Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › A DIY electrostatic amp for intermediate DIYers?
New Posts  All Forums:Forum Nav:

A DIY electrostatic amp for intermediate DIYers?

post #1 of 593
Thread Starter 
I have long lamented the lack of any kind of electrostatic amp that a less than utterly advanced DIYer can safely build.

There are plenty of designs out there. Some of them even with board artwork available. But there doesn't appear to be anything for which you can buy a professionally made board and follow a bill of materials that includes parts that are easy to acquire.

Looking around at the available designs, there seems to be a preponderance of "no compromise" designs that would be extremely difficult for an intermediate DIYer to build on perfboard, and which cost hundreds of dollars to assemble. And then there are designs that are heavily compromised, or seem to be designed to fulfill a whim or to achieve a goal that is tangential to the objective of good sound.

I think the electrostatic contingent of the headphone enthusiast community has expanded sufficiently over recent years that there could be sufficient demand for a well designed, good sounding DIY electrostatic amp with a standardized build and professionally printed boards.

The problem at hand, though, is who will make this happen? I'm enthusiastic for sure but i don't have the time or skills to bring the project to fruition.

I've decided that instead of just continuing to wonder if it will happen, i should actually see who i can get on board and maybe try and make it happen.

I think the basic goals should be:

1: A total build cost (before casework) that is well under $300.

2: Strictly using parts that are in current production or which are otherwise in abundant supply. If possible, no or little reliance on NOS tubes.

3: No exotic iron in the power supply. Something off the shelf from a major vendor with a good north-american distribution network, please! Even if we have to buy two of them.

4: Must accept single-ended input. Even if it can be built with balanced input, it must be able to accept SE input. Whether that means including an SE-to-balanced conversion circuit on the board is dependent on the design chosen.

5: Powerful enough to drive an SR-Sigma in standard configuration. Omega-level power optional (power supply upgrade, probably). We're not trying to replace the Blue Hawaii here.

6: One (1) bias supply design that provides 4 or 5 different bias voltages in a single build. Certainly anywhere between 200v and 640v. 1kv for jecklins shouldn't be out of the question, perhaps with the builder modifying the circuit. I forget if there were 'stats with bias lower than 200v, and i don't recall what bias voltage the Beyer ET-1000 takes. Whether this is a supply with multiple outputs or a supply with a multi-position switch is up for debate.

As for solid state vs. tubes I'm agnostic as long as these basic goals can be met. I hope to see a day when there are a few of each available to build.

I envision the physical build as having two channels on a board that can be cut in half if the builder's case demands it, and another board with the power supply and bias supply.

I doubt there is any reason to come up with a completely new amp design - there are many designs out there - but the project may involve updating an existing design to accept obtainable parts, or to have a more pragmatic, more appropriate, or more affordable power supply.

So, who else is on board? I'm just a guy beating a drum. I'm willing to be some kind or project leader but i don't have the skills to do this on my own.

How many of you would be interested in building this sort of amp?
post #2 of 593
You know that I'm in. Hammond has a nice lineup of transformers which we can use and the SE/balanced input isn't a problem as with most circuits you just ground the - input for SE use.

The bias supply could be very complicated for those different bias settings but a single 700v supply and then using resistor dividers to get the desired output.
post #3 of 593
Admirable goal, tough row to hoe.
post #4 of 593
Thread Starter 
Quote:
Originally Posted by spritzer View Post
You know that I'm in. Hammond has a nice lineup of transformers which we can use and the SE/balanced input isn't a problem as with most circuits you just ground the - input for SE use.

The bias supply could be very complicated for those different bias settings but a single 700v supply and then using resistor dividers to get the desired output.

There are opamp solutions to the SE-to-balanced question, and purpose-designed ICs as well. Transformer-coupled works for me too. And some amps don't need you to supply a solution.

As for the bias supply, I figure it's reasonable to expect that most hobbiests will want stax normal and pro bias and maybe 620v for the ESP-950. I forget what the ET-1000, HE-90, HE-60, and other oddball 'stats want. I know a lot of them can work ok with a stax supply, but it would be nice to get closer to the designed voltages.

Like you say, it could be as simple as a rotary switch to select which divider you're using.

I just don't want to end up with a design where we've got the two major stax voltages covered but anything else means you're on your own, off the reservation, and have to come up with some other supply.
post #5 of 593
It would seem that an updated KGSS would fit all of your requirements pretty well, and probably the main thing would be designing a new pcb for it. Swap the 2SK389 with LSK389, update the power supply a bit, and you are basically there.
post #6 of 593
Thread Starter 
I agree - I'd love to be able to buy KGSS boards.

It looks simple enough - but not so simple that I'd dare build it on perfboard.

At 24v or 36v I'm comfortable with the concept that i could have a short somewhere or something hooked up completely wrong.

But not at 350v. Not with that many parts. I still haven't even attempted a simple point-to-point tube amp, though i do believe that a 6n6p-based cavalli-jones would be Pretty Neat.
post #7 of 593
I know this is a headphone forum, but are you talking about an amp for headphones or an amp for loudspeakers? I've been wanting to build a set of ES loudspeakers, last thing I need is another project but still

I've always wondered about using microwave transformers for the ESL amp, they have the turn ratio required just not sure if they meet any of the other specs, plus, they'd be cheap(or even free).
post #8 of 593
Thread Starter 
Just for electrostatic headphones. Direct-drive for ESL speakers is a whole different game.
post #9 of 593
Quote:
Originally Posted by ericj View Post
Just for electrostatic headphones. Direct-drive for ESL speakers is a whole different game.
Ohhh, nevermind!
post #10 of 593
I would also be interested in such a design. I've picked up the iron, tubes and a few other pieces to build Dr. Gilmore's all triode amp point-to-point, but it will probably be a couple of years before I can get to it. If there was a PCB-based amp I could knock off and case in a weekend and a couple of evenings, I would fit it in and get a pair of Stax.

Another benefit of such a design would be that the custom builders could start offering electrostat amps to a wider audience at a fair cost. Right now, you either have to do a very serious DIY build or fork over a few thousand to someone who may or may not provide you with an amp. But if there was a PCB and non-exotic parts, electrostatic amps would be as accessible as a Beta22 or M^3.

I think this is a great idea and would be happy to help support it.
post #11 of 593
Sounds nice, but the 700V lethal voltages are a bit scary.
post #12 of 593
Thread Starter 
Quote:
Originally Posted by FallenAngel View Post
Sounds nice, but the 700V lethal voltages are a bit scary.
Yeah, but 700v is still in the neighborhood of "not substantially more deadly than 100v".

If you can build a HV tube amp, you can build a 'stat amp. Just remember to keep one hand in your pocket at all times, and respect the voltage.

This wouldn't be for every DIYer for sure. But it wouldn't be strictly for advanced experts either.
post #13 of 593
Hell yes! I'll buy a stat if this comes to pass. The parts hunt for the DIY builds has kept me from getting a stat.
post #14 of 593
Parts hunt is 50% of the battle - I have been hunting electrostat amp parts for 3 months, almost full time. Not the easiest task, and minimum buys for only one part make it pricey for single builders to even try it.
post #15 of 593
Quote:
Originally Posted by pabbi1 View Post
Parts hunt is 50% of the battle - I have been hunting electrostat amp parts for 3 months, almost full time. Not the easiest task, and minimum buys for only one part make it pricey for single builders to even try it.
Perhaps PCB + Q pack group buy is in order then...
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › A DIY electrostatic amp for intermediate DIYers?