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An all DHT amp for Grados


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alldht.jpg

MachMat VCCS filament supply

Gary Pimm CCS

Design by HF member Roam, traced out by me while I was over at his place to pick up transformers for my own project. Yes I have his permission to post it. I spent about 20-30 minutes listening to it out of his Capitole CDP and my RS1, this amp is good, stupid good, but also stupid expensive thanks to the transformers and Emission Labs AD1 tubes. He says he has what should be a slightly purer version in the works using WE 205E's on the front end, but it may sacrifice a bit of bandwidth. No PSU schematic yet as he's still waiting for some parts to come in so it's running off an adjustable benchtop PSU.

Can also be built with Lundahls, using the LL1676, LL1635, and LL1620, with something like the Prometheus TVC as the volume control. Still not cheap, and it'll still weigh a ton.

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Interesting. Could you please ask Roam to join HC? He's one of a handful of people on HF that seems to actually know what he is talking about when it comes to amplifier design. Not that I'd know, I'm not in the handful. He would fit in well here.

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Very expensive. If you found someone to build one of these for you

and did up the power supplies to the level of the rest of it, its going to

be $10k. At least 2k in parts (i'm probably way low) if you build it yourself.

DHT amp for electrostats is easy. Going to need a fork lift for the

required power supply. First person to show they are serious by

putting $15k in a bank account and i'll publish the schematics.

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How much is expensive? Just curious.

He said it would be around $3k to $3.5k in parts alone for the Lundahl version, the tubes by themselves come out to something like $1.6k. Way beyond my budget unless I win the lottery or something, and doing a good parts layout is likely beyond my skills as well.

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DHT amp for electrostats is easy. Going to need a fork lift for the

required power supply. First person to show they are serious by

putting $15k in a bank account and i'll publish the schematics.

I'm volunteering ojnihs :laugh:

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That is a very nice and expensive amp you've got there. :kitty:

There is at least one published DHT amp design for electrostatics. It was in the second edition of the Morgan Jones "Valve Amplifiers" book and aptly called "The Beast". The whole chapter is a great read as he talks about how scary it was to test it and how none of his equipment was meant for 1kV+... ;D

The cost is a major obstacle so I went with a new BH instead as 15k$ for a headphone amp is insane. A properly designed DHT amp will drive the Quad ESL57, KLH Model Nine and Stax F81 directly with ease so it might be justified for a hardcore ESL nut... ::)

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The cost is a major obstacle so I went with a new BH instead as 15k$ for a headphone amp is insane. A properly designed DHT amp will drive the Quad ESL57, KLH Model Nine and Stax F81 directly with ease so it might be justified for a hardcore ESL nut... ::)

So out of college, my second speaker system was tripple stacked quad esl 56's with decca ribbon tweeters.

Owned a pair of KLH model 9's for a few years till the tweeters blew up.

Had a pair of accoustats for quite a while too.

My first surround system was 4 x quad esl 63's.

Hardcore ESL nut ????? You Betcha

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So out of college, my second speaker system was tripple stacked quad esl 56's with decca ribbon tweeters.

Owned a pair of KLH model 9's for a few years till the tweeters blew up.

Had a pair of accoustats for quite a while too.

My first surround system was 4 x quad esl 63's.

Hardcore ESL nut ????? You Betcha

Yup, you do more then qualify. ;D A triple stacked ESL must have been something else as I was mightily impressed by a double stack.

Sounds like that amp wold be a pain in the ass to haul to meets ;D

Who needs meets when you have the best... ;)

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  • 4 years later...

I've been following this thread myself. There's some interesting discussion going on, mostly about transformer design in relation to headphones. The design being discussed above is only going to work for something very sensitive, like a Grado. I imagine that each of those OPT are going to cost more than an RS-1. I wouldn't mind having a pair if the price were right. The Russian 4P1l and it's big brother the 6p21S are both excellent sounding tubes that are plentiful and dirt cheap.

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I'm working on a few Stax DHT amps but nothing as insane as Kevin's 12 tube monster.  Not going to start any new projects anytime soon though, it's time to clear some of this half finished stuff.  :)

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Nothing concrete really but one will have only two DHT's in it, rest will be transformers.  Not meant to sound nice though, it's just supposed to be bonkers.  :laugh:   Well that and very, very expensive. 

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From time to time I think of building a "poor man's" all DHT electrostatic amp. One idea is building an "Egmont" type circuit using Eimac 3C24's. The 3C24 is sort of like a DHT 6SN7 on steroids. Usually available on Ebay for about $25. The big problem, besides the exposed plate and grid connections, is the filament supply complexity. With a little creativity, you could probably do it with 2 6A supplies per channel. At the very least, it would be an interesting novelty, and might possibly be considerably more.

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