Feedback Destroyer with Power Mixer

[andresalex07]

Hi guys, I need some help to connect a feedback destroyer fbq 2496 with a phonic powerpod 740r power mixer. Any idea? I dont have insert plug... but in the hall I have a gratis problem with the feedback (using mic shure pga48).

[Wonks]

If yours has the power amp inputs on the front you may be able to take the main line outs through the feedback destroyer, and then back into the power amp in inputs.

I couldn’t see any reference to the power amp in inputs on the block schematic I found, but they normally break the feed from the mixer section if used. You could plug a jack plug in to a power amp in socket and see if it does cut the sound out. If so, then plugging the other end of the lead to a main line out socket on the front should restore sound (do this at a low volume).

If so, this will give a path for the feedback destroyer to be fitted.

However, they really are a weapon of last resort and can often lead to really bad quality sound if left to their own devices.

It’s much better to set the system up so there’s no feedback to start with.

Is the mic being used in front of the speakers? - almost impossible to stop feedback above a certain volume.

Are people cupping their hands around the mic grille? This destroys the cardioid pickup pattern of the mic (which rejects sound from the back of the mic) and turns it into an omni (picks up sound equally from every direction) which greatly increases the risk of feedback.

What does the rest of the system consist of, and how is it set up (arrangement within the room) and what is it being used for? Speech, vocal PA with a band etc?

[James Perrett]

Rather than buying a feedback destroyer, it would be much better to buy a better mic. Feedback destroyers really mess up the sound in my experience. For the ultimate in feedback rejection I'd recommend an Audix OM7.

[shufflebeat]

I’ve had lots of experience with feedback destroyers over the years and would generally agree with what has been said. I believe they can be useful in a very limited and specific way but not in the way the sales-pitch suggests.

Any PA system will cause problems if badly set up and, even if properly managed, can only do what it’s capable of before running out of reliable puff. It’s worth noting that one symptom of a small system being driven beyond its capacity is that clipping/distorted/compressed input signals lead to increased feedback.

A feedback destroyer will often appear to solve one problem while introducing another, best to solve the initial problem at source.

The only mixer/amp I’ve seen in that format that reliably does a decent job is the Mackie 808s (coupled with EV sx300s) which I used for years and sold on to its current owner who is still using it. It was heavy and bulky by modern standards but was clean with lots of headroom.

My buddy had the Phonic (different model) and it was harsh, ill-defined in comparison and stopped getting louder, just increasingly distorted as you turned the master up.

I suspect he only kept it so I would bring my PA.

I'd recommend an Audix OM7.

Great mic.

[Wonks]

Though the OM7 requires a good mic technique, so may not be applicable if it’s for someone without much experience or for multiple users.

Plus the mic new is probably more than the cost of the PA being used.

[James Perrett]

Plus the mic new is probably more than the cost of the PA being used.

The feedback eliminator is £189 from Andertons. An OM7 is £169 from Amazon so you save £20 by buying a better mic instead of the FBQ. The Audix OM5, which isn't quite as feedback resistant as the OM7 but still good, is under £140 from quite a few places.

[Wonks]

The OP already has the feedback destroyer.

Unless the OP comes back with a fuller description on the rig, then we are all guessing.

The 200W per channel mixer amp is unlikely to raise the volume to a level where the OM7 is the only option, and though the pga48 isn’t the best sounding mic in the world, its cardioid pattern should still make it feedback-free if used in a sensible PA arrangement. If it’s being used directly in front of a speaker, then even an OM7 is going to howl.

It’s obvious to me the OP has a limited budget, so I think we should wait until they come back with more details before we tell them to buy something that may not provide any benefit.

[shufflebeat]

Fair point.

At last night’s gig we were dogged with unexpected feedback. I had my om7 in the bag after a recent gig involving a flute player (great rock and roll flute mic) so switched over on my vocal (e935 to om7) assuming it would improve things. It didn’t, and I was disappointed, I switched back to the e935.

During the break I did a quick sweep and found a house speaker tucked into the corner high up and behind the mics. I have an aux feeding the house system and the gain staging of that system meant my respectable line level was being clipped and squashed, then amp’d and fed back (ha!) to the stage area. I hadn’t heard any change because I’m on IEMS.

No specialised mic would have dealt with that and no FBD could have solved it without totally destroying the sound quality.

In the end some systematic assessment and the appliance of basic rules made the difference.

May or may not be relevant.