I recently obtained some output iron from a sansui 100A. Some say it is 6k, but it measures 5k5 plate-to-plate. Not sure what to do with them. It has no UL taps and I'm looking to build something efficient with aprox 40W output and of course good sounding. I am having trouble deciding, but am thinking something along the lines of:
Class AB1 7591 tetrode (like in the reciever which they were pulled from). $80+ on a quad of tubes is a little (lot) pricier that I'm hoping to spend. But it's high screen rating would allow me to keep it in AB1.
Class AB2 807 or 829B tetrode = Both are cheap and plentiful, but with the screen voltage limitation, I'd probably have to run it in AB2 to achive the desired output with this transformer.
Class AB1 6BG6 tetrode = Should be able to obtain output power without going into AB2. Availability seems kind of scarce. The resonably priced ones are typically singles. Most quads that show up are priced high.
Any input or other suggestions?
Class AB1 7591 tetrode (like in the reciever which they were pulled from). $80+ on a quad of tubes is a little (lot) pricier that I'm hoping to spend. But it's high screen rating would allow me to keep it in AB1.
Class AB2 807 or 829B tetrode = Both are cheap and plentiful, but with the screen voltage limitation, I'd probably have to run it in AB2 to achive the desired output with this transformer.
Class AB1 6BG6 tetrode = Should be able to obtain output power without going into AB2. Availability seems kind of scarce. The resonably priced ones are typically singles. Most quads that show up are priced high.
Any input or other suggestions?
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The Soviet surplus 6П3С-Е (6p3s-e) is a "meaty" member of the 6L6 clan. They are good sounding and not especially expensive. Jim McShane has properly culled and matched stock.
Petes magic red board with any cheap sweep tube that will fit the board and 400 to 450 volts of B+. Plenty of power and great sound. I run mine at 600 volts and 3300 ohms for 125 WPC and I have seen 250 WPC on 650 volts and 250 ohms, so ignore the 18 WPC claims.
http://www.diyaudio.com/forums/tube...p-p-power-amp-design.html?highlight=red+board
http://www.diyaudio.com/forums/tube...p-p-power-amp-design.html?highlight=red+board
Thanks for the suggestions.
I was initially considering those. The price is right, but their Vg2 and Vp ratings seem more restrictive than the 807/G-807. Though I know people are using the 6p3s-e's beyond their rating with success.
I was initially considering those. The price is right, but their Vg2 and Vp ratings seem more restrictive than the 807/G-807. Though I know people are using the 6p3s-e's beyond their rating with success.
I'll check it out.
Got any sweep tube suggestions? I'd like to keep it AB1 if possible.
If to use them within ratings they would not sing. But in order to get good sound from them they need such regime that not even electrodes, but the glass bulb would melt down.
See their more complete curves than you see usually, to get better picture:
Attachments
A bit of a half serious suggestion. Triode curves look a lot like 6L6's, some people swear by them as about the best tube they've ever used, and they used to be easy to find for about $10 each. Unfortunately, the price has gone up, and supply is low, though lots of people seem to have a dozen of them sitting around waiting for a project. There was a thread a while back: http://www.diyaudio.com/forums/tubes-valves/68216-where-307a-vt225-amps.html
Right. They don't have optimal regime, because optimal regime for sound quality for them means overheating and death, so compromise is needed between better sound quality and longer life. Or, to use paralleled tubes with lowered G2 voltage, like I did the last time I used them (7 years ago).
At the power level your OPT's support any 12 pin compactron that can be used in the board will work. The board isn't designed for AB2, all power numbers quoted in the thread are in AB1. The thread has almost 1000 posts in it and tube numbers are scattered all through it. I am leaving for the Dayton hamfest (for more tubes of course) in a few minutes so I don't have time to search. I can remember the 6JS6, 6LR6, 6KN6, 6KD6, 6HF5, 6HJ5, and the 6HD5.
A lot of us that are building for 50 to 125 WPC have decided on the 6HJ5 since it can still be found for $5 and it doesn't have a plate cap. A minor circuit change is required for this tube. No board modifications are needed. I have run a couple dozen different tubes through the board and other users have run lots more. All seem to work well. Pete originally recommended the 6JN6, the 6JM6 or the 6GV5 all of these will work well up to 60 WPC. The 6GV5 was on several vendors $1 list until we grabbed them all.
If you are interested in building this board I would advise reading through most of the thread since Pete originally designed it (very conservatively) for 18 WPC. Many of us found different ways to crank it up. All are explained well, but the two transformer method works best for 80 WPC and up. 40 to 60 WPC can be done with only filter cap voltage changes.
I have also wired octal sockets into the board and used the 6DQ5, 6DQ6, 6BQ6, E130L, and a few others that I can't remember. The schematic is on Petes web site and at least one member has PTP wired his amp.
Sweep tubes seems like the way to go. Thanks for the suggestion. I came across a russian tube 6P13S. The curves look promising for class AB and they can be had new-in-box for $2 a pop. I also found a power transformer from a fisher TA-600 which has taps on the secondary that would work perfect for a low voltage screen supply.
Petes board looks interesting, but is a little overly complex for my tastes. These tubes should only take 16V peak to drive to full power in this application. I'm just going to do a point-to-point common cathode - cathodyne - output type of arrangement.
Petes board looks interesting, but is a little overly complex for my tastes. These tubes should only take 16V peak to drive to full power in this application. I'm just going to do a point-to-point common cathode - cathodyne - output type of arrangement.
I'd run the 807's. Regular 6L6's, 5881's, or even 1625's would work too. Heck, 5.5k will work with many tubes even if it isn't what the data sheet specifies. A pair of EL34's would work fine and give an easy 40 watts with simple drive requirements.
Whatever you choose, use tube rectifiers
Whatever you choose, use tube rectifiers
An externally hosted image should be here but it was not working when we last tested it.
i built an amp with these 6P3S tubes using a dynaco A470 traffo with very good results......
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