Which master volume works best for the one wire mod and ZL FX loop?

[trt1972]

Hi everyone, after much experimentation I have finally got my 1987 about where I want it to sound. I installed the Michael R/T 1 wire mod, and the gain sounds fantastic through this amp now.

I’m just curious, though, I’ve installed a post phase inverter (Lar/Mar) master volume on it, and also the metro Zero Loss Loop. The issue is when the gain is turned up, pedals do not sound good through the loop (flanger, chorus, delay). I’m not getting the usual, dirty, repeats or anything like that, it’s more that the effects are barely audible, like they’re not on.

So I’m wondering, would it be better to pull out the master volume I have installed and install a pre-phase inverter master volume? Just inquiring for advice, experience, thoughts, etc.

Appreciate your help!

[danman]

I'm gonna say that the loop would work better with a pre-pi MV vs a ppimv. The ppimv allows the phase inverter to get pushed into saturation when you dial down the volume but push the preamp gain up. Any signal from the loop passing through the PI would be saturated also and which will affect the sound. If you set the ppimv at 10 when you play, it is basically out of the circuit so the loop should work and sound good at this setting.

The pre-pi MV will reduce the signal before the PI and prevent it from saturating when you increase the preamp gain. This will allow the loop to work better but you may notice a change in the amps tone because you won't be getting the PI saturation that you would with the ppimv. You will just have to try it and see if it sounds good to you.

[trt1972]

Thanks for the advice! I’m getting to work on installing the pre-phase inverter master volume now. It looks as though the hook up from the middle lug of the master volume attaches to the same place that the loop sits on the board. This seems to cancel out my loop when I hook it up this way. Any ideas?

[Reg18]

New to turn but this might help answer one of my questions too.
I have recently bought a JCM800 1959 model which had some mods done including what I assume is a pre pi MV.
The MV also increases the gain significantly when turned up which is good and bad. I like having some control over getting a clean sound so my question is, if I convert it to a PPIMV will it act like the other MV on full? If so I won’t get as much clean is my worrie.

[danman]

https://ceriatone.com/british-style-jcm800-2204-hw/

Without seeing your amp, it's hard to offer advice about what's happening. The forum doesn't allow pics to be uploaded anymore but you can link to a hosting site if you have any pics of the wiring. I linked to this layout of the Ceriatone 2204 because it has a pre-mv and a passive effects loop. If you wire your mv and loop just like they show in this layout, you should be good to go.

[danman]

There is a link to the layout drawing at the bottom of the page.