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Dynaco Stereo 70

Stereo Power Amplifier Kit (1971)

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Dynaco Stereo 70


The Dynakit Stereo 70 is a complete dual 35 watt power amplifier kit which offers the highest possible fidelity, at low cost and in a compact arrangement.

It uses a patented circuit of outstanding performance characteristics, along with top quality parts, including the new Dynaco Super-Fidelity A-470 transformers - the finest available.

The measured specifications show that the Stereo 70 is an amplifier of unequalled performance, and its listening quality is also unrivalled by any regardless of price.

This amplifier has characteristics and power rating ideal for either stereophonic or monophonic use. The two non-interacting 35 watt channels provide adequate power, in a stereophonic or two channel system, for loudspeakers of any level of efficiency.

The channels can be paralleled for a full 70 watts of low distortion output, suitable for practically any monophonic use even where several loudspeakers are in use in different areas.

The high power capability and low internal impedance provide excellent damping for all types of high quality speaker systems without need to make adjustments to match specific speaker installations.

The design features of your Dynakit which contribute to its superior listening quality include some which are not revealed by the customary steady-state laboratory measurements.

For example, it does not exhibit bounce and flutter when pulsed with a transient signal. Thus a sharp percussive signal like a drum beat or a piano note will be reproduced with sharpness and clarity and neither overhang nor muddiness.

The Stereo 70, unlike many other amplifier circuits, has been designed to provide its specified performance on a loudspeaker load, not just under laboratory measuring conditions. Therefore, the connection of a loudspeaker to the amplifier does not deteriorate its performance or listening quality.

In addition, due to the high quality of the output transformers used, the Dynakit's power handling capabilities are maintained over the entire audio band without the sharp rise in distortion which characterizes most amplifiers at the extremes of high and low frequencies.


  • Power output: 35 watts per channel into 8Ω (stereo)

    Frequency response: 10Hz to 40kHz

    Total harmonic distortion: 1%

    Damping factor: 15

    Input sensitivity: 1.3V

    Signal to noise ratio: 90dB

    Speaker load impedance: 4Ω to 16Ω

    Valve complement: 4 x EL34, 2 x 7199, 1 x GZ34

    Dimensions: 13 x 9.5 x 6.5 inches

    Weight: 32lbs

    Finish: nickel plated chassis, charcoal brown vinyl paint cover

  • Power output: 35 watts per channel into 8Ω (stereo), 70W into 8Ω (mono)

    Frequency response: 20Hz to 20kHz

    Input sensitivity: 1.3V

    Speaker load impedance: 4Ω to 16Ω

    Valve complement: 4 x EL34, 2 x 6GH8A


instruction/owners manual   English -

series II instruction/owners manual   English -

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Reviewed Jun 07th, 2015 by craigtone

Dynaco ST-70 ... the PERFECT gateway drug! This was my first tube amplifier and it turned my into an audiophile. $10's of thousands of dollars later ... but that is another story! The stock amplifier is pretty rolled off on the upper and lower end of the frequency spectrum but with the addition of some added power supply capacitance and MANY choices of driver alternatives, this amp has HUGE potential. My final configuration was the tubes4hifi 12AU7 driver board w/RCA Clear Tops, NOS Mulled brown base GZ34 and a quad of Shuguang Treasure 6CA7-Z's. I also upgraded the power transformer with the larger unit from Triode as the stock one started humming and got very warm. If you have the opportunity to pick one up, DO IT! You will not regret it and the sky is the limit as far as upgradability. Best part is that parts are fairly affordable compared to other tube amplifiers.

Reviewed Mar 19th, 2015 by davidbarash

My dad built this amp and it still has the original tubes and sounds great! It's running with Realistic tubes (German, not Japanese). I've only had to replace the AR4. Sounds great at any volume - no distortion, just sparkling highs and full lows.

Reviewed Nov 17th, 2014 by Vicè

(MKII) Dynamic and with a little loudness sound, ST-70 is a very musical amplifier, ideal for monitor speakesrs.



This website is not affiliated with or sponsored by Dynaco. To purchase Stereo 70 spares or accessories, please contact the company via their website or visit an authorised retailer.