Peavey problem

[guygorilla]

A local player that frequents a venue that seems to exude hum swears by an electroharmonix "humDebugger". Everyone I talk to always says it's just the venue and has nothing to do with the gear that's used. He was the first one that was able to clean it up using the pedal.

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I will check this out too...many thanks

 

[Two Leggs]

they're playing through Fender amps and I seem to recall 9 times out of 10 they get their amps miked, or they're using a 1/4 inch cable to a DI box (pre-amp), which is what I end up using...I could understand if my amp did it at every club, but it doesnt, so that tells me it's not the amp

No it’s not your amp , the sound guy is fishing for power anywhere he can find it . Just run a long 12gauge ac cord to the front on house and have him plug all his stuff into it. Normally clubs do not have good power .
Usually one leg of the 220vac coming in the building is for powering the lights and the other leg is for sound.a good sound guy should know this. Do the dimmers on the lights buzz in the pa when activated, do you get a little shock on the lips when touching the mic and your strings at the same time ? Unless you bring in your own A/C distro. there will always be a chance of a buzz somewhere . good luck. Me i would just use an external di and be done with it.

 

[Slevage]

No it’s not your amp , the sound guy is fishing for power anywhere he can find it . Just run a long 12gauge ac cord to the front on house and have him plug all his stuff into it. Normally clubs do not have good power .
Usually one leg of the 220vac coming in the building is for powering the lights and the other leg is for sound.a good sound guy should know this. Do the dimmers on the lights buzz in the pa when activated, do you get a little shock on the lips when touching the mic and your strings at the same time ? Unless you bring in your own A/C distro. there will always be a chance of a buzz somewhere . good luck. Me i would just use an external di and be done with it.

It’s a nice idea that the sound and lights are on separate legs— probably not reality.
Most clubs I’ve played—- getting more than 2 separate circuits was a challenge.

These days, with the lower power consumption of LED lighting rigs, some issues have been mitigated.

I believe the OP has ground loop issues.
With proper ground paths, even audio circuits on separate legs can be free of 60 cycle hum.

 

[Two Leggs]

It’s a nice idea that the sound and lights are on separate legs— probably not reality.
Most clubs I’ve played—- getting more than 2 separate circuits was a challenge.

These days, with the lower power consumption of LED lighting rigs, some issues have been mitigated.

I believe the OP has ground loop issues.
With proper ground paths, even audio circuits on separate legs can be free of 60 cycle hum.

There is a ground loop , it’s becouse FOH is on a diff. Leg. Than the bass rig. Use and external di. Or send him good power and get off the the wall socket . he is lucky that he has not damaged the di circuit on his amp.
It’s not the the fist time i have heard of this and will not be the last!
This is a real easy problem to fix.

 

[guygorilla]

like I said, some clubs everything is fine, the ones that arent I end up using a DI, either the house or one of my own.

 

[JGbassman]

Here. I keep one in my kit. It will fix most ground loops I’ve found in my circumstances. If the amp D.I. hums this little guy usually fixes the problem.

Whirlwind Lifter

 

[guygorilla]

but my amp does have a built in ground lift already, doesnt seem to affect the hum in certain clubs when it's on..so would another ground lift make any difference...??

 

[guygorilla]

No it’s not your amp , the sound guy is fishing for power anywhere he can find it . Just run a long 12gauge ac cord to the front on house and have him plug all his stuff into it. Normally clubs do not have good power .
Usually one leg of the 220vac coming in the building is for powering the lights and the other leg is for sound.a good sound guy should know this. Do the dimmers on the lights buzz in the pa when activated, do you get a little shock on the lips when touching the mic and your strings at the same time ? Unless you bring in your own A/C distro. there will always be a chance of a buzz somewhere . good luck. Me i would just use an external di and be done with it.

..and no, everything seems to be grounded, I dont get that nasty lip shock when singing into the mic.

 

[agedhorse]

Make sure your FOH in on the same power or leg as the stage. Or just use an external di (thats the best way) Any bass player that gigs should have a good external di box in there gig bag anyways. Better safe than sorry .

