MATT0404 Posted July 28, 2019 Share Posted July 28, 2019 Thought I'd share this fun project here since I'm using this amp on my Cornwalls. This was my first kit build and I have to say, this is a very well put together kit with quality parts. The build itself took around 10-12 hours in total. I plugged away at it a couple/few hours at a time. The only hiccup was my own fault. I deviated from the manual and installed a CL-80 thermistor on the line in. Problem was that I installed it in the wrong location and the amp blew the fuse when I first turned it on. I removed the thermistor and it fired right up. All voltages checked out and it's been making fine music now for 12+ hours. Really great little amp and it was a lot of fun to build. Here are some pics from the build and a demo video. Kit as it arrived Dynakit ST-35 by Audio Database, on Flickr PCB's stuffed and installed Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr Transformers and can cap installed Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr WIring in process Dynakit ST-35 by Audio Database, on Flickr WIring complete Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr Testing Dynakit ST-35 by Audio Database, on Flickr DONE Dynakit ST-35 by Audio Database, on Flickr Dynakit ST-35 by Audio Database, on Flickr Demo video 5 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted July 28, 2019 Share Posted July 28, 2019 Awesome!!! Still breaking in? 1 Quote Link to comment Share on other sites More sharing options...
DizRotus Posted July 28, 2019 Share Posted July 28, 2019 Thanks for sharing this. It looks great. It warms the heart of this 70 year-old with many Dynakits and Heathkits under his belt. 2 Quote Link to comment Share on other sites More sharing options...
MATT0404 Posted July 28, 2019 Author Share Posted July 28, 2019 Thanks, guys! It's still breaking in, but I've probably got 15 or so hours on it now. Sounding pretty damn good if I don't say so myself. The top end opened up quite a bit after the first few hours. I haven't noticed too much of a change since they. I'll incorporate the Gillespie power supply board and EFB mod at some point in the future, but I wanted to hear it in stock configuration first. Quote Link to comment Share on other sites More sharing options...
Schu Posted July 29, 2019 Share Posted July 29, 2019 What tube selection are you using? Quote Link to comment Share on other sites More sharing options...
Emile Posted July 29, 2019 Share Posted July 29, 2019 Congrats Looks like a great job! Build an ST-70 about a year ago and was pretty pleased with it. Haha; but went back to higher powered SS amps 1 Quote Link to comment Share on other sites More sharing options...
MATT0404 Posted July 29, 2019 Author Share Posted July 29, 2019 23 minutes ago, Schu said: What tube selection are you using? Very closely matched quad of Sovtek el84m's and a pair of NOS RCA 12dw7's. 4 minutes ago, Emile said: Congrats Looks like a great job! Build an ST-70 about a year ago and was pretty pleased with it. Haha; but went back to higher powered SS amps Thanks! 👍 1 Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 29, 2019 Share Posted July 29, 2019 Daves thinking on the subject is bar none... way smarter than me... that said. I would suggest 2 simpler mods you might really like. 1st, bypass C1. Its for DC blocking... you don't need with anything modern. 2nd and more interesting... replacing the 50ohm resister in the PS with a C354 choke will go a long way to reducing the noise floor... likely to improve the bass too. You'd drill 2 holes and mount it up too. I think Dynakitparts even has pictures of this done. The ST35 was called the poor mans Macintosh for good reason. Its sonics are lovely. At 15watts, its likely more than enough power for your Cornwalls. Congrats! 1 Quote Link to comment Share on other sites More sharing options...
kevinmi Posted July 29, 2019 Share Posted July 29, 2019 Very nice build! 1 Quote Link to comment Share on other sites More sharing options...
MATT0404 Posted July 29, 2019 Author Share Posted July 29, 2019 17 hours ago, justinsweber said: Daves thinking on the subject is bar none... way smarter than me... that said. I would suggest 2 simpler mods you might really like. 1st, bypass C1. Its for DC blocking... you don't need with anything modern. 2nd and more interesting... replacing the 50ohm resister in the PS with a C354 choke will go a long way to reducing the noise floor... likely to improve the bass too. You'd drill 2 holes and mount it up too. I think Dynakitparts even has pictures of this done. The ST35 was called the poor mans Macintosh for good reason. Its sonics are lovely. At 15watts, its likely more than enough power for your Cornwalls. Congrats! The kit came with mounting hardware and instructions for the choke, but I needed to order it separately. I'll order it now and report back my findings. I'll also look into bypassing C1. Thanks for the info! Quote Link to comment Share on other sites More sharing options...
avguytx Posted July 30, 2019 Share Posted July 30, 2019 That's a good looking amp build. Great job! I built a VTA ST-70 about 2.5 years ago and it's still running strong and drives my Belle clones with authority and ran my CF-3's great, too. Unlike @Emile, I kept mine. Oh, and I do still have a 60wpc, 125wpc, and 460 wpc amps just in case for other speakers as Belles dont need it. 2 Quote Link to comment Share on other sites More sharing options...
rhing Posted August 2, 2019 Share Posted August 2, 2019 Nice work. I used some Dynakitparts.com components in restoring an original Stereo 35. I went further and purchased Dave Gillespie’s Enhanced Fixed Bias (EFB) circuit board to improve the performance of the amp. The EFB modification reduces distortion, increases headroom and extends power tube life. I highly recommend this modification of an already fine amp. http://tronola.com/html/daves_store.html You will be rewarded with cleaner and smoother mids and highs, and a better defined bass. It sounds like the amp is weightier and more powerful, but still maintains that rich EL84/6BQ5 tone. Quote Link to comment Share on other sites More sharing options...
