Today I tried to set up my GT-8 with the 4CM, but unfortunately the parallel loop on my JCM2000 didn’t play along.
The 4CM works best with a series loop. A parallel loop means that the amp mixes the wet sound with the direct sound. Your amp contains an “FX” knob that allows you to set the level of the loop.
Depending on your amp, you might have success with a parallel loop. You will need to set your effects to 100% wet if this is the case. In most cases, however, you will get an out of phase sound due to the small amount of latency introduced in the GT-8’s processing.
If your series effects loop introduces noise when connecting the GT-8, it could be a ground issue, in which case you will need to use shielded cables.
To get connected, you can follow the instructions (listed below) on Boss’s website. It can be a little confusing at first. The main thing to keep in mind is that the LOOP can be moved around freely inside your FX chain, in order to determine where the SEND is. This will allow you to isolate effects such as delay and reverb so that they only get sent to the L (main) output.
You will likely also want to disable the preamp section of the GT-8, and only use the stompbox section to boost your amp.
– Connect your guitar to INPUT of the GT-8.
– Connect the SEND of the GT-8 to the input on your amp.
– Connect the SEND on your amp to the RETURN on the GT-8.
– Connect the L/MONO OUTPUT on the GT-8 to the RETURN on your amp.
