[LAU] Sync and digital audio transport - was Sample rate vs. SNR

[Len Ovens]

On Fri, January 25, 2013 7:21 am, Fons Adriaensen wrote:
> On Fri, Jan 25, 2013 at 06:44:31AM -0800, Len Ovens wrote:
>
>> Our on air was 2" machines. 5 of them. A very busy place during
>> commercial
>> breaks.
>
> Know that :-) We had Ampexes on-air, and RCAs in the editing suites. Those
> were really lovely machines. All moving parts were controlled by pneumatic
> actuators, it was phssst, pfff, pssssst all the time while editing. Below
> the actual tape deck there was something like a cubic meter of
> electronics.

Our on air machines were ampex 1100s (I think) with germanium semis except
one 1200 which was a converted 1000 (tube to silicon). We had one inch
machines (ampex) for editing... and slow mo.

> For slow motion playback (mainly used for soccer) there was an analog hard
> disk recorder. The disk was around 40cm diameter and the whole thing was
> packaged in a glass case, you could see the heads moving.

We learned about the slow mo disk recorders, but I think the only one in
town was owned by CBC. Never saw one.

Speaking of sync and digital audio transport...

The AES seems to recommend AES3 (like s/pdif... almost) as the sync signal
in a digital facility. There are a lot of things that will sync to AES3 or
s/pdif, but there are a lot that will not too, while they will sync to
word clock or ADAT... even if they output aes3. Not only that, but word
clock seems to max out at 48k for many units while those that do lock to
AES3 will lock at higher clock rates. (The D1010 for example has word
clock in but only locks to 48K yet will lock to 96k AES3 or s/pdif) The
few master clocks I have seen (not that I have looked at a lot either) all
seem to output word clock only. What is standard practice for master
clocking?

Question two: I read a comment that a studio ( I am not sure if this was a
recording studio or broadcast but got the idea it was recording) had
removed all their MADI equipment and replaced it with aes3 as this allowed
them to set up physical patch bays per channel pair. Seems like a lot of
work and extra wire compared to the benefits. Does this make sense? or
these guys just odd balls?

I thought it odd that MADI cards were so expensive when AES3 equipment is
so cheap... but I have since noticed that a lot of AES3 stuff is called
"s/pdif professional" and does not use balanced lines. I guess the s/pdif
standard is free to use?


-- 
Len Ovens
www.OvenWerks.net