FX loop scratchy and crackles

[xero0620]

I have a boss eq in the series loop on my rm50. At higher volumes or when i do a heavy palm mute there is a crackling or scratchy type noise almost a popping. Its hard to explain the noise it sounds like the speaker is busted but when I run nothing through the loop the amp sounds fine? The noise happens when the eq is on or off, as long as its plugged in it happens. Any idea what this could be before I start guessing. Any ideas on how to trouble shoot the problem? Thanks.

 

[JKD]

The line level (+4db) of the loop is overloading the guitar signal (-10dB) input of your pedal..you can either use very, very low volumes and put up with the boominess or get something that pads the output of the loop, like an Ebtech line level shifter.

 

[walshinator666]

I wonder if that's the same problem I have.There's a crackling sound at the end of a note,so if i'm doing something stacatto with palm mutting it's like note crackle...note crackle... you what I mean?It's really noticable at high volumes,it drives me nuts!

 

[JKD]

A good troubleshooting tactic for this is to jumper the Send/Return with a patch cable....no noise or issues and you know your loop components are working.9

 

[walshinator666]

By jumper do you mean plug in the send to the return using one cable?

 

[JKD]

By jumper do you mean plug in the send to the return using one cable?

Yes...so there is basically nothing but the cable in the loop...of course if you happen use a broken cable that's another point of failure ;-)

 

[xero0620]

I did this and all was good but if I plug any pedal into the loop the problem continues and it also happens in the parallel loop. Any thoughts?

 

[JKD]

I did this and all was good but if I plug any pedal into the loop the problem continues and it also happens in the parallel loop. Any thoughts?

Your pedals are not built to cope wit the signal level of the loop....you need a pad like the EbTech line level shifter

 

[xero0620]

Is it normal for the signal levels to be like that? I have never had a problem with pedals on other amps. Is this mainly a Randall thing? I guess 80 bucks isn't bad but it will have to wait, I don't need the pedal that bad. Thanks.

 

[walshinator666]

I have a decimator prorackg(rack unit) on the back it has buttons called ground lift also on the back of my rm4 theres a switch ground and lift.Are these not the same as that pedal you are talking about?

 

[JKD]

Is it normal for the signal levels to be like that? I have never had a problem with pedals on other amps. Is this mainly a Randall thing? I guess 80 bucks isn't bad but it will have to wait, I don't need the pedal that bad. Thanks.

Well...the units were designed by Bruce Egnater I believe....the general opinion was that it rack type/pro effects at +4dB sound better I guess.

There are a few amps on the market that have line level FX loop....I wonder if someone could mod the loop with a -10/+4 switch...I've seen that on some amps and it's a neat idea.

I don't do pedals particularly nor many FX at all...

 

[Julia]

That would be a cool mod. IMO they should have done that when they built the amps in the first place. Marshalls have it stock. It did piss me off that I had to go to rack units. Now I've got like a bazillion effects pedals I've got to sell. Talk about a pain in the arse.

The only positive thing I've gotten out of going rackmount is that it's gotten a bunch of stuff off the floor, but I still use some boutique pedals for added dirt before the amp (like fuzz, treble boosters).

 

[Zander]

Is this mainly a Randall thing?

It's mainly a preamp thing.

That +10 line level signal is what a preamp does.