Dolby SR XP Series - Help

Posted: Fri Nov 09, 2007 9:59 am

Hello all!

I'm new to Analog Recording now (from Digital to Analog):
I own an Soundcraft 2400 and a Otari MTR90II with Dolby SR Wink

I was reading the manual of the Dolby up and down - so I am realy confused now... I need some advice from a Prof:

How is the main procedure to calibrate a "Dolby SR XP Series"

I don't need interchangeability, since i use this just for my own pleasure.
Is there someone outthere who rebembers the Dolby things?

Cheers, Roman

Posted: Fri Nov 09, 2007 6:06 pm

I would only use Dolby SR if you need to decode existing encoded recordings.
Dolby is only really viable for 15 IPS, just use 30 IPS no Dolby.
Dolby's intention was to minimize noise when recording across tapes.
In the old days, a show was recorded on 24 track Dolby encoded, it was then decoded, submixed through the console, back to 9 through 24 of another 24 track encoded. Those submixes were then decoded, mixed down to stems through the console, back to 1 through 8 encoded.

There is absolutely no reason to use Dolby NR just to track to tape.
Do you really want to introduce a compading circuit in the works??

That being said a 1K tone from the console through the SR to tape for encode, then tape tone through the SR to the console meters. Do not use Dolby tone to align, its for playback reference only.
The 24 track needs to be aligned first, and the console meters calibrated.

You'll also need to calibrate the record circuit (MTR90) to the auto switching (SR input/output) circuit. Unless you are good friends with a tech from the old days, you'll rip your hair out getting the auto-switching to work flawlessly. Otherwise you will hear every punch!!

Posted: Mon Nov 12, 2007 3:14 am

Thank you for reply.

I know, that it's fine to track to tape with 30 ips without any dolby.
that's the way i've done it till now.

The thing is, i have the dolby and i've made the connection already,
so i like just to be able to use it. (and 2" tape is expensive, so for me
15ips is an option...)
The auto switching (rec/play) is working, the alignemet of the console and the MTR90 is clear for me.

Would you say im on the way, if i record just 1khz trough the dolby,
then play back and adjust every channel to the same level?
no other "special" things to do?

thanks for the advice,

R.

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