Help with onstage feedback

[Joboxer]

I have a AER Domino - old but still good going into 2 AER AS 281 speakers. Solid quality acoustic/P.A. system.
Hadn't used it for 2/3 yrs and had a gig last night where I said I would bring it along. Solo acoustic with a singer. Put it together at home in the morning - and all good - at low volume.
On set up last night - a pub/bar - the vocal mic began to feedback at volume 4. Had to keep the treble pretty much turned to zero, and the high pitched whine was dreadful. Changed speaker locations countless times, changed mic 3x.
The guitar (2016 Taylor 614ce) through a Baggs Session Acoustic DI just kept humming through the body - again at relatively low volume. Every time I found the frequency on the notch - another layer would come in. If I dared kick in the Baggs chorus then people covered their ears!
It was a nightmare. This is kit I've used a gazillion times over the past 10 yrs, with similar set up, with pretty much zero problem. I was left scratching my head, and incredibly embarrassed!
Any thoughts folks?

[Cuki79]

Was it a venue you gigged previously or a new place?

Sometimes it comes from the room.

[Joboxer]

It was a new venue, but not unlike any other. Relatively low ceiling but dealt with that before with no hassle.
I have removed the foam from the Domino as it was degrading badly. But that should not make a difference.

[L20A]

Try you system at a different location as a practice run. If the problem doesn't happen, chalk it up as a bad night and try to learn from it.

It could be that your PA is in need of a good cleaning. Dust and other pollutants
can cause distortion.
Be sure all of your cables are in good condition and getting solid contact.

Change the battery in your guitar.

Any of these things can cause problems.

Let us know if you find what the problem was, so we will be able to use your information should we have similar problems.

[Mandobart]

Were you running mains and monitors? When I've experienced feedback it's usually the monitor(s).

Hard surfaced reflective room? So many venues around me have concrete floor, front glass window wall, exposed metal ductwork, hard metal chairs, etc.

[YamahaGuy]

Originally Posted by Mandobart

Were you running mains and monitors? When I've experienced feedback it's usually the monitor(s).

Hard surfaced reflective room? So many venues around me have concrete floor, front glass window wall, exposed metal ductwork, hard metal chairs, etc.

I agree with this. With the (I assume, satellite setup) speakers out of the equation, did the amp still feed back? Was the amp behind you or in front of you or beside you? Can you give us a diagram of your setup, including which way everything (you, speakers, the amp, your mic) were facing.

You mentioned you used this setup with "pretty much" zero problems in the past. What problems did you have in the past?

Are you using a new mic?

Had you used the same guitar with the system in the past?

[Joboxer]

I have spoken to an amp tech and he wants it on his bench next week. Given the age of the Domino (2010) and the lack of a recent service, he reckons there could be a host of potential issues. He said its an old amp, not been looked at for 5+ years, heavily gigged, and lay idle for 2 yrs. What could possibly go wrong??!!

[Lost Sheep]

Why has no one focused on removal of the foam as a causative factor?

If not the loss of acoustic dampening the foam may or may not have provided, loosening of exposed wire connections, perhaps? Or moving wires around, so changes in induction (which in a well-designed amp should not happen).

I have very little electrical experience, particularly in AC (which audio signals are, after all). So take into account that my comments are speculative.

[shufflebeat]

Originally Posted by Lost Sheep

Why has no one focused on removal of the foam as a causative factor?

Foam used in applications like this is usually as acoustically transparent as is possible so it's removal is unlikely to make an appreciable difference.

If not the loss of acoustic dampening the foam may or may not have provided, loosening of exposed wire connections, perhaps? Or moving wires around, so changes in induction (which in a well-designed amp should not happen).

Not sure I understand this.

The physics behind feedback are pretty predictable so it should be easy enough to identify whether normal conditions are causing it.

First issue:

Is the sound actually mic feedback or some other high-pitched squeal?

[EZYPIKINS]

When using a gazillion times. Were you using a mic?

What mic were you using the other day.

What you describe, is why I never went with an acoustic amp.

First, trying to push a couple hundred watts in a PA setting is giong to be a delicate balance.

Running an acoustic with a vocal mic. (If amp is set behind you, facing into the grille of the mic. Any significant volume is going to produce feedback.

You mention removing some foam? Could this foam have been there for a reason?
I'm thinking.

Could be there to cut certain high frequencies that may find their way into the mic, and loop into feedback.

Without seeing, and hearing your setup. It's hard to pinpoint your problem.

Possible you could benefit from an EQ unit The more bands the better. So you can cut each individual offensive frequency.

I use a 15 band. Set a 1500 watt powered speaker behind me.

Notch out a few trouble frequencies, as the room designates.

Can cover a fairly large room, Will run a couple acoustics and a couple vocal mics, with ease.

If a bigger venue. I'll run a pair of 1500 watt powered mains. With one in mon position in front of me. Aimed at the back of the mic.