Re: [Harp-L] Feedback?

[steve warner <10reedsbent@xxxxxxxxx>]

Hey Vern, hope all's well down the 405.


Here's some food for thought since I've built them all over the years.
Several years ago I did a little experiment using the exact same amp, exact
same low Z Dynamic element, exact same low Z 99E556 CM and CR element and
the exact same Hi Z  XFMR  and standing at the exact same spot on the floor.
  Start with the  low Z  mic element and turn up the amp to the point of
feedback  and measure/ listen to the loudness.  Then take that same mic
element and apply the hi Z  XFMR and you'll end up with pretty much the same
output/loudness when feedback starts, but you'll just get there faster with
the hi Z.   I personally like the tonal result from Hi Z better.   I
rebuilt a 12 watt amp with high quality componets that will not feedback
with a low Z mic when the amp is dimed and the tone dimed, so a Low Z mic is
useless with that amp...plates at 140v running 12AX7's.  It can be done.
There are amps out there like this that have much bigger  power such as the
beautiful  MegaTone Amps that really growl with big volume before feedback.

If you own an amp that lets you turn it up with a Hi Z mic then that's the
ultimate.    Some amps are high gain and  made with cheapy parts and do
nothing but feedback, but there are those that will never learn.  This is
where a low Z  dynamic mic works to thicken up the tone and allow you to up
the amp.  Not your ordinary cardiod vocal mic, though.  Some secrets I won't
divulge.



On Fri, Apr 29, 2011 at 8:28 PM, Vern <jevern@xxxxxxx> wrote:

> Every time I see a report on the feedback tendencies of a mic, I have the
> following questions.
>
> Q. Why is the gain of the mic more important than the gain of the entire
> system including the mic and the amp?
>
> It seems to me that the following things are important concerning feedback.
> - The amount of sound (at each frequency) from the speaker that enters the
> mic.
> - The phase of that sound with respect to the source and the speaker.
>
> Q. How can that involve the mic unless it is allowed to affect the overall
> system gain which would affect speaker loudness?
>
> Q. If the loudness at the speaker and the positions of the speaker and mic
> don't change, how can a different mic affect feedback?
>
> Q. If the responses of two mics are different at different frequencies,
> could not this be corrected by equalizer controls?
>
> Vern
>
>
>
>
>
> On Apr 29, 2011, at 10:26 AM, Peter Madcat Ruth wrote:
>
> > Another approach to avoiding feedback is to get a harp mic with a lower
> output.
> > For decades I've been using a Shaker/Madcat Harmonica Microphone which
> has a much lower output than a bullet mic.
> > This is an advantage rather than a disadvantage.  With a lower output mic
> there is much less problem with feedback in any guitar amp and no need to
> change tubes in your amp to compensate for a hot mic.
> >
> > Here is a video clip of me (with the Big Joe Manfra Blues Band) using a
> Shaker/Madcat Harmonica Microphone:
> >
> > http://www.youtube.com/user/petermadcatruth#p/f/2/fWs9vNdTBfY
> >
> > At one miniute and 8 seconds into the video I leaned into the speakers
> and got my mic 6 inches away from the speakers to get one little intentional
> squeek of feedback...
> >
> > Peter Madcat Ruth
> > Musician - Grammy Award Winner
> > madcat@xxxxxxxxxxxxxxx
> > www.madcatmusic.net
> > www.youtube.com/user/petermadcatruth
> >
> >
> >
>
>
>
>


-- 
steve
http://www.facebook.com/home.php#!/profile.php?id=100000237341322