Sure, 6HJ5 should work fine.
I think George got 135 Watts (-edited-) out of a pair, and recommended them for a conservative 100 Watt output per pair. Only thing is paralleled tubes require some matching, or individual idle current adjustments. The screen grid however should be much more consistent than grid 1 for matching, and all the 6HJ5 tubes around appear to have been built by Raytheon (and re-labeled for everyone else). Might get away with a single idle adjust for a parallel pair.
21LG6 is very similar to it also. Different pin-out unfortunately, and has a plate cap. 6CB5A and 26DQ5 are some other inexpensive octal alternatives.
Be aware of the hefty heater current the 6HJ5s draw. One PL519/509/6GK6 draws less heater power.
I think George got 135 Watts (-edited-) out of a pair, and recommended them for a conservative 100 Watt output per pair. Only thing is paralleled tubes require some matching, or individual idle current adjustments. The screen grid however should be much more consistent than grid 1 for matching, and all the 6HJ5 tubes around appear to have been built by Raytheon (and re-labeled for everyone else). Might get away with a single idle adjust for a parallel pair.
21LG6 is very similar to it also. Different pin-out unfortunately, and has a plate cap. 6CB5A and 26DQ5 are some other inexpensive octal alternatives.
Be aware of the hefty heater current the 6HJ5s draw. One PL519/509/6GK6 draws less heater power.
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The 6HJ5 will make 135 watts on about 650 volts into a 3300 ohm load. It will just begin to show a faint red plate in a dark room if running a continuous sine wave for several minutes at this level. No issues at all with music.
This was measured in one of Pete Millett's big red boards running on a big HP power supply capable of 1.7 amps. Power was about 120 watts in the real amps with a pair of cheap Ebay power transformers. The B+ dropped to about 620 volts at full tilt. I created a modified version of his little 18 WPC sweep tube amp that used 6HJ5's or 6HD5's to crank out 125 WPC. Mine often sat at nearly full volume hitting clipping on peaks into a pair of 96db speakers for several hours at a time. I did this while mowing my lawn so I didn't have to hear the lawnmower. I still have that amp, and it still has the same tubes in it. I built 3 of them, and at least a dozen others were made. Nobody ever complained that theirs blew up, but the thread has grown rather quiet.
I imagine 4 tubes into a 2200 ohm load would hit over 200 watts on 600 to 650 volts.
I have no experience with the PL519. I have exactly one PL519 and zero 6KG6 or 40KG6.....they are just too expensive, especially when I got a big box full of 6HJ5's for $2 each!
Great!
This plan is coming together nicely! So for this old Carlsbro Its looking to get 4 x 6HJ5 and the new mains transformer. The original O/P transformer appears to be fine, as the amp does actually work,--even with only 400V and very tired mis-matched type output valves!
(Doesn't sound very good though....)
--At least the power output should be much the same--if not a bit more than it was originally made to develop....
It will be an interesting learning experience of this new drive format--although I think 'Crazy-Drive' isnt a nice moniker!
This plan is coming together nicely! So for this old Carlsbro Its looking to get 4 x 6HJ5 and the new mains transformer. The original O/P transformer appears to be fine, as the amp does actually work,--even with only 400V and very tired mis-matched type output valves!
(Doesn't sound very good though....)
--At least the power output should be much the same--if not a bit more than it was originally made to develop....
It will be an interesting learning experience of this new drive format--although I think 'Crazy-Drive' isnt a nice moniker!
I used to call it "Dual Drive."
See post #29 here:
http://www.diyaudio.com/forums/tubes-valves/163940-g1-g2-mu-scaled-drive-strawman-design-3.html
"--although I think 'Crazy-Drive' isn't a nice moniker!"
Well, Crazy Drive, Hybrid Drive,... or whatever one wants to call it, is using a voltage drive for grid 2 and a current drive for grid 1 (Rg2g1 with positive g1). The very sight of the connect-up, by experienced designers, looks unlikely to work well, hence the moniker. But it could be called something more respectable I guess. On the other hand, it may still drive some designers crazy...
