Nice looking amp; I'd keep the current color scheme which I find soothing. I hope you find a second one, or maybe use this one to drive the center channel of your home theater sound system. Can't wait for the next installment!
Probably not a factory wired job. The paint job leads me to believe this unit was kit built by someone in the USAF. The color is Strata Blue 25045. The orange peel paint job looks like ratttle can quality with no surface prep. Saw plenty of that during my time with Uncle Sam. Properly powder coated, this amp could look really good. It would be interesting to see a factory wired job and compare it to the Spaghetti Os you are working on. Looking forward to viewing the rest of this project.
This was a great first look video. I wish videos like this were around when I undertook my very first Tube amp rebuild, a pair of Heathkit W-5Ms. I went through about 4 units before finding 2 working power transformers. The best part was the fuse… I laughed out loud when you showed it on the camera and I impulsively yelled “that’s like 15A” at the screen. I laughed even harder when you confirmed… that’s crazy. I vote for hooking up the 125V tap. I always do that on Mac amps when they have 117 and 125 options.
Thanks, Novalux, glad you got a laugh from that fuse! Now that I’m over my shock, I’m gonna also try to have fun with this mess and see the humor in this project. It’s so perfectly bad it’s almost a shame to repair it. Almost.
Interesting kit versus assembled price back then. When everything was hand wired, a kit did actually save the manufacture money which could be passed directly to the consumer. But when electronics went to PC boards which could be machine stuffed and soldered, selling a kit versus assembled unit was not that much of a savings anymore. Dynaco had a neat idea - supply the PC boards assembled and tested. Then it's just the manual chassis work which was still a manual job either kit or factory wired. That idea even lasted well into the 1980s with Hafler products. McIntosh also sold one of their amps (MC 30?) in kit form in the 60s but abandoned it because of soft sales. See Roger Russell's site. I guess people who could afford McIntosh did't do manual labor!
Thanks, didn’t know about the McIntosh kit, will have to check that out. Kits obviously allowed someone to get a level of quality they might not otherwise be able to afford and sometimes Dynaco is referred to as the the poor man’s McIntosh. There’s gotta be some truth to that. Personally, I’ve always disliked that Dynaco prebuilt their PC boards, but I can absolutely understand why they did so. They were trying to get the difficulty down and success rate up. Heathkits are always more fun and challenging for me as they left their boards unpopulated. There is a company called ANK Audio Kits that still makes audio kits. I built a tube phono preamp of theirs a few years ago that was rewarding and the unit works well. Very pricey stuff, though, and unlike the old days, I think you actually end up paying more for what you get because it is a kit.
Nice challenging project there FC. Obviously, whoever built the amp, knew just enough about electronics to be dangerous. You'll have to go connection by connection while double-checking with the schematic, as a bare minimum, cleaning up a lot of terrible terminations. On the plus side, that amp is worth restoring for the sake of the audio output transformer alone; which the manufacture of is a lost art these days. Actually, whoever painted the amp, did a reasonably good job. Some of the paint jobs I have seen over the years are the type where someone just blasts away with a spray paint can, painting over pots, tube sockets, components, with overspray on the front panel. Those EL34s are a European copy of the 6L6, with slightly higher power and more linear operation. The audio output transformer has the screen taps to degenerate the output stage for more linearity and with all that iron in the audio output transformer, the low end response is likely very nice. I would go with the 125 volt tap on the power transformer primary winding, it would place less stress on the EL34s. My best regards on the project.
Jeff, yeah, those things are great. They’re part of a Fluke accessory kit I purchased a while ago. All the included probes in the kit I find invaluable. I’ve just added the kit to my store for you, so you can find it there now if you check back.
Sorry for the late reply, I’ve been away from the amp the past few days. Yes, that is a rather nice Bugle Boy! Good eyes. It’s Holland-made and I believe from 1957. Probably worth a couple hundred bucks alone if it’s working. The output tubes are more generic, but still quite nice JJs. The rest of the tubes are fairly ordinary examples from EI, RCA and Channel Master.
Judd, those come as part of a kit of leads that Fluke sells. It has all sorts of great probes. You can find them on my Amazon link page of products I recommend: www.amazon.com/shop/fluxcondenservintageaudioelectronics
@@FluxCondenser Thanks for the info! Yes, a bit pricey. I've been an auto tech a lot of my life so i've accumulated a good bit of Fluke accessories. The part of that kit i really need is the long reach probes. Found that p/n: AC283A. Thanks again for your help!
The selenium rectifier is for the bias voltage supply. the GZ34 supplies the power for everything else. The bias supply is a negative voltage, so it's much easier to make it independent from the positive supply.
