Dynaco PAS-3 tube preamp mods and parts
original circuit replacement PCBs
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.
VTA PAS3-Z modification
Vacuum Tube Audio Zmod upgrades for the PAS3Finally, a set of hi-end modifications 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 is for customers that want to KEEP their PAS3 chassis rather than building an all new preamp in a newer chassis.
Our Vacuum Tube Audio upgrade circuits for the PAS3 replace the 50 year old circuit designs with modern high performance high fidelity drop-in replacements.
The Zmod-PC5 line stage uses a pair of 12AU7 in a cascode SRPP gain stage with excellent linearity and low output impedance.
The Zmod-PS power supply makes use of the original 12X4 tube rectifier for soft-start, replacing the old "quad cap" with 266uF of B+ power supply capacitance
Printed Circuit Boards are mil-spec FR4 double-sided with plated-thru holes. Easy installation, with full documentation included.
We also have available every part that is used in a PAS3 preamp, most are higher quality than the original types.
Zmod TCLA (tone control line amplifier) modification/upgrade
Finally, a hi-end modification for the Dynaco PAS3 preamp that INCLUDES TONE CONTROLS !!This modern circuit uses four 12AX7 tubes in an active Baxandall design for the extra required gain and tone control processing.
New accurate linear tone controls are included that allow +/-12db of boost/cut for bass and treble frequencies.
Easy installation takes about 1 hour. Full documentation included with the kit includes assembly manual, schematic, layout diagrams,
parts list, and installation instructions.
our new regulated power supply for the PAS preamp
This includes two new power transformers (one for B+ and one for filaments) and fits right where the old transformer and power supply were.
It will require drilling two small holes. Simple installation. Fantastic performance, our ultimate power supply for the PAS preamp.
NEW input-output RCA jack panelOur 2nd most popular upgrade (after the power supply) is this high quality RCA jack panel.
The old cheap quality RCA jacks that are crowded together too closely are replaced with a PCB with wider spacing and gold-plated RCA jacks.
This has 7 pairs of jacks rather than the original 9 pair (most of those were never used anyway!).
replace this mess . . . . . . . . . . . . . . . . . . . . with this . . .
Our new selector switch replaces the old fragile original with a modern 2P6T rotary switch, a nice match to the new RCA jack panel.
This will eliminate the "rats-nest" of wiring on the original.
I just wanted to thank you for looking at my Pas-3. It arrived safely today and I had a good session with it for several hours. At first I thought it sounded a bit forward, but then I realized that I had become accustomed to the sluggish/slower presentation of my stock Pas-3, a backup unit. Your circuits are faster, tighter and more revealing. Also, I do not have to "crank" the volume knob. Even better, when I do- the hum that I was experiencing with my stock Pas-3 is for the most part non-existent. It was a nice revelation when I switched from my backup Pas-3. Using your boards- I realize now what an improvement the TCLA and PH10 are. Dan F.