In triode mode it is often OK to use a higher voltage than the max g2 rating, since g2 will never be higher than the anode.
Furthermore, modern 6L6 versions can handle a lot more voltage on the screens than the original 6L6(G). I run mine in triode PP at 450V.
In SE triode 400V should be OK.
I´ve ordered me a couple of 6P31/EL36 for future experiments.. 🙂
But still wonder if someone has driven this tube in grounded grid?
I will do a search on grounded grid and see what I find..
But still wonder if someone has driven this tube in grounded grid?
I will do a search on grounded grid and see what I find..
I've built a pair of triode straped 6v6se amps and the sound is very nice. Very low power so it won't shake the house but does play plenty loud. The vintage 6v6 comes in so many flavors and fairly cheap. You can tube roll for the rest of your life and never break the bank.
Jason
Jason
The guys who have been experimenting with screen drive say that EL36 (6CM5) is one of the very best choices of tube for this. Extrordinary claims were made of its linearity when screen driven. Might be worth an experiment.
Cheers,
Ian
Cheers,
Ian
OK i'm convinced that the 6v6 performs very well as a triode in SE mode. I've read how tubelab uses the 6v6 at a voltage and dissipation far above book values. What operating points are recommended for good sound without affecting tube longevity too much?
The 6L6GC is rated to 450 volts in triode mode. The Tubelab SSE board can use a 6L6GC and most users build them with a 360-0-360 or 375-0-375 volt power transformer for a B+ voltage in the 420 to 440 volt range. All of the typical 6L6GC tubes including the $5 Chinese tubes will live in this amp and will make about 5 or 6 watts in triode with a 5K ohm OPT.
6L6GB's, GA's, G's or metal tubes must be run at about 350 volts B+ for about 3 watts.
Vintage RCA grey glass 6V6GT's run best at 320 volts and produce about 2 watts with a 5K ohm OPT. Modern Sovteks and other "6V6" types will eat a lot more voltage, as will some of the older stuff, but they just don't sing as sweet as the old RCA's on 320 volts. The 6V6GT is rated for 315 volts but many guitar amplifiers ran then as hot as 385 volts. They lived as long as you kept them out of the red zone. I use 320 volts in my SSE because that's what I get from an Allied 6K56VG power transformer.
The original metal 6L6 tube was designed for audio amplifiers. The glass type 6L6G was also developed for audio amplifier use. This is stated in the application notes and the tube manuals. It is interesting to note that the data for the original metal 6L6 type contains characteristics for AB2 showing 60 watts of output from a 400 volt supply. This was reduced to 47 watts in later tube manuals. I can attest to extracting over 100 watts from a pair of metal 6L6's back in high school electronics class (1968). We had hundreds of brand new RCA's to experiment with.
When the 6L6GB was developed the 807 and 1625 versions had some additional RF shielding added for transmitter applications. The plate connection was moved to the top cap so that all the driving circuitry was below the chassis, and the output circuits were above it for RF shielding.
The 6BG6G was developed for TV sweep applications. Again the plate is brought out through the top cap to handle the high voltage pulses seen in flyback applications. All of these tubes have identical structures between the mica spacers.
I built the booze hound labs 6v6se triode. I built monos so I used a 6j5 in place of the 6sn7 he uses.. It's a very sweet little amp I used a dual choke in the power supply..
This was my build and I still use them today
http://www.diyaudio.com/forums/tubes-valves/207244-new-amp-build.html
This was my build and I still use them today
http://www.diyaudio.com/forums/tubes-valves/207244-new-amp-build.html
I have not run the 6V6, but I have built this amp using 12W6 in a parallel SE configuration and it sounds very good to me. My 2-way speakers are ~95-96dB, no hum or noise.
Attachments
EL36 are not too common on this side of the pond, so I have not tried them. I have experimented with grounded grid output stages. All experiments were done with 13GB5/XL500 because I got a deal on 150 of them (75 cents each!).
To achieve grounded grid operation I grounded the control grid, and wired a P-fet follower up to the cathode. Drain grounded, source to cathode, positive bias and drive applied to gate. G2 is where things get tricky. You can zener clamp it to the cathode with a CCS feeding the zener for true pentode, or you can apply positive or negative feedback for interesting applications. I had to use a second (N-channel) mosfet to make this work which just got too complicated.
I started down the road to a more conventional grounded cathode circuit that works with only one mosfet when all experimenting ceased. I will likely not do much more tube stuff this year.....
Thanks for the answers.
Is another tube stage neded before the P-fet?
There´s over half a year left on this year,why this?.. 😉
Yes, the P-fet is just a source follower and has no voltage gain. I don't like mosfets used as gain stages in tube amps, but source followers are more sonically neutral than many cathode followers. I did my experiments with a 6EJ7 / EF184 pentode gain stage, again because I have a bunch. A triode probably has enough gain to drive the 13GB5 (probably not big sweep tubes) but I wanted to experiment with feedback from the output stage into the drivers screen grid. This simulates well, but wasn't stable in initial experiments. I didn't spend much time on it though.
