[sdiy] TASCAM / DigiDesign 8-channel DB25 cable shield

[rsdio at audiobanshee.com]

I just designed a circuit to sit between my Roland 13-pin SynthAccess guitar and a balanced audio interface. Since 1/4” jacks take up a lot of space, and buying 7 more short balanced patch cables seems like a pain, I decided to use the DB25 input on the interface. It’s wired in the TASCAM / DigiDesign standard for 8 channels. 24 pins are used, and each channel has its own ground in addition to the (+) and (-) wires.

Considering the infamous “pin 1 problem,” should these channel grounds all be connected with a series capacitor, instead of directly to ground?

Seems likely. If the channels each had their own XLR connector, they’d have the capacitors for DC blocked noise reduction, while still allowing the shield to function.

The TASCAM wiring diagram spec that I looked at showed earth ground on those 8 pins, but I don’t think I should take that literally.

Brian