This Dynaco ST-70 driver board PC-3 has been developed and designed to be a drop-in replacement for Dynaco 7199 board. It follows the original wire hole layout, but it was modified to use widely available 6GH8 / 6GH8A / 6KD8 / ECF82 tubes instead of the obsolete and hard to find 7199 tubes. Today one can find many high quality European and US NOS tubes of any of these types at accessible prices and enjoy tube rolling with this driver board. It was also modified to accept modern and NOS coupling capacitors of various types and dimensions. Thanks to that, the board maintains the musical mid frequency character of the original Dynaco 7199 board and extends that performance to bass frequencies, where in the original design the weaknesses are apparent.
Made of high quality epoxy fiberglass FR4 material of 1.6 mm (0.062’) thickness, it is double sided with solder rings on the top layer. The solder reflow process is performed on both layers and inside every hole. A blue solder mask is applied on both sides. All connections and elements on the board are silkscreened with the original DYNACO numbering, so you can use the original DYNACO ST-70 manual to complete it.

We have them available as bare PCBs, retro PCBs, PCBs with matched pairs of NOS 6GH8A (ECF82) tubes (EI Philips, Telefunken, Mullard, Siemens, Valvo, …), KITs, stuffed boards, …

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Dynaco ST70 6GH8A Board

Polypropylene coupling capacitors, silver mica capacitors, metal film, metal oxide and carbon oxide resistors were used, as well as one NOS platinum matched pair (two tubes) of 6GH8A (ECF82) EI Philips, Mullard, Siemens, Valvo or Telefunken. Each pair used is selected from the same batch with the same date codes. The tubes are real platinum matched pairs, tested on a calibrated METRIX U61-B tester.

Dynaco ST70 Parts List 6GH8A
Dynaco ST-70 Manual

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