Hi All
I've got some iron I want to use for PP: a pair of Peerless S273 Opts with 8k primary and 4,8,16 ohm secondaries and pair of Lundahl LL1660s 18ma ITs.
I'm thinking about an all dht pp amp.
So far ideas are for 4p1l or 71A driving into the ll1660 and either the 2a3s from 8k to 8ohm or the 801A from 8K to 4ohm (reflecting 16K a-a back).
Any thoughts/ideas/suggestions?
Any less expensive output DH tubes you can suggest? I don't need a lot of power. Maybe 47s, 46s, 45s (never seen the 46 or 45 used with such a high primary). I suppose a 10Y would work into these options and I could run the same b+ of ~300V.
Thanks!
I've got some iron I want to use for PP: a pair of Peerless S273 Opts with 8k primary and 4,8,16 ohm secondaries and pair of Lundahl LL1660s 18ma ITs.
I'm thinking about an all dht pp amp.
So far ideas are for 4p1l or 71A driving into the ll1660 and either the 2a3s from 8k to 8ohm or the 801A from 8K to 4ohm (reflecting 16K a-a back).
Any thoughts/ideas/suggestions?
Any less expensive output DH tubes you can suggest? I don't need a lot of power. Maybe 47s, 46s, 45s (never seen the 46 or 45 used with such a high primary). I suppose a 10Y would work into these options and I could run the same b+ of ~300V.
Thanks!
How about the DH Rod-Pentodes wired as triodes? These are weird little Russian military valves, used in comms gear and space stuff--Sputnik had these things in it...
--They are quite a different breed and rely on focussed electron sheet flow focussed/controlled/guided/accelerated by rods rather than wire ladder grids...
The likes of 1p24B for o/p tubes and 1j18B for gain stage. In ppp you'll easily get around 3W from them, +B around 200V and 8K p-p.
Really pushing a single pair in pentode-mode at 300v up to 9W isnt impossible, all from a tube the size of half a pencil!...
(Although probably only for a handful of hours at this power)
You'll build the whole amp for less than the cost of a NOS 2A3! Rod Pentodes were made by the million and are dirt cheap. The Koreans love 'em especially wired as triodes in pre-amps....
Personally I could never get on with 4P1L--Way too fussy Microphonics wise...
Rod tubes are pretty free from Microphonics IME.
--They are quite a different breed and rely on focussed electron sheet flow focussed/controlled/guided/accelerated by rods rather than wire ladder grids...
The likes of 1p24B for o/p tubes and 1j18B for gain stage. In ppp you'll easily get around 3W from them, +B around 200V and 8K p-p.
Really pushing a single pair in pentode-mode at 300v up to 9W isnt impossible, all from a tube the size of half a pencil!...
(Although probably only for a handful of hours at this power)
You'll build the whole amp for less than the cost of a NOS 2A3! Rod Pentodes were made by the million and are dirt cheap. The Koreans love 'em especially wired as triodes in pre-amps....
Personally I could never get on with 4P1L--Way too fussy Microphonics wise...
Rod tubes are pretty free from Microphonics IME.
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not cheap tubes, but I would think push pull 300B's in a deep class A, no feedback design would be a sweet spot for those 8k Peerless
I'm going to recommend my own setup because I've been through multiple builds of 2a3, 300b and all the common solutions, and I'm now using 4P1Ls in the output. I bought 150 when they were really cheap like less than $5 each. No way I'm going back to expensive tubes. PP 4P1Ls will work into 8 ohms. You can drive them with more 4P1Ls, which can run OK at 18mA. I have some LL1660/18mA myself. I'd be tempted to use the Lundahl as a phase splitter and just use a single 4P1L driver. 2 stages is all I need in total - the 4P1L has a gain of around 11. You would use filament bias for all the tubes - Rod Coleman regulators. Plenty of information in the threads about 4P1L SE amps and 4P1L line stages. It's a bit more complex but you won't regret it. With filament bias you use tiny resistor values, so no cathode bypasses. That's a huge plus for me.
1st off thanks all for the creative ideas:
I did think about the 300B, given the rare and gigantic peerless iron (the 273 is the 8K version of the famous 271)--but boy good 300Bs are a lot of cash.
