Re: feedback WAS Preamp tube substitutions

[Richard Hunter <turtlehill@xxxxxxxxxxxxx>]

Regarding feedback, Jim Jordan wrote:
"I want to share my opinion that preamp tubes substitutions are not as
useful to me as numerous others have expressed."

A player's sound is a very personal thing, and every player should
always use equipment whose sound inspires that player.  Period. That
said, this is probably a good time to review some of the low-cost ways
to reduce or eliminate feedback.  In order of low cost to higher cost:

1)  Get the @#$%^&* guitarist to turn the #$%^&*( down.  On second
thoguht, this is a high-cost option.  Never mind.

2)  Make sure the amp is in front of you, not behind you.  The amp
placed directly behind you is the worst possible arrangement for
feedback. If you need the amp somewhere behind you, move it to the side.

3)  Swap tubes.  Like Jim says, this changes the sound of the amp.  Be
prepared to experiment until you find the combination that produces an
inspiring sound with low feedback, especially if you use a bigger amp
with multiple preamp and power tubes.  

4)  Behringer's DSP110 "Shark" is a combination line tester, preamp, and
anti-feedback device that sells for about $70 new.  Reviews by the major
music mags seem to indicate that it does its various jobs well.  It's
certainly nice to get all that function with a single relatively small
purchase.

5)  Feedback almost always is concentrated in a very retricted frequency
range.  Putting a graphic EQ -- even a stompbox model designed for
guitarists, with 7-10 frequency bands -- between the mic and the amp
will usually give the player enough control over the frequencies that
are feeding back to eliminate the problem.  (Feedback reducers like the
Kinder and Behringer in fact work by identifying the narrow range of
frequencies that produces a constant howl, and eliminating those from
the output.)  In most cases involving harmonica, the feedback
frequencies are in the mid-high range, and most harmonica players,
especially blues players, will find that they like the tone they get
without the "bad" frequencies.  Such devices sell new for about $90-125,
used for less. 

6)  Change your microphone, in particular to one with flatter frequency
response.  Mics that emphasize frequencies in the mid-high range
(4K-10K), like many vocal mics, are more prone to feedback when cupped.
  
7)  Buy a Kinder or other high-end feedback remover.  The cost is in the
multiple hundreds of dollars, I think.  I've never used one of these,
but other players on this list seem to find them effective.  Because of
the cost, my personal choice would be to test one or more of the low or
zero cost options first.

Regards, Richard Hunter
http://www.hunterharp.com