Re: [Harp-L] Fender Blues Jr tube swap ? & Hot Bullet Mic FS/T

["Splash" <celtiac@xxxxxxxxx>]

----- Original Message ----- 
From: "blues62" <deleted to prevent spambot harvesting>
To: <deleted same reason>
Sent: Sunday, May 24, 2009 12:31 PM
Subject: Re: [Harp-L] Fender Blues Jr tube swap ?


> starting from the right to left: 12ay7, 12at7 and then  12au7: this is for
> me the best setup. Marco
>
> 2009/5/24 Ron Hall <deleted>
>
> > What would be a good tube swap for a Fender Blues Jr ?
> > Any advice will be appreciated Ron Hall



Be advised that although the 12AU7 provides less gain than the 12AX7, it
draws considerably more current.

If you're going to be gigging with this amp and playing it hard for hours at
a time, and want it to last a long time... it wouldn't hurt to change R 12,
14, 16 & to 1/2 Watt and R 17 & 19 to 1 Watt resistors.  And while you're at
it, you might as well use Allan Bradley Carbon Comps instead of those cheap
Chiree resistors.

That's not necessary on the good old vintage American made point-to-point
amps because they're already slightly over-engineered and using quality USA
components, but these modern Chiree circuit-board amps use the cheeeeep
stuff. quote: "All resistors 1/4 watt unless otherwise noted."  Ah Sooo.

I like the 12AU7 in V1 which is the primary gain stage.  If you use a 12AU7
in V1, then resistors R 4,5,9 & 11 change to 1/2 watt and R 3 & 10 to 1
Watt.

One half of V2 is the Push-Pull divider for the pair of output EL84'S
therefore if you want the output tubes to get max saturation, you want max
gain from a 12AX7A at that stage.

http://www.schematics.ca/uploads/PDdownloads/blues_jr_schem.gif

Perhaps the reason I like the 12AU7's so much is because I acquired a bunch
of great Jan Navy surplus 12AU7's from the early 1960's that are so warm and
buttery they just oooooze with tone. =8^D  I have one in V1 of my '68 Super
Reverb. I use the non-reverb channel for harp, but keep 12AX7A's in the
guitar section for more gain with Guitar.

I have one of the Navy 12AU7's in V1of my old Kazoo2 and an old Navy 6BQ5 in
there as well.
Great tubes = great tone!  Yummy.

I have a pretty good number of old vintage 12A(*)7 tubes and swap them in
and out to see which ones sound best.
If you're in the South Florida area, maybe we can do some swapping and see
how they sound, and then work $omething out. I'm regularly acquiring audio
and RF transmitting tubes as part of another endeavour of mine.

I also recently acquired another Hot Shure Controlled Magnetic element
1083Ohms from the Mid 1960's and put it in a vintage JT-30 shell.  It's
excess to my needs at this time.  My digital camera quit on me last week so
no pics at present. Shell body Silver hammertone is in excellent condx 9.95
of 10, grill is powdercoated perfect bright Red, Black silk.  Label is
Conneaut Ohio sticker.  I repeat... my camera died, so maybe willing to
trade for a good digital camera.

PEACE
Splash
W4PJ