An 845 amp is really jumping into the deep end of the pool. Unless you have experience building amateur radio transmitters, stay away! Most caps and transformers are not available above 500 volts ... and the build technique itself is very different, following transmitter technique. The cost of a mistake is lethal.
Aside from that, getting a 211 or 845 amp to sound as good as a well-designed 45, 2A3, or 300B amp is very difficult, bordering on impossible. A few exist, but not many. I've only heard one or two. The scale of difficulty is comparable to building a really good tri-amped system.
However ... if you can live with a 45, 2A3, or 300B amplifier, there are massive gains with a split power supply design, with separate B+ supplies for input+driver and the output section. It just gets heavy, but is otherwise straightforward.
Aside from that, getting a 211 or 845 amp to sound as good as a well-designed 45, 2A3, or 300B amp is very difficult, bordering on impossible. A few exist, but not many. I've only heard one or two. The scale of difficulty is comparable to building a really good tri-amped system.
However ... if you can live with a 45, 2A3, or 300B amplifier, there are massive gains with a split power supply design, with separate B+ supplies for input+driver and the output section. It just gets heavy, but is otherwise straightforward.
As Lynn says, I use a split B+, better than 2 monobloks. One chassis for the output stage, SE 2a3, and one chassis for the input stage, 10Y in filament bias with a Hammond 1140-LN-C step-up 1:4 on the input. All DHT. Cap coupling with FT-2 teflon caps. I prefer the 2a3 to the 300b all day and twice on Sundays. Cheaper too.
I also once built an "inverted SET" with 2P29L input in filament bias and EL12n output and that sounded pretty nice. Very easy to build and you get the DHT sound on the input. Works well. The EL12n is a very good sounding tube, still available cheap in Europe. So all round a cheap and excellent SE amp. Dissipation of the EL12n is 18W so more power than a 2a3. Older European 8 pin base.
I also once built an "inverted SET" with 2P29L input in filament bias and EL12n output and that sounded pretty nice. Very easy to build and you get the DHT sound on the input. Works well. The EL12n is a very good sounding tube, still available cheap in Europe. So all round a cheap and excellent SE amp. Dissipation of the EL12n is 18W so more power than a 2a3. Older European 8 pin base.
I might humbly suggest you learn your chops with a known good EL84/6BQ5 push pull design. The EL84 is a fantastic sounding tube and rivals many DHTs.
My vote would go to the Baby Huey (less the loop feedback) or Morgan Jones’ design.
Other’s opinions may vary with regard the above.
But you can spend relatively low amounts of money without jumping directly to an amp that is very likely to kill you while you build it if you are not careful and particularly if you are still learning your craft.
I have DHT amps of good quality, and 300B design and an 845 design. I had the 845 amp built for me as I didn’t want to deal with 1000V DC.
And I’ve been building tube amps for 20 years.
So, start wil a known good design, invest in some quality OPTs, Ideally ones that can be used in other designs and different tubes.
250V to 400V can still kill you, but not as easily as 1000V DC.
You may well find that something like the Baby Huey will surprise to the extent that you are completely happy with it. And 12 W of class A is plenty for your 95dB@1W speakers IMHO.
My vote would go to the Baby Huey (less the loop feedback) or Morgan Jones’ design.
Other’s opinions may vary with regard the above.
But you can spend relatively low amounts of money without jumping directly to an amp that is very likely to kill you while you build it if you are not careful and particularly if you are still learning your craft.
I have DHT amps of good quality, and 300B design and an 845 design. I had the 845 amp built for me as I didn’t want to deal with 1000V DC.
And I’ve been building tube amps for 20 years.
So, start wil a known good design, invest in some quality OPTs, Ideally ones that can be used in other designs and different tubes.
250V to 400V can still kill you, but not as easily as 1000V DC.
You may well find that something like the Baby Huey will surprise to the extent that you are completely happy with it. And 12 W of class A is plenty for your 95dB@1W speakers IMHO.
As I let the dilemma settle in I feel more and more comfortable with the 300B amp. I've found the most documentation on them and am considering a Bottlehead Kaiju. It's pricey compared to the, say Willsenton R300, which looks like the same design with a preamp section. Does anybody here have experience with Bottlehead or advice for/against it? I would want to change the plans to include, say, a separate B+ based on advice here, but I wonder if such things are possible with a Bottlehead Kit...
