Help removing/bypassing an effects loop.

[antieatingactivist]

I've been searching for this for a while and can't find any information on this, or at least any that I understand. I see a lot of info on adding an effects loop to an amp, but never removing or bypassing it. From just looking at a schematic of an amp with a series effects loop, it looks as simple as removing the cathode follower (i think) that buffers the send, and maybe the stage after the return jack that brings the signal back and bridging the gap with a coupling cap. If it were this simple, why don't I see many amps with a switch on the back that does this? I am looking at a schematic for a yamaha t100. I figure a really awesome, but not particularly valuable amp makes a good learning tool. I've already put a choke in and changed the filter caps. If anyone could point me to any resources that would be great.

[Chuck H]

Provided the loop is actually designed for unity gain you would need to bypass bothe the cathode follower AND the return stage. Just bypassing the cathode folower would result in an enormous gain boost that would likely eliminate any clean possibilities from the amp. In truth the circuit doesn't really contribute enough distortion or noise to bother with bypassing it. You would however invert the phase of the amp, and therefore the "feel", for better or worse.

[diagrammatiks]

in the slo circuit which is what the t100 is based on...

the effects loop is basically bypassed all the time anyway...since it's not really a full featured effects loop by today's standards.

the 2 cathode followers are important for the distortion voicing of the amp and the first cathode follower would need a coupling cap on it anyway so there's not really much to be done in terms of getting rid of the loop in that amp.