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

[Neil Johnson]

Hi Brian,

> 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.

http://pin1problem.com/

No capacitor, shortest path to chassis.

Neil
-- 
http://www.njohnson.co.uk