[johnmatrix]

I have most of my KGSS built with the power supply operational and I have one last question. I went with the MAT02 dual bjt as apposed to the dual fet used in the schematic as per a suggestion found in the addendum. I was wondering how to wire this up. Right now, I have the base tied to the input, the collector tied to the diodes, and the emitter tied to the output end. Thanks for all the input and for the transformer help you guys gave earlier as well.

KGSS Schematic

HeadWize - Project: A Current-Domain Electrostatic Amplifier for Stax Omega II Headphones by Kevin Gilmore

 

[johnmatrix]

Well, I emailed the guy who used the MAT02 and he told me to simply match the pin numbers to use the MAT02 in the circuit. I did that and I have quite a lot of drift in the circuit. I cannot get the outputs to be stable at 0V DC. This is more than likely due to the BJT not being as suited to this circuit. I will look over my circuit, but I will probably order the dual JFETs as a backup.

 

[johnmatrix]

Another quick update

I got the 2SK389s in and now the circuit seems more stable and I can dial the outputs to 0VDC. However, a new problem has arisen. There is a buzzing sound when I listen to my headphones. However, the channel and intensity of the noise switches as the volume is increased and finally disappears at full volume. I have tried switching pots, which only served to change which channel the noise starts.

I am currently using cheapie 250k pots of unknown origin as they are the only 4 gang pot I could find. I have all 4 gangs going to a common ground from my circuit. The KGSS is a balanced circuit and I am using the signal from the RCA as + and ground from the RCA plugs as -. If anyone has any suggestions, please let me know.

 

[borisov57]

Do you have grounds of your source component and KGSS connected ( RCA - to KGSS ground ) ?

 

[johnmatrix]

I do not have them connected.

 

[borisov57]

If you want to use balanced connection, you can connect grounds of you source with KGSS, connect + of your source to + input of KGSS, then solder resistor to ground in your source ( or in RCA jack ) and connect it to - input in KGSS. Resistor value should match output impedance of + output.

If you want unbalanced connection, ground - input of KGSS, connect + output to + input and connect grounds of your source and KGSS together. In this case you can use dual gang potentiometer.

 

[luvdunhill]

Quote:

Originally Posted by johnmatrix /img/forum/go_quote.gif Well, I emailed the guy who used the MAT02 and he told me to simply match the pin numbers to use the MAT02 in the circuit. I did that and I have quite a lot of drift in the circuit. I cannot get the outputs to be stable at 0V DC. This is more than likely due to the BJT not being as suited to this circuit. I will look over my circuit, but I will probably order the dual JFETs as a backup.

you need to adjust the front end to use the MAT02. It's not plug and play. Why didn't you do the other adjustments that were present in the headwize addendum? Decided to pick and choose?

 

[johnmatrix]

I decided to pick and choose and got bit in the butt. Oh well, the 2SK389s work well. I will try to modify the front end in the future. Right now, I have the amp running at 95%. There are some intermittent noise gremlins most likely caused by the strain on the unmounted jacks. I just need to shorten the wires, case this bad boy, and I am done. I am currently enjoying the vastly superior sound from my ESP-950. Thanks for all the help.