[ffdpmaggot]

I plan to build some electrostats and an amplifier, I understand how to build the electrostats, but I need some help with the amp, I plan to use this schematic here - http://www.tubecad.com/november99/page8.html could someone please identify where the DC current from the power supply enters the circuit, where the line in audio goes to on the circuit, and where the bias is on this circuit? Also, is this one channel, or two? Thanks.

 

[Avro_Arrow]

The line in is at the left side of the 12AX7 tube.
Power comes in on the right side, +310 volts, -310 volts and 0 volts.
The headphone out is in the middle, just above the 5965 tube.
There is no bias adjustment point.
The schematic represents one channel.

 

[ffdpmaggot]

Is there a "bias wire" present in these schematics at all? Also, what do the triangles represent?

 

[deadlylover]

The triangles are pretty much ground I believe, and the bias comes from the power supply.

 

[Costia]

Don't build the electrostatic amp and headphones yourself if you don't understand how it all works
There is seriously high voltage in there and if done improperly might injure or even kill you
Another thing that worries me in that schematic is that i don't see a current limiter or some kind of kill switch
it probably assumes your power supply has one
 
 

 

[ffdpmaggot]

There isn't anything special I'll need to do for the bias supply, is there? Just a single 550 volts dc line with a simple rheostat to the respective pins on the stax jack, right? I'm fairly comfortable working with high voltages, I've read up on what not to do, how to not be a moron with HV, and I know people with experience with HV that could assist me.

 

[FrankCooter]

Quote:

Don't build the electrostatic amp and headphones yourself if you don't understand how it all works
There is seriously high voltage in there and if done improperly might injure or even kill you
Another thing that worries me in that schematic is that i don't see a current limiter or some kind of kill switch
it probably assumes your power supply has one
 
 

 
X2 on the above post. You really need to completely understand not only the circuit, but also the safety factors involved before attempting a project like this. Despite its surface simplicity, this is definitely NOT a beginner's project.
 
Make sure you put a HV 5 meg resistor in series between the bias and the headphones. The last thing in the world you want for either yourself or the headphones is a low impedance HV source on the output.
 
This amp is essentially the "Egmont" circuit. It's been discussed both here and on "other" sites. 
 
Spritzer is the man you need to talk to.

 

[chinsettawong]

Hi ffdpmaggot,
 
I've built two amps using this very same schematic.  They sound nice.  I hope you can find something useful with my posts: http://www.head-fi.org/forum/thread/498292/my-diy-electrostatic-headphones
 
FrankCooter is also the man you want to talk to if you are looking to build some other different and unique amps for electrostatic headphones. 
 
Wachara C.

 

[ffdpmaggot]

I found your thread in a google search, brilliant work. Did you use the first TubeCAD design or the second one as the basis for your amp?

 

[chinsettawong]

I've only built the second one.
 
Wachara C.

 

[Uncle Erik]

You might want to pick up Morgan Jones' book on building valve amps. Loads of invaluable information about layout and design. It is worth every cent.

Good luck and please be careful - take the other posters seriously.

 

[ffdpmaggot]

Chinsetta, in that case, if you don't mind, I will be printing out your schematics and using them rather than the tubecad plans, they are much more detailed and are formatted in a manner that should be easier to wire up. Again, brilliant work man, I hope I can come close to what you did with this project.

 

[pabbi1]

There are other amp options, like the eXStatA... might want to inquire if you can find boards.
 
Ditto on the build warnings, but the eXStatA was designed for intermediate stat builders, and is pretty straightforward..