Catalog History

Here's what I have about each and every Dynaco component. I included as much information as I reasonably could locate: manufacturing dates, specs, designers, etc. If I have additional info, I include a link to another page where you can browse and learn more about the component. If I have suitable pictures of my own equipment, I have used them to illustrate the page; if not, I have selected some pictures from the net to use as examples. I always cite sources when available.

Again, I welcome corrections to any of this information if you have a definitive source. I have interviewed a small number of the people actually involved in the Dynaco organization, including circuit designers; in some cases, I rely on printed interviews or articles by the individual, and where appropriate, I have credited those folks with the source of data. Lots of correlation info was obtained from the Dynaco parts list, the equipment owner's manuals, schematics, anecdotes from former employees, and from reviews in Audio, High Fidelity and Stereo Review magazines in the 1950s and 1960s, and Stereophile in the 1970s. A note on the inconsistent use of units in these descriptions: the descriptions are copied exactly from Dynaco manuals and brochures; Dynaco used "kc" instead of "KHz" in the early days, and later units specified FTC power output ratings. I have tried to preserve the "flavor" of the actual text, even when this resulted in inconsistencies in the technical presentation.

Thanks to Ed Laurent for "owning up" to being the principal designer of Dynaco's tube equipment and much of its early solid-state gear. Anyone with further contributions to the list of designers, please contact me.

It has come to my attention that many old versions of the Sunn musical instrument amplifiers (such as the 1000S and 2000S) used Dynaco transformers for their power amplifier stages, and some of them (the 100S and 200S, for example) actually contained most of the guts of a PAM-1 and Mk. III system! This is apparently only true of the earliest units; they were replaced by Dynaco clone transformers and similar circuitry from Western Transformer Co. during later production runs. This information was revealed in an interview with Conn Sundholm, founder of Sunn.

Here is a document describing the Dynaco parts numbering/serial number scheme.

Thanks to Ned Carlson from Triode Electronics for the scan of David Hafler's classic article on the Williamson high-power design in Radio-Electronics magazine in 1955.

Dynaco Mk. II monophonic power amplifier. The first piece of equipment offered by Dynaco, in 1955. 50 watts continuous power. Identical in physical size with the later Mk. III.

Dynaco PAM-1 monophonic preamplifier. Companion piece to the Mk. III, offered in 1957. Powered by DC from an octal socket on the Mk. III or ST-70 power amplifiers, or the optional PS-1 power supply adapter. Sometimes seen in a combo installation as two PAM-1 units plus the DSC-1 stereo adaptor using a common faceplate; incorrectly dubbed the PAS-1.

Dynaco Mk. III monophonic power amplifier. The classic 60 watt monoblock. First sold in 1957, widely coveted even in the year 2000 as an honest, faithful amplifier. Much modified by amateurs and professionals alike, thanks to its flexible circuitry.

Dynaco Stereo 70 power amplifier. The classic 35 watt per channel stereo tube amplifier; sales continued from its introduction in 1959 until mid-1990. Channels could be paralleled for use as a single-channel 70-watt amplifier. Almost as desirable a collector's item as the Mk. III, and for the same reasons.

Dynaco PAS-2/2X stereo preamplifier. The quintessential tube preamp, also widely sought after as the starting point for audiophile modifications today. "X" indicates modified tone controls and lowered output impedance. Introduced in 1960.

Dynaco Mk. IV monophonic power amplifier. A 40 watt monoblock, essentially half of a Stereo 70. Introduced in 1960.

Dynaco FM-1 monophonic FM tuner. Dynaco's first FM tuner, which was offered with the FMX-3 stereo adapter available separately, in kit or pre-assembled form. Introduced in 1961.

Dynaco Stereo 35 power amplifier. A 17 watt per channel power amplifier, essentially a reduced-power version of the Stereo 70. Extremely rare and collectible. Introduced in 1963.

Dynaco SCA-35 stereo integrated amplifier. A simplified PAS-series preamplifier section mated to a Stereo 35 power section in a single chassis. SCA stands for Stereo Control Amplifier, as Dyna referred to their integrated amplifiers. First product to use the new flanged aluminum front panel and knobs(?). Introduced in 1964.

Dynaco FM-3 stereo FM tuner. Essentially a re-packaging of the FM-1/FMX-3 units with the new front panel and some minor circuit changes. Introduced in 1964.

Dynaco PAS-3X stereo preamplifier. The quintessential tube preamp, updated to the new front panel and with tone control and output stage modifications to improve drive capability. Introduced in 1966.

Dynaco Stereo 120 power amplifier. One of the first modern high power transistor power amplifiers (60 watts per channel), featuring capacitive output coupling inside a feedback loop, plus a regulated power supply. Introduced in 1966.

Dynaco PAT-4 preamplifier. Dyna's first solid-state preamp, incorporating front-panel tape in/out jacks and a variable high filter. Received a rave review in Stereophile. Introduced in 1967.

Dynaco Stereo-80 power amplifier. A pared-down version of the Stereo 120, with 40 watts per channel, and an unregulated power supply. Introduced in 1969.

