This amp is built on a Genuine Dynakit Mirror Polished Stainless Steel chassis. The amp comes with a brand new Dynakit Stereo 70 perforated steel cover in Satin Black and has a specially made solid aluminum matching badge. This is a really cool looking amp, you'll never see another one like it. This is a brand new build with all new parts. Photos are of the actual amplifier.
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 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 F&T capacitors with Takman 1% 2W 10K metal film audio grade resistors for quiet, accurate and smooth power. All of the other resistors under the chassis are heavy duty metal films for super quiet and dependable operation.
So, are you still thinking using 6GH8A/6U8A tubes is questionable?
View this scan of an original Dynaco Series 2 Tube Amplifier manual, these amps came direct from Dynaco with 6GH8A tubes! A great Read and full of information.
Here is a quick look at an important excerpt from that 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. The printed circuit board material......................." (read more)