Yes, thanks, John. And further, any winding from the transformer that supplies DC requires its own rectification. Tube filaments and lamps run fine on AC, so no rectification needed there. It is a strange looking rectifier in this one, though. I’m use to seeing them layered with the fins. This one is encased in a package which made it difficult for me to spot at first. Do you know anything about these, John?
@@FluxCondenser had look at the scematic and I see what is going on. Like John said use in the biasing circuit. Makes sense a Selinum rectifier used as a diode would be used today. Of course that will be the first thing you swap out for a Diode as a smoking selenium is something you would want to avoid. At the time they where much cheaper than early silicone diodes
Utterly horrible original build job and subsequent "rebuild". As someone who does vintage audio repair and restoration myself, I shudder at some of the things I see. Quite a few amps have come my way that looked even worse than this one. When point to point wiring was the main construction method, technicians were taught how to properly install components, dress and trim leads, etc. It's truly a lost art in this day of multi-layer circuit boards and ribbon connectors. And the 15 amp fuse....pretty much par for the course. You lucked out on having an undamaged set of transformers.
Wow, love the fuse. Almost shocked you didn’t find it blown and it wrapped in foil. 😳
I had the pleasure of building many EICO kits-it was fun!
Nice little 'birds nest'. I'm sure you can tidy things up nicely. Seems worth the effort now you know the transformers are viable.
That's the plan, stay tuned!
Very informative and clearly presented. Well done and thanks!
Thanks so much! Glad to hear you enjoyed it.
I’ve got two of these awaiting restoration. Nice presentation!!!
Thanks, and good luck with your restorations!
@@FluxCondenser Just watched part two. I’ll probably do the clean slate deal too!
Excellent. Keep us posted on your progress.
Nice looking amp; I'd keep the current color scheme which I find soothing. I hope you find a second one, or maybe use this one to drive the center channel of your home theater sound system. Can't wait for the next installment!
Thanks, Darth. Glad you’re liking the series so far. I do have something planned for this amp I’ll tell you all about at a later date. Stay tuned!
Probably not a factory wired job. The paint job leads me to believe this unit was kit built by someone in the USAF. The color is Strata Blue 25045. The orange peel paint job looks like ratttle can quality with no surface prep. Saw plenty of that during my time with Uncle Sam. Properly powder coated, this amp could look really good.
It would be interesting to see a factory wired job and compare it to the Spaghetti Os you are working on. Looking forward to viewing the rest of this project.
This was a great first look video. I wish videos like this were around when I undertook my very first Tube amp rebuild, a pair of Heathkit W-5Ms. I went through about 4 units before finding 2 working power transformers. The best part was the fuse… I laughed out loud when you showed it on the camera and I impulsively yelled “that’s like 15A” at the screen. I laughed even harder when you confirmed… that’s crazy. I vote for hooking up the 125V tap. I always do that on Mac amps when they have 117 and 125 options.
Thanks, Novalux, glad you got a laugh from that fuse! Now that I’m over my shock, I’m gonna also try to have fun with this mess and see the humor in this project. It’s so perfectly bad it’s almost a shame to repair it. Almost.
I like the blue, I vote to keep it.
Thanks, John. Glad I’m not the only one who appreciates the blue!
A 12AT7 does not have as much gain as a 12AX7. A 7025 is a low noise version of A 12AX7 used in low level audio preamps.
Thanks for the input. The gain issue was addressed in the video.
06:40 Cue the stab music from Psycho....REDRUM! REDRUM!!
Man, that would have been perfect! You get to edit my next video ;-)
Interesting kit versus assembled price back then. When everything was hand wired, a kit did actually save the manufacture money which could be passed directly to the consumer. But when electronics went to PC boards which could be machine stuffed and soldered, selling a kit versus assembled unit was not that much of a savings anymore. Dynaco had a neat idea - supply the PC boards assembled and tested. Then it's just the manual chassis work which was still a manual job either kit or factory wired. That idea even lasted well into the 1980s with Hafler products. McIntosh also sold one of their amps (MC 30?) in kit form in the 60s but abandoned it because of soft sales. See Roger Russell's site. I guess people who could afford McIntosh did't do manual labor!
Thanks, didn’t know about the McIntosh kit, will have to check that out. Kits obviously allowed someone to get a level of quality they might not otherwise be able to afford and sometimes Dynaco is referred to as the the poor man’s McIntosh. There’s gotta be some truth to that.
Personally, I’ve always disliked that Dynaco prebuilt their PC boards, but I can absolutely understand why they did so. They were trying to get the difficulty down and success rate up. Heathkits are always more fun and challenging for me as they left their boards unpopulated.
There is a company called ANK Audio Kits that still makes audio kits. I built a tube phono preamp of theirs a few years ago that was rewarding and the unit works well. Very pricey stuff, though, and unlike the old days, I think you actually end up paying more for what you get because it is a kit.
