[Harp-L] Feedback

["Smith, Richard" <rismith@xxxxxxxxxxx>]

As I've mentioned before, I'm pretty new at this, and so
I wondered if anyone on list can explain this.  I'm baffled.
I played out at the local jam a couple weeks ago, and it 
was the first time I've played amplified in public. 
I'm playing with an Astatic T-3 (crystal element), through
an ART "Tube MP", and through my Fender "Red Knob" Champ 12
(Class A, 12 watt tube amp w/ ss rectifier).  My thought was 
that the Tube MP would allow me to turn the amp volume to 9, 
and adjust the Tube MP to a reasonable output volume. 
I played it many times at home, and had no problems with 
feedback.  When I played through this rig at the Jam, I thought\
it sounded great.  All the volume I wanted, with absoulutely
no feedback problem whatsoever.  I was feeling good.  To be honest, 
I thought, "after so much talk about feedback problems on Harp-L, 
I must have accidently put together a pretty good rig".  However, 
it seems the cocky are soon brought low.  The very next week, 
I played at the same Jam, in the same room, through the same rig, 
with all the same settings, and it squealed like a banshee. I did
manage to tweak it to where I could play, but I was on the edge
of feedback the whole time.  I was blowing too hard on my harps,
because I didn't seem to have the amp volume I needed.
How can this happen when everything was the same both times?
It was very embarrassing.  Can anyone help?

Richard J. Smith
Wormleysburg, PA