Dynaco ST-70 totally restored vs Dynaco ST-70 Kit

I would agree and disagree with Amadarae. The original Stereo 70 power transformer, runs very hot and this bothers some people. On the other hand, as he points out, many of these are fourty years old and functioning perfectly.

What the original design does not take into account is that the aftermarket driver boards that are so popular, add the filament current draw of from one to five extra small signal tubes. This additional current draw can certainly put stress on the transformer beyond the design envelope. Some of these boards use octal drivers like 6SL7 and 6SN7 that are particular current hogs. And yes some original transformers can last another fourty years with even the added current draw of additional tubes. And, of course, if you have converted B+ rectification from the 5AR4 tube to solid state rectification than you have decreased the current draw on the transfomer.

i am considering a stereo 70 myself. i will only buy an original, stock stereo 70. if i want more "resolution", i'll buy another amp.

why take an orange and turn it into an apple, when you can buy an apple ?

Agree 100%. I have a completely UNRESTORED ST70 in pristine condition. It makes my (restored!) Quad ESL 57s sound incredible.

If you don't like the original, get a different amp.

hi jeff:

i too have restored quads,namely, quads unlimited esls.

i am looking forward to auditioning the stereo 70.
so you use mullard el34s, some other nos tubes, or some current production tubes ??

yes. mullard el34s -- from the blackburn factory.

I too use Mullard El-34's/6CA7's. I have accumulated 3 pairs all NOS and should be enough. Took me a while to shop, test, and burn in to see if it holds bias current to arrived at my "set". I never had any luck with the metal base ones though (Noisy and un-stable). Oh, btw, I highly recommend to have a reliable tester when buying NOS EL-34's.

FWIW, I never considered my power tranny as "very hot" when operating. I just got lucky perhaps because my unit is pristine (you can tell signs of burning looking at the original enamel paint of the power transformer and also how the original paper base input board looks like inside). I bought mine for $295 way back with original cage, Mullard 5AR4 rectifier, RCA 7199 drivers and Mullard El-34's and all test great.

You can see my unit on my system page here (Winged-C Output tubes) with the Curcio input board with Yageo metal film resistors, Orange Drop caps, and 6922 driver/splitter tubes. I was thinking of replacing the input board caps (from Orange drops to PIO's) but really like what I am hearing so I kept it as it is.

I tried my amp on Magnepan(1.6), Bozaks, Fostex base MLTL, and now my Altec 604's in OB and sounds really nice (except on MG 1.6 where I can only listen at low levels).
I have a friend who has a Polk Audio Vintage speaker (big ones with 4 woofers and 4 HF drivers) and so happened to try the ST-70 there, it sounds pretty nice. My friend wants to buy my amp on the spot. I replied by saying to give me a couple of weeks (I want to shop for a comparable unit to replace the one I have but all I saw during that time are not as mint). That was almost three years ago. I still have my amp.

One other thing, in mono mode (using mono cartridge, and phono preamp), the ST-70 will surprised you thinking that you bought a mega-dollar amp even if you use Winged-C (highly recommended provided that you burn it in for about 12 hours before critical listening)instead of the Mullard 6CA7's.

So in retrospect, give me an Original ST-70 or give me a different amp. Life is too short to waste time on copycat's.

Oh, with regards to "whatever his name" selling kits for the ST-70, follow the link below. If this is not "self promoting" post, I do not know what it is.

[url]http://db.audioasylum.com/cgi/m.mpl?forum=tubes&n=208085&highlight=bob+latino&r=[/url]

In a public forum, is it wrong to post something good about what you are currently selling? I do not know.