Source Information for Updates and Modifications

The Dynaco PAS-2 and PAS-3 vintage vacuum tube preamplifiers can superbly deliver accurate and detailed sound quality, surpassing many high-end preamplifiers currently on the market. Many options are available to restore the original classic design, or upgrade and modify the original PAS to a brand new level of performance.

During the PAS production years, Dynaco sold over 100,000 PAS-2, PAS-3 and PAS-3X preamplifiers.

The difference between the PAS-2 and PAS-3 preamplifier is the PAS-2 has a flat brass faceplate with plastic knobs, and the PAS-3 has a silver anodized faceplate with metal knobs, otherwise both preamps are the same.

The PAS-3X preamp has a revised tone control circuit which takes the tone controls out of circuit when set to the flat position.

The information printed below is for a quick reference. Please follow the links for up to date information on pricing, specifications, descriptions and the availability of services offered from the various web sites.



Unofficial Dynaco Home Page

The Unofficial Dynaco Home Page created and maintained by Greg Dunn. Copyright © 2000-2002 Greg Dunn. ... Dynaco is a registered trademark of Panor Corporation.

Dynaco PAS-2/2X Vacuum Tube Preamplifier Designed by: Ed Laurent, Year Introduced: 1960 - Tubes: 4 12AX7 (ECC-83); 1 12X4

Dynaco PAS-3X Vacuum Tube Preamplifier Designed by: Ed Laurent, Introduced: 1966 - Tubes: 4 12AX7 (ECC-83); 1 12X4

1966 review of the PAS-3X in Stereo Reviewmagazine
1966 review of the PAS-3X in High Fidelitymagazine.

Audio by Van Alstine

AVA is well known for their Dynaco modifications. Their PAS modification spent several years on Stereophile's Recommended Components list. They're at 2202 River Hills Dr, Burnsville MN 55337, Ph 612 890 3517. They also sell custom selector switches and gold jack sets for PAS preamps, which are very high quality and useful to any PAS modifier

Dyna PAS Rebuild: Super Pas Three

Super Pas Three Rebuild for the Dyna Pas-2, 3, and 3X
Price: Factory Rebuild (includes jack set and new tubes) $799
Kit $399
Circuits: Super Pas Three
Chassis: Your Dyna PAS-3, 3, or 3X
Options: Jack set kit $79; fiberglass selector switch $59

Curcio Audio Engineering

High Resolution Vacuum Tube Audio Systems

1686 Hyacinth Lane    San Jose, CA 95124
Phone: 408-269-4273 (PST) FAX: 603-584-6573



PAS 2/3 Owners Manual (full)
Removing the PAS Tone Controls
Replacing the PAS Selector Switch
Replacing the PAS Filament (Selenium) Rectifier

PAS http://www.dynaco-doctor.com/pasdes_3.htm

Power Supply Supplement Module - Resolves the weakest part of your PAS - its power supply. It totally eliminates all hum. The 7A module contains a high speed low "Z" HV regulator and a complete high current regulated filament supply (with transformer). Bass impact is dramatically improved & dynamic contrasts are extended across the entire frequency spectrum.

Blank Board (P/N PWB-7A) @ $55
Blank Board w/ parts (P/N KIT-7A) @ $178
Assembled & Tested Board (P/N ASM-7A) @ $198

Basic Line Stage (PC-5) Module Upgrade - Dramatically improves every aspect of the line stage - the heart of your preamp. An audiophile's line stage that will transform your PAS into a world class preamp. Removes veiling and extends imaging while retaining the musicality of the original. Lowers output impedance (finally) so that any power amplifier (or crossover) can safely be driven. A "drop in" board replacement for the original Dynaco PC-5 that's a snap to install.

Blank Board (P/N PWB-5AH) @ $55
Blank Board w/ parts (Includes Tubes) (P/N KIT-5AH) @ $178
Assembled & Tested Board (Includes Tubes) (P/N ASM-5AH) @ $198

Basic Phono Stage (PC-6) Module Upgrade - A high resolution replacement for the original Dynaco PC-6 phono PC board that incorporates high transconducance low noise triodes with a perfectly executed RIAA topology that thrills vinyl enthusiasts.

