Re: [Harp-L] 12dw7 tube

[Mojo Red <harplicks@xxxxxxxxx>]

--- Michael Fugazzi <mfugazzi67@xxxxxxxxx> wrote:
> I had read in the archives that some have used a 
> 12dw7 tube in place of that (for a similar 
> result).  I was wondering if anybody could share 
> the results they have had with that tube?

Hey Mike,
        
You asked about tube swaps for your Fender Pro Jr.,
particularly about the whacky unbalanced 12DW7 tube
for the phase inverter slot. 

I put one in my Blues Jr. about 6 months ago and it
has helped me add quite a bit in volume/crunch
before hitting feedback. 

As you know the BJ and the Pro Jr are identical in
their inner guts (15 watts, 2 EL84 power tubes,
same pre-amp tubes). The BJ has three pre-amp
tubes, but I'm not sure how many are in the Pro Jr
since there?s no reverb. The main difference being
that the BJ, in addition to volume/gain,
master/volume controls, also has treb, mid, bass
and reverb controls... and of course a bigger, 12?
speaker. 

Anyway, I got my 12DW7 on a suggestion from the guy
at EuroTubes who sells the JJ Electronics brand
(great tubes, great value, btw!!) and JJs use
different tube designations (ECC83S=12AX7, etc).
Anyway, here?s how I?ve got my pre-amp tubes in my
BJ right now:

* ECC832 (12DW7) - unbalanced tube placed closest
to the power tubes (phase inverter slot)
* ECC83 S (12AX7) ? middle slot
* ECC81 (12AY7) - farthest away from the power
tubes

If your amp only has two pre-amp tubes, I?d suggest
using the 12DW7 in the phase inverter slot and
putting the 12AY7 (or 12AU7) in the other slot.
This will reduce overall gain enough to let you
crank more before feedback and will lessen the some
of the harshness. 

The 12DW7 allows you to really work the tubes for
tone. It will not kill feedback altogether, but
makes it more manageable at higher volumes. It
mainly allows you to push the tubes more and pull
more tone from them. 

The speaker makes a huge differnce in actual tone.
In my Blues Jr I put in a Weber 12A100, 15 watts,
?50s style straight cone with AlNiCo magnet (like a
Jensen P12R, but better). This helped the amp break
up smoothly at much lower volumes than before,
without sacrificing overall volume. MUCH improved
tone in my amp. 

For the Pro Jr. you?d want the 10A100, a 10?
version of the same speaker. Maybe that's what you
got. I got mine with the H dust cap too, and it
helped some, but didn?t kill feedback completely. 

I think the Kinder may be about the only thing out
there that will really kill feedback.

Anyway, good luck!

Harpin? in Colorado,
--Ken 

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