Dynaco ST70 update

[@georgecovetskie6717]

Back around 1972 I was walking home from school and it was a misty damp day. Was looking forward to getting home. Along the way I seen someone put to the curb a big ol console unit like the Magnavox TV and stereo together in this big piece of furnature. I was (and still am) I big sound enthusiest. I learning electronic in school at the time and worked part time in a TV repair shop. So, I ripped the the back cover off and seen the speakers were ruined from the moisture. That is what I was after. However, sitting in the bottom was this Dynakit ST-70. It was in tact, had no burn smell to it so with the only tool I had on me (pocket knife) I got that amp out. Caried home, dried it out and the next day brought it to the TV shop. My boss was impressed by it and we hooked it up. Dam, it sounded good. We let it play for 3 hours, all working well. Best part is I still have that ST-70 and it still freakin works! I recently did a test by replacing my ol Marants power amp for the st70 just to see how it sounded. IT WAS Better than the Marantz! Not as much power but the dynamics, even sounds and listening pleasure was all still there. Yes, that AMP is all it is said to be. Congrats, enjoy it.

[@drde4010]

It's great when you hear stories like this, provoke memories like that. Thanks for sharing.

[@orwhat24]

Love these videos. I'm making the assumption that you prefer the PAS3>ST70>Klipsch chain over say the PAS3>Vidar2>LRS+ combo. In a time when it is so hard to go hear equipment, you are providing a great service to those of us who are interested in the less-than-mainstream gear. Thanks.

[@williamkleckner9844]

My friend and I are using PlayStation 1 as source component once in awhile ! It’s getting harder to find a good one so, if you can get one, very good , great source. It’s nice to see someone else who knows what they’re looking at. Still holds up well though. Nice review. I want to try a ST70 with a separate tube rectifier stage!

[@MrRourk]

For the Heathkit AA-50 and AA-100 there is a gentlemen out there making new boards that include classic mods to make those units sound so much better.

[@AudioElectronicsChicago]

classic beautiful tube amp

[@EddyTeetree]

My friend who is a pro vac valve amp builder has one of these. I really like it. Unfortunately so does he haha. I have a Leak stereo 20 (c 1958/59 myself it puts out enough volume with very sensitive full range 16ohm drivers. The sweet spot in my room is about 85 dbl though. Nice combo for me anyways. I had a really nice rebuilt Marantz 240 power amp for the heavy lifting but it got damaged in disaster level floods here and I couldn’t find a replacement transformer. Worms from the floods got in and ate the insulation! C’est la Vie.

[@briancampbell7712]

where can I buy a Kenny Russell Dynaco ST70

[@geedaddy45]

Hello drD! Your set up looks/sounds amazing! I’m half way through my ST-70 rebuild right now and got my PAS-3X working just yesterday. Put it on a scope and it all looked promising. To tell you the truth, I’m a little confused as to what RCA input to use as an “AUX” input. Is it “Special” or “Spare”?

[@HoomanR17]

I'm enjoying your videos. New in the exploration of my first tube system. Wondering what's your exprience in the SET realm? These Dynaco's are push pull. While I'm open to the possibility that there's no value in being a purist, but wondering about your take on the SE vs. PP and if you have a current SE amp you like?

[@drde4010]

It depends on what speakers you are running. I don't really have strong opinions on push pull vs single ended because honestly I've heard great examples of both. If you go through my history of videos, you'll see I'm now happily using ST35 and ST70 builds by Kenny as my primary amps. You can get away with set amps if you have reasonably efficient speakers but trying to find the holy grail is an endless endeavor. I think these Dynakit's are simply amazing to say the least and they can be acquired in reasonable amounts of time. They are also priced extremely reasonable too. You'd be amazed how well they stack up to just about anything as long as you use compatable speakers. I've gotten to a point where I'm quite content with these Dynakit's.

[@MrRourk]

A cheap speaker for set amps - the JBL Baby Butt will work with a 300b set amp

[@MrRourk]

You need to try a Russian Set Tube like 6c33c-b or GM70. There is just something about a big watt set amp. The Dynaco is very nice one of the best push pull of all time. I would not be surprised if Will Vincent and Bob Latino are using the same boards for their builds. Ever try the Heathkit AA-151 with Sam Kim mods?

[@briancampbell7712]

excellent review...thanks..just liked and subscribed... now I will look to buy one of these amps...what nestone stock tubes are those and how do I set the bias...? i'm using a pair of Spendor S100 but getting a pair of Tannoy Berkeleys soon...one last question...is that a pre amp sitting on the speaker? what brand & model ?

[@drde4010]

@@briancampbell7712 The NessTone EL34 are provided by Kenny Russell. The provide a warmer tone in my opinion and I love them. The voltage is set to about 145. The process to bias takes about an hour worth of adjusting. Just go back every ten or 15 minutes or so and keep adjusting until it settles.

[@wronghandshooter]

I think I may have asked this question on a different video but I can't find your reply. What are the legs on your Heresy speakers.

[@drde4010]

Just google mid century wood couch legs. Amazon

[@jaredbrown3083]

What makes you like this more than the Allen eaton monos

[@drde4010]

It has a thicker meatier sound.

[@rickg8015]

Looks really neat.. What are the Red coupling caps on the board?

[@getdynaco]

Those are New Old Stock TRW/Goodall .047uF caps, they test perfectly, better than most new caps do. I have a number of them on hand for future builds.

[@rickg8015]

@@getdynacoThank you.. Your builds looks the business.👌🏼..

[@joma620]

Interesting , what brand/ series are those 4 big black coupling caps?

[@getdynaco]

Amtrans AMCY Series "Golden Black" - from Japan

[@bobkrueger194]

What upgrades did you make over stock?

[@drde4010]

I didn't make specific upgrades other than what Kenny suggested which I wouldn't know exactly, however, I did upgrade to a full set of genuine Baldwin tubes all the way around. After hearing the first ST35, I requested another one built identically the same.

[@geevee1045]

Love your videos. Just wondering if you can still switch out the solid state rectifier with the original tube rectifier, if you wished to? I'm of the belief that tube rectifiers add dimension to the sound while solid state rectifiers add tighter bass but more 2D solid state sound to the mix. If you feel like experimenting with that idea, would love to hear your findings.

[@getdynaco]

The solid state rectifier has an octal base, just like the glass tube version. It can be removed and swapped at any time. The bias will need to be checked and adjusted accordingly, every time you swap rectifiers. The solid state is more efficient than a tube so if you simply swapped it for a glass tube, the bias would typically be too high.

[@geevee1045]

@@getdynaco Yes I thought so. I suppose it's a little like comparing the tube rectified ST70 with the solid state rectified ST35 to see if the tube rectifier contributes any more dimension to the sound, or not. Thanks for your reply.