Is this normal for the effects loop?

[Garveyte01]

Hi everyone, I recently completed my Dumble 124 build, I learned a ton on this amp! I’ve been playing it everyday, I’m thoroughly happy with it, but when I tried to plug into the effects loop and very diminished volume. I first testing a patch cable into the send to the return on the amp, and although sound is coming through it is very low. I then plugged my delay pedal into amp effects loop and the volume increased, I’d imagine this is due to the 9volt power supply of the delay pedal, is this correct? So next I setup my dumbleator into the amp and although I can get great volume it is slightly less than having nothing plugged into effects loop at all, also the dumbleator’s drive, in, and out pots are maxed out. I’m just trying to determine if this is normal or if it isn’t is there anything I should be double checking? Thank you

[GAStan]

There is 220k||250pf connecting signal to FX output that is also in the circuit when a jumper is used. This does attenuate the signal.

Edit: Congrats on your build!!!

To expand on this...anything plugged into the Send jack goes through this RC circuit and gets attenuated. If nothing is plugged into the Return the contacts are made and RC bypassed to PI, but if something is plugged into Return contacts are open disconnecting signal from PI and only signal from whatever is plugged into Return is applied to PI.

This does come after MV, did you try turning it up?

I believe the RC can be replaced with a wire if you do not like it. Hopefully someone will confirm this or correct me if I'm wrong.

[martin manning]

The 220k//250p feeding the preamp out seems to be an oddity of the 124. It doesn't appear in the other ODS amps documented here, and I believe most people are deleting that network.

[fred.violleau]

I would add that using a D-Lator on my dstyle builds adds volume significantly. And when that input gain is maxed, I get distortion, which is normal.

Try and clip an alligator cable bypassing the resistor/ capacitor, and play. Listen to what the network does. IF I remember correctly, the network would shave of some of the high end.

Fred.