I tried grounded grid operation with a 6BG6GA ( A Sylvania with 7027 guts). I was using a modified circuit that applied negative feedback to G1 instead of grounding it. G2 was at AC ground. It took a lot of drive but produced very little distortion. I decided that true sweep tubes worked better.
My 41 year engineering career came to an end last month without much notice. We are in the process of moving all our stuff about 1200 miles to a place where the cost of living is less, and life is less hectic......some may call it retirement, but I will be melting tubes! Tubelab is being packed into boxes and stored until I have a place to set it all back up.
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retirement or not, good luck and have fun.
i think you should consider a job as a electronics teacher. not b.s. realy you have a gift.
i think you should consider a job as a electronics teacher. not b.s. realy you have a gift.
George,
Wish you all the best, and look forward to reading more about your experiments/developments sooner rather than later!
So hope you find a suitable place really soon. 🙂
Life has changed.
George,
You really put your life out there in the ether for us all to see. You are putting your work & hobbies into a box and transplanting your life to Tennessee or some similar place. You wake up in the morning and wonder if it is your turn to cook breakfast. It is all new, even the relationship with your wife. Take your time and enjoy your new world, turn towards your wife with a smile. When you are ready under your new roof break out the boxes, dust off the old stuff, and see what you want to keep.
I pulled the plug about a year ago. Things were slowing down, the young engineers were being laid off, I walked into the manager’s office had a chat about things and told him to send me my money. Now I get up in the morning and find money deposited to my account. Life has changed. Life is good.
Hobbies are artistic expression, life needs to be settled before you can sculpt or in your case solder.
Take your time and enjoy every day!
All just for fun!
DT
George,
You really put your life out there in the ether for us all to see. You are putting your work & hobbies into a box and transplanting your life to Tennessee or some similar place. You wake up in the morning and wonder if it is your turn to cook breakfast. It is all new, even the relationship with your wife. Take your time and enjoy your new world, turn towards your wife with a smile. When you are ready under your new roof break out the boxes, dust off the old stuff, and see what you want to keep.
I pulled the plug about a year ago. Things were slowing down, the young engineers were being laid off, I walked into the manager’s office had a chat about things and told him to send me my money. Now I get up in the morning and find money deposited to my account. Life has changed. Life is good.
Hobbies are artistic expression, life needs to be settled before you can sculpt or in your case solder.
Take your time and enjoy every day!
All just for fun!
DT
The northern tip of West Virginia, near my wife's home town.
Where I have worked, its the old engineers that get laid off. They offered buyouts to the older higher paid engineers. There was even a boldface message at the bottom of the buyout memo stating that there would be a layoff if they didn't get enough volunteers, so I signed up. With any major decision like this there are always second thoughts.......then the layoff came, about 1/3 of the entire engineering and engineering support staff were laid off. There were about a dozen of us old-timers left...Now there are three, none of them are EE's. I guess I made the right choice.
There are 3 small colleges in the area, but only one has any kind of a technical program.....pre-engineering is what they call it. There is a tech school that offers industrial electronics in Ohio. Neither are currently hiring.....already been there. Not much work for a 61 year old engineer in a small town. I have been offered only one job so far.....a maintenance man in a prison for $12 per hour.....I don't think so.
We inherited my mother-in-law's house, so we have a place already, but neither of us wants to spend the rest of our life there. There is NO ROOM FOR TUBELAB!!!!! We bought some land about a mile out of town and will likely build just what we want there, then sell the other house. We were up there for the last two weeks sorting this kind of stuff out.
I don't want to move what I don't want to keep. I have been hitting all the hamfests selling stuff that I don't want to move. I already have a computer in the WV house and have been committing ideas to the simulator and PC board layout tool. If even 1/3 of them work there will be some cool new Tubelab stuff next year.
This thread was about 6V6's and 6L6 types.....I think we have wandered it about a bit. I think I covered my thoughts on the topic, and I have already packed up my 6V6 amp. The 6L6GC amp is still hooked up for now....but I stuffed KT88's into it a long time ago and haven't looked back. In fact, the amp will run EL34's, 6L6GC's and KT88's and the 6L6GC is my least favorite of the three. The same amp with different transformers is what I use with 6V6's, and within its power limitations, it is my favorite of all 4 tubes. Oh, you can stuff 6EZ5's into it and pick up a little more dynamics with a very little loss of detail. 6EZ5's used to be $1 each until we talked about them too much.
George, good luck on your new move......
it seems the more we talk about these dollar tubes, the scarcer they get and the more pricey they become....the 6LU8 now sells for 4 bucks at Rogalskie's....
i have tried the 6EZ5 in place of the 6V6 and i couldn't tell the difference, my impression was that it was better sounding...
ditto with the 12W6, i like them a lot on my pp amps, 5k a-a opt and 300v B+, G2 regulated using the 0A2....
it seems the more we talk about these dollar tubes, the scarcer they get and the more pricey they become....the 6LU8 now sells for 4 bucks at Rogalskie's....
i have tried the 6EZ5 in place of the 6V6 and i couldn't tell the difference, my impression was that it was better sounding...
ditto with the 12W6, i like them a lot on my pp amps, 5k a-a opt and 300v B+, G2 regulated using the 0A2....
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