Video: Bad hum from Racktifier

[4nkam]

Any ideas what it could be? Everything else is fairly quiet but the recto has this always present hum and it gets louder with the orange/red channels. Even on the clean mode it is there. I don't mind some noise/hum but this is irritating especially if I'm using a clean tone or don't even have the recto in the signal.

Video: http://www.youtube.com/watch?v=HDD4evySwg0

I tried switching a few preamp tubes, cables, guitars, etc. Running directly into the amp itself, same thing.

 

[Lurch]

Hey MJ,

That's a ground loop. Unfortunately, the Ractifier doesn't have the Ground switch on the back like some of the Dual Rec heads have (A-off-B).

I'd have to know more about your set up to isolate the problem, but a simple fix for now would be to try putting the 2 prong adapter on the 3 prong power cord of your amp or effects box. (this is only a temporary fix and slightly dangerous as your guitar may not be grounded, and you can get a shock when touching it and other equipment at the same time like microphones etc.)

Let me know how your rig is set up for more details,
LURCH

 

[4nkam]

Well basically I'm running into the GCX, splitting the signal so it goes to loop 5 (recto) and then the preamps from loops 6-8 with their own output. now I figured out that the preamps are causing it to hum when it's in the GCX so I can address that in a bit, however I still can't figure out what's causing it to sound noisier when it's totally on its own with nothing else plugged into it.

 

[Lurch]

The split signal is definately your problem. I've dealt with this problem many times since I use a fairly complicated stereo rack setup myself.

Let me get this straight first- you want to split your regular uneffected guitar signal to feed different amps/preamps is that correct?

 

[4nkam]

Kinda. There seems to be two issues here really. The first is that there is a bad hum from the racktifier and I don't remember it being like that within the past few weeks. I've been running JUST the racktifier and it just has this loud, annoying hum but it goes away when I turn my guitar volume off.

The second issue it that when I'm running it in the gcx, it will still hum no matter if it is selected or not. With this setup, I am just trying to take one signal to the rectifier going into its own cabinet and then the feed through out is going into loop 6-8 which are my preamps and they too have their own output. So I'm just trying to have access to everything with the ability to combine the recto with any of the preamps (which I can do but the hum is annoying). So I removed the cable feeding loop 6 (from the feed through) and the recto was fine when I rolled the volume down/not selected via the gcx.

Also, the hum seems to change when I use the controls of the recto.

 

[stratman62]

That is definately the good ol' 60 cycle ground loop hum. I had that when I was running two amps at once (plus stomp boxes). The only way I was able to get rid of it was to use a two prong adapter on one of the amps or the affects. Of course after that I couldn't kiss the microphone without it kissing me back (if ya know what I mean). I basically stopped using two amps. Amps these days dont have ground lifts anymore because they aren't allowed to.

In any case, that hum is a ground loop hum so atleast you know what to look for. Sorry I can't be more help.

 

[Lurch]

The only successful way I've split my signal without the ground loop hums and buzz is by using a Voodoo Labs amp selctor: http://cgi.ebay.com/Voodoo-Lab-Amp-...9QQihZ013QQcategoryZ22669QQrdZ1QQcmdZViewItem

There are cheaper units out there, but some don't address the ground problem with isolation transformers, and others will drag your battery down extremely fast (if you use EMG pickups). This unit does it all perfectly.

While that splitter will solve your connection ground loop problems, you also said there was a problem with nothing connected to the Mesa. To solve that problem, first make sure your amp and guitar are not placed near Computer Monitors, TV screens, Lights, cell phones, wireless units, or any other device that causes electrical interference. Next, examine what other devices are plugged into the same electrical outlet. Try removing them to see if it eliminates the buzz.

These are just the simple things to try first. Hopefully it will be only a simple problem. Let me know how it turns out.

 

[4nkam]

Yup, I've tried all that and there's nothing around that would cause any interference. It does sound a bit cleaner with one guitar, an ibanez 7 string with dimarzios. The guitar in the vid is a edwards lp with duncans.

 

[Russ]

Maybe have your amp checked out. I am sure that the jolt of whatever it is that bent that ear may have been enough to knock something wacky inside.

 

[Lurch]

Ground loops can be very tricky to find. Sometimes even placing two units in a rack together can start one due to the chassis' touching each other, or being connected by the rack screws and rail.

Before you take your amp to a tech, try placing it in another room with a cab and only your guitar plugged in. No pedals, effects, etc. nada, hehe.

If it still does it then you will have narrowed it down to your amp head and guitar.

Since you are using passive pickups, make sure your bridge ground wire is intact. (the wire leading from the control pots to either the Floyd Rose spring claw or the stop bar tailpiece.)

 

[Elpelotero]

what an awesome cab.

 

[user 1198]

When I first got my GCX audio switcher and put it my rack it was causing a lot of hum. I called Voodoo Lab and they told me to isolate the GCX from the rack rails as well as any other chassis that might be mouinted in the rack. I bought and installed some plastic rack isolation washers and the hum went away.

However, I recently added another amp to my rig so I can run in stereo and that caused some hum in my system. I am using two loops in the GCX to perform A/B/Y switchng capabiliy. I have yet to find a safe way of getting rid of the hum caused by the ground loop. I'm thinking about trying one of the Ebtech hum eliminators. Let us know if you find a good way to kill the hum.

 

[Tuna141]

I have a rack setup with a Triaxis and Egnater IE-4 preamps, G- Major, all controlled via a GCX & Ground Control pedal. I had been powering this setup via the effects return of my Mark IIC.

Several months ago I added a Mesa 2:90 power amp to the rack and then got a pretty bad ground loop hum as an unexpected bonus :evil: .

I was finally able to cure the hum by electrically isolating one of the units in the rack (can't remember exactly which one) using nylon screws and electrical tape to prevent it's chassis from grounding to the rack rails. It has been silent ever since...