Hi all, I have a dynamic pickup inside a steel drum with an amplified speaker out at the bottom of the drum. Naturally, I am getting feedback, even with sound matting inside the drum. Frequency range is around 250Hz (by ear) . I can record it and dump to PC to check exactly.
Anyway, I am looking for advice/schematics on building a notch filter (adjustable) to mitigate this situation.
I have NE5532s on hand.
I was considering this:
Notch Filter
or this:
Simple, Easy Parametric and Graphic EQ's, Plus Peaks and Notches
Can I get advice on the approach?
thx
Ancel
Anyway, I am looking for advice/schematics on building a notch filter (adjustable) to mitigate this situation.
I have NE5532s on hand.
I was considering this:
Notch Filter
or this:
Simple, Easy Parametric and Graphic EQ's, Plus Peaks and Notches
Can I get advice on the approach?
thx
Ancel
Do you know anyone who will let you borrow a 31 band EQ or a parametric unit? Then you can try your idea first. If those commercial products won;t handle it, then your home made will probably not either.
Why must your speaker be under the drum? Feedback occurs when the acoustic sound gets back into the pickup. Work to eliminate that pathway.
Why must your speaker be under the drum? Feedback occurs when the acoustic sound gets back into the pickup. Work to eliminate that pathway.
Hi,
Your wasting your time. I'm sure I've answered this
in another post. Killing the first feedback frequency
will just move you on to the next one in the list.
rgds, sreten.
Your wasting your time. I'm sure I've answered this
in another post. Killing the first feedback frequency
will just move you on to the next one in the list.
rgds, sreten.
@ Enzo: it's a requirement in the design for a single system. I can't alter that so I must deal with the symptoms. Thus I ask for advice.
@sreten: I suspect you are right, but if I can achieve a decent amplification by nulling the resonant freq's I will have met the target. I must try.
@sreten: I suspect you are right, but if I can achieve a decent amplification by nulling the resonant freq's I will have met the target. I must try.
So it's a matter of mic'ing.
What about making a hole near the end ( about 10 cm before the "end") and let the mic
get the sound from it? And what about the mic itself ? Resonance could be caused by the shell containing it; it can be the cables.
Please make a sketch on how you positioned it. You could suspend it with rubber bands
What about making a hole near the end ( about 10 cm before the "end") and let the mic
get the sound from it? And what about the mic itself ? Resonance could be caused by the shell containing it; it can be the cables.
Please make a sketch on how you positioned it. You could suspend it with rubber bands
He is NOT using a mic. He is using a guitar-style pickup.
I guess if you use the PU's output to record the steel drum instead of amplifying it, that particular resonance does also degrade the recorded sound. So it may be a good idea to tame it. You can build a tuneable notch by using a biquad filter whose highpass and lowpass outputs are summed. Such a filter can be tuned in frequency using a tandem pot and the Q value can be tuned with a single pot. You may use this circuit just for finding the correct tuning and then resort to a simpler circuit.
Regards
Charles
I guess if you use the PU's output to record the steel drum instead of amplifying it, that particular resonance does also degrade the recorded sound. So it may be a good idea to tame it. You can build a tuneable notch by using a biquad filter whose highpass and lowpass outputs are summed. Such a filter can be tuned in frequency using a tandem pot and the Q value can be tuned with a single pot. You may use this circuit just for finding the correct tuning and then resort to a simpler circuit.
Regards
Charles
Ok folks, here is the situation.. The 33" tall steel drum 'skirt' is shaped like a v.e.n.t.u.r.i 'opposing cones' and work like old acoustic amplifers as found on early 20th and 19th century gramophones. The KAM RT1 percussion pickup is in a spider mount on a vertical slide giving about 6" of vertical positioning flexibility below the base of the tenor pan dome which is at the top of the instrument. The speaker (8" mid woofer) is in a sealed 1 gallon cylindrical housing ALSO spider mounted using zip ties, located at the bottom of the skirt facing away from the instrument.
I have determined that the sound from the speaker is being acoustically amplified by the 'cone' skirt and then being reflected back to the mic by the dome of the tenor pan. Thus no alteration of mic polar patterns will help. For now there is feedback inherent in the design and I am going to try a feedback destroyer to see how much amplification can be obtained.
I have determined that the sound from the speaker is being acoustically amplified by the 'cone' skirt and then being reflected back to the mic by the dome of the tenor pan. Thus no alteration of mic polar patterns will help. For now there is feedback inherent in the design and I am going to try a feedback destroyer to see how much amplification can be obtained.
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