eXStata DIY Electrostatic Amp for Intermediate DIYers

[Beefy]

First things first, once the amp is fully warmed up, touching the sinks doesn't do anything. Only seems to help when the amp is cold.

But now for the interesting part. The buzzing is definitely present when the back grille is installed, and seems to stop soon after the grille is removed. I say seems to, because the hockey is on the TV, and it is hard to tell for sure with the background noise......

Perhaps there is a slight short from the bias to one of the stators when the back grille is installed? Now this is obviously a bad thing, but it doesn't seem to follow that the heatsinks could relate to this in any way.

[EDIT] No, still some small crackling with the back grille removed, but it is an improvement. This is driving me nuts!

 

[luvdunhill]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif If there is any way you can attach another set of headphones that will really help. We need to have some kind of control in the testing. What we don't is: is it the headphones? is it the amp? or is it the combination? If we can eliminate any one of these ...

agreed. Beefy did state: "Doesn't seem to show up on my SRD7-SB, but I need to do more tests to confirm this tonight." Perhaps he'll have a second to give this a quick whirl...

 

[studeb]

i would double check the grounding, and ground all four heatsinks. I soldered resistor wires to the heatsink pins, and have had trouble with those breaking, as well i had to ground all four heatsinks on each amp.

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif I haven't yet tried to repeat the specific effect of the touching heatsinks losing effectiveness. Perhaps it is more a case of things getting worse as the amp heats up?

 

[Beefy]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif agreed. Beefy did state: "Doesn't seem to show up on my SRD7-SB, but I need to do more tests to confirm this tonight." Perhaps he'll have a second to give this a quick whirl...

I'll hook it up now.

 

[Beefy]

Now it is not even doing it with the Exstata, let alone the SRD7. I absolutely hate troubleshooting intermittent problems

Will sleep on it and do some more testing tomorrow night.......

 

[Sathimas]

Got the measured jfets back from my friend today.

The best (and only) quad I have is:

10,44mA
10,16mA
10,86mA
9,86mA

Would this be good enough? Or is it strictly necessary that the value does not drop under 10mA?

 

[runeight]

Probably good enough.

 

[Beefy]

Doing more testing, and the Lambdas are dead silent tonight......

 

[Postal_Blue]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif

LOL, I a terribly sorry you are struggling with your amp, honest I am. But. holy smokes that gif got me giggling.

 

[pabbi1]

Well, I'll chime in with a different observation while we await additional data points...

One question folks might have about this amp is how well it scales. Admittedly I am fanboi numero zero, but through the Cambridge 840c I always had the question about how much was the player / DAC and how much was amp? And I had this nasty clip on a few Tool cuts (a daily dietary item), so I changed sources.

Now, the Cambridge is definitely a nice player, but quite mid-fi, good above it's cost, but still limited by it's manufacturing budget. I am also an even harmonic guy, not too much interested in the 3rd order 'horrormonics'. So, I got a tube output stage source.

The CD-1 is quite different from the Azur in a pretty dramatic, but quite good, way... psychoacou$tics aside. The main point here, for purposes of this design, is that eXStatA scales right with it. Perfectly. There is NO wonder if the amp is holding the player back, at all.

Off to Tool 'Aemina', then Monster Magnet, with a full compliment of Radiohead tomorrow night. So far the 'poor man's' stat amp is keeping up with the $4k source, far better than others we might mention. The adjustment once again is to listen for what is presented, not what we remember former presentations to be like, from sound staging, instrument placement, and just the overall mix.

Oh, yes, useless without pics.

Edit: And, yes my damn black oxide threads and bolts will be here tomorrow... oy.

 

[BoilermakerFan]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Well, I'll chime in with a different observation while we await additional data points... One question folks might have about this amp is how well it scales. Admittedly I am fanboi numero zero, but through the Cambridge 840c I always had the question about how much was the player / DAC and how much was amp? And I had this nasty clip on a few Tool cuts (a daily dietary item), so I changed sources. Now, the Cambridge is definitely a nice player, but quite mid-fi, good above it's cost, but still limited by it's manufacturing budget. I am also an even harmonic guy, not too much interested in the 3rd order 'horrormonics'. So, I got a tube output stage source. The CD-1 is quite different from the Azur in a pretty dramatic, but quite good, way... psychoacou$tics aside. The main point here, for purposes of this design, is that eXStatA scales right with it. Perfectly. There is NO wonder if the amp is holding the player back, at all. Off to Tool 'Aemina', then Monster Magnet, with a full compliment of Radiohead tomorrow night. So far the 'poor man's' stat amp is keeping up with the $4k source, far better than others we might mention. The adjustment once again is to listen for what is presented, not what we remember former presentations to be like, from sound staging, instrument placement, and just the overall mix. Oh, yes, useless without pics. Edit: And, yes my damn black oxide threads and bolts will be here tomorrow... oy.

Al, I know you just got it an all, but can you please disassemble it in order to take very good pictures and full dimensions of the top disc ring and the lid?

I need that setup for my Shigaclone!

 

[pabbi1]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Al, I know you just got it an all, but can you please disassemble it in order to take very good pictures and full dimensions of the top disc ring and the lid? I need that setup for my Shigaclone!

Manana when I have to disassemble the rack for the new parts. I'm actually still warming it up from shipment, as it is still cold to the touch.

Oh, and here is a pic of the insides... I'll be taking an exhaustive series this weekend just to see how many ways I can violate the warranty.

 

[macm75]

Have not listened to my eXStata for a week. It's been apart waiting for a permanent box. Finally finished minutes ago (forgot to put the knob on). I tested the voltages again - look good. Now I can finally start listening.

 

[macm75]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif CD-1

Congrats! Must be a wonderful experience particularly with those HE60's.

 

[gilency]

I love the proto I bought from Alex, and when more boards are available, would love to jump in and build one myself. In the meantime, as soon as time permits, I may look for a nicer case.
Haven't been able to buy the O2's for financial reasons (kids going through college and burning money like crazy) but I will, eventually.
This amplifier is wonderful and makes my Sigma Pro sing.
I just hope there is another run soon......