Started down the road.

CNCfan wrote:Hello everyone,  new here so please excuse my lack of knowledge.

Been interested in a Dynaco ST70 for longer than I can remember but the price has always held me back.
Was wasting my time on ebay and came across a parts chassis, it has the cage and bottom,  a few sockets
and a few other parts.  Decided to get it and start picking up parts to finish it as I can afford them. (going to be a long journey)

On the positive side, every part as was ever made for the OEM 70 is available in the equivalent today. Do a little bit of comparison-shopping before making choices in the driver board - I would never suggest anyone purchase an OEM Phenolic board (the orange ones with the raised solder traces) for latter-day installation, as one example. I would also suggest that you look for an alternative to the OEM 7199 as they can be both scarce and expensive - as well as being microphonic on occasion.

Also snagged a  Pas preamp that the seller said was mostly original and in working condition. Figured the preamp and
parts chassis would be a good start.  

Start with a full recap and consider replacing the original power and bias-supplies. There are some fairly elegant and easy to install options out there. Also, do clean the controls and make sure that the wiring is all good and tight. Many of these were kits, so QC varies quite a bit to that regard.

Will be asking a lot of pretty basic question most likely but will be researching youtube and this forum before I do.

My plans as of now is to get the ST70 up and going. Will need power xfmr, output......well to make it simple, I will need everything
that has a wire connected to it.

See above. Transformers are available from several sources, including those numbered as the OEMs, and from US-made sources. DO TRY to avoid Pacific-Rim transformers at almost any cost. There are also EDCOR and Hammond equivalents - I have heard, but not used them. Superficially, they seemed fine.

On the preamp,  I plan on doing a once over and buying any upgraded parts that are available.  

Start with caps and power supplies. Don't go overboard until you have heard it in its originally designed state. You may be pleasantly surprised and not need to go any further.

Also want to get a Dyna FM receiver,  any suggestion on which version to get?  

An FM-3 (Tube) would be the natural partner to the above. These are pretty basic tuners, and surprisingly mellifluous for what they are. I keep one (1) heavily tweaked unit and one (1) very nearly stock unit. If you are going to go Solid-State, the FM-5 is not half-bad, and the AF-6 is very good indeed if you can find one of the two-dozen or so out there that are actually properly aligned. But, in terms of something subject to amateur care-and-feeding, the FM-3 hands-down.  

I am only an expert in one area of electronics.  I have first hand knowledge on what happens when you grab the
bare wire going to the "on" light on a 220 volt electric stove even when it is off.   Have no plans on finding out
what happens when you touch 350+ volts.

Peter W. wrote:Of the stuff on your list, the scope is likely the least important. Unless you intend to start aligning FM tuners, or you are getting distortion problems, the scope is overkill on most Dynaco products.

audiobill wrote:Many miss the fact that although Dynaco advertised the ST70 at 35 watts per channel, the 1974 FTC requirement that both channels be driven from 20-20khz resulted in the ST70 producing only 17-19 wpc.

Bob's VTA version sports substantial power supply upgrades as well as a much larger power transformer that allows the amp to produce, and has been tested, at least 35wpc.  These transformers are not available separately from Bob.

So, for those refreshing "vintage" ST70s, please realize that you will likely spend as much and end up with half the power of Bob's VTA version.

CNCfan wrote:

I was planing on putting in an upgraded driver board which if I understand will require the upgraded transformer which I see by your post Bob does not sell by itself.  So I will stick with the two tube driver board and get the version that takes 6GH8A  tubes.

Peter W. wrote:
Don't be swayed by the cut-out-the-tone-controls crowd. Even on the PAS2, if clean and undamaged, they are quite neutral in the null position.