The output tubes are fixed-bias. The 10 ohm resistors are more than likely there to create a small voltage drop for measuring cathode current.
Last post was 4/28, who's built this?
A friend and I, 1400 miles apart, are each planning to build this over the next few months. 922 posts and not one amplifier in service?
A friend and I, 1400 miles apart, are each planning to build this over the next few months. 922 posts and not one amplifier in service?
The amp should work wonderfully. A lot of thought and effort went into it. I built a slightly different version and it is in use daily. I hope somebody builds this.
Be the first, Bill!
I still plan to build this, but life got seriously in the way. Haven't hardly touched amps lately.
..Todd
I still plan to build this, but life got seriously in the way. Haven't hardly touched amps lately.
..Todd
Steve and I each ordered the Edcor power transformers today. It'll be a project of some months, so stay tuned.
Well, one will be on the East Coast and one on the West, I'm sure you're welcome for an audition in either location!
Standing by.....
Yes! Finally! Can't wait to see how they turn out.
I'm presently distracted by a motorcycle, but my plan is to build a mosfet 5-20 triode mutation of Sgregory's Opus when I find some time.
Yes! Finally! Can't wait to see how they turn out.
I'm presently distracted by a motorcycle, but my plan is to build a mosfet 5-20 triode mutation of Sgregory's Opus when I find some time.
Aw gee, now I'm getting all enthused about building this again, just when car insurance and hockey registration are due. Damn, I'll never have the money to order those stupid output transformers. Time to dig out the BOM and see what else I need -- that I can afford.
..Todd
..Todd
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My decision was go sacrifice a tiny bit of power and go with the 5k, 100w Hammond 1650R for the output (I already have them on hand). So as soon as the PT arrives from Edcor and I can repaint the blue off it, we'll be ready to drill chassis!
If time and opportunity permits, would like to do a comparison of the amps so will have to go east or west. Wouldn't mind heading west to my old stomping grounds of McMinnville ;-)
Well, you're more than welcome to audition. I'm in Portland, not too far from McMinnville, in fact I was there this weekend to see the air museum where the Spruce Goose is housed. What an AMAZING airplane. Hard to tell from the pictures, but just unbelivable when you're standing under it gazing up at the tail - has to be several stories high.
That would be an impressive site to see. It was housed in a hanger when I lived there but was not open to the public yet.
Oh, I guess you weren't referring to your Avatar. Still, that hairline is pretty high!😀
With Steves help I spent the day loading the credit card with parts from Mouser, Digikey and Parts Connexion. With the Edcors already on order, All I need is the fundage for the Hammond 1650R OPTs and it's Game On!
Any updates? This looks to be a great project. Any changes to the schematic? Inquirying minds want to know?
As it happens, yes a fun update: Notice today from Edcor that the power transformers are on their way! I think that pretty much completes all necessary parts so it is now time to start laying out the chassis for machining. Over the last few weeks, having had lots of think time on the design, I keep having this nagging idea that, without too much work, this could be adapted for a pair of 300Bs on the output instead of KT88's, but I'm trying to resist that thought.... KT88's it is.
I have had similar thoughts as I have several 300b's laying around. I think will be a winter project on a different thread. The kt88's don't let down in this application though. I predict you will like them and the overall end result.
While I was at the sawmill this morning, picking out the cherry for the amps chassis', I missed Fedex with the Edcors power transformers.
Not 5 minutes after I returned from my Mt Bike ride just now, here's UPS with the Gold Lion KT-88s, M Cap ZN coupling caps and the few remaining PRP resistors. BTW, Parts Connexion is an absolutely first-rate supplier in terms of customer service. When I didn't respond immediately to their e-mail asking for confirmation of my shipping choice, they called me on the phone so the parts would get out quickly. From Canada. Amazing!
Tracking tells me the Hammond 1650Rs will arrive Friday and the parts procurement phase will be over 🙂
If lovely parts make a great-sounding amp (they don't), the Gold Lions will be amazing. They're not just pretty; the quality of the physical construction is really impressive.
I've made up my mind to make a simpler cherry wood box than in the past, black anodize the top plate and use VT4C's silver towers to keep the tubes from 3 year old fingers.
Hope to be done in time to make the first play the Thanksgiving Classic "Alice's Restaurant"
Not 5 minutes after I returned from my Mt Bike ride just now, here's UPS with the Gold Lion KT-88s, M Cap ZN coupling caps and the few remaining PRP resistors. BTW, Parts Connexion is an absolutely first-rate supplier in terms of customer service. When I didn't respond immediately to their e-mail asking for confirmation of my shipping choice, they called me on the phone so the parts would get out quickly. From Canada. Amazing!
Tracking tells me the Hammond 1650Rs will arrive Friday and the parts procurement phase will be over 🙂
If lovely parts make a great-sounding amp (they don't), the Gold Lions will be amazing. They're not just pretty; the quality of the physical construction is really impressive.
I've made up my mind to make a simpler cherry wood box than in the past, black anodize the top plate and use VT4C's silver towers to keep the tubes from 3 year old fingers.
Hope to be done in time to make the first play the Thanksgiving Classic "Alice's Restaurant"
Well I was going to get gold lions but kept having this nagging feeling I had kt88's stashed someplace. Sure enough I bit of digging and found an unused quad of "winged c" ... Life is sometimes kind.
I had that thought about 10 years ago, maybe more. The result was called the 300Beast. It was a push pull 300B amp that made about 25 to 30 watts and was one of my favorite amps. It was made with junk quality parts but defied common sense with excelent sound. A few years ago it blew up with the smell of electrolytic cap stink. One of the photoflash caps in the power supply shorted frying the diodes. It has been awaiting a rebuild for a while now. I have been experimenting with different driver circuits and different output tubes too. The 307A is another good choice. Triode wired they sound like a 300B, or pentoded with Schade feedback, they rock. UL, just doesn't seem to work well though.