Dynaco 70 with 6SN7 Driver and Autobias

This Dynakit 70 features an incredible custom designed circuit utilizing the beautiful sound capabilities of the legendary 6SN7 dual triode preamp tube. The chassis is a genuine Dynakit 70 as are the transformers. Tung-Sol EL34 tubes are standard, Genalex KT66 and KT77 tubes are optional, the perforated metal cover is included for this amplifier.

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The 5AR4/GZ34 tube and the multi section filter capacitor are both eliminated in favor of fully solid state rectification with increased capacitance. The overall soundstage is considerably larger and the bass response shows massive improvement when compared to the stock Dynaco 70. This amp sounds amazing.

The autobias system monitors and adjusts each of the 4 output tubes individually and needs no maintenance or adjustments. It even has four LED indicator lamps relative to each output tube for a visual aid in detecting a faulty tube.

Autobias module, mounted discreetly under the chassis

Note the four green LED indicator lamps, indicating the health of the power tubes

The stock Dynakit cover fits right in place and is included. Installed, the amp looks rather ordinary, retaining the classic look and design. Remove the cover and this one screams "look at me, listen to me". Even a casual observation should indicate instantly and cause anyone to conclude this amp is far from ordinary.

Mundorf Supreme Series capacitors in the standard build. These caps are made in Germany and are of the highest quality and sound very warm and full like a tube amp should sound. This is simply the best sounding Stereo 70 I have heard, period.

The standard build also includes a full set of Tung-Sol tubes. (3) 6SN7 and (4) EL34B. These are brand new, factory tested and matched. Options are available at checkout for alternative power tubes. 




  • EL34 by Tung-Sol - A Pentode Power Tube - Factory tested and plate current matched, an excellent tube. (standard tube for the 70 6SN7 Amplifier)
  • KT77 Genalex - This EL34 is a True Pentode and sounds fantastic in this amplifier. The Genalex KT77 is a Beam Tetrode nevertheless they are plug and play interchangeable and they will sound different. ($100.00 upgrade)
  • KT66 Genalex -  A Beam Tetrode with a larger bottle shape envelope. Increased bottom end with more detail than the EL34's.  ($100.00 upgrade)
  • I currently build and ship this amplifier with (3) Tung-Sol 6SN7 current production tubes. There is a wide variety of NOS and current production tubes on the market. 

The Stereo / Mono switch is omitted in this version of the amplifier, the opening is blocked off with a nice black ABS plate from the interior side of the chassis. The old fashioned screw terminal speaker outputs are upgraded to Banana plug style binding posts. Due to limited space the 16 Ohm outputs are eliminated, their taps are soldered to a tie off lug under the chassis. The 16 Ohm output can be wired for use if needed, but only by sacrificing either the 4 or 8 ohm outputs. There simply isn't room for all three of them at once due to the size of the binding posts and the opening size in the chassis. I can build and ship the amp in either output impedance configuration you need, just let me know ahead of time.

The amplifier comes with a new heavy duty grounded power cord. Use of grounded power cords  always opens the possibility for a ground loop hum due to the common/shared ground circuit created with other components in your system. Be prepared to invest in a Hum-X or similar ground isolation device if this issue arises with your amplifier.