The Nelson Pass First Watt are considered to be some of the best solid state amps ever designed. Fortunately for us, the designs are all open-source so we can build them ourselves 🙂.
What would be the equivalent for a SET tube amp? The best of the best. I am looking for a new project 🙂. I wouldn't need more than 4-5 watts of power.
Thanks!
What would be the equivalent for a SET tube amp? The best of the best. I am looking for a new project 🙂. I wouldn't need more than 4-5 watts of power.
Thanks!
I am a devoted follower of Nelson Pass having built 3 or his amps. I am like you and wanted to hear what all the fuss was about SET amps. I built this and I am enjoying it very much. Not as detailed as a F6 with other differences but a very musical amplifier with the bonus of cheap to build. I am current patiently waiting for the SIT designs. Just 2 watts but more than enough for my horns. It even made plenty of volume with some 87db test speakers.
http://www.diyaudio.com/forums/tubes-valves/279303-6em7-set-amplifier.html
http://www.diyaudio.com/forums/tubes-valves/279303-6em7-set-amplifier.html
You are right best is a meaningless word, especially in this hobby.
Substitute with "most sonically satisfying which you have experienced" 🙂
I would look at 2A3 designs, I think it is a great tube.
I build a 6B4G amp form Shannon Parks that was really nice too.
diytube.com • View forum - get*set*go
I build a 6B4G amp form Shannon Parks that was really nice too.
diytube.com • View forum - get*set*go
I'd build this one as a starter SE triode amp.
https://www.hndme.com/storeschematics1.html
The original Radiotron design used a 6C6 rather than a 6J7 and I'd stick with that old tube for period correctness if you can find the tubes and 6 pin sockets.
Actually the original Australian edition used an SP13, whatever the heck that is!
https://www.hndme.com/storeschematics1.html
The original Radiotron design used a 6C6 rather than a 6J7 and I'd stick with that old tube for period correctness if you can find the tubes and 6 pin sockets.
Actually the original Australian edition used an SP13, whatever the heck that is!
Last edited:
I just read an article about using a 6BX7 with the sections paralleled in an SE for 3W. Going to add that one to my to do list.
I built a single-ended amplifier based on three paralleled 2A3s and the One-electron UBT-1 transformer. It delivers 10-12 W per channel, which may be more than you are looking for, but I have been pleased with it for many years. There is an app note on the One-electron website: that is not the amplifier I built, but it inspired my design.
One Electron home page
Iwan
One Electron home page
Iwan
There is no best.
If you want some sort of reference starting point I'd start with a 2a3 or 300b based amp with a cascaded 6sn7 or single stage 6sl7 driver. I like the One Electron UBT-3 output transformers...best possible musicality-to-price ratio vs the other options.
Certainly not a 6l6, 6bx7, or 6em7 as a "starting point". Nor a paralleled output stage. While they can possibly exceed the 2a3 or 300b, that seems unlikely on a first attempt.
The handmade is a good possibility, although I'd be inclined to recommend a triode driver stage vs. the pentode, again, as your starting point.
Check out the Reichert Flesh and Blood. That was kind of a reference design for a number of years during golden age of the SET resurgence. There's no reason that can't be adapted to 2a3 as well with some minor changes.
If you want some sort of reference starting point I'd start with a 2a3 or 300b based amp with a cascaded 6sn7 or single stage 6sl7 driver. I like the One Electron UBT-3 output transformers...best possible musicality-to-price ratio vs the other options.
Certainly not a 6l6, 6bx7, or 6em7 as a "starting point". Nor a paralleled output stage. While they can possibly exceed the 2a3 or 300b, that seems unlikely on a first attempt.
The handmade is a good possibility, although I'd be inclined to recommend a triode driver stage vs. the pentode, again, as your starting point.
Check out the Reichert Flesh and Blood. That was kind of a reference design for a number of years during golden age of the SET resurgence. There's no reason that can't be adapted to 2a3 as well with some minor changes.
Last edited:
6BX7 1.5a common heater voltage to go with drivers.
2A3 2.5a 2.5v
6BX7 paralleled plates driven by 20v sig. for full power
2A3 about 45v needed commonly.
6BX7 w/paralleled plate has @650R plate for better damping than
2A3 with 800R plates.
Tie grids, tie plates. 2500R tranny. 250v B+.
Last edited:
6BX7 is a twin triode. Don't need two for paralleling.
Missed the edit cutoff for my prior post.
Missed the edit cutoff for my prior post.
Trust me...pentode and 2A3.
I was Herb's editor on the Flesh and Blood article. I'd still recommend the Radiotron 2A3 for an intro to the genre.
6BX7 is good sound for a $5 tube but I built a couple and was never blown away.
Why mess around? Build something nice.
I was Herb's editor on the Flesh and Blood article. I'd still recommend the Radiotron 2A3 for an intro to the genre.
6BX7 is good sound for a $5 tube but I built a couple and was never blown away.
Why mess around? Build something nice.
IMO, it's 4 to 5 W. requirement that leads to expense and/or other complications. The 2A3 is linear and (I suppose) will get to 4 WPC, with the complications of mild Class "A2" operation. A 300B will yield 8 W. operating in Class "A1", but it has some linearity issues and will be costly. Remember that Harvey Rosenberg stated the 300B puts on a show.
If the OP is willing to make due with 2 WPC, very nice results can be had using triode wired 6V6 family tubes. It has been said that in this power range, only #45 DHTs are better sounding than triode wired 6V6 family tubes.
No matter what tube and associated circuitry are selected, a superior amp needs 1st rate O/P transformers and that never is inexpensive. I hope "audioexplorations" is prepared for some serious "sticker shock".
If the OP is willing to make due with 2 WPC, very nice results can be had using triode wired 6V6 family tubes. It has been said that in this power range, only #45 DHTs are better sounding than triode wired 6V6 family tubes.
No matter what tube and associated circuitry are selected, a superior amp needs 1st rate O/P transformers and that never is inexpensive. I hope "audioexplorations" is prepared for some serious "sticker shock".
And since a 6BX7 is way easier to drive than the 2A3 just stick an AX7 up front and bring about 20dB of GFB around front and you're done. Use whatever 5W OPT you have your heart set on.
Eli, I have heard some very precise "linear sounding" 300B SEs. If this is the goal, a strong low Z driver, maybe a CF, really helps. A design for A2 considerations might be on the right track in this respect.
T haven't told this story often but Harvey Rosenberg sent me a 700 page draft of his book on triodes, "The Search for Musical Ecstasy," for review BEFORE he ever heard a triode amp. I know because I asked him which triode amps he liked. Never heard one! He was good at coming up with the bon mot, though!
T haven't told this story often but Harvey Rosenberg sent me a 700 page draft of his book on triodes, "The Search for Musical Ecstasy," for review BEFORE he ever heard a triode amp. I know because I asked him which triode amps he liked. Never heard one! He was good at coming up with the bon mot, though!
While it's probably impossible to make a 2A3 sound less than great, it might be fun to also check the triode-connected curves of some of the unloved compactron sweep tubes: www.diyaudio.com/forums/tubes-valves/278043-6ge5-triode.html
All good fortune,
Chris
All good fortune,
Chris
I bought a bunch of 6HJ5 after reading some of that thread, and plan to use them in the near future. Made by Raytheon (!) but utilitarian looking. Looks aren't everything, or so I tell the ladies.
Thanks, as always,
Chris
Thanks, as always,
Chris
- Status
- Not open for further replies.