Tag Archives: dynaco

Dynaco PAT-5 Stereo Preamplifier

10 Jun

Dynaco Pat-5 Preamplifier

Dynaco PAT-5 Stereo Preamplifier (1974 MSRP  $239 Kit, $399 Built)

Dyna's replacement for the venerable PAT-4, adding such niceties as a high-power switchable outlet, speaker selector and terminals, dual tape monitors, an external "processor loop" intended for EQs or other signal modifiers, and an op-amp high-level stage. The BI-FET term is a trademark of National Semiconductor for the JFET LF357H IC used in the PAT-5 BI-FET version. This replaced the NS LM301 opamp in the PAT-5 preamp in 1977, opening the door for numerous audiophile mods including the highly acclaimed Frank Van Alstine and Walt Jung upgrades.


Semiconductor complement: 13 transistors; 2 integrated circuits; 3 zener diodes; 4 diodes.

Dimensions: 13-1/2" x 4-1/4" by 11-3/4".

Power Consumption: 12 watts, 120V or 240V, 50/60 Hz AC.

Shipping Weight: 13 lbs. (5.9 kilos)

Designed by:

Wade Burns



Dynaco / Dyna-Kit PAS 3X Tube Preamplifier

18 Feb

 Dynaco / Dyna-Kit PAS 3X Tube Preamplifier

Designed by Ed Laurent and introduced by Dynaco in 1966, the PAS series of stereo amplifiers are renowned by audio enthusiasts the world over.

As with many Dyanco products, the preamplifier was sold under the Dyna-Kit name for $69.95 as a build it yourself kit.  There was also an option to buy it fully assembled for $89.95.

Check the back panel of your PAS preamplifier - if the speaker binding posts and RCA jacks are attached with screws, then it was originally built as a kit.  If there are rivets, you have a factory wired unit.

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.

More specs and pictures after the break.


Dynaco PAS /2/3/3x Tube Preamplifier

16 Nov

Dynaco PAS PAS2 PAS3 tube preamp

Dynaco PAS Series Tube Preamplifier (PAS / PAS2 / PAS3 / PAS3x

The Dyanco PAS-3X stereo preamplifier is a two channel control center which permits either monophonic or stereophonic reproduction from any program source, with any modern amplifier.

This preamplifier design is most renowned for it's low noise and distortion, and it provides striking simplicity of operation while retaining full flexibility for the enthusiasts subtle adjustments.

Form Tube stereo preamplifier
Frequency response 10Hz-40kHz±0.5dB (Aux)
THD Below a measurement limit
Cross modulation distortion 0.05% or less (at the time of 2V Output power)
Signal to noise ratio Phono:74dB
Output voltage 10V/100kohm
Phono allowable input voltage 250mV
Tone control Bass: ±20dB (20Hz)
Treble: ±18dB (20kHz)
The semiconductor used 7:4 12AX
Dimensions Width 343x height 108x depth of 230mm
Weight 4kg
Option Wooden case (3,900yen, at the 1960 in-the-late time(?))
Wooden case DW-1 (6,500yen, around the 1976 time(?))


Inputs: 3 stereo low level, RIAA phono, NAB tape head, special, 4 stereo high level

Distortion: less than 0.05%

Frequency response: 10Hz to 40kHz

Gain: 60dB (phono, tape), 20dB (line)

Tubes: 12AX7 (ECC-83), 12X4


Dynaco / Dynakit ST-70 Tube Amplifier

3 Nov

Dynaco ST-70 Tube Amplifier

Dynaco / Dynakit ST-70 Tube Amplifier  (35 watts per channel, 1959)

Dynaco was based in Philadelphia, Pennsylvania. They manufactured several audio products in the 1950's, 60's and 70's. The equipment was available as both factory wired and as kit form. The most famous product was the ST-70 amplifier of which over 300,000 units were manufactured (factory wired and kit combined). Various incarnations of the ST-70 were produced over the many decades of manufacture. They all have the same circuitry, except for Series II, but the part type, chassis and cage type were all different. The very first and original ST-70 can be identified by the chassis (nickel plate), cage (brown), and output transformers (Dynaco A 470 with cloth covered leads).

Dynaco tube amps were often referred to as "the poor man's McIntosh." Even today, upgraded components, rebuild kits, and even a complete improved reproduction of the ST-70 is available.

More pictures after the break.