Archive / Classics, 1946 to 1969
Stereo 70
Stereo 70 (ST-70). Power amplifier, Dynaco, 1959
A 35-watt-per-channel EL34 stereo power amplifier sold as a kit or factory-wired, with an estimated 350,000 to 400,000 units sold.
A-15, isometric, same camera for both
- Drawing
- A-15
- Introduced
- 1959
- Produced
- 1959 to 1977
- Made in
- United States
- Designed by
- David Hafler, Ed Laurent
- Launch price
- US$99.95 (1959, kit)
- Size
- 330 x 165 x 241 mm
- Weight
- 14.5 kg
David Hafler and Ed Laurent founded Dynaco in Philadelphia in 1955 and brought out the Stereo 70 in 1959. It uses four EL34 output tubes, two 7199 driver tubes and a GZ34 rectifier, with two ultra-linear output transformers and one power transformer. Buyers could build it as a Dynakit or buy it factory-wired, and it earned the nickname the poor man's McIntosh. A Stereo 70 II followed in 1992 from Sound Valves for Panor Corporation.
Specification
| Item | As published |
|---|---|
| Output | 35 watts per channel into 8 ohms |
| Output tubes | 4 x EL34 |
| Other tubes | 2 x 7199 input and driver, 1 x GZ34 (5AR4) rectifier |
| Transformers | 2 ultra-linear output transformers, 1 power transformer |
| Form | Kit (Dynakit) or factory-wired |
Out of production
Find an original
The Stereo 70 (ST-70) is out of production. Originals change hands on the marketplaces listed here; buy restored, or budget for recapping and new valves.
The house
- Founded
- 1955
- Founder
- David Hafler and Ed Laurent
- Origin
- Philadelphia, Pennsylvania, United States
- Today
- The original company closed in 1980, and Wikipedia gives conflicting trademark owners, Radial Engineering Ltd in its introduction and Dynakit LLC as of 30 January 2026 in a later section.
Further sheets
Sources
- https://en.wikipedia.org/wiki/Dynaco
- https://www.gearpatrol.com/?p=853159
- https://www.radiomuseum.org/r/dynaco_dynakit_st_70st7.html
- https://www.prosoundweb.com/?p=38991
Notes for the record: Radiomuseum lists the first-year price as US$99.00 and rates the output at 70 W for both channels; Gear Patrol gives US$99.95 and 35 W per channel. Unit estimates differ: more than 350,000 (Wikipedia) and about 400,000 (Gear Patrol). Production 1959 to 1977 follows a Gear Patrol caption and is stated loosely as the late 1970s in its text. Dimensions and weight are Radiomuseum's 13 x 6.5 x 9.5 in and 32 lb converted. A ProSoundWeb item dated 30 April 2018 reports a Dynaco ST-70 Series 3 (35 W per channel, EL34, MSRP US$2,999.99) from Dynaco, a division of Radial Engineering. I could not open an official product page or confirm it is still sold, so still_made is null. Wikipedia gives two answers on who owns the Dynaco trademark today, Radial Engineering Ltd and Dynakit LLC as of 30 January 2026.