Dynaco SCA-80/80Q integrated amplifier. A Stereo 80 mated with a condensed PAT-4 in a single chassis. The SCA-80Q featured built-in DynaquadTM circuitry for add-on ambience speakers. Introduced in 1969.

Dynaco QD-1 QuadaptorTM. David Hafler's minimalist ambience-recovery circuitry available as a separate box add-on for any amplifier with common channel output grounds. Introduced in 1971.

Dynaco FM-5 stereo FM tuner. Dynaco's long-awaited solid-state FM stereo tuner. Featured the DynatuneTM auto-centering tuning circuit, switchable muting and an auxiliary input. Introduced in 1971.

Dynaco AF-6 stereo FM tuner. Added a good-sounding AM section to the popular FM-5 circuitry in place of the auxiliary input. Introduced in 1972.

Dynaco Stereo 400 power amplifier. Dynaco's blockbuster 200 watt per channel amplifier, continuing the tradition of value for price and enthusiastic reviewer response. Featured DynaguardTM speaker protection circuitry, sophisticated automatic output muting, and a colossal heat sink. The FAN-1 option further improved heat dissipation for PA and sound reinforcement applications. The MC-4 option added accurate power output meters and a range switch. The MBI-400 bridge kit allowed use as a single channel 600 watt amplifier. Introduced in 1972.

Dynaco PAT-5/BI-FET preamplifier. Dyna's replacement for the venerable PAT-4, adding such niceties as a high-power switchable outlet, speaker switches, dual tape monitors, an external buffered "processor loop" intended for EQs or other signal modifiers, and an op-amp high-level stage. The BI-FET version replaced the op-amp with a TI TL070-series FET input op-amp in 1977, opening the door for numerous audiophile mods including the popular Van Alstine and Jung upgrades. Introduced in 1974.

Dynaco Stereo 150 power amplifier. A reduced-power version of the Stereo 400, featuring a smaller power supply, identical output transistors and a roomy chassis which invited its own spate of circuitry upgrades. Introduced in 1975.

Dynaco QSA-300 power amplifier. Basically two ST-150 units in a single chassis, with separate power supplies. Usable as four independent channels or as a bridged stereo amplifier with 300 watts per channel. The MC2/MC3 meter kits provided output monitoring or two or four channels. Introduced in 1976.

Dynaco Stereo 410 power amplifier. A budget version of the Stereo 400, replacing the overdesigned chassis and heat sink with a smaller set of heat sinks and a fan. The DynaguardTM circuity and buffer were also omitted, resulting in what some people feel was a better-sounding amplifier. Introduced in 1975.

Dynaco SE-10 graphic equalizer. Dyna's foray into the graphic equalizer market; 10 bands for each channel, with adjustable channel gain and immunity to overload distortion. Introduced in 1976.

Dynaco Mk. VI mono power amplifier. The all-time killer tube amp. 120 watts in a monoblock configuration; big and heavy with a rack-mountable panel and large power meter. Introduced in 1976.

Dynaco SCA-50 integrated amplifier. A pared-down ST-150 type power amp (25 watts per channel) with all-IC preamp circuitry and sophisticated automatic power-on/off muting in a SCA-80 sized single chassis. Includes tone control defeat switch. Introduced in 1977.

Dynaco Stereo 416 power amplifier. Dynaco's last gasp; perhaps their greatest amplifier, this behemoth implemented Wade Burns' doubled output transistor configuration and fan along with a buffer stage bypass and the C-100 add-on power supply capacitor bank for unequalled drive and power capability. Built-in rack mounts, handles, and a sensitive LED power meter assembly added to the amplifier's no-nonsense appearance. Received rave reviews. Introduced in 1977.

Dynaco's speaker systems provided a tremendous value and durability among loudspeaker systems of the 1960s and 1970s.

While looking through back issues of The Audio Amateur, I found this lovely quote from the late Bob Tucker, Dynaco's master of ad copy and lucid instruction manuals:

"Separately, there are a few areas in even the best designs where cost considerations are evident, but the conscientious audio designer makes sure that to the best of his knowledge, they don't impose sonic strictures. But the more expensive approach does not always bring improvement -- audible or otherwise. Certainly improvement does not necessarily follow from increasing complexity. More likely, the reverse is true. Progress is made when you scientifically systematize and quantify noted effects. This industry has been besieged by a number of unsubstantiated hypotheses (and its share of sales malarkey) of late.

"We need more scientific methodology so there is less 'caveat emptor', even if the snake oil has been largely reserved for those who can (or wish to) afford it. Objective double-blind testing has eradicated some long-held audio myths -- to my ears at least. Not that all amps, or preamps, sound alike -- but a lot of good ones are not necessarily distinguishable. Sure, use a more expensive part if it really does sound better, but don't waste a lot of peoples' money if you can't prove it. The best designs evolve from those individuals and companies who maintain a healthy skepticism for unsupported postulates, but are quick to grasp the provable achievements. The real art is bringing the greatest good (music) to the greatest number."

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This page created and maintained by Greg Dunn.
Copyright © 2000 Greg Dunn