yaffstone Posted October 4, 2005 Share Posted October 4, 2005 I've just done a BIN for a Dynaco St-70. Pretty pristine original shape. Any pointers would be appreicated. Should this be left turned on so the bias voltage doesn't drift? Should I leave it alone, or apply upgrades like modern capacitors etc? Thanks for any advice. BTW, this amp will be driving a set of k-horns. Cheers, David Quote Link to comment Share on other sites More sharing options...
crazytubepower Posted October 4, 2005 Share Posted October 4, 2005 My advice is to send it to a pro (nosvalves) to have it gone over and have it electical restored. Craig offers a great service and he stands behind his work. Head over to his web site to contact him. www.nosvalves.com You won't be disapointed Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted October 5, 2005 Share Posted October 5, 2005 Welcome to the tube world David! I just bought some McIntosh MC-30's that should be arriving today so I will am officially a toob noob myself. Quote Link to comment Share on other sites More sharing options...
Colin Posted October 5, 2005 Share Posted October 5, 2005 The good news is that a refurbished vintage integrated tube amplifier less than a grand can sound as almost good in some wonderful respects - as the very best super amplifier I ve ever heard on big ole horns the Nelson Pass majestic $6K, Single-Ended, Class-A, X250 Stereo Amplifier (February 2002, http://www.enjoythemusic.com/magazine/equipment/0202/passx250.htm). <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> The bad news is that their sound degrades slowly. The parts get old, yet the amplifier still works. Unlike modern solid-state receivers, where if any goes the slightest wrong, boom! The thing stops working. The tube amplifier keeps chugging along, but the sound gets worse and the magic is just not there. Anything that has or has not been used in the last decade or two or three or four (!) needs a overhaul. Most of the major parts that wear with mileage; tubes, starter, alternator, etc. will need replacing with newer ones, but the chassis and wiring should still be good. [H]PS horns LOVE tubes! Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 5, 2005 Share Posted October 5, 2005 If it is indeed original do yourself a favor and either rebuild it yourself or have it done. Like Colin stated above these old babies may work but 99% of the time there not working properly but still play music. The longer there let run in that condition the harder it is on the transformers. Craig Quote Link to comment Share on other sites More sharing options...
3dzapper Posted October 5, 2005 Share Posted October 5, 2005 David, The truth is, if you can figure out which end of a soldering iron is hot, you can spruce it up yourself. The guy that built the amp you just bought in all likelyhood had to go out and buy a soldering iron too. There are many good kits for upgrading the safty features on an ST-70 and at the same time they improve the sound. Properly installed, the amp can be converted back to original for future "collector value". Have some fun!!!!! Rick Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted October 5, 2005 Share Posted October 5, 2005 If you want one that has already been serviced by Craig, I think TravisC (Wayne) has one that he may want to part with last I knew. Couldn't hurt to have a pair of them, have one running while the other is getting serviced. Wish I knew you were looking for one. Wayne is up here in the Burlington area. Quote Link to comment Share on other sites More sharing options...
cjgeraci Posted October 5, 2005 Share Posted October 5, 2005 Yes, getting it refreshened with modern caps would be a good idea. If I am listening to my Stereo 70, I will leave it on for awhile. But, as soon as I leave the room for extended periods of time (or go to sleep or leave the house) - mine goes off. Saves wear and tear on tubes and the whole safety issue thing....... Enjoy - its one of the old workhorses. Carl. Quote Link to comment Share on other sites More sharing options...
lwhaples Posted October 6, 2005 Share Posted October 6, 2005 Congrats on the ST70! Nice amp,and well worth having an upgrade done to it. Wayne just got his back from Craig and is looking to sell.Hook the two together and really enjoy! Larry Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted October 6, 2005 Share Posted October 6, 2005 Well Fedex managed to put a damper on my spirit and only delivered one of my amps, so I was at least able to admire it anyway. The tubes I need and the other amp are in the other box scheduled to be delivered today. Well I at least cleaned it off and polished the chrome with Never-Dull and it looks sharp, I can't wait to hear it working. Boy they are sure heavy for their size. The anticipation continues! Quote Link to comment Share on other sites More sharing options...
yaffstone Posted October 6, 2005 Author Share Posted October 6, 2005 I've been reading some and find that there are numerous upgrades available for an ST-70. The power supply quad cap replacement seems like a great idea. Has anyone done the triode input stage conversion? Wonder if this one is worth it. BTW, I have quite a few soldering irons, DVM's an o-scope, and some experience with solid state design and trouble shooting. Never worked on or listened to tubes, but then I guess it's never too late to start. Thanks for the advice, David Quote Link to comment Share on other sites More sharing options...
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