Finally figured out what my ol princeton had in it for its "second" gain stage. basically an internal version of one of these with a push pull pot which dialed in the amount of gain vs reverb you desired. it basically jumpers the reverb input and output together. mine, as i said was on a push pull and i could dial in the reverb as well as the gain. that along with the added mid control was cool. i gotta say, the extra gain was pretty intense, very in your face, and could be wild!!

just a lil piece of history and my past i though i would share!

Gregg