Dynaco ST70 Review

The Dynaco was a basic, inexpensive, easy-to-assemble workhorse that probably supplied music to more college dorm rooms than any other amp of its period.

Dynaco is best known for the Stereo 70, a highly respected vacuum tube stereo amplifier. The ST-70 was launched in 1959 and was sold as a kit (Dynakit) for self-assembly or as a fully factory-wired unit (Dynaco). In this article, I will be reviewing the product, Dynaco ST70 – its features, alternatives, pros and cons etc. so keep on reading 

Product Overview

Output tubes (EL34), rectifier tube, input tubes, output transformers, a power transformer, and a driver circuit on a pre-assembled printed circuit board (PCB) were utilised in the ST-70. A single 7199 pentode/triode tube was employed in each channel’s driver circuit. The output transformers are ultralinear in form, with a piece of the primary coil sent back to the screen grid of the output tube. This design enhanced audio quality by reducing distortion.  It has a power output of 35 watts per channel. 

The ST-70 was a masterwork of circuit design, providing dependable, good-quality audio amplification at a low cost. Dynaco clearly spent the effort necessary to ensure the sound quality and dependability of all components of this upgraded design.


Rather than a kit, stereo 70s were sold. The machine has been beautified with an all-black exterior, in accordance with modern ideas and a price significantly greater than that of a nice second-hand original. The rubber feet, by the way, are brand new as well.

This amp’s branding and appearance are both quite appealing. To compare it to its bronzed and browned parent, it’s just too precise, skilled, and accurate. An original sound is positively compressed thanks to a lot of previously inaccessible extension at both sides of the harmonic spectrum, while a sense of more power improves both usability and dynamic possibilities.

The ST-70 is a fantastic amplifier that produces a clear, well-defined warm sound. The Dynaco box was a little weighty at 42 lbs., suiting an amplifier strong enough to stand out in both my recording Studio and living room listening situations. The multi-layer, well-insulated custom packaging that encased the ST-70 Version 3 simply peeled away, revealing a tube amplifier with a styled and curved grill shell through which the vacuum tubes can be seen. The grey color grilled cover is secured by four easy – to – remove safety bolts and provides protection from probing fingers or nosy dogs. And it gave the amplifier a fresh and compellingly modern aesthetic wherever I put it.

When it comes to connecting the tubes, everything is already in order, which is fantastic. So, after plugging everything in, turn on the amplifier via the back center toggle switch, and after a quick 30 second warm-up, you’ll have sound. The music quality will improve for up to an hour after warming up, but it will always be rich, strong, and delicious to the ears.

In a straight source-to-amplifier setup, I might propose utilizing them as volume controls, although the company does not advise you that. However, if a listener’s location is significantly off the centerline, they perform as intended.

A high pass button is also located in the middle of the front board, which can be used to eliminate rumbling heavy bass from heavy music. Tube bias lights and adjustment slots are also included, allowing the customer to change the bias for the four output tubes with a “non-metal” 1/16″ flat head screwdriver until all of the indications glow with the same light.


Dynaco ST35

The Dynaco ST-35, unlike its bigger sibling, the Dynaco ST-70, produced 17 1/2 watts per channel (half of the ST-70). The ST-35 is the most sought-after of Dynaco’s tube audio products, and it’s becoming increasingly difficult to locate these days. It occasionally appears on online auctions.

The Dynaco ST-35 is a unique amplifier due to its compact size and amazing sound it generated despite its diminutive size. It is quite heavy for a little amplifier, weighing in at 16 pounds. A Dynaco ST-70 weighs exactly half as much as this.

It’s great at playing music, especially when it’s been modified.

Where Can I Get The Dynaco ST70?

The Dynaco is a great option for any sound system, especially for those on a tight budget. Unfortunately, demand for this amplifier has skyrocketed, but supply remains plentiful. They normally sell for roughly $350 on eBay, but I recommend shopping for an original, untouched model.


Dynaco is a well-known brand, well known for its Stereo ST-70 tube amplifier, which was invented and built by David Hafler in 1959. Throughout its 350,000+ unit lifespan and ownership by three separate firms, it’s aim has indeed been musical involvement with premium sound quality at a reasonable price. And that nearly 60-year legacy has been meticulously updated to deliver both a 21st-century technology edition of this tried-and-true-sounding design, as well as an essential reference to all the components that have made this amp so popular over the years! 

And the outcomes are undeniable. If you’re seeking musical amplification with a cutting-edge tube circuit that has surpassed the expectations of countless listeners for nearly 60 years, you’ve come to the right place! Please test the new Dynaco ST-70 in your system or a trustworthy friend’s system and let me know if it doesn’t enhance your musical world.