Anti feedback device

[dhuebert]

A harmonica player friend asked me about anti-feedback pedals and how they work, heck, I don't know. Can any of you shed some light on this?

http://www.kinder-instruments.com/afb+.htm

Don

[TomMcNally]

Usually those things notch out a certain frequency,
hence the "dial it in" line in the ad.

We have a couple of fancy rack mounted units at work
made by "Sabine" that are supposed to do that.
I've never messed with them, they are in a remote
broadcast rack we inherited when we took over
another radio station.

They have a long explanation of how it works here:

http://www.sabine.com/sabine-professional-audio/SABINE-FBX-filters.html

[dhuebert]

Ya know, when Andre asked me about this, my first thought was a notch filter but I rejected that as being too inflexible. Turns out I was right; not only that but I thought a parametric eq would do the job but I rejected both ideas as being impractical due to the many variables involved in acoustic feedback. I was wrong about being wrong. Waddya know! I will suggest a parametric eq to Andre and maybe we can play around and see if it is worthwhile.

Thanks Tom, I learned something useful today, Something I wouldn't have expected while at work.

Don

[EWBrown]

In the church sound system, we have a rack mounted DBX sound processor which has an anti-feedback feature. That (allegedly) detects in-phase speaker-to mike feedback and automatically notches it out. Let's just say that it doesn't exactly function to the degree as described. It sort-of works, but a dedicated feedback killer would be a a LOT better.

The other problem is that the DBX is wired only into the main overhead speakers , and not into the stage monitors.

The previous sound guy made a real mish-mash out of the system wiring, and I'm slowly reworking it to a proper and correct configuration. He was a self-described "audio expert", but we are finding that his expertise was mostly just an illusion Add in a really cheap set of four "Wal Mart quality" 650 MHz wireless mikes, and it makes every sound session a rather exciting adventure

I've seen various rackmount units in the "Pro Audio" section of the Parts Express catalog.

/ed B

[dhuebert]

Well, now I need a schematic for a tube based parametric eq. On accounta I don't build with op amps any more. Like that guy in that movie I'm living backwards thru time.

Don

[burnedfingers]

Sabine is old school.

Check out a Shure DFR22. It will do the job and sound good in the process. Twenty years ago Sabine was considered a good piece but not by todays standards. I do commercial sound systems for a living.