Mark V:25 versus Mini Rectifier FX loop question

This is probably a better question for Mesa support but hoping someone here can help me figure out what is going on. So I have both a Mark V:25 and a Mini Rectifier, and want to use both. I have 2 separate cabs so that is not an issue. I have a G Major, and a midi foot controller. I purchased a Voodoo Labs Hex looper and a Radial ABY. So the idea is feed both amps from the ABY. Route the fx send from each amp to a separate loop return on the Hex, say loop 2 and loop 3. The idea is only one return can be active at a time. Then feed the output of the hex to the G Major, and the outs of the G Major back to each amps fx return. In theory that should work. I think.

But what is happening is it seems the fx loops work at different levels between the 2 amps. I can barely go above 8 o'clock on the master on channel 2 of the V:25 without hitting the return of the mini rectifier too hard, while i have to crank up the master of the mini rec channel 2 to about 10 oclock to get a decently audible signal in the return of the V:25. I have swapped cables and outputs and such, none of that is the issue. To simplify during troubleshooting, I hooked up just the V:25 to the G Major, got it working fine, then added the mini rectifier simply as a power amp from the other output of the G Major (not using the mini rectifier preamp at all. Same basic issue, can't go above 8 oclock without hitting the mini rectifier return too hard.

So it really seems like the loops just run at vastly different levels, which would kill my plan.

However, I noticed one other thing on the mini rectifier by itself. There seems to be some bleed of the preamp signal outside of the fx loop. In other words when using the fx loop, I can mute all output from the fx unit, but still hear a fairly strong but thin signal coming thru the power amp. I even unplugged the return and the signal bleed was still there. SO that does not seem normal. Has anybody else run into this? I'm almost hoping there is something wrong with my mini rectifier so I can get it fixed and hoepfully have this setup work.

Thanks for reading all of this and for any who have input.

On my Nova System, TC Electronic provided features to adjust global input/output gain and also individual volume control for the outputs. I don't have a G Major, but I would think it has similar features to handle the levels. The output to the Mini could be set that way. Otherwise, a passive volume pedal or other device might be necessary.

Rectifried said:

But what is happening is it seems the fx loops work at different levels between the 2 amps. I can barely go above 8 o'clock on the master on channel 2 of the V:25 without hitting the return of the mini rectifier too hard, while i have to crank up the master of the mini rec channel 2 to about 10 oclock to get a decently audible signal in the return of the V:25. I have swapped cables and outputs and such, none of that is the issue. To simplify during troubleshooting, I hooked up just the V:25 to the G Major, got it working fine, then added the mini rectifier simply as a power amp from the other output of the G Major (not using the mini rectifier preamp at all. Same basic issue, can't go above 8 oclock without hitting the mini rectifier return too hard.

So it really seems like the loops just run at vastly different levels, which would kill my plan.

Click to expand...

I ran a MV:25 and MR in stereo using a G System. The two outputs were pretty much the same, and it is my understanding that the power amp sections are pretty similar. I did find significant volume differences when using different speaker cabinets, as one cab was much more efficient than the other.

Rectifried said:

However, I noticed one other thing on the mini rectifier by itself. There seems to be some bleed of the preamp signal outside of the fx loop. In other words when using the fx loop, I can mute all output from the fx unit, but still hear a fairly strong but thin signal coming thru the power amp. I even unplugged the return and the signal bleed was still there. SO that does not seem normal. Has anybody else run into this? I'm almost hoping there is something wrong with my mini rectifier so I can get it fixed and hoepfully have this setup work.

Thanks for reading all of this and for any who have input.

Click to expand...

Yes, it is totally normal to get bleed around the FX loop, as usually there is one 12AX7 that acts as both FX send and FX return buffer. Each 12AX7 is actually two independent amplifiers (dual 6AX7), so each tube has TWO amplifier functions. They do not have good isolation, so there is crosstalk.

Note that you seem to be trying this whole experiment at very low volume. You will get completely different results at high volume. The master volumes for these amps work somewhat erratically at very low volume as they are at the end of their tapers, and crosstalk in the loop that would normally be massively overshadowed by the FX signal becomes a much more significant effect. Try turning up a bit to see if things fall into line.