G1 G2 Mu scaled Dual-drive, as I recall, was using voltage drive for grid 2 and approx. Mu scaled voltage drive for grid 1, so somewhat similar, yet somewhat different.
The resistive type g2-g1 connection version certainly exists in the historical tube literature, but they called it "special triode", which I think is even MORE misleading, since it has pentode like curves. Nowhere have I seen any historical comments about it being more linear (when tuned up). Which is mysterious to say the least. I think tube history should have been wildly different. Audio tubes should look like Sweep tubes now (low screen grid V).
But, well, here we are now.
It's quite possible that this drive mechanism is still not fully developed besides. It might be possible to drive a single grid (maybe one placed midway between typical grid1 and grid 2 spacing) with an impedance drive to get linear results. We may never know now. (unless tube design makes a comeback)
..
Well, Crazy Drive, Hybrid Drive,... or whatever one wants to call it, is using a voltage drive for grid 2 and a current drive for grid 1 (Rg2g1 with positive g1). The very sight of the connect-up, by experienced designers, looks unlikely to work well, hence the moniker. But it could be called something more respectable I guess. On the other hand, it may still drive some designers crazy...
G1 G2 Mu scaled Dual-drive, as I recall, was using voltage drive for grid 2 and approx. Mu scaled voltage drive for grid 1, so somewhat similar, yet somewhat different.
The resistive type g2-g1 connection version certainly exists in the historical tube literature, but they called it "special triode", which I think is even MORE misleading, since it has pentode like curves. Nowhere have I seen any historical comments about it being more linear (when tuned up). Which is mysterious to say the least. I think tube history should have been wildly different. Audio tubes should look like Sweep tubes now (low screen grid V).
But, well, here we are now.
It's quite possible that this drive mechanism is still not fully developed besides. It might be possible to drive a single grid (maybe one placed midway between typical grid1 and grid 2 spacing) with an impedance drive to get linear results. We may never know now. (unless tube design makes a comeback)
..
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The Only ever Twin-Drive G1G2 format Ive seen before, was by Alan Kimmel/Tubelabs in his 'Sweep-Tube Monoblock'.
OTL Circlotron, which I built as-is and worked really quite well....
In this, he used a MOSFET to drive the G2 and the raw signal from the diff gain stages to drive G1.
Quite different to the Crazy way but sorta similar, but as I recall, the G1 was negative and sets the bias the G2 was at some predetermined positive value, the drive signal sitting on top. He called it 'Enhanced Triode Mode' and summit that I had meant to play around with.
Crazy seems easier to implement and probably a better format...
As to the name, well--Whatever, I quite like Twin-Drive...
OTL Circlotron, which I built as-is and worked really quite well....
In this, he used a MOSFET to drive the G2 and the raw signal from the diff gain stages to drive G1.
Quite different to the Crazy way but sorta similar, but as I recall, the G1 was negative and sets the bias the G2 was at some predetermined positive value, the drive signal sitting on top. He called it 'Enhanced Triode Mode' and summit that I had meant to play around with.
Crazy seems easier to implement and probably a better format...
As to the name, well--Whatever, I quite like Twin-Drive...
Or maybe they think it refers to the few that are trying it??????
Whatever it's called it really doesn't matter. There will be a few that go forth looking for something new. The rest will resist it until it is proven to be an improvement over what has been STALE of the art for the last 50 years.
There are still a lot of people who won't use a mosfet source follower or a solid state rectifier because they have been told by experts that those things pollute their sound.
Absolutely!
If us Crazies don't try summit new--then nothing changes and only the same boring old schemes are built--nothing improves, and audiophoolery reigns
supreme!
George's 'Heretic' work gave us Superdrive with the MOSFET and got lots of flack in the early days--Now its more or less accepted, all to the good IMHO...
