The IRC GS-3 resistors ARE rated for 1kV, they are affordable, readily available and sound excellent!
IRC datasheet
Handmade Electronics IRC resistors
Stuart
IRC datasheet
Handmade Electronics IRC resistors
Stuart
Hmm...I'm not sure where how I got turned on to the 1kV rating, but the 2kV peak comes from the datasheet. 750V is the maximum continuous based on a standard, but I seem to recall it was overly conservative. Sadly I can't remember where I got that. There is a chart on page "113" of the spec sheet that shows the peak handling.
There were some posts about not changing R48 & R49. My intention is to use 500v on the "335v" line and a regulated Power-One 150v supply for the screens and a small 1.75' x 1.75" regulated supply for the bias. What other choices do I have for getting the plates of the 6CB6's at the right voltage or is there a better tube to use in place of the 6CB6's? My outputs will be 6LF6's.
Thanks everyone,
Ray
Thanks everyone,
Ray
Really you dont need that much more input signal. Most that are doing the monster watts are using a much lower output transformer. So while stock is 8k, with the big sweep tubes people are using 3.3k. Im using 6.6k and 600v for what i hope is 75 watts, with 100 watt edcore transformers.
You should not need 2vrms to push this thing to full output unless you are using 8-10k for the output.
You should not need 2vrms to push this thing to full output unless you are using 8-10k for the output.
How are you going to run the board at 500v with all the electrolytics on board? I havent seen anyone change R48/R49 yet (other then tubelab during his blow up everything by running the whole thing at 600v science experiment), and thats with running the red board well under and well over voltage.
The best bet still is: run the board at 300v, and run a booster of 200v just to the output transformer. This gives you your 500v, and very little mods to the red board, but you have to make an external power supply for the 200v booster. You might even be able to get away with omiting R48/R49 and using 2 identical 250v supplies.
The best bet still is: run the board at 300v, and run a booster of 200v just to the output transformer. This gives you your 500v, and very little mods to the red board, but you have to make an external power supply for the 200v booster. You might even be able to get away with omiting R48/R49 and using 2 identical 250v supplies.
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So I have been working on a few items with this amp. I was determining the phase of the filament wires and I noted that one of my transformers has a slight hum. I had the board totally disconnected at the time. I hadn't noticed it before probably due to me having the volume knob at 11. I may have to try out one of the other transformers I have and see if I can find a quiet one. Has anyone else noticed this with their 10lbers? I may try tightening up the bolts and make sure that wasn't the issue.
I have been out of town for 3 weeks, and then working late every night to prepare for a "justify the project" presentation tomorrow. The tubes have been dark...and lonely.
I ordered some vinyl, a new phono cartridge and some CD's from Amazon before I left West Virginia. The CD's were on one order and the cartridge and vinyl were ordered 3 days later. The CD's and the cartridge arrived Thursday in the same box. They haven't even shipped the vinyl yet!
I had some questions to answer about the hum level from a SSE, so I dragged out my 6 year old amp that hasn't seen power in almost a year and plugged it in. Still works great. Played 3 CD's at the edge of clipping. Hum, 1.6 mV across the speaker wires.
Today I fired up the 6HJ5 red board amp for the first time in almost two months. 15 inch woofers can stir up a bit of dust at full boogey with 125 watts. I have been building my speakers and amp chassis in a night woodworking class. I was informed that this summer session is the end of 5 years of woodworking classes. The evening classes are being closed due to budget constraints. The red board amp is now the next project to be completed. It stalled when I figured out how much real estate was required on the deck for 4 transformers, 2 BFC's and the area designated for the PC board. The amp is going to be heavy and I am using smallish OPT's.
To mittigate this I have decided that I will not use the 600uF BFC's in this amp, I will find something that I can fit under the deck in parallel with the electrolytics that I am using now. I decided to try using an Antek 2T230 for the boost transformer. It can go under the deck. I wired a 2T230 into my amp and cranked it for a few minutes. It is back in the lab and I don't want to blow my little speakers. I am putting it back in the living room so I can crank it hard for a few days to see if the Antek gets hot.
Now that I have one amp headed toward completion, and a completed untested board on the shelf, my original board is going to be used for some "out there" experiments. I didn't want to risk it when it was the only one I had. It gets hooked back up to all the adjustable power supplies and the quest begins. Quest...for what? To boldly go where no man has gone before.....
I got over a hundred tubes at the Dayton hamfest, all cheap....It's safe to assume, that something is going to go boom.....
I ordered some vinyl, a new phono cartridge and some CD's from Amazon before I left West Virginia. The CD's were on one order and the cartridge and vinyl were ordered 3 days later. The CD's and the cartridge arrived Thursday in the same box. They haven't even shipped the vinyl yet!
I had some questions to answer about the hum level from a SSE, so I dragged out my 6 year old amp that hasn't seen power in almost a year and plugged it in. Still works great. Played 3 CD's at the edge of clipping. Hum, 1.6 mV across the speaker wires.
Today I fired up the 6HJ5 red board amp for the first time in almost two months. 15 inch woofers can stir up a bit of dust at full boogey with 125 watts. I have been building my speakers and amp chassis in a night woodworking class. I was informed that this summer session is the end of 5 years of woodworking classes. The evening classes are being closed due to budget constraints. The red board amp is now the next project to be completed. It stalled when I figured out how much real estate was required on the deck for 4 transformers, 2 BFC's and the area designated for the PC board. The amp is going to be heavy and I am using smallish OPT's.
To mittigate this I have decided that I will not use the 600uF BFC's in this amp, I will find something that I can fit under the deck in parallel with the electrolytics that I am using now. I decided to try using an Antek 2T230 for the boost transformer. It can go under the deck. I wired a 2T230 into my amp and cranked it for a few minutes. It is back in the lab and I don't want to blow my little speakers. I am putting it back in the living room so I can crank it hard for a few days to see if the Antek gets hot.
Now that I have one amp headed toward completion, and a completed untested board on the shelf, my original board is going to be used for some "out there" experiments. I didn't want to risk it when it was the only one I had. It gets hooked back up to all the adjustable power supplies and the quest begins. Quest...for what? To boldly go where no man has gone before.....
I got over a hundred tubes at the Dayton hamfest, all cheap....It's safe to assume, that something is going to go boom.....
I think we need to start calling you CAPTAIN tubelab!
Let me know if I can do anything to help. Short of paying for your fire insurance, that is
Pete
"Captain the dilithium crystals are overheating"!
"Warp factor 11 Mr. Sulu."
"This one doesn't go to 11," oops wrong movie.
Cool idea, but I don't speak Photoshop. If someone makes it I'll put it on my web site, no money though Tubelab is wearing red ink this year.
They exist and are fairly common, but the really rare item is a picture with a shirt and tie, or even a jacket. I only have about 5. These usually involved a wedding or a funeral though. To prove it, I found these on my portable hard drive. Two weddings and a random old picture.
She just can't take much more of this....The plates are buckling.
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