Marshall JVM410H issue

W

Warheart

New member
I recently acquired a Marshall JVM410H and I gotta say, overall, I'm pretty happy with it.

One problem I am having though is a bit of a weird issue.

When I use the amp with Pedals in the serial/parallel loop, I have no problem.

However, when I use my GSP1101 using the 4 cable Method so that it is in front of the preamp as well as in the Serial Loop (The one with no FX send knob), If I turn the volume on the OD1 and OD2 channels past 2, I get this weird squeal. It kind of high pitched and sounds hollow? I thought it was a microphonic tube, as I could hear the tube rattling when I tapped the chassis and the tube guard. It doesn't do this without using the processor though, so I have ruled out that option.

The gain on these channels are around 11 o'clock, or on 4. Its a fair bit of gain, but no more than necessary for the sound I would like.

If I have a guitar plugged in or not doesn't change this sound. I can dial the sound out by turning the volume knobs down. However, It makes it hard to get the amp up and roaring since the master volume has to be dimed to get the volume up.

However, If I use Ground Lift Cables in the effects loop. I can actually raise the channel volumes up more, although it will still do the squeal when If I turn them up to 4. (found this idea on the JVM forum.)

I'm guessing it has to do with some kind of cascading volume levels or the FX loop send? I can set up the preset levels and the overall output level in my processor as well. Although again, if I turn this up too loud, it will again do the same squeal.

I believe it must be some kind of level send issue to my processor, but can anybody shed some insight on this matter for me? It would be greatly appreciated.
 
Re: Marshall JVM410H issue

I dunno man... but I had a similar issue trying to use the 4-cable method with my TC G-System into my Bogner XTC. Didn't matter what I did with the levels or whether I selected the serial or parallel loop. I didn't have the squeal but I had the hollow sound. I was able to get that tamed if I used the "Dry Kill" feature on the G-Sys. But using that feature really hurts time-based FX. No issues if I just use the whole G-Sys in the loop. So I just sacrifice being able to put the compressor and the selectable loops in front of the amp. Not optimal, but liveable.
 
Re: Marshall JVM410H issue

I also tried it as a Parallel loop too, using the dry kill feature from the mustbebeta upgrade.

Although I had the same problem as you, I couldn't use the noise gate properly, and that was a deal breaker for me.

I can't remember if it made the same squealing sound though. I don't think it did, but again, Parallel loops are not conducive to some things. I didn't think delay would be one of them though, I thought they were fine?
 
Re: Marshall JVM410H issue

I've the 410c and had very similar issue with the 4cm and a boss Gt8, I also found it to suck a lot of tone when using the 4cm so I was happy enough to just go into the front of the amp (although delay and chorus didn't really sound great)

I've switched to using stompboxes just recently bit haven't had time to mess around with my line 6 dl4 in the loop! I'll post back if I find anything interesting!
 
Re: Marshall JVM410H issue

Warheart said:
I also tried it as a Parallel loop too, using the dry kill feature from the mustbebeta upgrade.

Although I had the same problem as you, I couldn't use the noise gate properly, and that was a deal breaker for me.

I can't remember if it made the same squealing sound though. I don't think it did, but again, Parallel loops are not conducive to some things. I didn't think delay would be one of them though, I thought they were fine?
Click to expand...


Maybe it was modulation-based FX. I know that was one of them, cause the normally LUSH chorus of the TC G-Sys just sounded like a dog using Dry-Kill.

Sounds like this is a common issue when using the 4CM. Bummer... because in theory it's an awesome concept.
 
Re: Marshall JVM410H issue

I guess what I'm asking is this:

Why would using ground lift cables not change the sound but make this squeal less apparent? IS it simply a ground loop? or is it a line level issue?

Is there a way to measure -10/+4 levels in an effects loop using a multimeter? what should I be looking for?
 
Re: Marshall JVM410H issue

Can anybody else chime in on this?

Kinda makes me wonder whats up with the loops on the JVM to begin with!
 
Re: Marshall JVM410H issue

I don't know what to tell you. I run a tc electronic g major through my effects loop and I don't have any problems with it.
 
Re: Marshall JVM410H issue

JOLLY said:
I don't know what to tell you. I run a tc electronics g major through my effects loop and I don't have any problems with it.
Click to expand...

Which loop? Series/Parallel or just the Series one?

I've noticed there's a walkthrough for setting up G-Major's on the JVM Forum.
 
Re: Marshall JVM410H issue

Warheart said:
Which loop? Series/Parallel or just the Series one?

I've noticed there's a walkthrough for setting up G-Major's on the JVM Forum.
Click to expand...
You know, I'm such an idiot when it comes to that stuff that I really don't even know. I can't even remember. I'm more of a plug up and play kind of guy. I just plugged the damn thing up and went for it. It works for what I use it for, and that's good enough for me. Sorry I'm not much help.
 
Re: Marshall JVM410H issue

New development:

I used an ART Cleanbox II between the GSP guitar send and the Marshall front input.

It got rid of the squeal unless I turn up the GSP output a LOT more, from noon to 3 o'clock.

I tried using a ground lift cable instead, but that did not help the issue. So while it is a ground issue, the Cleanbox II isn't just a ground lift.
 
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