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Dynaco PAS-3 tube preamp


NEW PRODUCT ANNOUNCEMENT !!

after several years of questions, requests, and thought, I'm making available a high-end modification for the PAS3.
This is for customers that want to KEEP their PAS3 chassis rather than building an all new preamp in a newer chassis.
So our famous SP6/SP8 circuit is now available in a 3 piece set to fit the space in the PAS3 chassis easily.
Same design, same price, but made to fit.
Set of 3 bare PCBs is $95 (phono, line, upgraded power supply)
Set of 3 PCBs with all parts included except tubes $195.
Set of 3 PCBs assembled and ready to install (no tubes) $275
Set of 3 PCBs assembled and installed into your existing/working PAS3 preamp $495
*** please note, we recommend replacing the selector switch ($8 part, $30 labor) and the volume and balance controls ($50 parts, $30 labor) ***
*** additional note, this modification will disconnect all tone controls ***
Set of 2 new EH-12AX7 low noise phono tubes $25
Set of 2 new EH-12AU7 low noise line stage tubes $25
NOS 12X4 rectifier tube for power supply $8
PRICE COMPARISON to competitors - the Curcio PAS3 mod PCB KIT is $662 (compared to our $195 price) or assembled boards for $795. The AVA PAS3 KIT is $449.


Finally, a hi-end modification for the Dynaco PAS3 preamp.

We haven't seen anything new in the past dozen years or so, and the only real alternatives are the Curcio kit for $662 and the VanAlstine kit for $449, now VacuumTubeAudio at www.tubes4hfi.com
offers an easy plug-in 3 piece circuit upgrade for the PAS3 that is identical to it's highly reviewed SP6 preamp kit.
This design will give you extremely high value on your dollar compared to any other DIY kit that we know of.
Available as a PCB only ($95) or PCB parts kit $195 including shipping.
The circuit has a hi-gain phono preamp using a 12AX7 gain stage followed by a highly accurate passive EQ,
followed by another 12AX7 gain stage, for a total gain of 45 db.
The line stage uses a 12AU7 in a cascode SRPP gain stage for high gain with excellent linearity and low output impedance, for a gain of 15 db.
The power supply makes use of the original 12X4 tube rectifier for soft-start, with 500uF of B+ power supply capacitance (compared to the original 80uF).
All parts are high quality, Dale mil-spec precision resistors, WIMA polypropylene caps for phono equalization,
and Solen polypropylene caps for output coupling and power supply bypass.
Printed Circuit Boards are mil-spec FR4 double-sided with plated-thru holes.
Easy installation takes about 1/2 hour. Full documentation included with the kit includes assembly manual, schematic, layout diagrams,
parts list, and installation instructions.


SP6-PAS3-Z set of 3 bare PCBs $95


SP6-PAS3-Z set of 3 PCBs with all parts except tubes $195


to ADD the TUBE set to your order above, for either version
(includes 2 each 12AX7, 2 each 12AU7, and one 12X4)
for $55 plus $5 shipping click here:

SP6-PAS3-Z phono stage only PCB kit with parts $79

SP6-PAS3-Z line amp only PCB kit with parts $69

PAS3-Z power supply kit with parts $50


Dynaco PAS3 preamp rebuild

for those on a budget but wanting an updated/upgraded PAS3, we offer high-quality original circuit replacement PCBs with better than original parts.

new power supply board; $50 kit or $70 assembled
new PC6 phono PCB and new PC5 line amp PCB; $40 bare PCBs, $80 PCBs with parts kit, or $110 for assembled PCBs
new input/output jacks; $65 kit or $85 assembled
recommended replacement of volume, balance, & selector for better quality
NOTE - this is the present solution if you want to KEEP your TONE CONTROLS
although we still recommend removing the old tone controls for better quality sound with less signal processing and less negative feedback

new pair of PC-5 line stage and PC-6 phono stage PCBs

$40 bare

$80 with parts (no tubes included)

$110 stuffed (no tubes included)



highly recommended new power supply board, eliminates old quad cap $50



parts available for sale . . . .

add $5 for shipping smaller parts totalling under 1 pound

add $8 for shipping several parts totalling up to 2 pounds

add $11 for shipping larger items or any total package of over 3 pounds "flat rate priority"

sealed silver contact selector switch - $7 plus $3 shipping
(compare to others at $30)

new input/output jacks on new one-piece PCB
see photos below

$65 kit
$85 assembled


new original style quad cap $38
20/20/20/20 µF @ 475 VDC   


less expensive alternative quad cap and new clamp $22
40/20/20/20 µF @ 500 VDC   

   
stock PAS3 before mods & rebuild                             stock PAS3 gutted out



top view - notice new power supply board and new PC-5 line stage and new PC-6 phono stage
also notice new selector switch, new volume control & new balance control, tone controls disconnected



front view - notice new I/O jacks



rear view - notice new I/O jacks




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 tubes 4 hifi
 "the path of least resistance is through a vacuum"