Dynaco ST 70 vs.Dynaco Mk.IV

[Henry Love]

I heard the Mk. IV monoblocks the other night.I did like the sound of them and wondered how they stacked up against a ST70.Any opinions would be helpful.A few other questions,is $399 a fair price for a clean unrestored ST 70?Is it true that the earlier ST 70's are more desireable and if so what years were they made and how can you tell?Thanks.

[JMCIII]

Hi Henry,

$399 might be a tad high, but not overly so. I bought mine 10 years ago for $150 (very clean, but with a bad tube), and that was before word got out in the high-end press that the ST-70 was worth buying. Check E-Bay to see what they're selling for there. Find out if the store you're looking at the ST-70 has any kind of warranty and/or return policy. Then, if the answers are positive and the unit is in real good shape, you should probably be able to purchase it, listen to it for as long as you want, and sell it for what you paid for it. How many other pieces of high-end gear can you say that about.

[Henry Love]

Thanks,John.This store had a MK.IV setup and running and he had a ST 70 on a shelf and it was close to closing time.I have never actually listened to a ST 70 and I wonder if anybody can compare them sound and quality wise.

[Gary]

I know of a store that had both amps at one time but I never compared the two. I believe the 4's were 80 watts a side while the ST70 was 35 watts a side. You may want to confirm this (it's been a long time) but it *may* be a consideration for you, depending on speaker efficiency.

35 tubes watts is more powerful than 35 transistor watts.

There should be a bunch of stuff in the archives, too. I seem to recall that there was some discussion about the Mk IV's but I don't recall if it was positive or negative.

Sorry I can't be of more help!

Gary

....Oh - I ended up buying the McIntosh MC240. To me, it sounded better than the Dynaco!

[Henry Love]

Thanks,Gary.I'll bet that 240 is sweet but a tad more than a ST 70.

[Sckott]

Gary is correct. ST70 is 35 per side, and really IS powerful!

[TimB]

Much will depend on tubes, condition and other factors. I have heard mention by some that the Dynaco is as every bit as good as some Mac tube amps, and better than some as well. Specifically, the 240, I am not so sure about, but the one using 6L6 tubes was often judged as being not as good as the ST70. But in the end,YMMV, so listen for yourself.

[Gary]

I've owned both the ST-70 (traded it in) and the MC240 (in my system now). Although I prefer the McIntosh, I still wish I had kept the ST-70.

A lot may depend on your system, too.

I'd never turn down a ST-70 (I am keeping my eyes peeled at my local haunts). One can't have too much stereo equipment, can one?

And you're right, Henry. The McIntosh is at least three times the cost of a Dynaco (around these parts, anyway!). You'll enjoy the Dynaco!

[JMCIII]

The ST-70 uses 2 EL34's per side for its 35w/p/c. The Mk IV's use 2 6550's per side for its power. The tube difference sonics will be noticable, with the EL34's sounding sweeter, the 6550's gutsier. Listen to both, then decide which sounds more like real music to you.

[indy mike]

Hi, the Dynaco MK IV is designed to use a 7199, GZ-34 rectifier tube and a pair of EL-34 tubes; it's a mono block version of the ST-70, and is rated at 40 watts (just a tad more than a channel of a ST-70). I own a pair and occasionally run them to keep 'em alive. Both were obtained through Ebay for about $350 - I had to replace a couple caps and resistors, and upgraded the Russian EL-34's and Chinese rectifier tubes with Siemens outputs and Mullard GZ-34's (one from sckott, another via Ebay). The bass is a tad loose compared to my Dyna ST-150 transistor amps, but the midrange just soars, and the highs are nonfatiguing and sparkle. I'd go the MK IV route - no possibility of one channel sneaking into another channel (and it happens - can't remember the mag/article, but some stereo amps apparently have tiny amounts of bleed because of shared circuit paths) - St-70's are great (my pop built one in the early 60's - wish my older bro hadn't nabbed it)!

[Henry Love]

Thanks everyone for your opinions.I'm gonna have to listen to that ST 70. If I go that route I have a chioce of Svetlana,Sovtek or Electroharmonix.Which of these sound best?Thanks.

[jligon]

Originally posted by Henry Love
Thanks everyone for your opinions.I'm gonna have to listen to that ST 70. If I go that route I have a chioce of Svetlana,Sovtek or Electroharmonix.Which of these sound best?Thanks.

I can't comment on any of those but if you want to go the new tube route, I highly recommend EI fat bottles.

[Alan T]

What mods/updates are you doing to your ST-70? I was lucky enough to get vintage tubes in my units.
What speakers are you using and is there anyway to test for compatibility with tube amps.

[Sckott]

Right now, it's the Electro Harmonix EL-34's that seem to be the most ridgid, solid sounding tubes (for the money) available from Russia, new. You can go NOS, like Mullard or Telefunken, but the prices are quite high, for higer tested tubes....

IMHO, The Fat Bottles are great for guitar amps.....

Sovtek is good, but for EL34's and the 5AR4/GZ34 I've bought 2-3 pair and a few spare. All have died within 1-2 years of use.

Right now, I have some OEM Chinese tubes that have flown right by them. Sad...

AFA others, I'm sure Sovtek would be something I would choose for other applications...

[jligon]

Originally posted by Sckott

Sovtek is good, but for EL34's and the 5AR4/GZ34 I've bought 2-3 pair and a few spare. All have died within 1-2 years of use.


I tried 2 of the Sovtek rectifiers and they were both dead within 6-8 months. I thought there must be something going wrong with the amp. Had it checked out and put in a Mullard and it's been going strong for over a year now (and hopefully longer).