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Old 22nd January 2012, 12:31 AM   #1
ElCid79 is offline ElCid79  United States
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Default Dynakit ST-35?

what are y'all opinions of these?
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Old 22nd January 2012, 01:39 AM   #2
rhing is offline rhing  United States
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I love my refurbished original Dynakit Stereo 35. I picked up mine locally through Craigslist, and it looked like a rust bucket. After extensive refinishing work and rebuilding it using new blank boards and a new can cap from Kevin at Dynakitparts.com, I was really impressed with the results.

Dynaco Stereo 35 2.JPG

Dynaco Stereo 35 9.JPG

Dynaco Stereo 35 13.JPG

Dynaco Stereo 35 15.JPG

Dynaco Stereo 35 17.JPG

Next I installed a CL-90 inrush limiter and implemented Dave Gillespie's Enhanced Fixed Bias modification and installed a matched quartet of Russian 6P14P-EV power tubes. This amplifier is operating at a whole new level now.

Dynaco Stereo 35 EFB 9.jpg

I've had audio gatherings at my home and my DIY buddies and golden eared friends were very impressed with how this amp drives my upgraded Klisch Forte II speakers. At another gathering, this amp outperformed 300B Direct Drive Reactance SET monoblocks driving Klipsch Chorus I speakers. My friends and I have paired this amp with Altec Model 19's and Quad ESL-57's and it just sounds great with these speakers.

I have a refurbished/modified Magnavox 9304 6BQ5/EL84 push-pull console power amp with original Mullard 6BQ5 tubes, and I love this amp with it's highly musical sound, but the EFB-modified Dynakit Stereo 35 trumps that amp too.

Keep in mind that my amp has the original Dynaco iron with cloth-covered leads. I have compared it to a diyTube ST-35 using Dynaclone transformers, and the Dynakit Stereo 35 sounded noticeably better.

If I were to build a Dynakit Stereo 35 clone, I would get the Stereo 35 kit from Kevin at Dynakitparts.com without the output transformers and scavenge original Dynaco Z-565 OPT's from a Dynaco SCA-35 or buy new Magnequest MQ-565 OPT's since Mike LeFevre manufactures the MQ-565's to the original Dynaco specifications and plans.
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Old 22nd January 2012, 01:45 AM   #3
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check out diytube.com. Shannon has st-35 boards if you want to build it from scratch & the forum provides excellent support.
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Old 22nd January 2012, 01:56 AM   #4
rhing is offline rhing  United States
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I understand that Shannon Parks of diyTube is working on a new ST-35 board that will incorporate Dave Gillespie's EFB circuit. This will be a tremendous enhancement to the amp's performance. Using either the original Dynaco Z-565 OPT's or Magnequest MQ-565 OPT's made to Dynaco's original plans will bring the most out of this circuit with EFB.
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Old 22nd January 2012, 10:20 PM   #5
rmyauck is offline rmyauck  Canada
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Default Re: OPT

Rich,

Maybe the best way to tell if the old OPT trans are better is to swap the Dynaclone ones between them. Tube and component differences might make up diff too. Biasing is totally different and feedback might be different do to the different outputs 8 and 16 ohms on old and Dynaclone are 4 and 8. Are you using the same output tap in tests? I'm just wondering as the new ones are reverse engineered and wound just like the vintage ones. Only difference is the output taps. Mike's clones are not changed that way.

I was wondering if the old ones were better myself but couldn't find any evidence of that on the net or through all the threads on the diytube.com form. Triode does post a freq. response/distortion test in comparison on their site, showing them to be just as good. They don't make any comments on sound quality, but the extensive tests seem to show they should be just as good. The Magnequest came out just as good too. The only not liked ones seemed to be the handmade brand which went out of business yrs. ago.

Too bad you didn't live close to me as I last Nov. picked up a nice used pair of the mentioned Magnequest Z-565 without the Ni lams. Nice to have them in a swap for a listening test too! I read somewhere Jack of Electraprint makes a similar clone too.

Thanks,

Randy

Last edited by rmyauck; 22nd January 2012 at 10:29 PM.
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Old 23rd January 2012, 02:51 AM   #6
ArtG is offline ArtG  United States
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Rhing,
Nice cleanup job on the ST-35 and clever EFB circuit mounting!
What are the three bronze heatsinks(?) on the chassis support?
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Old 24th January 2012, 02:26 AM   #7
rhing is offline rhing  United States
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Quote:
Originally Posted by rmyauck View Post
Rich,

Maybe the best way to tell if the old OPT trans are better is to swap the Dynaclone ones between them. Tube and component differences might make up diff too. Biasing is totally different and feedback might be different do to the different outputs 8 and 16 ohms on old and Dynaclone are 4 and 8. Are you using the same output tap in tests? I'm just wondering as the new ones are reverse engineered and wound just like the vintage ones. Only difference is the output taps. Mike's clones are not changed that way.

I was wondering if the old ones were better myself but couldn't find any evidence of that on the net or through all the threads on the diytube.com form. Triode does post a freq. response/distortion test in comparison on their site, showing them to be just as good. They don't make any comments on sound quality, but the extensive tests seem to show they should be just as good. The Magnequest came out just as good too. The only not liked ones seemed to be the handmade brand which went out of business yrs. ago.

Too bad you didn't live close to me as I last Nov. picked up a nice used pair of the mentioned Magnequest Z-565 without the Ni lams. Nice to have them in a swap for a listening test too! I read somewhere Jack of Electraprint makes a similar clone too.

Thanks,

Randy
Hi Randy,

We used the 8 ohm taps with both amps since my Forte II's are nominally rated at 8 ohms. I am thinking of building a diyTube ST-35 once Shannon comes out with his next revision with the EFB circuit and use a set of oiriginal Dynaco transformers.

Give those MQ-565 OPT's a try; I am sure you'll like them.

Quote:
Originally Posted by ArtG View Post
Rhing,
Nice cleanup job on the ST-35 and clever EFB circuit mounting!
What are the three bronze heatsinks(?) on the chassis support?
ArtG,

Thanks. Those heatsinks are actually 1/2" square finned Copper heatsinks used for computer motherboard ICs. I mounted them on the Aluminum angle bracket opposite of the LM337 regulator that is part of the EFB circuit. This keeps the regulator from overheating since the internal space within the Stereo 35 chassis is so limited. For the angle bracket, I fabricated it from 1/2" x 3/4" Aluminum angle stock from Home Depot and drilled out the opening for the right channel OPT leads and mounting holes for the EFB circuit board.
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Old 31st January 2012, 01:14 PM   #8
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I am assuming from your other thread that you mean the dynakitparts new kit. I built one. Very straightforward. I posted in your st70 thread. If you can follow directions you can successfully complete this kit, and end up with a very nice sounding amp. Note that this does not have a volume control option from the mfr., something you mentioned in your st70 thread. I added the cage because the location of my equipment would allow guests to get burned or shocked.
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Old 31st January 2012, 01:36 PM   #9
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Nice job rhing!!!
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