eXStatA Build Thread II - Page 19

That does not look like an exstata. "Purple Haze", is that the name of the commercial electrostatic amplifier by Cavalli Audio?

No, this is a prototype of something quite different... just letting you guys know I'm not slacking. Pics with the purple case tomorrow after my finish dries. Don't think this ever sees the light of day as Commercial nor DIY - mainly because the tubes are already really scarce.

But, this is the origin of 'Purple Haze' (purpleheart):

Pretty sweet Kewlio!

Quote:

Originally Posted by pabbi1 

If anyone is still needs 6s4a, I have another batch - just have to sort and test, along with a bunch of other triodes.

 

Oh, and a little pron, just for good measure.

 

New power supply?

Love the Stax 5 pin socket.......

I need an opinion sort of thing again. This time is about the way to mount R31~R34 for the hybrid version. I see three choices here:

To all the hybrid builders out there, how are you mounting your R31-R34?

good progress tonight.........power supply came up perfectly, LEDs lit when they were expected to and outputs measuring

311 and 305 V output

and

327.4 and 328 volts at t1 and t3 testpoints.

bias adjusted high to 580 for stax pro and 230 for stax normal. i have a little more wiring to do on the hybrid board (6.3v heaters, heat sink ground wires, input and output signals, volume control) so i probably won't get to music for another day or two

question #1: my antek toroidal transformer has dual set of 6.3V output wires. should i use one set for 1/2 the tubes, 2nd for the other tubes?

question #2: for the star ground, should this also connect the A/C ground wire/chassis?

Quote:

Originally Posted by cat6man 

question #2: for the star ground, should this also connect the A/C ground wire/chassis?

Yep. Good idea to connect it through a ground loop breaker though.

Quote:

Originally Posted by ujamerstand 

I need an opinion sort of thing again. This time is about the way to mount R31~R34 for the hybrid version. I see three choices here:

 

To all the hybrid builders out there, how are you mounting your R31-R34?

I go vertical on the resistors, then angle the leads down.  Opposite of your #2 sketch.  I also use a round set of needle nose pliers to hold the lead near the resistor to keep from cracking it. 

oh, so close......... hooked up the power supply to the hybrid amp (no connection to either inputs or outputs though) and no smoke, which is a good start.

rails are at or above 300V, as they were with the dummy load on power supply, and all tubes are biased and glowing nicely.

however:

measuring each amp board i get 12v and 20v between each of the two output pairs, no way adjustable to below 1v with P2

measuring one output side to ground i get over 100v on each, which convinced me something is definitely wrong.

any ideas?

do i need to load either the input or output before making these measurements?

oh, so close......... hooked up the power supply to the hybrid amp (no connection to either inputs or outputs though) and no smoke, which is a good start

measuring each amp board i get 12v and 22v between the two output pairs, no way adjustable to below 1v

measuring one output side to ground is get over 100v on each, which convinced me something is definitely wrong.

any ideas?

i can make measurements or send pix if needed

thanks

Quote:

Originally Posted by BoilermakerFan 

I go vertical on the resistors, then angle the leads down.  Opposite of your #2 sketch.  I also use a round set of needle nose pliers to hold the lead near the resistor to keep from cracking it. 

Too late. :( I've tombstoned them yesterday.

Quote:

Originally Posted by ujamerstand 

Too late. :( I've tombstoned them yesterday.

 

No big deal.  I just do the angled lead to minimize the lead length. 

Closer and closer to start my SS. My first ever amplifier (a Cmoy of course) went without a hitch. Building a better one next (JDS labs) before I start my eXStatA.

Many thanks to Frank Cooter for the Stax connectors.