Please help me with noise issue running two amps!

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cameron711

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Hi all!

I'm trying to get fancy and run both my D-moll and Vh4 through a TC Electronic G System. The signal chain is

Guitar ->TC Guitar input to these loops:
Insert Loop Send->Vh4 input->Vh4 Serial Send->Insert Loop Return->TC Effects-> TC Output Left->Vh4 return

Loop 4 Send->D-Moll input->D-moll serial send->Loop4 Return->TC Effects->TC Ouptut Right -> D-Moll Return

On the back end, i have the speaker out of each head going into a Radial Headbone and the Headbone speaker out into my Diezel 4x12 cab. A sweet feature is that my G System control's the headbone.

My goal is to have presets where i'm playing thru my vh4 only or my d-moll only. When each is connected separately, no problems. When I connect both, i get a serious high pitch squeal in higher gain channels to the point of unplayable. When I remove either of the outputs, I get resolution of the squeal.

Any thoughts?

Thanks!
 
Sounds like a ground loop and/or phasing issue. Is there a ground lift or phase option on your splitter?

Using two separate power points can make ground loop noise worse as well.
 
My AB/Y box has a lift switch on it...
It needs to be switch in the opposite direction of you here noise
 
The TC offers no ground isolation at all. Both heads are seeing common input all the time. You need more stuff. Your amp basically needs to be selected in front of the TC, not behind it.
 
you should invest in an RJM Y-not. Killer midi stereo switcher, and if you order it with the y-b mod you can invert the phase of your second amp per preset in case some of your channels are out of phase with eachother. Only issue is there's no midi through, and if you daisy chain midi through your amps you could get some noise issues. I solved this by buying a midi solutions quadra-thru which splits your midi signal before you put it through any amps or anything
 
Thanks for the input. Just ordered an ebtech him eliminator and some trs-trs cables to go from the g system to the hum eliminator and some ts-ts cables to go from the eliminator to the effects return. Will report back!
 
I can usually solve these "two-amps hooked up ground-issues" with my Lehle P-split. It's a y-splitter with a ground lift and phase inversion option.
 
cameron711":3p6h7b7i said:
Thanks for the input. Just ordered an ebtech him eliminator and some trs-trs cables to go from the g system to the hum eliminator and some ts-ts cables to go from the eliminator to the effects return. Will report back!

Cancel that order. I threw the Ebtech in the garbage. You need something with ISO transformers in it to isolate one amp from the other. Essentially, what you are doing is using a Y cable from your guitar plugged into both amps.

Lehle makes good gear. Palmer makes really good stuff.....

http://www.palmergear.com/pga03.shtml

http://www.palmergear.com/pli02.shtml
 
Kev":2unjq6ng said:
I can usually solve these "two-amps hooked up ground-issues" with my Lehle P-split. It's a y-splitter with a ground lift and phase inversion option.


where in the signal chain do you put it? i was thinking i would connect output L of the g system into the p split, and the psplit outputs to amp 1 and 2 fx return?
 
or if i wanted to only use one sound at a time should i do a lehle ab/y switcher in the same position?

thanks!
 
Usually I put it just in front of one amp and use the "iso"-out with ground-lift. Basically it works like an iso-box then. However I did not connect both amps sends back into the same unit that already did pre-effects.

Mixing both preamps into one poweramp will not work with the g-system, since the g-sys-loops are in serial.

To use one amp at a time, sharing a cab, you should try using one or more iso-boxes (such as the p-split) at every position possible.

I also often got rid of ground-issues/hum by using a digital effect (like the POD xT) in front of one of the amps or even to split the signal, which worked more often then my p-split.
This might seem unorthodox, but if the iso-box/es don't work, maybe try the POD xT or a digital processor that can pan the signal via midi. I would hook it up the gsys-loop4-send > pod-input
pod-Left-out > VH4-input, VH4-send > gsys-loop4-return
pod-Right-out > Dmoll-input, Dmoll-send > gsys-instert-return.

