Sunday, January 15, 2012

And now, it's time to clean pots & switches.

Patchbays are wired up, 1-4 stereo XLR on A bank (channel 5 pair is just dummy infill at the moment, we can credit laziness for this), and 1-8 stereo pair of 1/4" on B bank. Audition and Program output are fed to the right end of the patchbay, Program output being normalled to the amplifier input (and still available at the XLR output when something is front panel patched into the amplifier).

20 four conductor shielded wires. Shield is connected at the mixer end only and one conductor is unused in the XLR feeds which require one cable per connector. The 1/4" feeds utilize all conductors for the stereo pair per wire.

I misplaced channel 6B in this shot, it is wired on the A bank. The vertical "columns" are similar, for example: farthest left is A channel LEFT, the A channel RIGHT, then B channel LEFT and B channel RIGHT, etc.. Terminals within the tabs are from "top" down: signal hot (+/-), signal neutral (C) and ground (S), the characters in parenthesis being call-outs in the Autogram AC-8 manual (Common and Shield).

When I originally wired up a few XLR to try this thing out, I was scrounging up crimp connectors from my parts boxes. Pictured here is a connector type that became the bane of this installation: the closed ring, which requires the complete removal of the terminal screw. I also wound up trimming off the insulation after the first two. My advice is if you're going to wire one of these up, do it with uninsulated fork type connectors, a thousand times more pleasant to work with.

I should also mention that these boards are set up for pretty high level signal (rated at +8 dBm nominal, with a +24 dBm headroom cap) while most studio gear is +4 dBu, so actual results of mixing may be fraught with complication (higher noise levels than preferred). My application is to drive the inputs off other mixing desks which will shoot my signal a bit closer to being in nominal range, having driven the channels last night direct with an EMU Morpheus synthesizer I wasn't getting deflection of meters. The Autogram (and really, any radio mixer, especially when all input modules have been set up as passive transformers) needs to be fed healthy levels of juice.


MKULTRA said...

No grommet ?

Clutch the pearls !!!!

crochambeau said...

That plants an incredibly funny image in my head. Yeah, no grommet around the hole through which the wires pass, I can even see scrapes on the insulation...

I think I may have some edging in the storage pile, but if not we'll just have to hold our breath.

MKULTRA said...

Busting your chops of course.

I don't imagine the unit is going to experience many load ins and load outs.

Stellar work.

crochambeau said...

Busting of chops is wholeheartedly deserved, thanks for the good words!