Dynaco ST-70 totally restored vs Dynaco ST-70 Kit

am considering a stereo 70 myself. i will only buy an original, stock stereo 70. if i want more "resolution", i'll buy another amp.

why take an orange and turn it into an apple, when you can buy an apple ?

Me too! The power tranny in the original model is fine, no need to step up to a larger rating. if not, why do they last more than 20+ years and counting?

For me, I am bias to the true original output transformers the ST-70 uses. I agree, that the input board needs to be replaced (I use one with 6922 drivers) as well as the power supply main caps (if not replaced already!) and the selenium rectifier. I heard and compared other ST-70 wannabees (not the original power and output transformers) and to me, there is no substitute for the original.

My opinion only.

I would agree and disagree with Amadarae. The original Stereo 70 power transformer, runs very hot and this bothers some people. On the other hand, as he points out, many of these are fourty years old and functioning perfectly.

What the original design does not take into account is that the aftermarket driver boards that are so popular, add the filament current draw of from one to five extra small signal tubes. This additional current draw can certainly put stress on the transformer beyond the design envelope. Some of these boards use octal drivers like 6SL7 and 6SN7 that are particular current hogs. And yes some original transformers can last another fourty years with even the added current draw of additional tubes. And, of course, if you have converted B+ rectification from the 5AR4 tube to solid state rectification than you have decreased the current draw on the transfomer.

i am considering a stereo 70 myself. i will only buy an original, stock stereo 70. if i want more "resolution", i'll buy another amp.

why take an orange and turn it into an apple, when you can buy an apple ?

Agree 100%. I have a completely UNRESTORED ST70 in pristine condition. It makes my (restored!) Quad ESL 57s sound incredible.

If you don't like the original, get a different amp.

hi jeff:

i too have restored quads,namely, quads unlimited esls.

i am looking forward to auditioning the stereo 70.
so you use mullard el34s, some other nos tubes, or some current production tubes ??

yes. mullard el34s -- from the blackburn factory.