Dynaco Stereo 70 Tube Amp - Mod/Restore Advice Needed

[felix]

I recently acquired my father's old Dynaco (or Dynakit) Stereo 70 (or ST-70) tube amplifier that he used with his first "real" stereo system starting back in the '60s. I brought it home based on my childhood memories of how mysterious, warm, and glowing it looked as it sat under the coffee table that held my Dad's stereo.

 

I looked it up on the web, and was surprised to find out just how much information was out there on it. In fact, there's too much information. This amp is apparently very popular for restoring or modding - and there are numerous varying opinions on what's best to do to an old ST-70.

 

Here is just one ST-70 article:

http://vintage-audio-gear.com/dynakit-st-70-review

 

What do I want to do with it? Well, crazy as it sounds, I think I'd like to fix it up and run an iPod through it, along the lines of a wannabe Manley Labs Stingray iTube sorta thing.

 

Advice?

[Musicale]

First of all I would try it out and see how it runs. Then decide on whether or not you want to keep it as a remembrance. It's certainly a nice stereo tube amp and when running to spec it's just fine. Compared to the cost of a new Manley or another with a similar tube complement it's a bargain. Look at Audiogon.com, you see them over there fairly often from stock to highly modified. As I recall this was sold pre-wired or as a kit. Unless you are pretty capable with tube amps, or have a desire to take on rewiring and checking it for distortion with a signal generator and scope, I would consult a shop capable in restoration.

 

I just went through a similar experience with some expensive film cameras I got from my dad's estate, and I had them restored completely. They were in fine cosmetic condition but needed CAL (clean,adjust and lubricated). Now they are perfect and I use them regularly. They also are now heirlooms to help remember my dad, conversation pieces and fine caameras that you don't need a battery to use them !!

 

Thus, try it out play around with it, get some estimates for restoration and take it from there. This is not a B3 of tube stereo equipment, but maybe a M3. You'll probably never forget those moments of laying on the floor by the coffee table......

 

Regards,

 

Musicale

[mister natural]

this : http://www.avahifi.com/root/equipment/amplifier/ultimate70.htm

[burster]

FWIW. I have been into tube equipment for years and have built many things, The first thing to is replace the electrolytic caps. These dry out and short. The last thing you want to do is blow a trannie. A cool trick is to wire a 40 watt light in series with the black wire of a power cord. Use this while testing the amp out. The light bulb will glow bright if there is a short instead of something blowing up in the amp. The best coupling caps are oil filled types like old school Sprague Vitamin Qs. This have a liquid midrange that compliments the tube sound. Things like silver solder, carbon or metal film NTE resistors are good to look for.

 

Here is a preamp I built for a company. This is the prototype and the production models will be coming out in a few weeks.