Post by ZoranI got ShakerMadCat harp mic. Buy it cause thought that will be less
feedback on the stage, but nothing, feedback is still make mess of my
harpin even I harpin on PA or through the Amp (on tube either).
I have been learning about feedback over the last 8 months or so. The
following is just based on what I have done and experienced and I am
not an expert in this area:
If you are playing a microphone through a guitar amplifier it is going
to be a challenge. Most microphones have a high output compared to a
guitar which the amp "expects," so right off you are driving the input
side harder than the amp was designed to handle. To deal with that you
end up using a very low input volume setting on the amp as well as
rolling off the top end using the tone controls of the amp, but all
that combines to limit the quality of the sound you may want. it does
not allow you to drive the input side very hard so you don't get any
crunch. It also presents a VERY narrow band of volume control, or at
least to say, it makes any volume adjustments very touchy.
I went through that with my Genz Benz Black Pearl 30 amplifier. I
began by building an adjustable attenuater- an inline volume control.
Just a box with a potentiometer and two 1/4 jacks in back- one in and
one out. The 3Meg pot was not enough so I added a couple of resistors.
I later added a 500Ohm pot inline so it was like a coarse and fine
adjustment. iirc, I ended up with about 2.5megs of resistance. That
helped and headed me off in the right direction. This was done with
parts from my parts box, so it was just what was on hand.
I then started playing with the input tubes (of course, that is not
possible with solid state amps). You will find that guitar amps tend
to use 12AX7 for the preamp tubes which are high gain. I ended up
switching the second and third phase tubes to a 12AU7 and a 12AT7. I
tried two 12AT's and it was still a bit "hot," but two 12Au's were to
low of an output and I lost volume. With the AU/AT configuration I
was able to eliminate the inline attenuater I built. I am still
experimenting in this area.
I recently picked up some older microphones. In terms of feedback
while maintaining tone, my current favorite is the Astatic 335H-7
which cranks out tons of mix-cutting tone and is very feedback
resistant. I am just finishing building a bullet mike- the body is an
old Turner S22 that had a toasted element. I gutted it and ground the
fins off and the element is going to be an Electrovoice ceramic
element from a model 715.
Randy G.
http://www.EspressoMyEspresso.com