Has anyone built the new Dynaco ST-35 kit?

RE: Has anyone built the new Dynaco ST-35 kit?, posted on July 25, 2015 at 14:28:05
briggs Audiophile Posts: 1674 Location: Connecticut Joined: April 16, 2002	Why? The original was not a good amp. Dynaco, in my opinion, built a few good monoblocks, and some very nice loudspeakers, but the rest of their stuff was mediocre at best and often crap.

Beg to differ, posted on July 25, 2015 at 14:46:58

unclestu
Dealer

Posts: 5851
Joined: April 13, 2010

The St-35 is a workhorse amp. Our local Mac repair center used one for decades as a bench amp. Not only that, but the EL-84 based amps boasted the sweetest sound from any Dyna product. Many, and not limited to myself, consider the small Dyna iron to be their best ever output transformer.

Of course, Dyna built their products to a price point and employed inexpensive parts. Still the basic platform was decent, if not first class. Perhaps the prevalence of the numbers they churned out makes many believe that they were not very good (ST-70's production numbers are close to half a million). The fact that the majority were sold as kits also makes their construction very dependent on the kit builder, too. That can make a noticeable difference in sound and performance.

Still I would not look down at Dyna gear especially after restoring and modifying many.

Dynaco ST-35 was undoubtedly their best stereo amp effort..., posted on July 25, 2015 at 16:01:53

Interstage Tranny
Audiophile

Posts: 3063
Location: Eastern
Joined: October 4, 2006

Yes ! The original stereo amp ran hot and cracked the phenolic boards in time. Yet, nobody I know has ever heard of a blown PA-774 power tranny. Using a good Stereo 35 with vintage Euro or UK EL84s and 7247s will be a rewarding sonic experience.

Upgrading the boards to teflon, rebuilding the power supply sensibly, replacing the few caps sensibly, plus separating the cathode bias arrangement for each channel if quads of EL84s are unavailable could be what the doctor ordered...Stereo 35 is one fine stereo amp.

I have not seen a "new" version, but I can envision one with two power trannies, a la dual mono, plus a bit more conservative operating voltages for the outputs; but the Z565 output iron is hard to beat...

RE: Beg to differ, posted on July 25, 2015 at 16:03:48

Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000

Yes, the Z565 O/P transformer (OEM or "clone") is a price/performance champion. That "iron" also works very well in non-Dyna designs, including the "El Cheapo" I'm associated with.

The single RC bias network for all 4 O/P tubes is "Cheap Charlie", but is easily corrected. A pair of inexpensive, low noise, UF4007 diodes in the PSU is the another (IMO) obvious tweak.

The Dyna ST-35 is quite decent. Yes, there are better 6BQ5/EL84 amps available, for a price. TANSTAAFL!

Eli D.

Dyna ST-35 Schematic

RE: Dynaco ST-35 was undoubtedly their best stereo amp effort..., posted on July 25, 2015 at 16:16:21

Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000

IT,

You don't have get conservative with the B+ rail voltage, if you use Russian 6Π14Π-EB (6p14p-ev), AKA EL84M, O/P tubes. The Russian bottle is a VERY tough 7189 equivalent whose sonics are good. "Monkey" with the small signal triodes to get the desired voicing, perhaps P2P wiring and a 12AX7 and a 6CG7 shared between the 2 channels.

You might want to contact "inmate" Jeff Yourison about the vacuum rectified (2X 6CA4/EZ81) "El Cheapo" he built around the ST-35 "iron" package. NICE!

Eli D.

RE: Has anyone built the new Dynaco ST-35 kit?, posted on July 25, 2015 at 19:28:26
hahax@verizon.net Audiophile Posts: 4310 Location: New Jersey Joined: March 22, 2006	In general all the Dynaco tube amps, including the Stereo 70 were considered very good amps in their day, just a smidgen behind the Marantz and McIntosh amps which were considered the super amps of the day. And, of course, the Dynacos were the winner of the performance per dollar events.

RE: Has anyone built the new Dynaco ST-35 kit?, posted on July 26, 2015 at 04:19:59

TimeConstant

I purchased one of the last remaining ST-35 Clone Chassis on Ebay in 2010. The fellah who used to sell them also provided them to Triode Electronics. But they are no longer available.

Apart from mistakes on the Silk Screening, the concept of making a ST35 Chassis in the likes of the ST-70 form factor makes the layout look good from an aesthetic point of view.

