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Dynaco ST70 audio research mod (D76 I think?)

B

Bnoyes12

New Member
Anyone know what happened to this mod kit? I know you can buy VanAlstine kits for the Stereo 70 but I’ve been trying to find the Audio Research kit that I seem to remember for the ST70. Anyone know if someone sells this kit or licensed it? I’d just love to be able to mod this ST70 with the audio research mod.
Cheers!
 
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There is a long thread concerning the original board that was originally posted in the tube forum. It turns out, it's pretty hard to beat. I have the VTA driver board in mine just because there are so many new manufacture and old stock 12au7's in the world. The original pentode driver tubes?, not so much. You may want to read through this thread
https://dynacotubeaudio.forumotion.com/t2677-the-audio-research-versions-of-the-dynaco-st-70
I read a few other threads on these and there did seem to be a fair amount of problems with the various versions of the AR kits. I don't think you will find them sold anymore.
The VTA boards are stable and sound nice. Erhard Audio sells a nice kit with the power supply built to the board also. There is also a VTA board configured for 6SN7 octals.
 
wow, 6 twin triodes jammed into the space of the stock board. Thats actually kind of impressive.
 
I will admit I like the idea of incorporating cathode feedback via the transformer secondary. Should be able to do that with any driver. Would be an interesting experiment to see what the results are both on paper and "in ear".

one of these days I really ought to get an ST-70 just to play with this stuff, but the prices are kind of high just for something I'd buy to experiment with. I already own 2 EL34 amps in that power range so I really don't have a strong reason for owning one otherwise.
 
Most of the shortcomings in the OEM Dyna Stereo 70 are power supply related, and surmountable with a few additional bits. There are minor changes elsewhere to provide better reliability and more drive margin. Otherwise, it's not easy to demonstrate conclusively that total redesign makes a better listening amp vs one that just sounds different.
 
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