Here's a technote from Rane Corporation that goes into
some pretty good detail about the interconnecting of
audio gear, both balanced and unbalaced.
http://www.rane.com/note110.html
The bottom line is that there isn't one single answer
or approach that is applicable to all situations and
all types of gear. You really do need to know how your
gear is configured internally as well as the gear that
it needs to connect to. Unfortunately most ham gear
manufacturers provide very little such information, so
you need to dig into the schematics to figure it out.
The whole audio (mic) problem is further compounded by
the fact that not every manufacturer of equipment
agrees what is the best method is. So we end up with
different pieces of gear that are optimized for
different wiring practices that aren't always friendly
with each other.
And yes AES/EBU spec sure does go a long way toward
eliminating most of these kinds of headaches. It's
also a natural starting point for those Ethernet based
radios I would like to see ;).
Duane
N9DG
--- Robert & Linda McGraw K4TAX <RMcGraw@Blomand.Net>
wrote:
> If one is gonna do this then I want an AES/EBU
> input. That way I can forget
> all the other crap and be pure digital.
>
> Unbalanced, if done correctly, WORKS. If it doesn't
> work, it's not correct!
> No isolation is required. I've dealt with
> unbalanced INs and OUTs and
> balanced INs and OUTs in a professional environment
> for more years than most
> have been hams.
>
> Isolation transformers are a true invitation for hum
> being induced. What
> was experienced in this situation is a simple case
> of "ground loops".
>
> 73
> Bob, K4TAX
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