Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
Dynaco ST-70 Premium Tube Amplifier
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Evolution Series Dynaco ST-70 Premium Tube Amplifier

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Dynaco/Dynakit ST-70 Tube Amplifier with Bias Balance Control

Two Channels - 35 Watts Per Channel - 70 Watts of Super Sweet Tube Saturated Music!

This amp sounds and looks absolutely stunning, what a great centerpiece for your audio system or collection. 

Very musical, very detailed and a pure joy to listen to - this is a very nice Dynaco 70 to be modest.

Assembled and tested amplifier, Traditional Brown Steel Cover and Tube Set Included.

Pre order - custom built - Ships in 3-4 weeks

It is fairly safe to say that most people today have no idea of just how wonderful a Stereo 70 amplifier is capable of sounding like. Isn't it the buttery smooth sonics, the impeccable details and sweet tones of those great recordings what you seek? Like a musical time machine, this amplifier will take you back to when tubes ruled. But there's even more to consider here. All of the components used in this amplifier have greatly improved characteristics over the ones available and used 50 years ago. That makes the sound quality of this amp even better than it would have been then, as a new one 50 years ago. Take a good close look. This Stereo 70 offers superb sound, high build quality, safe and reliable operation.

The Vintage Vibe - Modern Reliability - The Beautiful Sound of Tubes

Okay, so, how does it sound? - “Magical” - this is not your average Dynakit Stereo 70 folks. Enhanced with premium components, this amp has a very musical presentation, highly detailed voicing and plenty of solid, clean wonderful bass. This amp is absolutely dead quiet - no hum, no buzz, no hiss. It sounds like it is supposed to, actually better than it is supposed to, it sounds beautiful, like you want it to. If you're in search of that "golden age of audio" quality and sound combined with “stunning looks”, you've just found it. This ST-70 delivers dramatically improved sonics as the result of being built with technologically advanced components and high-end parts.

This amp has a Genuine Dynakit Mirror Polished Stainless Steel chassis and comes with a brand new perforated steel cover in the Classic Original Brown. 

This is a brand new build with all new parts. Photos are of the actual amplifier you are buying.

This amplifier is equipped with the Dynakit "bias balance control" system. This allows standard biasing and then provides balancing of the bias between the individual output tubes for enhanced sonics, extended tube life and higher overall reliability. Bias is initially adjusted using the original 10k bias pots just behind the circuit board. Then, using the additional secondary adjusters the balance is adjusted, this is for equalizing the current between each pair of output tubes. The secondary balance adjustments are made using the adjusters for the two additional balance pots which are installed conveniently behind the already existing front octal sockets. The adjuster is very discreet and is accessible at the center holes of the front octal sockets. Full easy to follow bias setting instructions are included.

The Upgraded Premium Dynakit 80/40/30/20uF multi section capacitor is rated for 550V (600V surge) and uses four discrete (individual) caps inside the metal can style enclosure. The bias section has two 100uF 100V Nichicon capacitors with 1% 1W 10K metal film resistors for quiet, accurate and smooth power. All of the other resistors under the chassis are heavy duty metal films by Dale and Xicon for super quiet and dependable operation. 

The transformers are new production by Dynakit. The huge PA060 power transformer and two A470 output transformers are wound for modern day voltages. These operate cooler, produce less distortion and will outperform vintage transformers in every category. The current production Dynakit transformers were reverse engineered from the original Dynaco designs, but using modern technologies and insulations. An increased lamination stack on this power transformer allows it to run cooler and provide better regulation. These transformers wont buzz or hum like the originals often do either. A major factor to consider here is that the original transformers were designed to operate on 117 Volts. Modern household AC current is often 125 Volts or more so the use of a "step down" or "bucking" transformer is necessary to reduce the voltage down to a safe operating level for amps having the original transformers. These are USA made transformers that meet and exceed every aspect of the originals. If there were some sort of "magic" in the use of cloth leads, Dynakit would have certainly insisted on using them again. There's simply no magic in cloth covered lead wire, period, it is inferior. In any comparison, these new transformers are better than those old originals, no offense intended. Modern advancements in materials, methods and technologies used in the production of these transformers has resulted in superb transformers that produce cleaner power, operate quieter and run cooler than the originals while providing less distortion and increased reliability.

The new A470 output transformers are also greatly improved, like the power transformer. The output transformers are interleaved/layer-wound and incorporate high quality M-6 grain oriented laminations. These also use better quality wire with better insulation, the primary is wound the same as the original A470 using the same number of turns on the same number of sections. These are made using the same patented Dynaco winding method, and made on the same core size and material type as the originals. These transformers are in one word, exceptional.

