[MaloS]

One of things that continuously comes up in discussions of e-static equipment is lack of versatility - you either use one of the few dedicated amp, mostly from Stax, or you buy an out-of-production transformer box and use power amps, but getting a transformer is an activity of its own.

There are 2 DIY designs for electrostatic amps - KGSS and KGBH, both very complex and high-priced, designed for driving one headphone, Omega 2.

That begs the question - where are others? For dynamic headphone you can find huge variety of SS, Tube, Hybrid amps, of various shapes, sizes, complexity, available for DIY builders.

But - for e-static headphones, given that there are fairly small amps available (SRM-252 is tiny), while it is definitely plausible to have a few designs for various tiers of headphone, the entire DIY market is stuck in two amps, and there is not even a published design of SRD-7pro, out-of-production transformer box which many would probably gladly build if the design was available.

Question 1: why?

Question 2: what are the specs for an amplifier to be able to run various electrostatic headphones?

 

[nikongod]

there are a couple other DIY able electrostatic headphone amps.
the good DR gilmore has published schematics for 2 more on headwize, and there are records for some of the older STAX tube designs on the internet.
Quote:

Originally Posted by MaloS /img/forum/go_quote.gif Question 1: why?

NOTE: i cant spell andrea cufoli so good...
andreia cufoli published a schematic for building a stax transformer using lundahl transformers. other transformers could be used, but he KNOWS that the only transformers worth using are lundhals in any of his designs. its sort of like saying that the only headphones worth owning are electrostatic.
i THINK it was andrea cufoli who published the schematic for yet another stax amp which used a single transformer to couple the output but cant remember.
ooh, there is another still in the book "valve amplifiers" by morgan jones.
Quote:

Question 2: what are the specs for an amplifier to be able to run various electrostatic headphones?

it depends on the headphones, preferences, and transformer.

generally it should have alarmingly low distortion at the necessary power while driving a reactive load. good luck.

 

[onyu]

here is a stax amp
I actually don't know much about diy

AURIDUX, a directly coupled Stax Electrostatic Headphone Tube Amplifier

maybe it is useful for you

 

[krmathis]

The DIY energizer by Andrea Ciuffoli, as posted by 'nikongod' above
the STAX Transformer

The Gilmore designs:
HeadWize - Project: A Current-Domain Electrostatic Amplifier for Stax Omega II Headphones by Kevin Gilmore
HeadWize - Project: All-Triode Direct-Drive Amps for Electrostatic and Electret Headphones by Kevin Gilmore
HeadWize - Project: Blue Hawaii Hybrid Electrostatic Amplifier for Stax Omega II Headphones by Kevin Gilmore

 

[akione]

It's that 500+ Volt bias that scares me ......

 

[utilisateur]

There's also these
[size=xx-small]English version if you scroll down in the sidebar[/size]

There is quite some praise in the german forum, the newest hybrid was aparently perceived as better than the BlueHawai and KGSS by some

 

[luvdunhill]

Quote:

Originally Posted by MaloS /img/forum/go_quote.gif There are 2 DIY designs for electrostatic amps - KGSS and KGBH, both very complex and high-priced, designed for driving one headphone, Omega 2.

what do you consider high price, or in other words, what do you think these cost to DIY?

what do you consider complex design, or in other words, what don't you understand, given the excellent articles at head-wize? Also, what is your electronics background?

 

[pabbi1]

Anything Marc (over?)builds is scary... now, about that BH...

Calling Spritzer...

Oh, I did see this - a 'micro-KGSS'.

 

[spritzer]

There are dozens of Stax amp designs out there using everything from opamps to really scary tubes but many are in Japanese and most aren't really good. I remember one tube amp that used two 12AX7's and two 12AU7's which could be very tiny. The Egmont (or what ever it was originally called 50+ years ago) could be built by a drunken monkey into a tiny chassis but it will never come close to the GES let alone the BH.

 

[kevin gilmore]

Good luck building the one with the 2sj109, as those are just not
available and single parts drift like crazy. I have been using the 6s4a for
more than 10 years now, and a small hybrid using 4 of them should
show up within 18 months, called the KGST. Uses the lsk389 as the
front end.

2) specs...

voltage gain 1000 (60db)
This is usually the killer for opamp based designs as they give up long
before 20khz

voltage swing a minimum of 1200 volts peak to peak stator to stator.
(spritzer will say that 1800 is better and it is) Very few tubes do this
in anything but huge packages, and the number of semiconductors that
can do this is small and decreasing every day.

full differential output absolutely required.

slew rate as fast as possible, >100 v/us and thd as low as possible,
<.01 % or it sounds like crap.

Able to drive 50pf pure capacitive load. Not so easy, especially for
things with opamps in them.

 

[spritzer]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif (spritzer will say that 1800 is better and it is)

Hurray for more power!!!

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif slew rate as fast as possible, >100 v/us and thd as low as possible, <.01 % or it sounds like crap.

It's good that you brought up slew rate as it is a very important spec in every amp and espcially in our current topic. The faster the amp the better.

 

[MrMajestic2]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif The DIY energizer by Andrea Ciuffoli, as posted by 'nikongod' above the STAX Transformer

Just checked the price for the Lundahl transformers: Ouch. Would be great to use this with my B22, but I think for that price I might as well build a KGSS.

 

[Icarium]

And now I must of course ask what tubes/semiconductors can do 1800 volts peak to peak ;p

 

[krmathis]

Quote:

Originally Posted by MrMajestic2 /img/forum/go_quote.gif Just checked the price for the Lundahl transformers: Ouch. Would be great to use this with my B22, but I think for that price I might as well build a KGSS.

Care to share how much they are? Guess you have been in personal contact with them, cause I have looked at their several times (in the past though) and never found any prices..

 

[spritzer]

Quote:

Originally Posted by Icarium /img/forum/go_quote.gif And now I must of course ask what tubes/semiconductors can do 1800 volts peak to peak ;p

There are plenty of tubes that can pull that off without breaking a sweat and much more even. Most of the obscure TV tubes were designed for HV operation and then there are the old transmitter tubes.

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif Care to share how much they are? Guess you have been in personal contact with them, cause I have looked at their several times (in the past though) and never found any prices..

Check out the US distributor site for prices, K&K Audio.