I'm not much of a 300b fan, to be honest, and I can see the reasons for starting with a PP EL84 build. Or another way to do it is to modify an existing design like a Dynaco ST70 or ST35. Both fine amps and should come in cheaper than a Bottlehead 300b build. Dynaco amps hold their value as well - a very sound investment. Plus there are a few other nice US amps with PP EL84 outputs. Should be good user support on all these, plus you have all the hardware built and you can start getting used to choosing good audiophile parts to upgrade your amp. I think that's what I would do. I started by upgrading a Leak Stereo 20.
The best 300B amps I've built or heard were really quite simple, two-stage amps with uncomplicated power supplies. The Joe Roberts WE91 clone is a lovely amp and extremely easy to build:
https://www.enjoythemusic.com/magazine/sound_practices/1/single_300b.htm
In the 1990's this was a terrific gateway project for countless numbers of DIYers like myself. It's the first amp I built and my wife still asks me why I didn't stop there--she loved it. Sometimes I ask myself the same question...! ;-)
All the great 300B amps of the '90's--Cary, Wavelength, Welbourne, Fi, to name a few--were simple amps using high-quality components like Magnequest output transformers. Most of them were monoblocks because the feeling was that this offered the best channel separation and the most robust sound, but Cary sold a very popular stereo amp, and Dennis Had of Cary still builds very simple stereo SE amps which are in very high demand. His recent 300B amp has gotten rave reviews and is a single 6SL7 driving two 300Bs.
I have not heard the Bottlehead kit but I think if you're going to do it, do it as designed. Those folks know what they're doing.
IMO the best 300B amps have light-weight power supplies, the best output transformers you can afford, the best 300B you can afford and a simple front end.
I’m with Andy - I’d give 2a3 a go. Elekit-8900 accepts 300b or 2a3, but I think the more cerebral / less euphoric, but natural presentation of 2a3 is a good move.
I’m doing Radu Tarka ‘shiny eyes’ 01A into pass F4, but I think the elekit would be really interesting with 2a3 tubes.
I’m doing Radu Tarka ‘shiny eyes’ 01A into pass F4, but I think the elekit would be really interesting with 2a3 tubes.
My 2 cents - this coming from a guy who has built tube kits and can now build from schematics. Not an expert. I recently built a 300B amp (monoblocks), a couple of preamps and most recently a 3C24 pair of monoblocks. The 300Bs will give you a bit more power than the 2A3, well established designs and there are tons of tubes to roll into there if you choose ranging from a few hundred dollars to the new WE300B at about $1,500/pair. Also consider your room size! I have my 300Bs driving a pair of 88dB sensitive speakers to more than adequate volume in a small room.
I would be leery of things needing much more voltage as I've been bitten by 400V and it really hurts! Get some practice first.
The Bottlehead thing. They build great kits at great prices and the instructions are GOOD. However, they are not about teaching you what is going on in their circuits. There is plenty of handholding via their forum and there is a great resource over at HiFi Haven (Link to my 3C24 build). Lots of friendly help over there in general BTW.
I certainly would NOT spend extra money on fancy feet/fuses/binding posts/RCAs because you think it'll improve the sound. Sometimes I buy a certain binding post or RCA for more money because I like its form/function. Binding Post I Like. Never in a million years would I believe a fancy fuse buried in the middle of steel leaded parts could possibly improve the sound. There needs to be some possible scientific rational for using things. Just use quality parts from sources like DigiKey, Mouser or Newark.
Feel free to PM me if you want to talk privately.
I would be leery of things needing much more voltage as I've been bitten by 400V and it really hurts! Get some practice first.
The Bottlehead thing. They build great kits at great prices and the instructions are GOOD. However, they are not about teaching you what is going on in their circuits. There is plenty of handholding via their forum and there is a great resource over at HiFi Haven (Link to my 3C24 build). Lots of friendly help over there in general BTW.
I certainly would NOT spend extra money on fancy feet/fuses/binding posts/RCAs because you think it'll improve the sound. Sometimes I buy a certain binding post or RCA for more money because I like its form/function. Binding Post I Like. Never in a million years would I believe a fancy fuse buried in the middle of steel leaded parts could possibly improve the sound. There needs to be some possible scientific rational for using things. Just use quality parts from sources like DigiKey, Mouser or Newark.
Feel free to PM me if you want to talk privately.
Just curious, do you mind elaborating on light-weight power supply circuit? Thanks!