Power on the same leg is an urban myth. It's NEVER done this way in big touring audio, in fact I (used to) have all 3 phases brought out to FOH when I had a big console and drive/fx racks. All 3 legs were used stage left, stage right, monitor world and stage power too.

It’s a nice idea that the sound and lights are on separate legs— probably not reality.
Most clubs I’ve played—- getting more than 2 separate circuits was a challenge.

These days, with the lower power consumption of LED lighting rigs, some issues have been mitigated.

I believe the OP has ground loop issues.
With proper ground paths, even audio circuits on separate legs can be free of 60 cycle hum.

Has nothing to do with separate legs.

There is a ground loop , it’s becouse FOH is on a diff. Leg. Than the bass rig. Use and external di. Or send him good power and get off the the wall socket . he is lucky that he has not damaged the di circuit on his amp.
It’s not the the fist time i have heard of this and will not be the last!
This is a real easy problem to fix.

This is absolutely incorrect, and being on separate legs will not harm a DI either.

Here. I keep one in my kit. It will fix most ground loops I’ve found in my circumstances. If the amp D.I. hums this little guy usually fixes the problem.

Whirlwind Lifter

He already has this on his amp. Not going to help.

 

[Geri O]

Andy, I’m sure you’ve done this ad nauseum in your career, but would you explain how ground loops aren’t formed by being on different legs? And in a perfect world, how all grounds are supposed to terminate at one point in the building’s service entrance? I know this stuff in a haberdashery kind of way, but I’m terrible at explaining it. I just know that I’ve never had a ground hum I couldn’t fix. Including replacing a piece of gear as a last resort because it wound up being faulty.

 

[DWBass]

Do you get the hum through your amp as well or is it just his mixer?

 

[agedhorse]

Andy, I’m sure you’ve done this ad nauseum in your career, but would you explain how ground loops aren’t formed by being on different legs? And in a perfect world, how all grounds are supposed to terminate at one point in the building’s service entrance? I know this stuff in a haberdashery kind of way, but I’m terrible at explaining it. I just know that I’ve never had a ground hum I couldn’t fix. Including replacing a piece of gear as a last resort because it wound up being faulty.

The safety grounding system is totally independent from anything related to the hot legs. It is a conductor system the bonds all metal parts of a power installation to a common point and this point is loosely referenced to the earth/ground (along with plumbing, building steel, TELCO/CATV, reinforcing steel and gas lines). This is the same point that the electrical installation's neutral (or phase common) conductor is bonded, this conductor carries the normal return currents from the hots after they have passed through the load.

The grounding conductor connects all the metal parts, and if the hot conductor touches any metal part of the electrical installation (conduit, metal parts of the building, plumbing, the amp's chassis. etc.) the fault current will flow through the ground path and open the breaker. Under normal operating conditions no current flows through the ground. The purpose of this grounding system is to prevent any metallic object that is accessible to being touched from rising significantly above the local ground voltage level. In theory, the grounding system is "equipotential", meaning that the ground is exactly the same at every point.

Ground loops are caused by tiny leakage currents that may be capacitively or inductively couple to the ground from the operating voltage and current in the power system which causes tiny voltage differences between the ground points. When these ground points are connected via the audio grounds, tiny currents will now flow between the audio grounds, inducing noise into the audio.

None of this cares one bit about phases, or phase legs. It's all about proper wiring to avoid introducing unintended currents into the ground through wiring errors like shorting neutral to ground in a receptacle box or bonding neutral to ground in a subpanel. Another common fault is reversing neutral and ground on a receptacle. These are idiotic kinds of errors, but sometimes they happen and are a huge cause of noise in those instances.

 

[byacey]

There might be more to this. I use a Peavey Tour 450, and have tried using the XLR out on a few different occasions with my own PA and power distro, which I know inside out.

I had hum, ground lift switch engaged or not, and even with a short XLR cable that I physically clipped the ground on. I started thinking that perhaps one of the opamps that drives one of the signal pins on the XLR was damaged, thus destroying the common mode rejection balance of the line. I also tried putting a line level isolation transformer between the XLR out and the mic line back to the console. This reduced the hum, but not completely. If it was a CM issue, it should have been silent with the 1:1 isolation transformer.