In my clone I upped the Power Supply capacitance to 200uF/C-354 Choke/200uF.

The amp I made also uses a Dynakit Cathode Bias PC Board so I can adjust each EL84 individually.

The Output and Power Transformers I use were sourced from Dynakit. The C354 Choke from Ebay and the PC boards (of which I have 9 sets in stock to make more of these amps) were puchased un-stuffed from a Chinese fellah at my behest. Having had the experience of using the light brown PC boards one finds for sale, these are brittle and the PC traces lift easily when we get the urge to swap caps, I have the Green Epoxy Boards, heavier duty.

The ST35 Clone I made works super well, and I do plan to have the Chassis reproduced locally, powder coated to create a run of these amps for future use as kits to be made of built and made to order with whatever parts one can muster.

Here's a photo of the resulting amp, I am playing it now enjoying a morning session of Diana Krall and Vangelis.

No, but..., posted on July 26, 2015 at 06:56:17

Vinyl Valet
Audiophile

Posts: 1346
Location: Tempe, Arizona
Joined: November 13, 2003

IMHO, for $130 more, the tubes 4 hifi ST70 kit would be a much better choice.
Open up your mind, in pours the trash. - Meat Puppets, 1987

ST70, ST120 & M125 Kits

Heath UA2, posted on July 26, 2015 at 07:43:33

briggs
Audiophile

Posts: 1674
Location: Connecticut
Joined: April 16, 2002

I won't get into the sweet sound debate, which is subjective, but the Heathkit UA2 monoblock was a very fine EL84 amp, more conservatively designed and operated, did not have the problems that the ST-35 had, and did not require extensive redesign/rebuild. I known that Dave O'Brien, who conducted the McIntosh clinics, had a high opinion of the UA1 and 2, and had a chart of it in his book as an example of an excellent competitor's amp.

I don't recall doing it back in the day -- probably because I wasn't much impressed with the ST-35 -- but I would be confident putting a pair of stock UA2s up against whatever has been done with the ST-35.

More, posted on July 26, 2015 at 07:58:27

briggs
Audiophile

Posts: 1674
Location: Connecticut
Joined: April 16, 2002

If you run tubes as hot as Dyna did with the ST-35, the circuit boards of that time were a poor choice, as experience with the SC-35 has shown. I think that was the main reason for my indifference to the Dyna at the time. However good it may have sounded, it was not going to be reliable. When you sell the things, that is important.

During my time in the business, when it came to kits, I spoke well of Heath basic amps, confidently sold EICO kit amps, integrated amps, tuners and preamps, and sold the occasional Dyna to those who insisted on it. My own gear was Mac.

RE: Has anyone built the new Dynaco ST-35 kit?, posted on July 26, 2015 at 09:17:12

SETdude
Audiophile

Posts: 3944
Joined: January 20, 2000

No, but I remember the original from my U.S. Navy days. Nice sounding little amp. If I were getting a 6BQ5 amp today I'd be looking hard at Bob Carver's Black Magic.

Black Magic review

RE: Heath UA2, posted on July 26, 2015 at 10:56:39
unclestu Dealer Posts: 5851 Joined: April 13, 2010	The Dyna SCA-35 had a lot of issues with heat. The ST-35 was a different animal. Same outputs but with a 7247 input, whereas the SCA 35 had a 7199.

Heath UA2 were fine monoblocks...might be even better with Dyna opt iron..., posted on July 26, 2015 at 11:14:05
Interstage Tranny Audiophile Posts: 3063 Location: Eastern Joined: October 4, 2006	Yes ! UA-1 and UA-2 were fine performers...very favorable reports noted through the years. Original Quad ESL owners loved the UA amps. I imagine a Dyna ST-35 built with twin power trannies, as in dual mono, with more conservative B+ HV operating points (i.e. choke input filters), independent bias for each channel, plus beefy power supply cap banks could be even more favorable...

Perhaps, but the ST-35 wasn't built that way. nt, posted on July 26, 2015 at 11:55:11
briggs Audiophile Posts: 1674 Location: Connecticut Joined: April 16, 2002	nt

My Turn to Beg to Differ, posted on July 26, 2015 at 12:04:41

briggs
Audiophile

Posts: 1674
Location: Connecticut
Joined: April 16, 2002

The ST-35 ran hot, baked, cracked and warped circuit boards and burned up output tubes. There are several accounts to that effect right here.