Blackbird Posted August 2, 2019 Share Posted August 2, 2019 On 7/28/2019 at 9:41 AM, MATT0404 said: Nice system! Who makes the sub? Specs? Quote Link to comment Share on other sites More sharing options...
rhing Posted August 2, 2019 Share Posted August 2, 2019 I would also recommend using the Dueland DCA16GA or DCA12GA Cotton-insulated, Tin-plated Copper wire for speaker wire. It’s not terribly expensive, and you’ll be amazed at how this wire will enhance your listening pleasure. Quote Link to comment Share on other sites More sharing options...
MATT0404 Posted August 2, 2019 Author Share Posted August 2, 2019 10 hours ago, rhing said: Nice work. I used some Dynakitparts.com components in restoring an original Stereo 35. I went further and purchased Dave Gillespie’s Enhanced Fixed Bias (EFB) circuit board to improve the performance of the amp. The EFB modification reduces distortion, increases headroom and extends power tube life. I highly recommend this modification of an already fine amp. http://tronola.com/html/daves_store.html You will be rewarded with cleaner and smoother mids and highs, and a better defined bass. It sounds like the amp is weightier and more powerful, but still maintains that rich EL84/6BQ5 tone. Thanks, I have read up on the EFB mod and would like to incorporate it into this amp at some point. I even went as far as ordering the board/parts, stuffing the board, then, when I realized how big the heatsink was, I noticed I ordered the board for the SCA-35! It won't work with the ST-35 obviously, so I'll have to do the power supply board to incorporate the EFB mod. 9 hours ago, Blackbird said: Nice system! Who makes the sub? Specs? Thanks! The sub is a Power Sound Audio S-1800. Specs: Sealed 22x20x20.5" enclosure USA built, proprietary 18" driver with powerful motor strength and efficiency. Patented digital ICEpower® 725W amplifier with DSP control CNC precision cut cabinets that are finished in our industry exclusive satin black texture 17Hz-200Hz +/-3dB (7Hz-11Hz typical in-room extension) 2 hours ago, rhing said: I would also recommend using the Dueland DCA16GA or DCA12GA Cotton-insulated, Tin-plated Copper wire for speaker wire. It’s not terribly expensive, and you’ll be amazed at how this wire will enhance your listening pleasure. I'll take a look. Thanks! Quote Link to comment Share on other sites More sharing options...
a9050lx Posted August 2, 2019 Share Posted August 2, 2019 On 7/28/2019 at 9:22 PM, Emile said: Congrats Looks like a great job! Build an ST-70 about a year ago and was pretty pleased with it. Haha; but went back to higher powered SS amps How about a low powered class A amp? Try a JLH 1969 10 watt per channel, or one of its variations.It sounds much more powerful than 10 watts and is a wonderful sounding ,simple amplifier. 1 Quote Link to comment Share on other sites More sharing options...
Godataloss Posted September 3, 2019 Share Posted September 3, 2019 Love my Mullard powered ST35. Hate that the RCA's are on the opposite side of the chassis though. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted September 3, 2019 Share Posted September 3, 2019 On 7/28/2019 at 10:29 PM, justinsweber said: Daves thinking on the subject is bar none... way smarter than me... that said. I would suggest 2 simpler mods you might really like. 1st, bypass C1. Its for DC blocking... you don't need with anything modern. 2nd and more interesting... replacing the 50ohm resister in the PS with a C354 choke will go a long way to reducing the noise floor... likely to improve the bass too. You'd drill 2 holes and mount it up too. I think Dynakitparts even has pictures of this done. The ST35 was called the poor mans Macintosh for good reason. Its sonics are lovely. At 15watts, its likely more than enough power for your Cornwalls. Congrats! Just thinking that mods are always a possibility. It's freshly built (awesome, by the way!!), and I guess I would recommend becoming familiar with its in-born sound signature first -- which I'm sure you were also implying. As you indicated above, Justin, "Its sonics are lovely." Always in agreement with using a choke in the PSU, the requirement of course being adequate chassis space. Thanks for sharing this Matt0404! The lighting on the new chrome and transformers is elegant looking; really nice! Quote Link to comment Share on other sites More sharing options...
Marvel Posted September 5, 2019 Share Posted September 5, 2019 On 9/3/2019 at 3:57 PM, erik2A3 said: The lighting on the new chrome and transformers is elegant looking; really nice! It does look beautiful! I was looking at the site and those chassis are polished stainless. Should look great for a long time. How's the Moth rebuild going? I hope you will post some pics of the work. Bruce Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted September 5, 2019 Share Posted September 5, 2019 Hi Bruce, On my bench, on hold until after my back surgery tomorrow. I should be able to start getting into it 'lightly' in a week or so. Happy to share a "Kodak Moment" right now if interested. Being a stereo SET, it's a heavy amp, so can't turn it upside down to work on it until I heal up a bit. Quote Link to comment Share on other sites More sharing options...
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