Just use the pan-effect and fiddle around with the output level. It might seem crazy to put another piece of powered gear in the chain, but this method has worked for me most of the time. You might think: doesn't the gsys do the same thing already? No. The gsys loops and insert act like a analog loop-switcher, the however POD goes trough AD/DA.
You might also be concerned about tone-loss. I have never experienced any tone loss from running the POD xT just using the effects (no ampsims. The gate can degrade your sound if you use very low tunings or a bass). Actually I have less "high-gain-noise" when I max the output on the POD.

PS: Did I mention already: the POD can also fry bacon and make lasagna.
PPS: Do you want to buy my POD for only a million bucks? :P
I just felt like a Line 6 sales person... But seriously this thing really helped my when running two amps at once and I all I want here is to help you run your killer rig!
 
I did same thing for 2$ buy the adapter at any store that takes 3 prongs to 2 prongs. Thus lifting the ground on one amp. Killed the noise immediately !
 
cujo":1ksatklh said:
I did same thing for 2$ buy the adapter at any store that takes 3 prongs to 2 prongs. Thus lifting the ground on one amp. Killed the noise immediately !

Be aware that if something happens in that amp that has the ground lifted (like a tube/ground fault) there's nowhere for that 500V to go but straight back to the guitar until the fuse blows.

Just sayin..... :checkthisout:
 
Yeah, what Steve said! NEVER remove the ground connection on a valve amp. The ground should be lifted at the splitter not the amps power cable! This could as Steve mentioned be very dangerous!
 
Wow thanks for the info fuck I've been lifting a grd for years. Doesn't radial bone sell a thing for this problem. I need the correct answer myself. We run two heads wet/dry set up.
 
so here's what i have so far....still noise :-( not illustrated is my radial headbone that my d-moll and vh4 both send their speaker outs to and from the headbone to the 4x12 cab, all impedance matched. the one neagtive is that my place is older and all the outlets in the area come from the same source, not sure what solution to do for that....any thoughts?!
 

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cameron711":zouxm5ww said:
so here's what i have so far....still noise :-( not illustrated is my radial headbone that my d-moll and vh4 both send their speaker outs to and from the headbone to the 4x12 cab, all impedance matched. the one neagtive is that my place is older and all the outlets in the area come from the same source, not sure what solution to do for that....any thoughts?!

Your problem is still on the front end. You might as well use a Y-cable as to use the G-System for what you are intending. You need heavy duty signal isolation from guitar to inputs.
 
so how bout this....
guitar output ->g system guitar input -> insert loop send -> lehle dual

lehle dual a ouput to vh4 inpuit
lehle dual b output to d-moll input

vh4 serial send to lehle 3@1 input A
d-moll serial send to lehle3@1 input B

Lehle3@1 ouput 1 to g system insert loop return

g system left ouput to vh4
g system right output to d-moll

then use a radial headbone to switch speaker ouputs to the amp i want to use (only want to use one amp at a time for now)

i'm think i'm getting dizzy
 
To use the same unit and maybe supplied by wall power
on the front end and on the loops is a big challenge
to the effect unit manufactures. It needs to avoid
ground loops and buffering signals.

Sorry to sound rude and destroy your signal flow.
Use only the Lehle to split the signal into the amps.
Use only battery powered units like wah wah or
distortion pedals in front of the amp of course
there will be noise.

If you can get a effect unit with external power
suppy for the loops, you will be happy.
 
break the ground on some cables.

by that i mean, open your cable barrels, and snip the ground (the one that is soldered to the body of the cable shield, not the tip) and then place that snipped end plugged into the amp side.

work backwards (from the last part of the signal path to the beginning)

meaning, try this cable first: TC Output Right -> D-Moll Return


if that doesnt solve it (it should though) then also snip the amp side ground on this cable:

TC Output Left->Vh4 return

if THAT doesnt work try one of those snipped cables in each spot in your setup until you eliminate the hum.

DONT do this with speaker cables. just guitar signal/patch cables.

i used to use a 3 prong adapter. DONT use these. they open the door to some dangerous possibilities, even though some people will tell you that the system is grounded through everything else, it's NOT if you use one on an amp HEAD (rack mounted amps can be grounded through the chassis to the rack to the ground IF wired that way).

personally, i have one guitar cord that has the ground lifted at the amp side, and i use it to patch in and eliminate the loop when using my 2 amp setup.
 
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