Ultrasimple MM/MC RIAA Preamp mkIII

[GlidingDutchman]

A friend of mine (Ludo) tweaked the circuit by Mads K.

I a having trouble getting it to work so I thought I post it here for some discussion.

 

[peranders]

Have you checked the working points for all three JFET's? Are the JFET's capable of 12 mA Id?

 

[GlidingDutchman]

Have you checked the working points for all three JFET's? Are the JFET's capable of 12 mA Id?

20mA max...

D

 

[Conrad Hoffman]

You're at the mercy of whatever current flows with the gates grounded (Idss?, I forget), and this can vary. You might have to adjust the upper three resistors to get the voltage drop you want. Other than that, it looks like it should work fine. I assume the gain is rather low and another gain stage has to follow this.

 

[GlidingDutchman]

You're at the mercy of whatever current flows with the gates grounded (Idss?, I forget), and this can vary. You might have to adjust the upper three resistors to get the voltage drop you want. Other than that, it looks like it should work fine. I assume the gain is rather low and another gain stage has to follow this.

I guess so...

Conrad - this design stems from here: http://www.diyaudio.com/forums/showthread.php?s=&postid=1550522

and the unit, as designed by Mads K works just fine as it stands with my Kiseiki Purpleheart Sapphire low output MC cartridge...!

D

 

[tschrama]

If you really want to optimize the circuit, read the optimum Voltage supply idea of Nelson in:

http://www.diyaudio.com/forums/showthread.php?postid=1552988#post1552988


and posts before there...