#1
OK, WEIRD one here.
I have a Genz Benz El Diablo 60 head.
I HAVE been using a Rocktron Hush Super C (meh) to cut back on some of the pre-amp noise (Running the Hot channel between 7-10 on the gain...Very "metal" tones. Not much mid, pretty high on the treble, just a tick over 1/2 way on the bass (this thing is a BEAST on Bass!!! For "Kill em all" tones, Bass never gets beyond 11:00...And Justice/Black...Bass never above say 1:00-2:00)
ANYwho...I didn't like that every time I click on or off any of the gain modifiers (high gain/classic, compressed/dynamic, global attack) I would need to adjust the Hush threshold. That and at higher volumes, it would rob some tone. So I purchased an ISP Decimator Pro Rack G (Yeah, the $420 noise gate). I hook it up as instructed, guitar into channel 1 in. Chan 1 out to amp input. FX loop send to chan 2 in, chan 2 out to FX return.
NOW ANYTIME the amp is on the Hot channel (chan volume at 5) I get a HUGE feedback if I turn the master vol over 1.5 (3 is VERY loud, 1.5 would be KINDA loud, practicing alone at home (small room))
I can roll the volume down, but if I try to get the same volume back, I get the squeal (the gate WILL cut it....but it is there even when playing).
Now, if I JUST use channel 1 on the effects loop...it works fine...NO squeal. JUST chan 2, NO squeal. run BOTH channels and she squeals like a pig!!!
I'm am 99% sure it is NOT a cable issue (running 3' cables to and from the gate). I have run the cables on ONE channel, no squeal, and I ran the cables from send to return to cheack to see if that made a difference...still NO squeal...ONLY when running chan 1 AND 2 and the ISP.
NOTE: there ALSO seems to be a grounding issue with the chassis....mount into rack, I get a hum! Unit is now sitting on a chair to avoid that hum.
The hush unit does NOT hum when mounted into the rack.
The ONLY other thing in the rack, is a Furman PL-8C power supply/filter.
The ISP also seems to pick up a SLIGHT bit of noise if it's CLOSE to the power supply...the Hush does not.

Any clues?
It SEEMS as though the signal from the effects loop (chan 2) is interfering with chan 1. Even with the volume on the guitar at ZERO (with active OR passive pick ups) I get the squeal.

MY guesses:

1) there is something not connected properly...maybe a wire touching the chassis allowing the channels to interfere with each other, also contributing to the ground loop hum when mounted in rack, and sensitivity to the proximity of the power supply.

2) The Genz Benz uses an unusually high output level in the effects loop. TOO much for the ISP to handle without any "crosstalk". (I don't KNOW that the effects loop is any hotter than any other amp....this is a guess at a possibility)

I HOPE AND PRAY that #1 is the issue. If it's #2 can anyone suggest a DIFFERENT noise limiter/gate that runs off the guitar signal AND clamps down pre-amp noise when run through the effects loop? One that doesn't need to be adjusted everytime I change gain or volume settings? I PREFER NOT to use a pedal (i.e. ISP G string) but I will If I MUST.

P.S. Running the effects loop into chan 1 of the ISP DOES work, but no better than the cheap HUSH unit....I thought the ISP would be MUCH faster clamping back down after a note is muted.

Thanx 1,000,000 for any good ideas!
Ibanez RGR421EXFM, Michael Kelley Vex NV, Ovation Celebrity. Carvin V3
Peavey 412M w/Eminence Wizards & Swamp Thangs, Rocktron Hush Super C, Furman PL-8C,15 band EQ, Boosta grande, ISP Decimator, Dano EQ, Ibanez TBX 150,TC Elec Polytune
Last edited by Vinson at Dec 31, 2009,
#2
You should probably get in touch with the guys at ISP and ask them. Sorry that I don't have any helpful advice for you.
I Survived The "Silent Deftone Cocksucking Forum"!-August 15th, 2006
#3
UPDATE: Testing the gate on a Bugera 6260 head, it works fine.
We found that engaging the gain modifiers (hi gain/classic, and compressed/dynamic) seemed to give the effects loop too strong of a signal, or some other reason, but with those engaged, the squeal was there. turn them off, no squeal, but now the amp is much more limited.
Running them on WITHOUT the gate, no squeal.
I DO think part of the problem is added ground noise from the gate. I'll try insulating it from the rack to reduce that. The reason I say that is when running my amp at the store, (just into a wall, without a power filter) I started to get some of that squeal without the gate. With my rack, and the HUSH unit, I get ZERO hum....with the ISP, I get hum when mounting to the rack.

Saturday I bring my cab to test 6260 on MY cab didn't like the cab they had there...it was a VERY old cab, VERY quiet. There is a chance I might just trade the amp in if I can find one I like, otherwise the ISP is going back.
Ibanez RGR421EXFM, Michael Kelley Vex NV, Ovation Celebrity. Carvin V3
Peavey 412M w/Eminence Wizards & Swamp Thangs, Rocktron Hush Super C, Furman PL-8C,15 band EQ, Boosta grande, ISP Decimator, Dano EQ, Ibanez TBX 150,TC Elec Polytune