Hi Steven,
why you used relay and why you didn't uses switch directly? any concern about it?
The lug 3 of V4A (1st hakf of 12ax7) on tremolo section is conected to Red LED, I guess you uses LED as indicator for the tremolo?
On the power section, I do not understand circut of 100R (Potentiometer?) and 47/5W (tied to 6v6 cathode), can you tell me how this works? Why you did not use two 100 Ohm to create a center tap for the heather?
Sorry, if I ask you to much.
Agu
I used the relay to switch the boost. I don't like running signal outside of the amp (which happens with the standard Fender reverb switching), which I would have had to do to switch the boost without a relay. The relay board has a second relay. Instead of not using it, or using it for reverb (I've never found footswitchable reverb particularly useful) I used it to switch the tremolo.
The LED is the cathode R for the oscillator, and serves as a visual indicator. The idea came from Merlin.
The 100R rheostat is a "humdinger" to balance the heater string and minimize hum. Just using two 100Rs works fine, but the Rs might be slightly different, the two halves of the heater winding might be slightly different, and so on. With the rheostat, I can really balance it for minimum hum. The 47R off of the center insures neither side of the string is directly at ground, if the rheostat is turned all the way one way or another, or in the unlikely event that it fails. At some point I stopped connecting it to ground in cathode-biased amps, and started tying it to the cathode. Using 2 100Rs will work just as well in nearly every practical case. I always do the humdinger because that's just the way I do it. The amp is laid out to have minimum hum and noise and I can dial it in to be so quiet you wouldn't know it is on if the pilot wasn't on. After building something more than 30 amps, some things just work for me, and I repeat those things without thinking about it anymore. The humdinger is one of those, as is the direct wiring, the Hoffman grounding scheme with the buss on the back of the pots, and the way I wire heaters. I get consistently good results with these techniques, so I continue to use them.
steven
