Re: Hot Rod... (Thanks to Elliott)

[icepick@xxxxxxxx (Christian Laferriere)]

>>I've finally had a chance to take a good look inside that Hot Rod/Crystal
>>Balls mic.  In talking to Kevin at Kevin's harps, this mic might be
>>a straight Hot Rod and not a hybrid like I thought.  I haven't talked
>>to my friend again about it, but Kevin said that the yellow colored
>>mics are Hot Rods and that all the Crystal balls are silver-green (like
>>an old JT-30).  Anyway, here's what I found...
This info is great. Thanks for getting it out on the Harp-L.
Well guess what I did this week-end??
I took my old Astatic apart and picked up a 2.5m Ohm pot (linear) along with 
a 2.2ufd capacitor and wired it as specified. It didn't work properly. The 
diagramm showed that the capacitor was wired directly from the hot wire to 
the + post of the element bypassing the pot. The only thing I got with this 
was on and off. I re-wired it so that the capacitor would run from the hot 
to the hot post on the pot. It worked fine. Although I didn'T find any major 
increase in performance, I did notice that the capacitor seems to act as a 
band pass filter and has given the mic a little more high and midrange and 
knocked out the lower frequencies somewhat.
What I'd like to know from any electronic engineer lurking around is how to 
calculate the effect of the capacitor in the circuit. I guess I could set up 
my sons Radio Shack test bench and try a bunch of them out but if someone 
knows how to calculate this circuit, please let us know. ie: what freqs will 
be knocked out by what capacitor setting.

Just my $0.02 worth...
  
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                          Christian Laferriere
                           Gatineau, Quebec
                          Icepick@xxxxxxxx
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