I don't use the XLR out very often; Usually I DI the bass before the amp input, so this problem was put on the back burner. I'll have to open the amp and check the XLR grounding and drive stage to see if everything is as it should be.

 

[Slevage]

Power on the same leg is an urban myth. It's NEVER done this way in big touring audio, in fact I (used to) have all 3 phases brought out to FOH when I had a big console and drive/fx racks. All 3 legs were used stage left, stage right, monitor world and stage power too.



Has nothing to do with separate legs.



This is absolutely incorrect, and being on separate legs will not harm a DI either.



He already has this on his amp. Not going to help.

My comments were meant for the weekend warriors where you get what you get for power. Often finding separate circuits are a challenge— separate legs? Good luck finding the distribution panel.
Three phase in building— usually not.

 

[Slevage]

There is a ground loop , it’s becouse FOH is on a diff. Leg. Than the bass rig. Use and external di. Or send him good power and get off the the wall socket . he is lucky that he has not damaged the di circuit on his amp.
It’s not the the fist time i have heard of this and will not be the last!
This is a real easy problem to fix.

Good solutions.
I can’t figure out how the DI would get damaged. Most have a switch to engage (ground lift)when the hum occurs. If there’s no switch,
Then your solutions would come in handy.

No switch on amp’s DI— time for a new amp or separate quality DI.

It is possible to run on separate legs without hum. Much of my band room in my house is intentionally set up that way to balance the load st my panel. There loops raise their ugly head when the path or termination points of the grounding conductor are questionable.
This often happens when the ground and neutral are bonded at more than one point—- a common violation of the National Electric Code.

 

[agedhorse]

Outside of residential, 3 phase is the most common power system encountered in a commercial environment. I deal with it at least 90% of the time.

There is a difference between an improperly installed grounding system and power coming from different phases. A big difference.

 

[guygorilla]

Do you get the hum through your amp as well or is it just his mixer?

mixer

 

[guygorilla]

Outside of residential, 3 phase is the most common power system encountered in a commercial environment. I deal with it at least 90% of the time.

There is a difference between an improperly installed grounding system and power coming from different phases. A big difference.

as I said, it's not happening in all clubs..I always give a big thanks to a soundman who either a) connects me up with no problem, or b) says "just a minute" and rectifies it immediately...it's the ones who say "it must be your equipment" that piss me off, and when I say "we played with it last night at such and such a club and we had no problem", then they come back with "hmm, maybe your amp got damaged since then"...

 

[Two Leggs]

posted this elsewhere, but I'll try here for a quicker response..I have the Peavey Max 112 and while I love it for its sound, I have one problem..seems like half the clubs I play in, the damn thing hums when the soundman uses the XLR out...I took it to my repairman, he said there is nothing wrong with the amp, it has something to do with whether the soundboard ground is matched to the amp's ground impedance (or something)..anyone else have this problem?..and is there a simple solution? (right now we just bypass the XLR out and use a DI box, which makes the built in feature kinda useless)

If you eliminate ground loops, there will be no hums. Use your di like everybody should.

 

[Two Leggs]

Power on the same leg is an urban myth. It's NEVER done this way in big touring audio, in fact I (used to) have all 3 phases brought out to FOH when I had a big console and drive/fx racks. All 3 legs were used stage left, stage right, monitor world and stage power too.



Has nothing to do with separate legs.



This is absolutely incorrect, and being on separate legs will not harm a DI either.



He already has this on his amp. Not going to help.

This is not a tour situation, yes, I worked with big touring acts and tied in huge generators using all legs.that’s a different story when you’re in a club ,you do the best you can ,if you can’t get on the same leg if possible, if not, use a DI. I always carried a distro with a big breaker tied in the club myself. And had no issues , I’m older now stopped doing clubs and bands now i just repair broke sound gear. Good luck.

I’m still repairing amps with bad DI circuits from ground loops. That’s a different story ,some people believe , some people don’t