Negotiating for Dynaco ST-70

inspiredsports

I have an out of town friend who is absolutely NOT into audio who inherited his father's Dynaco ST-70 almost 3 years ago. He knows I have been contemplating getting deeper into tube gear after enjoying great improvements with tube buffers. The ST-70 really appeals to me because it is an old-school American-made classic.

This ST-70 has been slightly modified and was in perfect working order at the time his father passed away, but has not been used since January, 2006. The mods were that a couple of caps had been replaced, an IEC female power connection added, and banana plug speaker connections added.

I mistakenly thought the unit was 80WPC X 2 when this idea was hatched, but have just learned it is 35WPC X 2 (I believe at 8 ohms).

I could always drive my SDA-2B's with it, but the real intent would be to drive my TL'd SDA SRS 2's (1986 4ohm version).

I'm wondering if the ST-70 will have the power to properly drive the SRS 2's (that then makes me wonder if maybe I should go for a tube preamp and continue to use an SS power amp?)

I did not ask about the tubes in play as I'm guessing some may need to be replaced, but he did share the main tubes are Mullard 6CA7's (England) which I guess are equivalent to the EL34's specified by Dynaco? I guess these are pretty good tubes if they test out as his dad was into audio.

My friend will be in town for the Holiday so I will be able to see it on Friday and I will know more, but I think I'm going to buy it if the price is anywhere near reasonable.

Any hints from the gang?

Libertyc

The Dynaco ST-70 (stereo 35w x 2) is probably the most popular stereo tube amp of all time. It will power your SDAs but don't expect it to have the punch of a more powerful SS amp. It's probably worth around $400 depending what tubes are in it. I would go for it if the price is right but remember it not going to shake the house down.

george daniel

I'm gonna' go out on a limb and say that the ST-70 will be a tad shy of what you want/expect,,BUT,, if you can,try it out and see,,I gave up on "absolutes" a looong time ago--good luck--let us know how it turns out.

inspiredsports

george daniel wrote: »

I'm gonna' go out on a limb and say that the ST-70 will be a tad shy of what you want/expect,,BUT,, if you can,try it out and see,,I gave up on "absolutes" a looong time ago--good luck--let us know how it turns out.

Thanks George, I've done a lot of research on this amp tonight and I think you hit it right on the head.

There are many mods out there that add capacitance, and more robust transformers are available to add headroom and bass, but I think even then it's just a bit underpowered for my larger speakers. One article I read said that stock it proves to be closer to 25 than 35 WPC

I tend to listen to a lot of classic rock / hard rock at moderate to higher levels.

It's just that after experimenting with my tube buffers I'm developing a strong desire to get a tube amp, and I thought this might be an economical first step. I am going to try it out and see and report back.

inspiredsports

Well, it's after Thanksgiving and my friend is on his way back to Minnesota . . . WITH HIS DYNACO.

We listened and listened with the unit hooked to my SDA SRS 2', SDA-2B's and pair of stock Monitor 5B's I just picked up at yard sales as a restoration project.

As expected, the sound was thin from the SRS 2's, but quite appealing from the 2B's at mid to moderate levels. However, it did not do the job I need to enjoy rock at the volumes I'm used to.

Surprisingly, the stock 5B's (still dust covered and sporting and sporting SL2000's), sounded great. I wanted it bad!

Cutting to the end of the story, we had negotiated $200 for the Dynaco and I was salivating as I reached for my wallet before he got pretty emotional about letting his Dad's amp go .

The 5B's ended up in his trunk for the $65 I paid at the yard sale and I'm guessing we might end up with a new CP member

thsmith

Great story inspired. Sounds like a great ending. Your friend can now enjoy what his father enjoyed. That has to feel good.

george daniel

If you want something to "hump" those SRS's,, you might wanna' look at a VTL ST-150,, should be enough to make them sing.

inspiredsports

thsmith wrote: »

Great story inspired. Sounds like a great ending. Your friend can now enjoy what his father enjoyed. That has to feel good.

You are 100% on it. The guy has been my best friend since 1977 and was my best man in 1981. I wanted him to just take the speakers. but my wife told him what I'd paid and there was no way out. It turned out the way that it should have, and I will feel good every time I think about tube gear!

inspiredsports

george daniel wrote: »

If you want something to "hump" those SRS's,, you might wanna' look at a VTL ST-150,, should be enough to make them sing.

I'm glad my son is just hitting his prime and has a weight bench in his room so he can toss a 100lb. behemoth like this around for me in my old age

I'm not even going to say, "I'm afraid it's out of my price range", because I'm so sick into this hobby that I will find a way when I find the right fit.

This sure looks like a contender that will get the job done!

inspiredsports

george daniel wrote: »

If you want something to "hump" those SRS's,, you might wanna' look at a VTL ST-150,, should be enough to make them sing.

Now this tells the story of what a high current tube amp's specs should look like. Power consumption: Idle = 280W, Full Power = 950W !!