Feedback at a show. Only guitars effected?

[Enzo]

To explore the feedback theory, just turn the guitar volume control to zero. Does that stop the feedback? And while the feedback is happening, if you turn and face different directions with the guitar, does that change the amount or tone of the feedback?

To explore the non-feedback theory, is the sound of this feedback more or less constant? Does anyone sit his cell phone on top of the amp? Is there any digital equipment AT ALL in the area? I mean digital sound processors, CD players, someone's laptop or other computer, iPad, etc.

[d95err]

Sounds like a Telecaster Bridge pickup with a loose microphonic baseplate on the Pickup?
T

My thought too. Unwaxed pickups? First thing I would do would be to see if the feedback happened with different guitars.

[Chuck H]

This was with the PA turned off. Nobody was connected to it apart from the vocals.

I would argue that Bassman clearly stated that the PA was turned off. I don't know of any significance regarding connections at that point. I only know that Bassman decided to include that information.

[Enzo]

We have a noise. He calls it feedback. Certainly we have all heard high gain amps that will feed back pickups even at levels you can talk over easily. But we need to know if it is really feedback, or just some high frq oscillatory sound he calls feedback. We can bust ourselves up looking for feedback and find it was a computer monitor on the other side of the wall in an office right next to the stage.

There is incredible electrical noise everywhere, and a lot of it is whiny tones that do resemble feedback. I listen to AM radio in my car, and usually a Chicago station from here in mid Michigan - 200 miles away or so. SO I can hear it but not a strong signal. And so I can drive along and pass by a block where the cable lines are spewing digital noise. Those large LED signs can be very noisy. A few Speedway stations have the large red LED price signs, those make a warble sound on the radio. Other places consistently make a whining sound, but I have no idea what makes it, nothing I can see.

SO if this amp and an unrelated amp both make this noise in the same place , but not everywhere else, then it sounds environmental. Not all amps are equally sensitive to ambient electrical noise. SOme have better filtering on incoming mains, others better shielding inside, whatever. As I mentioned, there could be something on the other side of a nearby wall radiating all manner of digital noise, an old computer monitor, a security device, a lighting dimmer.

[bob p]

Based on what the OP said, the first thing that came to mind for me was somebody's amp bleeding into a vocal mic. That kind of problem can be a real headache on a small stage, but it is pretty easy to fix if you give enough thought to how the gear is positioned on-stage. It's important to think about bleeding into a mic when you set up your amp; if your pothead is with it enough to use cardiod mics and proper EQ and you're smart enough to position your amp well, bleed through shouldn't be a problem.

OTOH if the problem is related to EMI, one solution would be to build yourself a great big Faraday cage and climb inside. Another idea would be to add some low-pass filtration to your amp, as it sounds like the low-pass filters that are already in there aren't tuned for the type of EMI you're receiving.

[blearyeyes]

I think what he was saying is:
The vocal mics were on and the PA was on.
The tube amps all had feedback issues and the solid state BASS amps didn't have issues
but the Roland SS did. That negates that.

So the stage monitors were feeding back through the vocal mics.
The sound man couldn't hear the feedback and the guitar players could. (had that happen to me)
The guitars were triggering the feedback by bleeding through the PA vocal mics pushing it above the feedback threshold which was within the guitars frequency range but not the bass' frequency range.

Solution:
Turn down the monitors, ring out the system and EQ it properly and do a proper monitor check. BAM!

OR, the tubes were picking up a space ship hovering over the venue..
OR I don't know because I wasn't there....

[Chuck H]

I think what he was saying is:
The vocal mics were on and the PA was on.

Why? He quite exactly said:

This was with the PA turned off.

That's a period at the end of that statement. That sentence is it's own entity. Finite. If he lied or was wrong that is a different issue that cannot be solved by speculation. What he exactly said as a finite statement should not be up for interpretation IMHO. If the statement is not factual then it's the OP's fault that he cannot get a well considered solution to the problem.

[blearyeyes]

"This was with the PA turned off. Nobody was connected to it apart from the vocals. The lights turned off and the DJ sound kit turned off"

Well perhaps turned off means muted?

[blearyeyes]

Ok, I wasn't there... sheesh.

[Chuck H]

Sorry. I'm only trying to break it down. As I see it "This was with the PA turned off." means the PA was turned off regardless of any statement that follows other than "Actually, it was on." or "I lied. it was on." or "I was mistaken. It was on." etc. I know that the obscurity of the problem inspires a lot of speculation about how the OP was mistaken or what information was left out. But the OP is sort of MIA right now. We're just spinning our wheels and getting further from an answer if we take to discarding the small information given to us.

[Steve Conner]

I've uttered many a statement that I believed to be true at the time, only to discover later that I was talking crap. Honest intentions, bad data.

I've also seen many sound guys who are completely incapable of driving a mixing board. Last time, the guy forgot to turn our drummer's wedge on. The drummer asked 3 or 4 times between songs to have his monitor turned up, but nothing happened, we had to do the whole gig without it.

If a sound guy can do that, then I can believe that another sound guy might make the opposite screw-up, leaving a couple of monitor feeds live when he thought he had turned them all off.

[eschertron]

"This was with the PA turned off. Nobody was connected to it apart from the vocals. The lights turned off and the DJ sound kit turned off"

Well perhaps turned off means muted?

Interesting question; the sound board at my church leaves the monitor sends active when the channel mutes are on. Never seen that before. Kind of a PITA since I like my monitors pre-fader. I could have been doing sound and told the musicians "yeah, the board's OFF" assuming all the while that the mute buttons would take care of it.

edit: having said that, the OP never specified whether the feedback noise was coming from the guitar cabs or the monitor wedges...

[km6xz]

All the suggestions are just confusing the situation Until someone looks at it that knows the basics of pa and stage gear, the conditions, settings, what was off, what was routed and what was not, is all speculation. The description does not add up, surely it is wrong on key points. Feedback or noise isolation is really simple, eliminating noise is not always so simple but in this case what terms were used and the description is far enough off to render any speculating a waste of time. The problem is simple, whatever it is, but none of us know what the problem is, let alone the cause. Have the sound guy check it and get out of his way. If he can't figure it out, he can't be expected to get a listenable mix to the audience either so the noise/feedback might be the best part of the show.

[blindboybenton]

Hi all

It does seem to be a big topic

WHen the guitar was plugged into the Hughes and kettner amp no pedals or pa connected. Very low volume ( Have it louder than that in the bedroom with your parents asleep in the next room LOL)
This was the same with a Princeston and roland cube. Myself and the other bassman using ss amps not a problem

Guitars used were Fender strat and ESP and jackson
But when connected to the PA is was the same but you could get a slightly louder volume

I was stumped never had it before I was thinking it was some interference from something.
I know enzo talked about mobile phone. we didnt turn them off, But my band never do and never have this prob
The feedback was coming from the guitar amps. Thinking back should of tried the guitars in the bass amps

In the future. can anything be done ????

bassman1965

[Chuck H]

Unfortunately it's impossible to give advice with the information presented. Something very specific was happening but the event has passed and the body of evidence isn't sufficient to identify the problem. Trying to advise on avoiding an unidentified problem would mean covering every possible problem! And it's fair ro say that new and interesting problems that can't be foreseen pop up on a regular basis. Imagine a 2376 page manual on road safety that starts off with "When on Canadian back roads, watch out for moose crossing."