Yes, true and proven, but for one PL509 type. The ones with "Barkhausen" plates, those extra fins without black "coating", probably made to supress some image "snivets" in colour TV's using them, will show mild red glow at night with more than 34W, with the red spot located only in these fins. The "non-Barkhausen" will start to glow with the claimed >60W, or at least far higher than the datasheet spec.
But even the "Barkhausen" ones don't glow with average audio power (peak power), so in class AB/B amplifiers, we can consider high peak power with them, also (oops, less class A
).Attachments
Or maybe some people are simply satisfied with the "common practice"...
Others with fear etc... (unjustified sometimes)
Or...:
I have a amplifier with 300B, and in these I choose to not use sand at most places possible. People often ask me if I made this for sonics, but the first motive is only "to prove the concept" (and results no sonics difference to me, if neither rectifier type produces EMI, but some snappy Si diodes seems to provoke more ringing in the secondary), and to make a inherent delay in supply... but I made so only because I can!
Like to seeing such low-tech in action. Like one project I have with with 100% Ge transistors/diodes, even in supply and regulators (damn it, the zener diode is a Si component, I don't find a Ge one )... Is only for fun...Same for MOSFET follower, or trafo-coupled systems. Sometimes I use, sometimes not.
Anyway...
In my PP amplifier with PL509 I use liberal rectification with knife whetstones in HV (SiC diodes; some knife whetstones are made with a SiC rock, so the sound, you know...
). And "pure" sand (BAV20) for bias and etc. No way to use colour TV dampers with LC filtering, to comply with high current +B, at least in this actual amplifier (no space for that). Maybe in another project...Also for fun I used some russian Ge "HV" diodes (Д7Ж - 400V/300mA) in my electrostatic headphones amplifier, only to see a improbable combination working: Ge and HV...
So...
Maybe some people avoid some options only due to preferences, and not prejudices... (I cannot to be the only one with this point of view...)
AARRGH!
I Cant Decide, just Which Tubes to use, PL509/19 or 6HJ5.....
6HJ5 Pros- Safer, no top-caps. 6.3V heaters, Cheap even when import is considered Known to work in this sort of 'Crazy' application. 770V Va
Cons,- Duodekar sockets not usually ever found in Europe or UK, only found in some very old Teleton TV sets or China supply ex. ebay.
An Unknown Tube in the UK, probably unknown outside the likes of this and similar Forums. Replacements would have to be Imported. I have only 10 NOS examples--which I imported for a different project.
PL509/519. Pros, A well known and used Euro tube,--practically every tube colour TV used 'em, Magnoval sockets, easy to get replacements most places both sockets and tubes. pretty rugged tube.
Cons-- 40V heater, Top-cap possible dangers. Unknown performance in crazy-drive. don't particularly like high Va supplies, Getting Stupidly Expensive for quality Euro made NOS (Philips/Mullard) tubes.
Leaning towards the 6HJ5 but cant decide....
I Cant Decide, just Which Tubes to use, PL509/19 or 6HJ5.....
6HJ5 Pros- Safer, no top-caps. 6.3V heaters, Cheap even when import is considered Known to work in this sort of 'Crazy' application. 770V Va
Cons,- Duodekar sockets not usually ever found in Europe or UK, only found in some very old Teleton TV sets or China supply ex. ebay.
An Unknown Tube in the UK, probably unknown outside the likes of this and similar Forums. Replacements would have to be Imported. I have only 10 NOS examples--which I imported for a different project.
PL509/519. Pros, A well known and used Euro tube,--practically every tube colour TV used 'em, Magnoval sockets, easy to get replacements most places both sockets and tubes. pretty rugged tube.
Cons-- 40V heater, Top-cap possible dangers. Unknown performance in crazy-drive. don't particularly like high Va supplies, Getting Stupidly Expensive for quality Euro made NOS (Philips/Mullard) tubes.
Leaning towards the 6HJ5 but cant decide....
