I think the new PCB will sell for $25 each. I should have them available in a month or so.
I hope to have 815 amps using this board at LSAF. I'll be there unless something comes up that prevents me from going.
Pete
I'm just curious.. Is it one 815 per channel, so PP w/ one tube, or are the sections paralleled?
Set those next to an android phone, and they'll sell out in no time
I'm just curious.. Is it one 815 per channel, so PP w/ one tube, or are the sections paralleled?
Set those next to an android phone, and they'll sell out in no time
Yup, 1x 6AC10 and 1x 815 = 50W in AB2 push-pull.
With a little silicon (MOSFET followers to drive the grids).
Pete
I'm loading it with 4.3k.
BTW, the 815 is exactly the same as a pair of 2E26 tubes. Mediocre performers, unless you go to positive grid voltage...
Pete
I did some preliminary experiments with this board. I have noted the following:
The tube socket must be installed on the side of the board without silkscreen. I screwed the first one up.
The components can be installed on either side.
There is a previously mentioned missing resistor from pin 9 of the tube to ground.
The positive ends of C2 and C8 are not grounded as shown in the schematic. They are left floating (isolated). This is visible in the board picture in post #1.
The electrolytic capacitors are sized much too big for any common 10 uF 450 volt part. They are just right for the 47 uF 450 volt caps that were all over the surplus market last year. I have some 100 uF 450 volt Panasonics that fit too.
I have not applied power yet so there may be more issues. I am not building exactly by the schematic either.....I need positive bias on the outputs for screen drive experiments.
The tube socket must be installed on the side of the board without silkscreen. I screwed the first one up.
The components can be installed on either side.
There is a previously mentioned missing resistor from pin 9 of the tube to ground.
The positive ends of C2 and C8 are not grounded as shown in the schematic. They are left floating (isolated). This is visible in the board picture in post #1.
The electrolytic capacitors are sized much too big for any common 10 uF 450 volt part. They are just right for the 47 uF 450 volt caps that were all over the surplus market last year. I have some 100 uF 450 volt Panasonics that fit too.
I have not applied power yet so there may be more issues. I am not building exactly by the schematic either.....I need positive bias on the outputs for screen drive experiments.
Yes, I looked through my junk box and found 3 well used 6AC10's. I am assuming that at least 1 of them will work. I believe that there is one other tube with the same pinout. 6U10 maybe? I am not sure about the number. It has two identical triodes, and one that's different. Fortunately the identical triodes are in the LTP.
I am just using this as a quick and rather dirty way to melt some 13GB5's
I am just using this as a quick and rather dirty way to melt some 13GB5's
Actually I was experimenting with G1 and G2 drive simultaneously when I let the smoke out of Pete's (now) midsized driver board. I accidentally plugged the B+ cable in backwards causing an instant stink cloud. There are 2 crispy resistors and at least one dead electrolytic. What's amazing is that the board still works, but the distortion went up.
To find tubes with identical pinouts get the RCA RC-30 tube manual. Pete has the PDF on his site. Look up the 6AC10 to find that it has the 12FE pinout. Then turn to the back of the book, page 603 in my paper book, to find all tubes that have the same pinout. In this case it lists the 6AK10, the 6U10 and the series heater variants. This only works on tubes that RCA sold, which is most of them.
Pete, I'm interested in the details of this one. I'm also planning to build an amp with these cool looking 815 robot tubes. I have plenty of other electronics and HV experience, but this will be my first audio amp, so I could use a "known to work" example to refer to. I was planning on using your other PP driver board with the MOSFET follower board, which I think is similar enough to your 815 amp to use the same power supply design, biasing, OPT... The documentation I found said 8k OPT, but it was assuming RF. I'm not sure what difference RF vs. audio makes.
Garth
I referred to them as two headded aliens. There is also the 7193 with two caps. It is 1/2 of a 6SN7. There is also a small RF tube with two caps (HY6??), and a two headded rectifier. Unfortunately I don't remember the numbers. I was going to build an amp with all two headded tubes, but I lost interest and never finished it. I was using a 6600 ohm OPT because I have several. The breadboard sounded good and made about 20 watts. I don't think I went into AB2, but it was about 10 years ago, I could be wrong.
The rectifier is 1641 or RK-60, basically a 5R4 with ears. RK-32/2C34/DET19, and HY-31Z are dual triodes, and HY615 and HY114B are squat little octal small triodes, all with two caps. HY75 is an interesting power triode with 2 caps and a graphite anode, always wanted to try A2 with it... and it features "low-loss lava insulation"!
http://www.tubecollectors.org/hytron/archives/hytron.pdf
Pete
http://www.tubecollectors.org/hytron/archives/hytron.pdf
Pete
Thanks for the memory jog.......squat little octal small triodes, that is a good explanation.
The little guys I had were the HY615's. I sold them all to a guy making radio transmitters.
The rectifiers were like a 5R4. Some had plate caps and some had pins. I had a bunch of 7193's and 3 or 4 815's.
All were pulls from military spares from WWII through Korea. I have sold or given away all of that stuff.
The little guys I had were the HY615's. I sold them all to a guy making radio transmitters.
The rectifiers were like a 5R4. Some had plate caps and some had pins. I had a bunch of 7193's and 3 or 4 815's.
All were pulls from military spares from WWII through Korea. I have sold or given away all of that stuff.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.