Updated for 18 May 2017

The Dynaco ST 70x saw its first appearance at the Munich High-End Show last year. Getting to the final version of the ST70x took many tests and once we were there it was time to get fully certified with CSA approvals and now the first production cycle of the brand new ST70 has already begun.

With an official launch date of June 2017, the ST70 will first be heading out to your local dealers where you can demo and purchase your very own! The price of the ST70x is $2,999.99 USD. If you would like to get yours early you can pre-order online now.

The new ST70 series 3

Dynaco (a division of Radial Engineering Ltd.) presents the re-launch of a legendary tube amp, the ST-70 Series 3 tube amplifier, at the 2017 High End show. Visitors to High End 2016 were given a preview of the first round prototype and, in the year since the last show, Dynaco engineers have completed work on this highly anticipated product.

The Dynaco ST-70 Series 3 tube amplifier is 35 watts per channel and switchable between both 4 and 8 Ohm outputs, with Class-A push-pull stereo topography , that has long been characterized as a robust, reliable design of exceptional value. The ST-70 Series 3 builds upon the proven design philosophies of the original David Hafler-designed Stereo 70, with contemporary design techniques resulting in exceptional performance improvements that meet the requirements of modern audiophiles.

Dynaco engineers have made extensive use of high-quality parts that were unavailable at the time of the original design including precision metal-film resistors, poly-composition capacitors and miniaturized high-capacity power supply electrolytic capacitors. In addition, many of the newer parts are also built to tighter specifications than the originals. For instance, the PCB is constructed of military-grade, double-sided epoxy fiberglass PC material. In compliance with modern practices, the speaker binding posts have been updated, and a heavy-duty three-pin detachable grounded power cord is provided. Signal ground is the same as electrical ground and chassis, and all signal connectors are gold-plated.

The latest rendition has seen a substantially overhauled power supply from the original version, employing a larger dual-primary power transformer with improved line regulation, increased filter capacitance, and a solid-state rectifier that results in a much more articulate response. The resulting bottom end is a dramatic improvement over the original Stereo 70’s low-end response. This is augmented with a three-position high-pass filter switch to allow listeners to tailor the low-end response of the amplifier to their personal tastes.

obsolete 7199 pentode signal tubes from the original Stereo 70 with more commonly-used 12AU7 dual-triode tubes as part of a configuration that harkens back to the classic Williamson amplifier – this in itself has a long-storied history in the audiophile community. The output stage and EL34/6CA7 output tubes retain the same elements as the original Stereo 70 yet with the new design, the bias adjustment for the output tubes can be individually set using a front-panel recessed trimmer for each tube. After a warm up period (and with no input signal present), the bias is easily set by matching the brightness of the front-panel LEDs. Tremendous effort was applied to improving upon the original output transformers in an effort to increase damping and tighten up the low frequency response . A rear-panel switch allows the listener to select between 4 and 8-Ohm speaker loads. The feedback location is also configured by this switch, and the gain is adjusted accordingly. This results in an improved transient response when compared to older Stereo 70 implementations. The redesigned front end of the Series 3 amplifier replaces theobsolete 7199 pentode signal tubes from the original Stereo 70 with more commonly-used 12AU7 dual-triode tubes as part of a configuration that harkens back to the classic Williamson amplifier – this in itself has a long-storied history in the audiophile community. The output stage and EL34/6CA7 output tubes retain the same elements as the original Stereo 70 yet with the new design, the bias adjustment for the output tubes can be individually set using a front-panel recessed trimmer for each tube. After a warm up period (and with no input signal present), the bias is easily set by matching the brightness of the front-panel LEDs. Tremendous effort was applied to improving upon the original output transformers in an effort to increase damping and tighten up the low frequency response . A rear-panel switch allows the listener to select between 4 and 8-Ohm speaker loads. The feedback location is also configured by this switch, and the gain is adjusted accordingly. This results in an improved transient response when compared to older Stereo 70 implementations.

Building on the legacy of David Hafler’s enormously successful Stereo 70, the new Dynaco ST-70 Series 3 incorporates advancements in component quality, improvements to the electronic circuit performance and an all new design that is sure to please the most demanding audiophile.

First Showing at Munich 2016

Dynaco’s first showing was at the Munich High End Show 2016. The Stereo 70 powered a pair of T+A ST20 Pulsar Speakers and the sound was quite remarkable. Massive crowds were lining up outside the Hafler/Dynaco showroom to listen to the ST70x. Social media was a buzz with ST70 enthusiasm for weeks following the ST70 launch.

Press Reviews from Munich

Enjoy the Music Review

AudioXpress Review

CEPro Review

The ST70x in North America

In North America the ST70x was at The Show Newport at a table ran by Rutherford Audio in partnership with Brooks Berdan Ltd. It was just on display there but following the show Brooks Berdan Ltd took it to their showroom for a week to give it a listen. You can read their post here and we have quoted their listening impressions below.

Brooks Berdan Ltd Sound Impressions of the Dynaco ST70x

Taken from Brooks Berdan’s impressions on their website here

As the this newly styled and reissue ST70x amp warms up the LED’s slowly come to life. A quick test with some rowdy music and the LED’s start to pulse. Punchy with healthy dynamics and a snappy pace. Our first impression was that the soundstage was deep and wide. This came from listening to BYU Vocal point, “Nearer my God to Thee”, as well as some other vocal arrangements. As you would expect the design implementation of the power supply lends itself to a beautifully rounded bass that is well rounded, taught,and just plain yummy. Listening to Donald fagen “Ruby Baby” and Shelly Lynne “just a little lovin” really showed off the bass. The overall character is reminiscent of of the pleasant and warm sound of many of the better EL34 amps of the past, not the least of which, the original ST70. Leaning ever so slightly neutral side yet still warm mids, silky highs.

After 3 days of pleasant and non fatiguing listening with the amp powering up a pair of Magico S1 speakers, and then with a pair of Spendor SP3/1r2 books shelf on stands. We couldn’t help ourselves and we rolled the tubes. Though the tubes the ST70x came with were certainly adequate, we had to roll them one by one. And with each new tube the sound became more relaxed, warmer, yet still capturing ever greater detail and articulation. By the end of our last evening we were particularly thrilled. This little amp played outside it’s expected price, and impressed like a high priced exotic. Final thought, it’s a winner.

Gramophone’s Gaithersburg Grand Opening

Norm Steinke visited the grand opening of Gramophones new Gaithersburg location where he helped set-up a TD 2035 in their main showroom. You can check out our Gramophone post here. Norm brought along the Stereo 70x with him but un-fortunately there was not enough time to give it a demo. We however snapped this awesome photo and I wanted to share it with you!

The Hafler Dealer list

Hafler/Dynaco dealers are steadily growing. As june is quickly approaching we will be sending out a list to all interested on what dealers will have the ST70x in store! You can sign up below to get on that list.

Get notified of what dealers will have the ST70!

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