Some time ago I made a small SMPS al, with tubes, with a 33GY7A (one of which is in my avatar). I had posted it anywhere in this site, I believe. It gives ±350V @ 20mA with a 275V input. It is a SEPIC & Cuk topology.
Also here:
http://www.diytube.com/phpBB2/viewtopic.php?f=4&t=6408
Also here:
http://www.diytube.com/phpBB2/viewtopic.php?f=4&t=6408
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Well, this is a very exotic and fun use for our beloved TV tubes...
More or less like this: Compound Tube Contest
This is other pulsed use for them
Now I thinking if one make a exotic monster using some tube SMPS with that class D output
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"cant decide...."
There are some octal base TV sweeps that are quite similar to the 6HJ5 and cheap, have plate caps though:
26DQ5 for $3 (made in Japan for Westinghouse, they look OK)
and 6CB5A for $5
The 6HJ5s all seem to be made by Raytheon (says LYFA on bottle, Raytheon a very top notch manufacturer) Pretty well matched without any selecting.
The Russian 6P45S (EL519 clones) seem to have characteristics all over the place according to Ebay sellers. Poor quality control (for TV) and expensive. I think only military type tubes are worthwhile there.
There are some octal base TV sweeps that are quite similar to the 6HJ5 and cheap, have plate caps though:
26DQ5 for $3 (made in Japan for Westinghouse, they look OK)
and 6CB5A for $5
The 6HJ5s all seem to be made by Raytheon (says LYFA on bottle, Raytheon a very top notch manufacturer) Pretty well matched without any selecting.
The Russian 6P45S (EL519 clones) seem to have characteristics all over the place according to Ebay sellers. Poor quality control (for TV) and expensive. I think only military type tubes are worthwhile there.
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i will choose el509.6kg6....the russian equivalent 6p45 seems plenty still and prices are reasonable...
Hmm--Looks like its gonna be the PL509.
Two reasons, I need a Negative supply not available with the current replacement transformer, so can add a 1.5A 40v to supply the heaters of the 4 PL509 which will double as the Negative rail after rectification etc, for the bottom end of the G1G2/MOSFET stages.
As this is a Musicians or a Stage amp, and myself not being in any way a musician, it will be passed on once Ive done it in a working condition (assuming I can get it to work reliably and be reasonably safe.)
At least with PL509 in there, any replacements at some future time shouldn't present a problem.
Two reasons, I need a Negative supply not available with the current replacement transformer, so can add a 1.5A 40v to supply the heaters of the 4 PL509 which will double as the Negative rail after rectification etc, for the bottom end of the G1G2/MOSFET stages.
As this is a Musicians or a Stage amp, and myself not being in any way a musician, it will be passed on once Ive done it in a working condition (assuming I can get it to work reliably and be reasonably safe.)
At least with PL509 in there, any replacements at some future time shouldn't present a problem.
Most of the 6p45s on ebay are used and those claiming to be NOS usually have very meagre looking gettering, which wouldn't inspire me with confidence. The smaller brother, 6p36s, looks like a better bet to me; it is difficult to take the published ratings seriously since the anode is of a similar size to the KT88 and the 6.3 volt heater draws 2 amps.
About 25 years ago I simply looked thru the RCA tube manual looking for the sweep tube having the highest heater dissipation. 42KN6/6KN6/40KD6/6KD6. Especially the ones that have the 40-42V heaters; not only are they cheaper but the current is much lower for ease of wiring. One day; AES had a sale on 42KN6 @ $1.50. I called them up and told them I wanted them all. The newer --KN6's are actually 6/40KD6; they have the extra grid connections. The Japanese ones are an exception. So now the mighty MC275/TV tube lives with the 42KN6 outputs and 6LU8s on the front end!!! I simply ran a single pair of output bananas to the 16-Ohm output secondaries; the huge cathodes handle even 4-Ohm speakers with ease. It's like a solid state amp; even the super solid bass; effortless power and no need to change taps for different speakers. Then that depth of sound stage lets you know that this is a thermionic amplifier.