Re: [Harp-L] Feedback w/ Shaker and Blues Jr.

[Grbullets2@xxxxxxx]

In a message dated 12/12/2005 11:57:47 AM Eastern Standard Time, 
ceudoazul@xxxxxxxxx writes:

(Guy sez
"Have you worked with a Shaker Dynamic mic?  I bought one and have been 
experiencing very stubborn feed-back.  I play through a Blues Jr. and 
cannot
for the life of me find a setting or spacial orientation that 
alleviates the problem.")
         Guy,If your BJr. is feeding back with a Shaker mic,then you 
apparently haven't changed any of the high gain preamp tubes.The Shakers are not very 
high gain.I use a VERY strong CR mic with mine and can get plenty of volume 
before FB.
        I would recommend trying a pair of 12AU7's and a 12AY7 or,a 
5751.Experiment with the positions.Also,I would highly recommend having the tone stack 
cap's changed to the following values.C11 is your bass cap,change it from 
.022uF to a .1 uF.Your mid cap,C13 you can leave alone if you want, or change it 
to .02uF.This doesn't sound like much of a change,but my experience has been 
that my BJ is very sensitive to slight changes in this position.(Mine is the 
older green board,pre 2001).
         If you have the green board too,I would also highly recommend doing 
Bill M's reverb mod.Bill's Blues Junior Modification Pages--Home.If you have 
the cream colored board,the reverb mod may not necessary (see mod page).If you 
do have the green board,you will notice that the reverb also adds feedback as 
you increase it.This is because of the way it's wired in the older BJ's.Doing 
the reverb mod will eliminate this and also eliminate the noise introduced by 
the old reverb circuit.It's an easy mod and easily reversible if you don't 
like it,but I doubt that will be the case.
         Also,while you're in there,remove the resistor in R18 if you have 
the green board,or,R29 if you have the cream board and replace it with a 
jumper.This will help increase output section distortion a bit.Theres no need to 
change any other resistors in the amp.
        The newer BJ's are much brighter sounding than the older ones.If you 
have the cream board,you can reduce the bright tone a bit too by replacing C35 
with a 1500pF silver mica cap, which is the stock value in the green board 
amps.This will reduce the brightness and add more mid and low frequencies to the 
overall tone.I would recommend replacing all the ceramic caps with silver 
mica caps,and use Sprague orange drop caps for your tone stack mods.I prefer the 
PS series caps myself.Sprague has 3 different types of orange drops,the 
716,715,and the PS series.The PS series are the same as vintage orange drop caps, 
and in my opinion have a warmer tone.
        Finally,replacing the stock speaker with a vintage Jensen P12R will 
give your BJ some serious harp tone.The stock speaker may sound OK,but once you 
put a good harp friendly speaker in it you'll never go back to the stock 
one.Finding a speaker with the right input sensitivity will also increase your 
volume.If you go with a Jensen,the R series will give you the most volume.
          I found a 1956 Jensen Professional Series P12R and put it in my 
BJ.The tone is unbelievable!!! I tried a P12S and a P12Q before I found the 
P12R.There is no comparison.Good Luck.......Dave