Marshall DSL 40 - FX Loop Issues

[juca]

Hi, so this my setup. Whenever the FX loop is on, there's a volume drop and the high end almost disappears.
Then all of a sudden everything works fine again...
Any idea why?
Thanks

 

[Leonard Neemoil]

I have very limited experience with the R version of these amps but maybe this thread can help: https://www.marshallforum.com/threads/dsl-40c-effects-loop-issues.101907/#post-2471169

 

[Georgiatec]

Hi, so this my setup. Whenever the FX loop is on, there's a volume drop and the high end almost disappears.
Then all of a sudden everything works fine again...
Any idea why?
ThanksView attachment 149327

I've noticed some effects are weaker (TC Flashback Delay), but it doesn't affect the overall volume of the amp on mine.
Your issue sounds like a dodgy contact somewhere.

 

[Georgiatec]

Hi, so this my setup. Whenever the FX loop is on, there's a volume drop and the high end almost disappears.
Then all of a sudden everything works fine again...
Any idea why?
ThanksView attachment 149327

Well blow me!! I was trying one of mine out tonight (I have two) and you are absolutely correct. With the loop engaged there is a noticeable drop in volume and a lack of dynamics. This did not go away until I switched the loop off. Then the amp returns to normal volume and all the dynamics are back. With the loop switched on it's like turning my amp around to face the wall.
I'm going to try the other amp tomorrow as well as experiment with the order of the pedals. Starting with one, then if that's ok, keep adding pedals until the drop occurs.
I will report back....most strange.

 

[guitarbilly74]

You have to troubleshoot this the long way:


First use a patch cable to jumper the send/return and turn the loop on/off. If you notice any loss the loop is defective and the amp needs service.

If no loss, start trying one pedal at a time until you find the one(s) that are causing the issue.

 

[Georgiatec]

Okay so here's the rub. Both my amps are the same. If I plug a patch cable across the Send/Return jacks there is a very small volume drop along with slight loss of top end, so little it's hardly noticeable. Plug in my effect board and it's blanket time when the loop is on. Switch it off and all is good. So the culprit is my 1980's Boss CE2 Chorus. If I take it out of the chain, then the sound is the same as a patch lead across the jacks. Interestingly, I tried another analogue Chorus (Joyo) and while not as bad as the Boss there was again a drop in volume and loss of dynamics. Could it just be chorus pedals?
If I put either Chorus in front of the amp, no issue, only if I put it in the loop.
As I posted earlier there is a loss of output from my TC Flashback Delay when in the loop. I've come to the conclusion it's a shite loop and I'm not going to use it. I tried both my amps with everything out front and they sound better in every respect.
I tried the same set up through the loop of my Astoria Dual and SV20H there was no difference between loop on and loop off, so it's a design / hardware issue in the DSL

 

[SkyMonkey]

I run my 40CR in 4CM with a Boss GT-100, TBEs in the loop.
Whilst I rarely use chorus, the one patch I made which is thick with the stuff has no volume drop.
But is comparing a pedalboard and a multi-effect apples for apples?
Never felt the need to patch the loop for a volume drop test though: I have the loop 'always on'.