Re: [Harp-L] Harp Amp Project: Fender Pro Junior

["steve warner" <10reedsbent@xxxxxxxxx>]

I've modded a few of these a several years back and off the cuff......First,
the fat button in a BJ is a complete joke and does virtually nothing to take
away  the trebly tone for harp.   The word "fat" sounds nice but it isn't.
   2nd)  Get a 10A100 Weber or a 10A125-0 Weber speaker....it'll add crunch,
break up and fatter tone.  I don't remember which fits, so you can email
them and they'll respond  3rd) change the coupling caps to .1uF   4)  up the
power supply dropping resistor so you have somewhere in the neighborhood of
140 volts on the preamp plates.  This you can play with to see what sounds
best.  I've tested as low as 90, but I think it's  too low and takes away
from the amp's bite.  The amp already has about 300 volts on the plates and
that's just too much gain.   5th)   This can be tricky, so if you don't know
what you're doing then have someone do it......Get a Weber WZ34 Copper Cap
Rectifier Module.   I've played with the W5Y3, but 50 volts B+ being dropped
is quite a bit with this amp and I feel causes a bit of muddiness and
overall loudness to be dramatically reduced with the amps general design
parameters.   A friend likes the 50 dropped volts in his, but I don't.  To
each his own.
Without the speaker change all the above parts comes to about 30
bucks...maybe less depending how much the Copper Cap Rect is these days.



On 8/20/08, Rick Davis <bluesharpamps@xxxxxxxxx> wrote:
>
> I'm looking for suggestions.  The other day I spotted a MIM (Made In
> Mexico)
> Fender Pro Junior at a very fair price on Craigslist, so I snapped it up. I
> owned a Blues Junior amp a few years ago but did not like it much. I may
> have given up on it too early. So now I'll take a shot at its simpler
> little
> brother, the Pro Junior.
>
> Where the Blues Junior is a Master Volume amp with a FAT button and all
> manner of bells and whistles, the Pro Junior is bereft of features. It has
> two chicken head knobs: volume and tone. That's it. One channel; no reverb.
> The speaker in the Pjr is a 10-incher, two inches smaller than in the Bjr,
>
> What the two amps share in common is basic circuitry: 15 watts, two EL84
> power tubes, a solid state rectifier, 12AX7 phase inverter, and a 12AX7
> preamp tube. They also share the EL84's tendency to sound trebly and to
> chime when driven hard. That is not a good sound for blues harp.
>
> Be that as it may, the Pro Junior is a pretty popular harp amp. I've heard
> passably good tone honking out of these little amps at blues jams. Some of
> my harp buddies swear that this or that speaker swap is the magic bullet
> that transforms the Pjr into a monster little harp amp.
>
> This particular Pro Junior looks to be completely original, and it is in
> excellent shape, the tolex and grill unmarked. The tubes are all
> Fender/Groove Tubes/Sovtek and are almost certainly the tubes that came
> with
> the amp from the factory. The speaker is the original Fender Special
> Design.
> I played the amp and it sounds like… well, it sounds like a stock Pro Jr.
>
> I'd like to hear your recommendations for inexpensively turning the Pro Jr
> into a better harp amp.
>
> Photos and details at the Blues Harp Amps blog:
>
> http://bluesharpamps.blogspot.com/2008/08/harp-amp-project-fender-pro-junior.html
>
> Thanks!
>
> -Rick Davis
> The Blues Harp Amps Blog
> http://bluesharpamps.blogspot.com/
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-- 
steve
www.thunderharpmics.com
fattest tone on earth!