Here are the schematics for my 845 electrostatic amp. Sorry for the hand drawings, but it's the way I've done this stuff for 40 years so it's a little late in the game to change   Electrically it's a pretty basic design. A simple 3 stage zero feedback single-ended design with a phase-splitting...

    This thread has gone flat. It's a shame, because in my opinion, after trying everything else, Stax makes the finest headphones ever produced.   So here is my contribution: a DHT based electrostatic headphone amp. As far as I can tell, this is uncharted territory.  I'll be posting full...

Want to express my appreciation for the time and effort you guys have put in to making this meet happen. Your enthusiasm and dedication are what makes this forum a community.   I've been attending NorCal meets for over eight years. Always have a blast. Unfortunately I won't be able to make...

First rule of digital audio is to buy used. Whatever the "flavor of the moment" is today, you'll see it on Audiogon next year for about 50% off the original price.   Extrapolating your tastes, and given your original price point, you might want to look at a Benchmark. If you're willing to...

Congratulations Alex!   Very clean build for a first project!   I really like the way you customized the case with the blowtorch.   This amp should give you many, many hours of enjoyment. The music will be great, but every time you turn it on you'll get the additional and unique thrill of...

Had a great time as always!   Thanks and kudos to Warren, Ethan, Jude, and all the behind the scenes crew that put in the sweat so that the rest of us could share a few hours of fun, music, and friendship!   Personal highlight was being able to hang out with fellow DIYer's Zashoomin and...

  At the moment it's just a breadboard. PM me if you're interested.   Appreciate your interest.

  In a commercial or public fully balanced design you pretty much have to go with either a LTP input or an input transformer. Building a personal amp, I would make it with either single-ended or balanced inputs, but not both. I like circuit simplification.   Not sure you can use CCS plate...

 I probably won't build a Megatron, but I would definitely build Kevin's direct-drive DHT amp if the materials costs can be kept to a couple of $k. Probably not his approach, but the only way I can think to do this for a reasonable amount would be to use Russian tubes like the 4P1L in the front...

  In general, I too prefer DC coupled amplifiers, but great amps can be built with all coupling topologies. No matter what you're listening to, no matter how extreme the equipment is,  there are always going to be  capacitors somewhere in the chain. Same goes with transformers, which are a...

Really appreciate you starting this thread.   There's a huge amount of work in a project like this and it's a great thing to share the results with us all.   Hope to see your Megatron at the upcoming NorCal meet.   I'll be there with my 845 electrostatic amp.   Should make for some...

Thanks for the advice! You guys pretty much confirmed my suspicions about expensive boutique caps and saved me a nice chunk of change in the process.   I went ahead and ordered 10 of the Russian MBGO's. I will bypass them with the standard Russian military teflons. I can live with the 160V...

I recently built a simple 2 stage balanced OTL amp for the HD800. The amp is a 112a DHT voltage amplifier  directly connected to a paralleled 6BX7 cathode follower. Output impedance is about 100 ohms, which is fine for the 300 ohm HD800's. The output capacitor is currently a generic 70uf...

I'm not really a fan of the HD800, but I've been listening to a friend's pair for the last few days with my Metrum Hex. (Amp is a balanced DHT OTL homebrew design ) . The Hex definitely does  good things for the HD800's.

Very creative and artistic use of normally banal  household materials!   Looks like something Don Draper would have in his office.   Love that "Mid Century" look.   Thanks for reviving this  very interesting thread.

  What kind of man only uses two 845's in a headphone amp?   EIGHT !!!! I like that!   Go big or go home!   Of course these 845's will need appropriate drivers. It could be done "Sakuma style" with 845's employed as drivers as well as outputs.   If somebody wants to front me $50k, I'll...

I appreciate the compliment, but I am not an expert on the 845, amplifier design, or electronics in general. I'm a pretty decent technician, and I've built a fair amount of audio equipment, but in the end I'm an amateur hobbyist.

Although I've worked a lot with tubes of this type, I've never actually measured the distortion.   According to RCA the 5% figure is at 10W  output.   In neither application discussed  here is the output power anywhere near that level.   I could be wrong, but I would expect the distortion...

Here's a couple of ideas that might aid in troubleshooting. Bear in mind that I have never built or even seen a Megatron.   Milos - Despite the obvious damage to your supply board, you probably have the easier task. Almost certainly you have a wiring error, solder bridge, or reversed...

As far as I know, there's no such thing as a "Stax transformer Amp" in the usual way one thinks of amplifiers. What is being referred to here is the SRD "energizer", which is simply a step-up transformer with a bias source. Same as your WEE.   The "energizer" assumes the character of whatever...

Looks like I can make this one. Sign me up for a table. Will be bring a Stax based system. Exact line-up to be determined.

  Been there, done that. Sounds like every project I've ever built.   Congratulations on a superb build of a superb amp. I am really looking forward to hearing this amp, Just looking at the circuit , it looks like something I would be attracted to.   Like to hear your comparisons of this...

If memory serves me correctly, the EL34's in the BHSE are run with standing plate currents in the 20mA range. This is barely breathing for an EL34. Good ones should last 25 years or more at this rate.   The EL34 was one of the last major developments of the tube era. It was specifically...

You probably know this, but Mesa does not make tubes.  No knock on the tubes, but they are most likely rebranded Sovteks.   The best places to learn about EL34's are guitar amp forums. On average,  these guys have way more knowledge about  types and brands of tubes than the audio crowd.

  You don't have to.   60's/70's East German RFT are still available in matched quads in the $250.00 range. They're not quite  NOS Mullard/Telefunken quality, but they're superior to any of the modern stuff I've heard. Plenty on Ebay as well as other sources.