[Harp-L] Low and High Pass Filter to fight feeback?

[Mike Fugazzi]

Anyone ever use these? If so, at what frequencies? I am assuming a
decent amount of bass and high end feedback rings at frequencies that
actually don't matter to the sound of the harmonica. In otherwords,
when played, the harmonica doesn't even reach that low or high of a
sound.

Thanks!

[Jeff Baker]

Playing through a Bassman I've found the most common hot frequency is
around 800 htz which can be removed with a simple 6 band EQ box
unfortunately
thats where most of your "balls" are so puling it out kind of
"neuters " your presence . I don't have much of a problem with high
end feed back if
I keep the mike away from the amp.

JB

[Richard Hunter]

Mike Fugazzi wrote:
<Anyone ever use these? If so, at what frequencies? I am assuming a
<decent amount of bass and high end feedback rings at frequencies that
<actually don't matter to the sound of the harmonica. In otherwords,
<when played, the harmonica doesn't even reach that low or high of a
<sound.

"Filter" is another name for "EQ." A low pass filter cuts out frequencies ABOVE a certain point (thus allowing low frequencies to "pass" through), a high pass filter cuts out frequencies BELOW a certain point.

Harmonica puts out a LOT of energy in the frequencies from 8 kHz and up, and it's usually useful to cut those frequencies back with whatever EQ you've got in order to reduce high-frequency content that will make the audience's ears bleed, even if the mic isn't feeding back. (I have killed a lot of small animals in my time with high notes that were well below the feedback threshhold.) But if you're using a bullet mic and a tube amp, you don't need to worry about it, because a bullet mic and tube amp combo produces a very steep dropoff in energy after 6 kHz.

Below 100 hZ, most harmonicas are putting out breathing noise and not much else. However, cutting EQ at 100 hZ on a typical mixer may also reduce surrounding frequencies in the 200-250 hZ range that contribute a lot to the tone of an amped harp.

Another poster wrote that he gets feedback issues mostly at 800 hZ, and that makes sense to me. When I check the tones I get from my Digitech amp modelers on a frequency analyzer, I see a LOT of energy in the 600-1000 hZ range. It's easier to deal with that kind of thing with a graphic EQ, as opposed to a high or low pass filter. I suppose you could use a band pass filter (an EQ that reduces frequencies on either side of a specific range), but why bother? You'll sound like you're playing through a telephone, which is cool sometimes but far from always, and most feedback tends to originate in very specific, relatively narrow frequency bands, which is exactly the problem that a graphic EQ addresses.

Regards, Richard Hunter

author, "Jazz Harp"
latest mp3s and harmonica blog at http://hunterharp.com
Myspace http://myspace.com/richardhunterharp
Vids at http://www.youtube.com/user/lightninrick
more mp3s at http://taxi.com/rhunter
Twitter: lightninrick

[Mike Fugazzi]

In general, I have little experience with the filters. I don't really
have access to them at this point. In reading about mixing vocals and
bass, though, they get brought up. I thought maybe if harmonica noise
went form x to y frequencies and feedback occurred lower or higher
than that, it would work. I think of the low end feedback that can
happen and thought maybe it came from a lower range than harp hits
anyways. I readily admit to knowing very little about this.

Thanks for the info!