The arguments seem to be that, if you do A, B, C and/or D, the ST-35 can be a good amp. My point is that Dynaco did not do that and the amp, as designed and built, had serious problems. If you were selling stereo equipment responsibly you would not have recommended it, and I didn't.

RE: Beg to Differ, posted on July 26, 2015 at 13:03:30
unclestu Dealer Posts: 5851 Joined: April 13, 2010	Worked on several St-35's. two were bench amps for a repair shop and on all day 6 days a week: No burned boards.....

RE: Beg to Differ, posted on July 26, 2015 at 13:22:18
briggs Audiophile Posts: 1674 Location: Connecticut Joined: April 16, 2002	You're not differing. I said cracked and warped, not burned, circuit boards, and there is other testimony to that right here. I said burned with reference to the output tubes. Our bench amp was an MC225. No problems there.

Your Dynaco ST-35 is BEAUTIFUL ! Great Job !, posted on July 26, 2015 at 13:54:45

Interstage Tranny
Audiophile

Posts: 3063
Location: Eastern
Joined: October 4, 2006

Have you considered building a dual mono amp with independent power trannies and power supplies ? The benefits of separate power supplies cannot be understated.

While a "stereo" power supply is adequate, if you use a stereo preamp and switched to dual mono preamps(separate power supplies), you will hear a difference with a stereo amp. Likewise, even if you use a stereo preamp with dual mono amps, you will definitely hear a beneficial difference. The dynamics, soundstage separation, height, width and depth will all benefit from any dual mono application. Even if you separate the cap storage banks in the power supplies for each channel, more details will be heard. After trying that, I am sure you would want to try independent power trannies...

Speaking of not being able to be understated, your amp's build quality is outstandingly nice !

Why would it be a better choice? (nt), posted on July 26, 2015 at 20:30:57
1973shovel Audiophile Posts: 10117 Location: Greenville SC Joined: February 25, 2007

RE: Your Dynaco ST-35 is BEAUTIFUL ! Great Job !, posted on July 27, 2015 at 04:09:12

TimeConstant

Thanks for the compliments on the Dynaco ST35! The beauty comes from the chassis and these are no longer available, I got the very last one from the fellah who had them built and powder coated.

Yes... I have built quite a few DIY amps, you can check them out on my web page www.shermanaudio.com

You are enticing me to build a set of Mono-Preamps.... (hint, hint).

This has always been in my plans, to have separate Preamplifiers to pair with the few Mono-Blocks I have made so the Power Supplies are totally separated.

I have always had a fondness for the Scott LC-21 and may just use this as the basis for a killer pair of Mono Preamps.

RE: Why would it be a better choice? (nt), posted on July 28, 2015 at 03:11:26
SETdude Audiophile Posts: 3944 Joined: January 20, 2000	The OP has a Sherwood 6BQ5 amp.

Yes, I'm aware of that, posted on July 28, 2015 at 12:46:05
1973shovel Audiophile Posts: 10117 Location: Greenville SC Joined: February 25, 2007	And airtime posted a question expressing his interest in another 6BQ5 amp, the ST-35. Your interpretation seems to be that Vinyl Valet thinks airtime should go with something different for variety's sake. My interpretation is that he feels the VTA ST-70 (which I own) is a "much better choice" for other reasons.

Black Magic not listed on Carver's website, posted on July 30, 2015 at 12:39:29
M3 lover Audiophile Posts: 6604 Location: SW Mich Joined: May 29, 2005 Contributor Since: July 4, 2007	But maybe the review includes all the important information? Still, you'd think it would be included there before any review was written. "The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

RE: Black Magic not listed on Carver's website, posted on July 31, 2015 at 13:25:36

rmyauck
Audiophile

Posts: 230
Location: Northern Manitoba
Joined: August 23, 2009

Dave Gillespie is an engineer whom posts on diyaudio and AK , and has come up with an ingenious Bias mod that is very low cost and greatly helps the tube life issue and as a bonus helps the sonics also. He also adapted this for non UL amps like Fisher's and more info in that is found on the Fisher forum in AK.

http://www.tronola.com/html/dave_s_lab.html

RE: Has anyone built the new Dynaco ST-35 kit?, posted on July 31, 2015 at 20:53:23
goldenthal Audiophile Posts: 1001 Location: Ontario Joined: March 28, 2003	Just as I recall Gordon writing in the '60s -- O, Nostalgia! Jeremy

Vintage Asylum

Has anyone built the new Dynaco ST-35 kit?

69.142.61.247