Members mlamarche Posted April 1, 2009 Members Share Posted April 1, 2009 I have a pretty good rack setup...consists of a furman power distributer, a korg rack mount tuner, a Marshall JMP-1 preamp, a Replifex effects unit in the effects loop of the Marshall, out to a VHT 2/90/2 power amp out to 2 Marshall 4x12's.. All fairly high end stuff.. If I plug into the headphone jack of the Marshall, my sound is clean and crunchy just like i like it...but...when I crank up the VHT and the cabs...man does it get noisy...loud hum, loud hiss, loud buzz enough to drive me nuts..I run direct out on stage so the sound out of the PA is pretty clean, like the headphones...but the noise from my cabs by where I stand is killing me...Am I the only one who's had this problem?...can someone give advice?thanks for any reply. Link to comment Share on other sites More sharing options...
Members krash73 Posted April 1, 2009 Members Share Posted April 1, 2009 I use Jmp-1 preamp and Gmajor. If the Replifex has a noise gate try running in behind the Jmp-1 in stead of in it's loops. Thats should kill some noise. Does it sound like ground hums? Might try isolating the grounds. Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 1, 2009 Author Members Share Posted April 1, 2009 Hard to tell...I have a channel setup on the Marshall that's real clean and low that I use for tuning purposes....when I switch to that channel, my amp is totally noise free....how does one isolate grounds? Link to comment Share on other sites More sharing options...
Members krash73 Posted April 1, 2009 Members Share Posted April 1, 2009 Try using replifex after jmp-1 and not in it's loop for noise gate. You can try using those little plastic washers on the rack screws for every rack for one. There's other things you can do also, I just never had to do them. Wish I could hear it to really tell you. How high are your gains on OD1 and OD2? If I remember correctly the loop on the Jmp-1 is parallel so the gate may not work as good as if it was straight out of the jmp-1 outs to the replifex/gate. I have never even used the effects loop on my JMP-1, I always come straight out of the outs to the effects rack. Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 1, 2009 Author Members Share Posted April 1, 2009 I will try that....what I will loose tho is my effects going out to the PA since I run direct from the speaker emulated o/p on the JMP-1 to the board....but I may trade that for less noise in my speaker cabs. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 1, 2009 Members Share Posted April 1, 2009 If you're running direct into the PA, why are you lugging around a 2/90/2 and a pair of 4x12's? Onstage monitoring? That seems a bit excessive. Maybe your gain staging is bad - how much level is coming out of your Marshall into the VHT? If you're not spitting out much signal to the amp, you'd get a bad signal-to-noise ratio. Try turning up the Marshall's master output. Hum is usually a grounding problem. You could try lifting the ground on some of your audio cables (NOT POWER CABLES). -Dan. Link to comment Share on other sites More sharing options...
Members NyteOwl Posted April 1, 2009 Members Share Posted April 1, 2009 If you're running direct into the PA, why are you lugging around a 2/90/2 and a pair of 4x12's? Onstage monitoring? That seems a bit excessive.I'll say, and having a clean and low channel programmed into the Marshall for tuning doesn't make any sense to me either. There's a reason tuners have mute/bypass buttons... Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 1, 2009 Author Members Share Posted April 1, 2009 I don't mind lugging 2 4x12's for onstage monitoring....and it looks pretty cool..maybe not to musicians but the fans like it...the clean channel for tuning is easy to get to...hit my midi controller and it's there...hit it again and I'm back in business....how does one lift the ground from audio cables??also ...yes I'm running very high gain ...as far as placing the replifex after the JMP1...I just tried that at home and the noise is just as prominent as it was with it in the loop channel ...thanks for the advice though..as you see I am checking out everything I get here.... Link to comment Share on other sites More sharing options...
Members NyteOwl Posted April 2, 2009 Members Share Posted April 2, 2009 also ...yes I'm running very high gain...Maybe an ISP Technologies Pro Rack G is the answer here... Link to comment Share on other sites More sharing options...
Members krash73 Posted April 2, 2009 Members Share Posted April 2, 2009 Are all the racks in a rack together? Try taking them all out, none of them touching, and see if that helps. Just surprises me the gate in Replifex didn't help. We need to pin point where the noise is coming from. If it is just from high gains adjusting the gate in the replifex will help. What all do you have in chain/rack. Try hooking up just JMP-1 and power amp seperated/not touching first alone and see if it does it. Then add other stuff one by one. Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 2, 2009 Author Members Share Posted April 2, 2009 All units in the same rack...power supplied by a furman pl-8...I have not tried to take everything out and plug everything in while it's spread out on the floor to see if the rack itself is the culprit....I will try to do this tonite allthough it will be a cumbersome chore. Link to comment Share on other sites More sharing options...
Members krash73 Posted April 2, 2009 Members Share Posted April 2, 2009 Yeah it's a pain but this way one by one you will find which is causing it and if there is a ground loup from rack case or one of the rack effect/ preamps. Link to comment Share on other sites More sharing options...
Members Scepter Posted April 3, 2009 Members Share Posted April 3, 2009 go in reverse plug the cabs into the power amp if there is noise then it's tubes or cabling, if there is no noise move down the chain. Plug the jmp into the poweramp is there noise now? If there is you know you have either an issue with tubes in the jmp or cabling (does the jmp have a ground lift, you could always flip that and see if that helps) If you still haven't managed to get noise then throw the replifex in there and see if that ends up being the culprit (probably not). If all that noise for some reason has mysteriously disappeared since it's been removed from the rack, well you have a ground loop through the rack, if not you may still have a loop issue but it could be cable related. Has this been an ongoing issue or has this manifested itself recently? Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 3, 2009 Author Members Share Posted April 3, 2009 Ok..I have taken the whole rack apart...made discoveries..1. VHT powered onwith no cabs makes a slight 60cycle hum...I hear it in the chassis...2.with cabs gets a little louder as you turn up but similar to most amps other than super clean transistor units...3. when I add in the JMP preamp it get much louder (this is with a clean undistorted channel) hum gets more and more as I turn up the JMP. 4. when I go to my high gain channel the Hisss (very loud)adds in. 5. When I add the Replifex (w/hush on max) ..Hiss comes down a bit but not much.....It seams like the rack has no bearing on any of the above..Any ideas...suggestions? Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 3, 2009 Author Members Share Posted April 3, 2009 By the way I'm using Monster speaker cables so I don't think cables are the issue at the cabs. I checked all the interconnect cables and they seam fine. Link to comment Share on other sites More sharing options...
Members mlamarche Posted April 4, 2009 Author Members Share Posted April 4, 2009 It got a lot better after I replaced my 2 pre-amp tubes... Link to comment Share on other sites More sharing options...
Members krash73 Posted April 5, 2009 Members Share Posted April 5, 2009 I was going to suggest that since it seems to be centralling around the JMP. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.