Mods for DYNA ST-70, What do you think??

I would look into some of the tube specialist forums. I'm sure that there are plenty of various opinions on this.

My take would be to replace all of the aging capacitors, clean all connections as best possible and then re-flow all the joints with a high grade solder ala Wonder, Cardas, WBT, etc.. This will basically maintain the integrity of the existing design while allowing it to function at top performance.

Obviously, you would need to check the tubes and replace accordingly. My one suggestion in this area is that if one output is bad, replace all of them at the same time, etc... Same goes for the driver section. Running tubes of different ages, production runs or brands can contribute to both lower performance and increased wear and tear.

Once again though, i would suggest checking out the various tube resources that are available to you to find out what tubes work best in your specific unit. Sean
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Curcioaudio.com is one of the better Dynaco ST70 mod sites. Joe, the owner, knows em cold. All the mods are discussed there and he carries all the parts. No "best configuration."

Some of the ST70s iron is great. They really vary as to condition in other ways. Some even say the phenolic boards cause chemical changes in the electronics and change over time and with it the sound - no two are the same.

If you have an older Series 1 the passive componants probabaly could use to be replaced. They weren't expected to go 50 years. There are lots of versions of these amps over the years so advice about moding is tough. What is the number stamped on the output transformer? A-470, maybe.

Lots of discussion in archives at Audioasylum diy tube section on point.

Have fun,
i remain,

www.avahifi.com/70rebuild.htm
This site has a reprinted article that explains in depth exactly how to rebuild/upgrade a Dynaco St-70. Very long, extremely detailed, step-by-step instrucions. I think you will find it very informative. It's on the Van Alstine website. He is currently no longer modding the St-70, but his does offer a complete re-make of the amp with new circuit board design using your old chassis and transformer.