JVM205H Fx Loop Issues

[Evan57]

The fx loops in my JVM205H have been giving me issues. The only pedals I use are a mxr carbon copy delay into a mr. black bloodmoon reverb that I put in the amp’s fx loop. I’ll try my best to explain the issue simply:

When I use the amp’s series fx loop, I have the following issues:
1. When the amp is clean and the reverb pedal is on, there is a crackle sound when a chord is strummed.
2. When the amp is distorted and I turn the delay pedal on, the volume is cut drastically and the sound is very muddy.

When I use the amp’s parallel fx loop, I have this issue:
When the amp is distorted and I turn the reverb pedal on, the volume is cut drastically and sound is very muddy. Both my reverb and delay pedals can go fully wet so I try setting the mix all the way up on the pedal when using the parallel loop. However, adjusting the mix does not help the issue.

Some additional information that might help:
1. I use a voodoo labs pedal power 2+ to power my pedals.
2. I do not have any pedals in front of the amp. The only gain I use is from the amp itself.
3. I have plugged my amp into a power strip as well as a wall outlet and the issue is the same.
4. I tested my exact same setup in a dsl40 combo amp and had none of these issues.
5. I have tried using a ds-1 in front of the amp instead of the preamp overdrive and still have the issue
6. I explained this to an established amp and guitar tech in my area and he did not know what the issue was.
7. I strongly feel that it is an amp issue and not a pedal issue because I have tried to put a noise gate in the loop using the cross cable method and a chorus pedal but I still had issues.

I know this is a lot of specific information but if there is anyone out there who has any idea what I should do I would greatly appreciate any suggestions.

 

[paul-e-mann]

The fx loops in my JVM205H have been giving me issues. The only pedals I use are a mxr carbon copy delay into a mr. black bloodmoon reverb that I put in the amp’s fx loop. I’ll try my best to explain the issue simply:

When I use the amp’s series fx loop, I have the following issues:
1. When the amp is clean and the reverb pedal is on, there is a crackle sound when a chord is strummed.
2. When the amp is distorted and I turn the delay pedal on, the volume is cut drastically and the sound is very muddy.

When I use the amp’s parallel fx loop, I have this issue:
When the amp is distorted and I turn the reverb pedal on, the volume is cut drastically and sound is very muddy. Both my reverb and delay pedals can go fully wet so I try setting the mix all the way up on the pedal when using the parallel loop. However, adjusting the mix does not help the issue.

Some additional information that might help:
1. I use a voodoo labs pedal power 2+ to power my pedals.
2. I do not have any pedals in front of the amp. The only gain I use is from the amp itself.
3. I have plugged my amp into a power strip as well as a wall outlet and the issue is the same.
4. I tested my exact same setup in a dsl40 combo amp and had none of these issues.
5. I have tried using a ds-1 in front of the amp instead of the preamp overdrive and still have the issue
6. I explained this to an established amp and guitar tech in my area and he did not know what the issue was.
7. I strongly feel that it is an amp issue and not a pedal issue because I have tried to put a noise gate in the loop using the cross cable method and a chorus pedal but I still had issues.

I know this is a lot of specific information but if there is anyone out there who has any idea what I should do I would greatly appreciate any suggestions.

Is this a new problem, did the loop work right at some previous time? I would find a certified Marshall tech in your area.

 

[davidj]

All I can contribute is I've had no similar problems with my JVM205H. I use a Boss DD3t with a dummy plug to give a fully wet output and controll it with the wet/dry knob on the loop. The pedal has a battery in it and distortion comes from the pre-amps only, Sounds great and no crackles or loss of volume/clarity. I set the loop at -10db. Never used the other loop (except to take the output from a modelling amp) so I can't comment on that. Good luck getting this fixed - a job for a Marshall tech maybe?

 

[PelliX]

Manners first!

to the MF!

When I use the amp’s series fx loop, I have the following issues:
1. When the amp is clean and the reverb pedal is on, there is a crackle sound when a chord is strummed.
2. When the amp is distorted and I turn the delay pedal on, the volume is cut drastically and the sound is very muddy.

Assuming that all connections/jacks are OK [hint] then it sounds like an impedance or signal level mismatch perhaps. Does it behave the same with the -10 and +4dB switch in either position?

If you plug your guitar into one of the pedals and feed that straight into the return jack of either loop, do you get the same crackle?

 

[Sacalait]

My opinion about the JVM FX loop is they "over thought" it. I've had some issues with mine but the tone is so righteous that it doesn't bother me much.

 

[EADGBE]

Have you tried powering the pedals with batteries and see if the problem continues?