Seventh Circle Audio

Posted: **Thu Jan 24, 2008 10:58 am**

Looking at the schematics for the A12 and the N72 I see slight differences in the schematic for phantom power. Wondering why these would differ... :?:

Posted: **Thu Jan 24, 2008 12:33 pm**

A12, C84, and T15 have emitter follower buffered slow-rise phantom circuits. N72 and J99 have two-stage RC circuits. Future revisions of N72 and J99 will have the same active circuits added, but we can't say when that will happen.

Posted: **Fri Jan 25, 2008 10:28 am**

I'm looking at an older version of the A12 schematic from when I built it (about a year ago?). Schematic shows 48v from pin 5 through a 150 ohm resistor, across 220uf and .1uf caps to the xlr 6k6 resistors. Is there a diode missing on the schematic?

BTW, it's working fine, I'm just trying to better understand the dots I've connected :wink:

Posted: **Fri Jan 25, 2008 4:01 pm**

The protection diode wasn't added until we realized some people preferred to connect their power supplies backwards.

Posted: **Mon Jan 28, 2008 2:08 pm**

tpryan \$m[1]:The protection diode wasn't added until we realized some people preferred to connect their power supplies backwards.

Guilty as charred, er, charged. ;-)

The good news was that the protection diodes on the expensive bits did their job.

Seventh Circle Audio

Phantom question

Phantom question