Blank Board (P/N PWB-6A) @ $55
Blank Board w/ parts (Includes Tubes) (P/N KIT-6A) @ $162
Assembled & Tested Board (Includes Tubes) (P/N ASM-6A) @ $180

PAS 2/3 Replacement Hardware Items - Common PAS 2/3 Ailments

Selector Switch Replacement Kit (P/N SSW-PAS) @ $36/ea
Selector Switch Upgrade w/ Download Instructions (P/N RSW-2P) @ $11/ea
Teflon Rewire Kit (4X 10ft Red, Black, Wht, Grn) (P/N TWK) @ $20/set
Stereo Volume Control Replacement - (P/N PAS-VC) @ $16/ea
Dual RCA Input / Output Connector Kit, Nickel (P/N P3-RCA-N) - $36/ea
Dual RCA Input / Output Connector Kit, Gold (P/N P3-RCA-G) - $50/ea
Replacement Power Transformer (P/N P3-XFMR) @ TBD
Anodized Aluminum Replacement Faceplate & Knob Set (P/N P3-FP) @ TBD

Dynaco-Doctor Forum

A cheap fix for the Dynaco PAS Preamplifier

SDS Labs - Vintage Audio Equipment Refurbishing

Dyna PAS Modifications

Dyna PAS Power Supply Replacement Board

Dyna PAS Filament Supply Rebuild Instructions

Dyna PAS Input Connector Board

Installing the SDS Labs Dynaco PAS Capacitor Board

Installing the SDS Labs Dynaco PAS Capacitor Board - A description on how to install a Sheldon Stokes Capacitor Board in a Dynaco PAS pre-amplifier.


P.O. Box 1499,  Lakeport, CA 95453  USA   Telephone:  (707) 263-5881   FAX:  (707) 263-7648

Dynaco PAS-2 and PAS-3  Tube Preamp Rebuilding Kit.

A very easy upgrade to do and the performance difference will be amazing.

$65  (Please specify PAS-2 or PAS-3)

Comes with all required parts including:

- eight metal-oxide low-noise carbon film plate resistors
- 22 high-quality 630V rating film capacitors
- two-high-capacity electrolytics for the filament supply
- two-1N4007 silicon diodes for the DC filament supply
- schematic of the preamp indicating replacement parts

Vintage Electron Inc.

(Vintage Electron has acquired the remaining parts inventory of the former Dynaco National Service Center.)

Dynaco PAS upgrades:

$23.00 Dynaco PAS (2, 2X, 3, 3X) re-tube set (Save $3.64 off individual prices):
(4) Sovtek 12AX7WA/7025's
(1) NOS 12X4 (Our choice of brand)
$75.00 PREMIUM Dynaco PAS (2, 2X, 3, 3X) re-tube set (Save $7.00 off individual prices:
(4) NOS Lewis and Kaufman 1960's 12AX7WA/7025's
(1) NOS Tung-Sol black plate 1960's 12X4 silkscreened "DYNACO"

Circuit Board Upgrades:  Definite improvements you can hear; designed with new layout, circuit board material, and improved components in these new production circuit boards.

Dynaco PAS 2, 2X, 3, 3X Circuit Board Refits:

We are pleased to announce the introduction of our new PC-5A and PC-6A circuit board re-fit kits for the PAS 2, 2X, 3, and 3X preamplifiers.  These boards are newly manufactured from FR4 fiberglass board material, use plated through holes, as well as solder re-flow on all the traces.  The refit boards offer components of much better quality and stability over the original parts.  High quality ceramic tube sockets are standard.
The boards utilize the original 12AX7 circuits and are a complete drop-in replacement solution to your restoration and re-building needs.  Simply unsolder the wires from your existing boards, unbolt the boards from the chassis, and drop in our new re-fit boards.
Boards come completely assembled with all components and include (2) new Sovtek 12AX7WA/7025 tubes (shown) for each board.  JJ 12AX7/ECC83 tubes are also available (bulk factory direct non-silkscreened), please request at order time.
PC-5A PAS assembled re-fit board & (2) Sovtek 12AX7WA/7025 tubes:  $75.00
PC-6A PAS assembled re-fit board & (2) Sovtek 12AX7WA/7025 tubes:  $75.00

Triode Electronics Online

PA211 Power Transformer

Power Transformer upgrade and replacement for the Dynaco PAS2, PAS3 and PAS3X preamplifiers.


Norman L. Koren

SPICE and the art of preamplifier design

Part 2: New preamplifier designs

by Norman L. Koren

Dynaco PAS preamplfier circuit and performance modifications.

Arthur Salvatore and High-End Audio LTD.


Bob Schneider

Dynaco parts and modifications sources

Richard Sherman - 'The Music Room' Richard's Personal Collection of Vintage Tube equipment.

Dynaco PAS-3 Stereo Preamplifier

Roger W. Stevens

Rebuilding the Dynaco PAS Preamp

Rebuilding Basics - Test Equipment for Tube Gear

Vintage Dynaco Pictures and Descriptions