Feedback from amp though PA problems..

[duped]

Hi, I play guitar plus vocals in a covers band here in Ireland.

We play pubs, some weddings/fuctions 500capacity venues max. I play a Fender Blues Deluxe on the clean channel with a Hughes and Kettner tube factor for OD and Analogman Sunface for some solos. Since I've joined the band I've noticed that I get a lot of annoying(not the cool kind) of feedback when I boost for solos. It only happens on positions 1/3/5 on my strats. We play loudish but not insane or anything, maybe a little over half way on my amp. I mic up too with an SM57 but keep it low thru the PA, most volume is on stage. We have 3 singers across the front, 2 guitars, 1 bass. 2 SM58s and I use a Beta 58.

 

I discovered last night that the FB comes when the PA is on. When the PA is on standby, the FB goes. We normally use 2 good quality speakers(duh) and a 1000W amp/desk. We dont use monitors unless for very big gigs. The FB is still there even when my guitar mic is switched off. So obviously one of the front mics are causing it. Any thoughts on how to solve the problem? I've never had the problem with other bands and PA's.

 

Thanks

 

Cormac

[Coaster]

first thing to do is figure out where the FB is coming from; switch mics off until it stops.

[samson3382]

any behringer in there?

 

or might have to take out a little high end on the guitar channel:idk:

[Unalaska]

I'm going to guess the saturation is too high on the distortion, this diminished GBF with the guitar sound overall. I think if you were to stand right in front of the amp and do the same thing it would happen again. Quit squashing your tone!

 

(this is a common problem with bands around here, they use a great amp and all the sound they get is from processing or effects pedals and the amp may as well be a powered speaker, it isn't adding to tone at all)

[stevie j]

Where in Ireland are you? I'm up in Belfast

 

It could be a microphonic pickup or valve, you may be getting the feedback from FOH (or monitors, make sure they're turned down) because the amp is so quiet and FOH is so loud.

 

I'd be happy to help if you're nearby.

[duped]

Thanks for the replies.

 

Ha, no Behringer in there..My amp is set at bass 6.5/treble 7 and mid 3.5.

I get no FB from my amp when the PA is off even when volume is high(I've checked). Only happens when the PA is live. I am however going to mess around with pedal placements tonight at my next gig. I love the sound of the amp, my H+K just drives it a bit, a little crunch. The Sunface gives the smooth sustain for solos.

 

Hi Stevie, I'm in Waterford.

I have checked my tubes and they're fine, dont think there's p-up problems either, I've tried 3 different strats and a tele.

 

I guess I'm going to check each mic and EQ tonight as was first suggested and try to isolate it. Its a bit of a pain as we're playing a private party in a packed little pub and I'm probably going to piss off a lot of people

 

I'll keep you posted..

 

Thanks again

 

Cormac

[stevie j]

Ah well, waterford's a bit too much of a drive:wave:

 

Are you sure it's the guitar?

 

It's very unlikely that a guitar will feed through the PA unless there's something microphonic in there.

 

It mightn't even be feedback, it could be interference, you say it only happens on p/ups 1, 3 and 5?

 

It could be that because 2 and 4 are a combination of p/ups on a strat it's canceling out any high pitched interference. And because your amp's so low you're not hearing it directly.

 

Have you tried different guitar leads and is your gear all earthed?

[duped]

Hi Stevie, the actual FB is coming through the guitar amp. It ONLY occurs when the PA is live. PA off, no problems... I noticed tonight that I was getting the FB on all positions on the strat, just more prominent on posns 1/3/5. All gear earthed, might check everyone elses now though!

 

Had a good gig tonight. Couldnt really isolate the problem too much as we were setting up in front of a crowd. I did however take some mids out around 2.5-4Khz on each channel and tried to keep the onstage volume lower. I also changed the reverb program and took off some high end.As suggested I took some gain off my pedals. It definitely helped a bit although as the gig went on the other guitar player started whacking up his volume(he's practically deaf) and I had to correspondingly go up to hear myself. It was still there but not as annoying. I'm going to go into a bigger venue this week with the band while its quiet and try to solve the problem..

[fireax]

We had a similar problem with our guitarist, and feedback through the PA when he punched the Overdrive for the solos.

 

I solved it by:

Having him lower the output on the effect, and I punched up the solo at the board.

Moving the monitor so the sound him and didn't hit the mic as much.

Finally, making sure his mic was butt-end to the monitor.

 

At the gig, he punched the OD, and went into the solo, I boosted him through the mains....no FB. Worked great.

[stevie j]

The feedback must be coming from FOH then, it's just that the feedback loop goes through the guitar, to the amp, to the mic, to the desk, back to FOH.

 

What FOH cabs are you using? and where are you standing in relation to them?

 

The problem, as others have said, is 99% a combination of the FOH speakers and the OD pedal.

[trevcda]

I agree with Stevie. I've had guitars and basses feedback through the pick ups when standing too close to the mains, even when running direct with the bass. Add a high gain overdrive pedal in front of that and it's even mor sensitive. Address the problem first by moving the guitar further away from the speakers and adjusting guitar, effects and the FOH channel. Then you could try creating notch filters with a multi-band parametric if there are just a few troublesome frequencies, but I suspect this will a temporary fix at best.

[Shaster]

 

Hi Stevie, the actual FB is coming through the guitar amp. It ONLY occurs when the PA is live. PA off, no problems... I noticed tonight that I was getting the FB on all positions on the strat, just more prominent on posns 1/3/5. All gear earthed, might check everyone elses now though!..

 

 

Are you sure the feedback is actually feedback and not ringing?

 

I've got a Fender Blues Deluxe. Once in an emergency situation, I had to bias some brand new power tubes "by ear". It got me through a few critical gigs, but I noticed that there was a ringing - especially on dirty tones by the end of the gig run. WARNING, DO NOT bias your own tubes unless you are trained/experienced in electronics. It can be potentially fatal if you slip up!

 

Perhaps you should eliminate the possibility of the feedback/ringing originating from your amp by having the bias checked by a professional (I believe you said your tubes were okay).