Zero Loss FX in 1959/2203 2in1

[klauswilliams]

Hi all. I just installed the Metro fx loop in my 1987/2204 switchable amp, and while everything works perfectly when in 1987 mode, I am having issues on the 2203 side. When the loop gets engaged, I get a slight reduction in volume, drastic loss of treble, as well as a diminished response from the effects in the loop. Sort of like a heavy blanket was thrown over the cabinet. When I turn the loop off on the 2203 side, it returns to normal.

I wired it up as if it were a 2204 model when following the Metro fx install instructions. Meaning, I tapped the signal between the treble pot middle lug and the master vol pot). All voltage readings were spot on, no issues whatsoever during the install.

Has anyone installed the loop successfully in a 2in1? Is the issue because the amp shares a master volume (dual pot)? Thanks for any help!

[neikeel]

Seems that would be the usual way of installing.
If you play in 2203 mode and crank the gain (with MV dialled back) does it sound ok?

How did you install the 2 in1? On my version I specifically use a dedicated MV pot and put my gain pot in the lo channel ii pot position. Then you are not automatically turning the PI drive off when you turn the MV.

Other thing is it is hard to understand why the treble is down so much. DId you use miles of cable (with high capacitance)?

[klauswilliams]

Hey to follow up here - looks like everything was wired and installed fine. Culprit turned out to be a pedal in the chain which was really sucking tone. I know that doesn't explain all the symptoms, but after playing with it for a couple months, it seems to operate fine on both sides of the amp. I don't use that one pedal (Boss Super Chorus) with the 2203 side, but that's a small price to pay. Odd since the pedal doesn't have as negative an effect on the 1987 side.