Jump to content


kevin gilmore

Recommended Posts

You only need about 90-100mm in height so 3U is plenty.  This one was built into a 3U chassis:




I'll take better pics when I prepare to list it for sale (only need one amp here) but there is a lot of room in there.  That chassis is 300mm deep which will work just fine with the KGST power supply.  It's just slight bigger than the one I used in that amp so we could use larger capacitors (in diameter that is) and put proper heatsinks on the 10M90 current sources. 



Did you build this one at 400v?


Yup, this one is running at 400V and sounds just lovely with RCA tubes.  A slightly different take from the KGSSHV and it's fun to compare it against the mini KGSSHV given the similarities in PSU, voltage and power. 


The servo settles at around 2V for one channel which is good as I could just manually adjust it to 6V.  The other one hovers around 0V.  Not bad at all...

Link to comment
Share on other sites

Hi Birgir..... I am too new to Head-Case and I can't pm you or reply to your ad in the Trader Section. I'm interested in building the KGST and saw a few nice pieces in your ad that I would like to purchase. Please pm me if this is possible.


Link to comment
Share on other sites

coming soon to a file server near you



4.15 x 4.17 inch


think of it as a cheap swiss army knife of electrostatic amplifiers

works with any standard dual triode suitable for voltage 1 per channel

Russian 6n1P, 6cg7,6fq7,ecc99,12bh7....


NOT designed by morons with just a digital voltmeter

NOT open loop

Not high distortion

rationally priced

(you get where I'm going here)

Edited by kevin gilmore
Link to comment
Share on other sites

The real problem are the tubes as not many can handle more than 300V.  Push them hard and it all falls apart...  The only dual I can think of that is rated for 500V is the 6CM7 but it's a dissimilar triode so not suitable for something like this.  That said some of the computer tubes and TV tubes were meant to handle 600V peaks (or even higher) so they might fair well. 


The amp features switchable heaters on the board for 6.3V so either pin4 and 5 or pin4+5 and 9 for the 12V units.  It also has switchable CCS so the current can be lowered with a jumper for tubes that can handle less power.  Right now the list of tubes this one can use is : ECC99, 12BH7, 6N6pi, 6CG7/6FQ7, E182CC, 6840, 6350 and 5687.  Should be more out there...

Edited by spritzer
Link to comment
Share on other sites

The plus side is also how cheap it is to build and everything is in current production.  No SMD parts either as the voltage is low enough to use KSA1156's and Antek transformers will work perfectly.  A pair of ECC99's is about 35$, 12BH7's less than that and 6N6pi's way less than that.  :) 


I also bought some parts to try a KGST with current made tubes. 

Link to comment
Share on other sites

If you want to run it at +/-400V then you need 325-335VAC rails.  280VAC for +/-350V.  For current 110mA is sufficient but I'd shoot for 140-150mA to be on the safe side. 


30-36VCT is about 500mA. 


Heater windings should not be CT as they have -400VDC floating on them.  You have to have two heaters or you will have massive problems so one for each board.  1.5A is more than enough to account for the variables in the tubes. 


No soft start for me as I simply don't think it is needed.  The tube won't arc at these low voltages.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.