DYNACO STEREO 70 (ST-70) Tube Amplifier

See How to Order One

Built to order, made just for you.

THIS IS A "SPECIAL ORDER". These ST-70 Amplifiers require a 3-4 week production period. Each amp is custom built. I need time to order the components relative to the options you've selected and of course time for assembling and testing the unit. Often there will be a few orders to complete before I get to your build. The component varieties, brands and features I offer are proven top performers. You can "pick and choose" with confidence and I will build you a great sounding ampIf you need one now, please check to see if one is "ready-to-ship".

The photos shown are of previous units, to provide visual examples. Generally speaking, most units look very similar when completed, but your specific unit will have all the special features you have chosen.  

A Special Dynakit ST-70 One-Off Retro Audiophile Build

STANDARD BUILD: $1,399.00 + $95.00 (FedEx Insured Shipping)


st-70 tubes (tubes not included)

The ST-70 amplifier uses the tubes listed below

You are not required to purchase the tubes from us, but we'd appreciate it. 

If you choose to buy tubes elsewhere, your amplifier will still be fully tested using our tubes, but it will ship without tubes. 

Shop for Apex matched tubes for the ST-70

options / upgrades

The standard build includes 1% metal film resistors. We offer several options for upgrading to better resistors. The resistors are very important to the sound quality, as well as contributing to the reliable operation of the amplifier. Upgrading to carbon film and carbon composition type resistors will make the amplifier sound its best.

The standard build includes CDE 940 series capacitors. We offer several options for upgrading the capacitors for your ST-70 amplifier build. The capacitors are critically important to the sound quality, as well as contributing to the reliable operation and overall the appearance of the amplifier. Although the standard CDE 940 caps sound great, they cannot come close to the Amtrans or V-Cap capacitors. 

There are several options available for upgrading the tubes sockets for the driver tubes on the PCB.

The standard build includes the standard screw terminals, these give use all three of the 4Ω, 8Ω and 16Ω (Ohm) terminals. The amp can be upgraded with binding posts/banana jacks, but with a choice of only two out of the 3 impedance ranges of 4, 8 and 16 Ohm. There's not enough room in the chassis opening for installing four binding posts. (Most people do not use 16 ohm speakers these days)

If you stick with the standard screw terminal outputs, we offer spade screw terminal to banana plug / binding post adapters to make things neat and easy. This allows you to keep all three of the 4Ω, 8Ω and 16Ω (Ohm) terminals, but with an easier way to attach speaker leads.

The stereo to mono switch is optional. If you want the stereo  / mono switch included, see the ST-70 options page and request this option with your order.

The amplifier uses the original bias circuit and bias set adjustment pots. 

You can upgrade to the bias balance control for more accurate and balanced tube biasing. (note: bias balance is NOT individual tube biasing)

See the Upgrades and Options for the ST-70

Want to hear what actual owners have to say? Click here to read some of their reviews.

Dynakit ST-70 / Amtrans capacitors & resistors

ST-70 with the custom bias supply, binding posts & typical wiring

Dynakit ST-70 / Mundorf capacitors / Amtrans resistors

about the st-70

The circuit board I use is a new OEM Dynakit board. This board uses the original 6GH8A circuit developed by Dynaco in response to the 7199 tube going out of production entirely back in 2007. Alternative tubes 6U8A and 6EA8 can also be used with this board. These tubes are equivalent to a 7199 but have a different pinout. The 6GH8A revision was a simple matter of rerouting a few traces to accommodate the different pin arrangement of the 6GH8A tube. 

I have always found the stock circuit to be the best sounding. They didn't sell over 350,000 of these because they sounded mediocre. Consider this, if you will. If any of the past or previous modified or alternative circuits were really better, wouldn't those have then, or currently dominate the market? Imitation is the highest form of flattery. Be aware, when you install a VTA (tubes 4 hifi), Curcio Audio, Triode Electronics or any other driver circuit, the amplifier is no longer a Dynaco.

I only use genuine Dynakit C-354 filter chokes. These new production chokes are fully encased in a metal housing for excellent shielding and won't leak and goop up your chassis like the old design could. The C-354 is varnish dipped for moisture resistance, improved electrical insulation and reduced vibration.

The filter capacitor is a 30/20/20/20uF 525V rated part by Dynakit. It's made in USA, hand polished to improve appearance.

I use a custom designed PCB style bias supply which uses Nichicon or Kemet 100uF / 100V electrolytic caps, audio grade film capacitors and metal film resistors for super quiet, stable and reliable operation. This uses the original bias circuit but the PCB allows for the neat installation of better performing, modern  components.

The RCA inputs are gold plated for improved contact and corrosion resistance. The jacks are spaced slightly wider apart, making more room for larger interconnects.

Carefully and expertly wired by hand using only Kester 63/37 eutectic solder for superb connections. 600V rated 22 AWG stranded wire throughout.

Safety diodes are installed on the rectifier tube socket for added protection against "flashback".

An "anti click" capacitor is installed on the 6 amp rated power switch to provide a thump / pop free power on and off.

The beautiful "trophy quality" chassis is made with mirror polished stainless steel (non magnetic) and is truly a work of art.

The included cover has a lightly textured finish, in Original Brown or Satin Black.

The amp rests on 4 oversized rubber feet for improved chassis ventilation and has a great looking stance.

Manuals, biasing instructions and initial set up printouts / diagrams all included. Email and phone support provided if needed. 

Be sure to check out the "ready-to-ship" units, they're assembled, tested and ready to go

ST-70 Dimensions:

ST-70 / V-Cap Tone & MOD capacitors / Carbon Comp resistors

ST-70 Amplifier Video Review and walkaround from drD E's Youtube Channel

Dynakit ST-70 / Upgraded Resistors & Capacitors

Dynakit ST-70 / PRP metal film resistors / Mundorf MCap ZN capacitors

Dynaco ST-70 / metal film resistors / Vishay 1839HQ capacitors

A One-Off Dynaco ST-70 "Super NOS" Build

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