[sachu]

oh excellent news..congrats!!
 
I think i might have an extra pair of JFETs lying about..will pop those in and see what comes off of it on this board i am fixing.  THe symptoms seem identical so i am hopeful replacing JFETs will cure it.

 

[HeadphoneAddict]

Quote:

oh excellent news..congrats!!
 
I think i might have an extra pair of JFETs lying about..will pop those in and see what comes off of it on this board i am fixing.  THe symptoms seem identical so i am hopeful replacing JFETs will cure it.

Fingers crossed.

 

[ting.mike]

I have some extra quads in case anyone needs them. I have a few quads in the 10s and 11s and a decent quad in the 14s. 
 
The Exstata is alive and is making sweet sound. I can't listen to it for too long yet, as I'm still having trouble with DC-offset and Bias settings. I used a 12.0, 12.3, 12.3, and 12.6 set of J271.
The Bias is still unnaturally low (520+V is maximum, 260-0-260 input on PSU) though surprisingly the O2 sounds quite good out of it. The DC-offset is impossible to nail down correctly. It jumps anywhere between the range of 200mV to -200mV, likewise the output to ground measurement on the amp also jumps around. Reading on the other thread, I found Alex saying that offset within 1V is okay, so I that problem is solved. 
 

If you get offsets, at temperature, that are less than 1V that's the best that this amp will do and it is plenty good enough for headphones that thrive on hundreds of volts across their stators. And, the offsets will wander around due to various thermal fluctuations. This is normal too.
http://www.head-fi.org/forum/thread/447950/exstata-diy-electrostatic-amp-for-intermediate-diyers/1380#post_6205632
 
The only problem is getting the bias voltage to reach 580V. Right now I'm wiring the primaries on 220V, and secondaries at 265-0-265 gives me a 530V max bias. I can play around with different primaries (say primary at 200V, and get 300-0-300 secondary and it'll give me a 600V max bias, but I will be stressing the travo).
 
Here is a shot of the wiring. I took out the output and input wiring for the photograph.
 

 
Here is a shot of the PSU underside: (The resistor and diode are put down there because I am using larger 1000V caps and have no space on the top side)

 
And the two amplifier boards:
 


 
 
 

 

[Alex_O Rules]

Hi all!
 
My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
 
Thanks so much!!!
 
Alex_O

 

[HeadphoneAddict]

Quote:

Hi all!
 
My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
 
Thanks so much!!!
 
Alex_O

I think the 106 x 310 is the 12 inch panel (that is what 310mm is), and the 106mm is a little over 4" which is about right on my 12 x 12 x 4 par metal case.  Are you sure yours is 12 x 12 x 5?
 
Unfortunately I don't think I have any part numbers.  I can look at my emails from Sachu though.
 

 

[Sathimas]

Why has it become so quiet here?
 
Are the boards sold out ?
Nobody else building the amp at the moment?
 
I used mine only rarely over the last weeks since I moved to a new place
but I'm still very happy everytime I turn it on and enjoy the sound.
 
What are the future plans for the exstata?
(If there are any atm, I think Alex is busy with the ehha and cth revisions and the liquid fire ...)

 

[sachu]

Quote:

Hi all!
 
My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
 
Thanks so much!!!
 
Alex_O

The files were for a 12 x 12 x 4 par metal chassis. 
These XLR jacks should fit
 
http://www.mouser.com/ProductDetail/Neutrik/NC3FD-L-B-1/?qs=sGAEpiMZZMv0W4pxf2HiV0%252bKdhvD8lQRjG7MHFl3694%3d
 
This IEC should work i believe
 
http://www.mouser.com/ProductDetail/Schurter/61003200/?qs=sGAEpiMZZMv1TUPJeFpwblxZ%252bgbqW48rXGwWN2q2RkE%3d
 
 
And this should be the fuse holder i use.
 
http://www.mouser.com/ProductDetail/Eagle-Plastic-Devices/441-R314A-GRX/?qs=sGAEpiMZZMukmSYeDOiaDI%2f%2f6RnPbptRBNrw2pwyBDA%3d
 
Double check everything though with their individual datasheets.
 
Course, feel free to change the template to do your own thing.
Quote:

Why has it become so quiet here?
 
Are the boards sold out ?
Nobody else building the amp at the moment?
 
I used mine only rarely over the last weeks since I moved to a new place
but I'm still very happy everytime I turn it on and enjoy the sound.
 
What are the future plans for the exstata?
(If there are any atm, I think Alex is busy with the ehha and cth revisions and the liquid fire ...)

Yup. Boards are sold out.
 
Don't believe there are any more plans for the exstata. Think it has served its purpose with  more than 150 board sets made.
 

 

[Alex_O Rules]

Thanks everyone!
 
Do any changes need to made to accommodate the Cooper 78-S6S jack?  If so, can I get a hand with it?  I've never done anything with FPE, and given how expensive the panels are I don't want to mess up. 

 

[Sathimas]

 
Quote:

Yup. Boards are sold out.  
Don't believe there are any more plans for the exstata. Think it has served its purpose with  more than 150 board sets made.

 
Sorry to hear that - the exstata was fun to build and as far as I know the cheapest way
to enter the stax-world - on a high level I think. But nonetheless, 150 units is much more
than I expected.
 
Does anybody have a clue how often the EHHA or Bijou have been built?

 

[pabbi1]

Jeff @GlassJar would most likely know, as he is the sole source of boards, AFAIK, or certainly the greatest majority of them, as there may have been some rogue boards on the EHHA (we'll let the sleeping dog lay). It is sad that the 150 eXStatA units don't testify more, and, just maybe, won't be the end of that lineage.  I still use mine on an almost daily basis.
 

 

[BoilermakerFan]

I know of at least 6 sets of boards that haven't been built yet.  Most due to their builders lack of time.  Seems we all became busy at once.  I've sold all of my sets off to others with two sets going to existing who previously sold off their amps then had sellers remorse so they bought new boards.  Three others went to new builders.  I've only sold off all of mine since I have the other prototype to build so I felt I should let somebody else have the open source DIY boards. 

 

[Lou Erickson]

I have a set of boards from the run in late 2009, and have every intention of building them.  I believe I have all the parts as well.  I'll probably be here in a few weeks asking questions.  Just as I got the parts in, I also started classes to finish the degree I dropped out of fifteen years ago, and that consumed all my time.
 
I'm done with that in a week.
 
I have a couple of little warm-up projects to build - a Cmoy, a Starving Student, and an odd card for the Apple II - but then I'll dive right in to the eXStatA.
 
I have a nabu case to put it into to get started with and may do something fancier if I am that motivated.
 

 

[Alex_O Rules]

Hey all.  I thought I had more time for this project, but it looks like my work life is going to attack me for a few months.  If anyone has an eXStatA (or 717 or KGSS) they are not using and wishes to sell, please drop me a PM.

 

[gooky]

I was told I should make a post here if I'm interested in commissioning an eXStata amp.  Please pm me if you are able to build one, or have parts that you would like to sell, thanks.

Hanson
 

 

[drclaw]

It's been taken. Thanks!