-Jack

can you post a pcb layout for the schem?

can’t piece together with the schem since im not that really familiar with schems.

thanks in advance.

doro

Very nice design! I have a couple of questions. I’ve not actually heard the unit, but was wondering if there’s any audible noise associated with the [J-FET] TL072 in this particular circuit. I’ve used this IC in “line level” applications with good results but with lower level signals I often needed to go to something quieter such as the [bi-polar] NE5532.

Also, is the [unlikely] presence of 48V phantom power a concern? I’m designing a special application “sub-mixer” with a couple of low impedance balanced line outputs to feed a house PA system. Like yours, my signal ground is midway between V and gnd so I too need to cap couple to the outside world. But it occurred to me that my rig could very well find itself connected to a console input with 48VDC phantom power present. Yow! This would therefore require two additional considerations. (1) The voltage rating of the coupling cap would need to be increased, and (2) the polarity would need to be at both ends of the cap (non-polar, or 2 electrolytics back-to-back) to allow for a positive voltage of 4.5V on one side and 48V on the other. I’m trying to be careful here because it would be too easy for this to happen, resulting in damaged coupling caps, op amps, and who knows what else. Your circuit has a 10K to ground, so that might shunt the phantom power and provide protection.

Thanks much,
Scott Morrison

-Jack

I can’t access the schematic. Could you update the link, or send it to me?

Thanks@

Will