Dynaco ST-70 / Dynakit Stereo 70 Tube Amplifier w/ Evolution 4T Dual Triode Driver, w/ Tubes & Cover

Brand New! - Dynaco ST-70 / Dynakit Stereo 70 Tube Amplifier with a Dual Triode Driver Stage & Bias Balance

Modern Audiophile Performance with a Classic Look

Utilizing the capabilities of 4 dual triodes, this amplifier will truly amaze you!

The driver circuit utilizes two 6CG7 and two 6922 tubes along with an LM334 constant current source for each tube. The (4) dual triode tubes are configured as differential amplifiers in both the input and driver stages. Each stage uses a temperature compensated constant-current sink to stabilize its operating point for both linearity and long-term reliability. This ensures that the current through each tube remains at its optimal level under all operating conditions and temperatures.

Caps are KEMET Metallized polypropylene film and MLCC (C0G NP0). The circuit incorporates "input blocking capacitors" which isolate the preamp from the power amp, thus eliminating any DC voltage that might appear on the input terminals of the power amp, preventing it from entering the audio path.

Careful measures were taken in this design to ensure the sonic presentation retained the holographic warmth associated with vacuum tube audio. The soundstage is wide and expansive with unbelievable stereo separation that engulfs the listener in a clear, articulate and immersive sonic experience against a dead silent background. The increased capacitance greatly improves speaker damping and low frequency response, which is of course buttery and smooth, yet powerful and readily available at all listening levels across the spectrum. A considerable sonic improvement when compared to the original ST-70 or similar circuit designs.

Rated power: 35 watts RMS per channel

THD at 1 watt: 0.05%

THD at 35 watts: 0.2%

Hum and noise: -100 dB unweighted

Frequency response: -1 dB at 15 Hz and 30 KHz

Powered by a massive Dynakit PA-060 power transformer wound for modern day voltages. These Dynakit transformers do not require a step down transformer, they operate cooler, produce less distortion and easily outperform vintage transformers in every category. Reverse engineered from the original designs using modern technologies and superior insulations. The increased lamination stack allows it to run cooler and provide better regulation too. Built in USA using traditional methods with better technologies.

The new production A470 output transformers are also greatly improved, like the power transformer. These modern version output transformers are interleaved/layer-wound and incorporate the high quality M-6 grain oriented laminations like the original design. These 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.

The amp retains its original 470K input impedance so virtually any preamplifier will be suitable whether you prefer tubes or solid state. Output is set up for 4 and/or 8 ohm speakers with heavy duty gold plated banana jack binding post terminals on the back. The 16 Ohm outputs have been intentionally eliminated. The mono function is also eliminated and this amplifier cannot be used in mono or in a monoblock configuration. Stereo operation only.

Sale includes all tubes:

(4) New Electro-Harmonix “Fat Boy” 6CA7/EL34 Power Tubes

(2) NOS GE (USA mfg.) 6CG7 / 6FQ7 tubes

(2) NOS RFT (Germany mfg.) 6922 / 6DJ8 / E88CC tubes

(1) New Genalex Gold Lion GZ34 / 5AR4 rectifier tube

All the tubes are brand new or (NOS) "new old stock" as indicated. The output tubes were tightly matched using the latest Maxi-Matcher 2 professional matching equipment and then screened/auditioned for noise. Tubes are then “burned in” for 48 hours in the amplifier. The 6CG7 and 6922 tubes were matched using a TV7/DU and the Jackson 648. The GZ34 is new and tested perfectly balanced with both sections being 120%. New or original boxes are included for each tube.

Authenticap (by F&T Germany) 80/40/30/20uF filter cap with higher rated voltage and increased surge capabilities compared to the stock ST-70 capacitor. The resistors are by Dale, TE, Panasonic, PRP and Vishay.

This amplifier has a bias balance system. There are two additional bias adjusters located on the PCB which balance the current between each power tube for each channel. The rectifier tube is protected by safety diodes. The bias supply circuit has safety resistors to protect the tubes and transformers.

Professionally assembled and built to last a lifetime, it's the ultimate ST-70

A thermistor (Inrush current limiter) is installed to provide a slower gradual voltage ramp up at power on.

• The power switch is a 10,000 cycle rated 6 amp switch with a dust sealed body and has a no click capacitor for silent on and off operation.
• The RCA inputs are gold plated for corrosion resistance, better contact and are spaced slightly wider apart for better compatibility with today's larger connectors.
• The output terminals are binding post / banana plug type with gold plating.
• All of the tube sockets are ceramic with Gold contacts for corrosion resistance and excellent conductivity
• Dynakit mirror polished stainless steel chassis with silkscreened labeling
• The new brown perforated steel cover is included, 4 oversized rubber feet for improved chassis ventilation and a great looking stance

This amp sounds absolutely stunning and will be a great centerpiece for your audio system.

The amp shown in the photos is the amp you are going to receive, nothing else in the photos is included. (sale includes these items: Amplifier + Cover + tubes + manuals/documentation)

For shipping purposes, all tubes will be removed and individually boxed, then boxed again, then packed carefully inside the larger box.

Tube installation guide, all assembly and operating manuals, bias instructions etc. are included. Phone or email support is available if you need it.

Prompt & Proper Shipping / Insured for full value - signature required*

No P.O. Box delivery

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

Please make certain you will be home as delivery changes are not possible once shipped.