Soldano Avenger 100 FX Loop Install

[keithb7]

Hi everyone. I have come here again to beg for you assistance in helping me install a tube driven FX loop in a Soldano Avenger 100W amp.
My experience is limited to mainly old vintage Fender amps. I am not keen to work on PCB amps, but I will give this little project a try. It seems fairly simple, with some help I think I can do it.
Here is the chosen FX loop.



Here is a shot of the Soldano amp.



Chassis is now drilled in top right corner and FX loop fits in there.
Being unfamiliar with PCB amps, I would like to confirm a few things.

First question. Does anyone have a schematic? I have not been able to find one by doing a regular Google search. I'll post more after we see if a schematic turns up.
Thanks, Keith

[keithb7]

Not exact schem but thinking this might help: http://5mp.eu/fajlok2/amp/soldano_sl...ww.5mp.eu_.pdf


A couple questions I have are:

HT connection. I am not 100% sure what this is. High voltage b+ connection going to first pre-amp stage?

Connection to pre-amp/tone stack out. I suspect from the treble middle pot? Pull treble pot wire and insert FX loop circuit input.

Connection to power amp in? I believe this is the output of FX loop. Wire from this connection goes to phase splitter input, where wire from treble pot
would have went?

Thanks, Keith

[nsubulysses]

I'm sorry I can't be of more help becasue I'm in a big rush right now but it might be worthwhile to compare/contrast SLO100 and Avenger schematics. Also you may not even want to do this anyway BUT:

Avenger is an SLO100 minus 2nd channel and minus FX loop I believe. THat might be the only differences? Mike SOldano is very helpful in my experience too. You can call or email him as a last resort.

Soldano SLO100.pdf

[defaced]

Avenger schematics are out there, but you really don't have to have one - it's a pretty simple amp.

nsubulysses is correct. The SLO and Avenger are different in that the Avenger is a single channel version of the SLO drive channel without a FX loop. The SLO is a dual channel loop with the FX loop before the tone stack. This arrangement is part of what gives the SLO its sound, but it's not a common arrangement on cascaded gain stage amps. I'd really encourage you to put the FX loop after the tone stack but before the MV - so the input I have below is written for that configuration.

You'll want to pull the HT from the phase inverter node. So locate the phase inverter tube and it's associated filter cap - probably the big black on in the middle of the preamp board. Tap your B+ from there. Ground back to this cap as well.

Pre out/power amp in: you are correct. You're essentially inserting the loop between the treble pot wiper and the top leg of the MV control. So lift the treble pot wiper (or cut the trace between the two controls, whatever you prefer to do), run your signal to/from the FX loop making sure that the pre out/FX in are connected at the treble pot and FX out/power amp in are connected at the top of the MV pot. This will give you a fairly consistent output level from the preamp, allow the tone stack to adjust the tone of the preamp as it did originally, and allow the master volume to control the volume of the preamp and the FX in the loop, thus not moving your send/return levels around.

The Avenger has almost 400v on the PI node, so their suggested 47K B+ dropping resistor might be a little low. Have a 100k, 68K and 56K handy.

I'd encourage you to also use shielded wire for the runs to/from the FX loop board.