and running in a modified Princeton Reverb no trem  bread board build.  The reverb recovery  is the standard Princeton Reverb.  A schematic (with voltages) of this implementation is attached here. 


2deaf's design called for a B+ of 350 volts on the driver triode.  After some trial and error I came up with a combination of dropping resistors that give this voltage at node C and the more standard Fender preamp B+ values at the other nodes.  In the Fender amps, node C is not connected to anything.


It seems to work fine.  It sounds like spring reverb.  I don't have any other amps with spring reverb around to compare it to, but I listened to some youtube clips of various fender and ampeg spring reverbs, and I do not notice any drastic difference.  At clean preamp volume settings (2-3) reverb is fairly subtle.  At higher gain levels, the reverb effect is a lot stronger.  This makes sense as the signal to the reverb tank is stronger.


Thanks to 2deaf and all the other forum participants who helped me get the reverb tank identified and into an amp circuit.  It worked out great because I had the tank and a couple 7247 (12dw7 substitute) tubes on hand, and didn't need to buy a reverb transformer.