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Adding effect loop

5/22/2000 8:38 AM
Kanord Adding effect loop
Is there anyone, who has built an effect loop to an amp lacking one? Is soldering connectors after preamp enough or should I add some kind of a resistor to lower the levels to a possible standard? Or would a potentiometer be a better option? I have got a marshall VS15 with reverb.  
5/23/2000 2:07 PM

I've never added an FX loop to an amp (internally) and am not familiar with the model you mentioned but ... the "basic" idea is to interupt the signal at the input to the power amp. The preamp signal is then routed through the FX and back into the power amp.  
There are problems with this (and someone else here could better explain why), like too much signal loss, so it needs to be boosted in some way.  
Thats why another tube is usually added.  
I wonder if a clean level boosting device, like the MXR micro amp, could be added as the last FX (?)  
I have never tried it tho. :)  
also Stew Mac makes a kit (tube FX loop) I think.  
5/26/2000 5:23 AM
Frank Clarke

Steve Ahola describes an unbuffered in/out loop for the Pignose G40V. He describes its limitations.  
Normally you'd want an extra tube for a buffer. There is a Dumbelator thread about an external buffered fx loop around here somewhere.
6/5/2000 4:10 PM

The Marshall is a solidstate one . The info in the g40_mod.pdf - file is very good . I think the DumbleAtor is way too good for this type of amp ........  
Good luck !  

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