Andy,
--Are you saying 4p1l-->1660-->4P1lPP? Because of the 8K primary of my opts, I figured that was out, but it sounds like you have tried it at the high primary impedance?
I'm currently using Ale's 01A linestage, btw. One idea was to use his 6c4c pp schematic. I suppose I could just adapt that for 4p1l and run filament bias on all stages. Any suggestions on the resistor values and voltage targets for the output stage?
And also:
1619 looks interesting too--there was a write up elsewhere referring to it as a poor mans 10Y:
1619 Triode Curves. - audio-talk
Anyone use it before?
The 6av5ga--is this the sweep tube? I didn't even know it was direct heated. I'll have to look that one up.
Same with DH-rod tubes. No familiarity with them on my end--love this forum
I did think about the 300B, given the rare and gigantic peerless iron (the 273 is the 8K version of the famous 271)--but boy good 300Bs are a lot of cash.
Andy,
--Are you saying 4p1l-->1660-->4P1lPP? Because of the 8K primary of my opts, I figured that was out, but it sounds like you have tried it at the high primary impedance?
I'm currently using Ale's 01A linestage, btw. One idea was to use his 6c4c pp schematic. I suppose I could just adapt that for 4p1l and run filament bias on all stages. Any suggestions on the resistor values and voltage targets for the output stage?
And also:
1619 looks interesting too--there was a write up elsewhere referring to it as a poor mans 10Y:
1619 Triode Curves. - audio-talk
Anyone use it before?
The 6av5ga--is this the sweep tube? I didn't even know it was direct heated. I'll have to look that one up.
Same with DH-rod tubes. No familiarity with them on my end--love this forum
Ah great - you know Ale's designs. He's a good friend and comes over sometimes to listen to equipment. I'm using his 01A Gen 2 line stage. So in that case you know all about filament bias. I personally use 2x4P1L SE into a LL1664/70mA. Very happy with that. I'm driving this straight from the 01A line stage - just 2 stages total.
I've had a 4P1L PP project in my head for a while. No rush since I don't need the power. Easy solution is to drive it with a 4P1L driver and use the LL1660/18mA for phase splitter. Enterprising solution is to use a LND150 as a solid state concertina - there's a thread on this going right now. But this would probably need around 400v HT, which is stupid for me since the 4P1L output stage works on 250v.
I've had a 4P1L PP project in my head for a while. No rush since I don't need the power. Easy solution is to drive it with a 4P1L driver and use the LL1660/18mA for phase splitter. Enterprising solution is to use a LND150 as a solid state concertina - there's a thread on this going right now. But this would probably need around 400v HT, which is stupid for me since the 4P1L output stage works on 250v.
"The 6av5ga--is this the sweep tube? I didn't even know it was direct heated."
It isn't directly heated. However triode wired it behaves like a 6B4G. Internally triode wiring 6AV5GAs is exactly what Sylvania did to fulfill a contract for military 6B4G spares. 😉
Perhaps even more interesting is the 6A5G. Use your favorite 2A3 signal circuitry topology and connect pin 8 to the bias/ground stuff.
The Peerless O/P "iron" is hefty. Maybe a little A2 action, courtesy of Tubelab's PowerDrive, is in order.
It isn't directly heated. However triode wired it behaves like a 6B4G. Internally triode wiring 6AV5GAs is exactly what Sylvania did to fulfill a contract for military 6B4G spares. 😉
Perhaps even more interesting is the 6A5G. Use your favorite 2A3 signal circuitry topology and connect pin 8 to the bias/ground stuff.
The Peerless O/P "iron" is hefty. Maybe a little A2 action, courtesy of Tubelab's PowerDrive, is in order.
6HJ5 Triode-wired is incredibly linear, well worth looking into, no top-cap sweep-tube with 27W plate diss.
Someone round here called it a 2A3 on steroids, and there's some guys built SE and PP amps who are very pleased,--Worth a look....
Someone round here called it a 2A3 on steroids, and there's some guys built SE and PP amps who are very pleased,--Worth a look....
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