@@FluxCondenser If you are not aware of Roger Russell'. McIntosh page, here it is:
www.roger-russell.com/aboutmc.htm
I think you will enjoy it.
Thanks, Andy. Yeah, I’m familiar with his site. Quite a resource.
Nice challenging project there FC. Obviously, whoever built the amp, knew just enough about electronics to be dangerous. You'll have to go connection by connection while double-checking with the schematic, as a bare minimum, cleaning up a lot of terrible terminations.
On the plus side, that amp is worth restoring for the sake of the audio output transformer alone; which the manufacture of is a lost art these days. Actually, whoever painted the amp, did a reasonably good job. Some of the paint jobs I have seen over the years are the type where someone just blasts away with a spray paint can, painting over pots, tube sockets, components, with overspray on the front panel.
Those EL34s are a European copy of the 6L6, with slightly higher power and more linear operation. The audio output transformer has the screen taps to degenerate the output stage for more linearity and with all that iron in the audio output transformer, the low end response is likely very nice.
I would go with the 125 volt tap on the power transformer primary winding, it would place less stress on the EL34s. My best regards on the project.
Thanks for your input, Bill. Much appreciated.
The blue and gold is giving me “major league sports uniform” vibes. But, to each their own.
I just bought this awesome shirt to go with it: share.icloud.com/photos/0-FR2TfydHoRGiHBxXXJE4THw
@@FluxCondenser Ha!
Did this amp ever work?
Ben, at first your comment gave me a chuckle, but then I thought, who knows? Maybe the only thing this amp was ever good for was blowing fuses.
Flux, on your multimeter what are those grabber probes called, and where can I get them? I didn't see them in your Amazon/shop
Jeff, yeah, those things are great. They’re part of a Fluke accessory kit I purchased a while ago. All the included probes in the kit I find invaluable. I’ve just added the kit to my store for you, so you can find it there now if you check back.
Nice Bugle Boy GZ34 tucked away in there Chris. What brand were the output tubes?
Sorry for the late reply, I’ve been away from the amp the past few days. Yes, that is a rather nice Bugle Boy! Good eyes. It’s Holland-made and I believe from 1957. Probably worth a couple hundred bucks alone if it’s working. The output tubes are more generic, but still quite nice JJs. The rest of the tubes are fairly ordinary examples from EI, RCA and Channel Master.
Where did you get those handy long reach clip style multimeter probes? I cannot find them anywhere.... Thanks
Judd, those come as part of a kit of leads that Fluke sells. It has all sorts of great probes. You can find them on my Amazon link page of products I recommend: www.amazon.com/shop/fluxcondenservintageaudioelectronics
@@FluxCondenser Thanks for the info! Yes, a bit pricey. I've been an auto tech a lot of my life so i've accumulated a good bit of Fluke accessories. The part of that kit i really need is the long reach probes. Found that p/n: AC283A. Thanks again for your help!
Odd why would it need a selenium and a valve rectifier? Will have to look up the scematic on that one.
This is very common in tube amps. The classic Dynaco ST70 also has a selenium/tube rectifier design.
The selenium rectifier is for the bias voltage supply. the GZ34 supplies the power for everything else. The bias supply is a negative voltage, so it's much easier to make it independent from the positive supply.
Yes, thanks, John. And further, any winding from the transformer that supplies DC requires its own rectification. Tube filaments and lamps run fine on AC, so no rectification needed there.
It is a strange looking rectifier in this one, though. I’m use to seeing them layered with the fins. This one is encased in a package which made it difficult for me to spot at first. Do you know anything about these, John?
@@FluxCondenser had look at the scematic and I see what is going on. Like John said use in the biasing circuit. Makes sense a Selinum rectifier used as a diode would be used today. Of course that will be the first thing you swap out for a Diode as a smoking selenium is something you would want to avoid. At the time they where much cheaper than early silicone diodes
Agreed. I don’t mess with seleniums. They always get replaced in my projects.
Utterly horrible original build job and subsequent "rebuild". As someone who does vintage audio repair and restoration myself, I shudder at some of the things I see. Quite a few amps have come my way that looked even worse than this one. When point to point wiring was the main construction method, technicians were taught how to properly install components, dress and trim leads, etc. It's truly a lost art in this day of multi-layer circuit boards and ribbon connectors. And the 15 amp fuse....pretty much par for the course. You lucked out on having an undamaged set of transformers.
Couldn’t agree more, John. Worse than this one? You gotta put a video up showing snapshots of that!
Pick me!
I love your videos, and I'm learning a lot, but goodness gracious the gratuitous dancing around of your hands is incredibly distracting and annoying.
Ha! Well I guess you haven’t spent much time with Italians! It’s a thing with us.