The custom red circuit board uses the stock Dynaco circuit designed specifically for 6GH8A or 6U8A tubes. The original circuit is hard to improve upon....Mr. Hafler and company knew what they were doing. This industrial duty PCB is 2mm in thickness, providing extra sturdiness to resist flex during tube swaps. The thicker PCB additionally provides better insulated and isolated traces for superb stereo channel separation and premium sonic performance. The .1 and .22uF 630 volt Mundorf capacitors provide a rich, warm and detailed sonic presentation.  The 82pF capacitors are 1,000 volt Murata MLCC type with C0G (NP0) dielectric and provide improved sound characteristics through their linear stability. The 390pF caps are by Kemet, also C0G (NP0) type and rated for 1,000 volts. All the resistors are metal films and a few carbon compositions for warmth and spectacular clarity. Two test matched Amperex (France) 6GH8A tubes are included. These are premium grade vintage tubes and sound fantastic. The black tube sockets are heavy duty NOS Cinch brand.

So, are you still thinking using 6GH8A/6U8A tubes is questionable?

Here is a quick look at an important excerpt from a Dynaco document: "The original ST-70's single tube (7199) is out of production and unavailable. The ST70II uses, instead, the 6GH8A. Since this tube has been extensively used in high frequency applications, availability is excellent. It works exceptionally well in this application, yielding better consistency and lower distortion. (TECHNICAL NOTE: Though most tube manuals do not list a spec for the 6GH8A, extensive testing by Dynaco of large numbers of 6GH8A tubes has revealed noise floors that are, on average, lower than modern production 7199's. The 6GH8A is NOT a drop-in replacement for the 7199 tube as pinout for the two tubes is different. Do not attempt to interchange them." I personally have built and owned and listened to countless Dynaco 70 amps in both configurations and prefer the 6GH8A or 6U8A tube. I also appreciate the availability and price for these great tubes.

The included rectifier tube is a Tung-Sol 5AR4/GZ34. The rectifiers standard 8 pin socket (V1) is also protected with two diodes that will prevent flashback current from damaging the tube and transformer in the event of a sudden power on-off-on sequence.

The output tubes are a perfectly matched quad of EL34's from NessTone. These are a premium grade EL34 from the Shuguang factory that are tested, graded and hand selected here in the USA. I have used and sold nearly 100 Dynaco amps with these tubes and have simply had no other tube that sounds any better. Not one failure, not a single complaint. They are excellent sounding and very reliable tubes, they look great too.

The back of the amplifier has 4 and 8 ohm banana jack binding post style terminals (4 mm).  These jacks will accept the full pin depth of standard banana plugs. The unused 16 ohm output taps are wired directly into the NFB circuit. The 16 Ohm outputs could be wired up with a little work if needed, however you would have to sacrifice either the 4 or 8 ohm output terminals. there's just not enough room on the chassis for all four terminals. There is a flush mount fuse holder using a standard 3AG slo-blo fuse. The use of the flush fuse holder helps to eliminate the most common damage seen on these amps, a broken fuse holder. Right angle banana plugs will help save some space behind the amp. 

This Model 70 also has a genuine Dynakit C-354 shielded design filter choke. 

This amp is dead quiet, zero hum and sounds just incredible. 

All wiring was done with 20 AWG solid core wire rated for 600 and 1000 volts, I only use Kester 60/40 rosin core solder. 

If appearance is important to you then you'll greatly appreciate the gleaming mirror polished stainless steel chassis and extra sharp details of the circuit board, wiring and the beautiful glow of tubes.


  • The Stereo/Mono switch is made by Alpha and is fully functional.
  • The RCA inputs are gold plated and have wider spacing to accept todays bigger and better RCA connection cables. 
  • 4 oversized solid rubber feet with steel bushings were chosen to give the amp a great stance. 
  • The power switch is a new upgraded C&K branded part rated for 10,000 cycles. It features a "sealed" type slide mechanism for a long trouble free life.
The amp shown in the photos is the amp you are going to receive, nothing else in the photos is included.
The tubes will be removed and individually boxed, then boxed again, then packed carefully in the larger box.
Tube installation guide, all assembly and operating manuals, bias instructions etc. are included.

Shipped insured for full value with UPS - signature required*

Professionally packed - double boxed - Promptly Shipped

No P.O. Box delivery


*All insured shipments require a signature at time of delivery.

Shipment is prompt, professionally packed and will be fully insured

Ships UPS Ground Only

Warranty is for 6 months from the date of purchase, warranty coverage is offered the original purchaser only. 

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