Satin Dolby Reference Levels

[jamesperrett]

Hi - I'm trying out the Satin demo with a view to buying it if it works for me. I do quite a bit of audio restoration and one of the things I'd like to do is to decode Dolby A encoded tapes in software. I already have a hardware unit but it is difficult to patch into my current setup.

My question is where should the Dolby line-up tone appear on the meters? Is it 0dB or is it some other level? I can set it up roughly by ear but I would rather set it correctly if possible.

Thanks,

James.

[Urs]

Sascha can probably answer this next week.

I was wondering if a compander actually operates level dependent... hmmm...

[jamesperrett]

As I understand it, Dbx is a compander that isn't level sensitive but Dolby changes the ratio depending upon level. The real Dolby hardware is certainly level dependent in my experience.

[jamesperrett]

Just wondering if you had a chance to look at this? I'm working on some old tapes from a well known 80's pop star and I think I've got it right by ear but it would be good to know for sure.

[sascha]

I'm going to have a closer look at the actual internal specs tomorrow, when I'm back at the desk. I think it's calibrated for 0vu, but I want to be sure. Stand by...

[sascha]

Ok, I had a closer look again. If I recall right, I had set the calibration to 0vu on Satin's meter (with the ref. knob to 0dB), where it behaved very similar to the two 361 modules we used at that time. Using 0vu as reference point resulted in 10dB gain reduction, but the in vs. out slope already returns back to 1:1 at -15dBvu (which I think was also how the modules responded).
Sadly, I haven't kept any files of the original 1k 'warble' tone, although all I know of these things is you'd have to make aural adjustments anyway.
On a side note, should you have any old test files (either encoder- or decoder-only), feel free to send us those if you want.

[xx JPRacer xx]

Hey Sascha, what are you working on right now? (if it's not top secret)

[jamesperrett]

Many thanks Sascha - lining up the warble tone to 0VU seems to work. I have a Dolby 365 unit with Cat 22 cards in the rack here which I could run some test files through - do you have any particular test signals that you would like me to use? I've just purchased Satin a few days ago so that I can decode tapes without having to be in the studio to do it. I've also just found the eq options in the service mode which looks like it could be useful for tapes which have been transferred with the wrong eq setting.

[sascha]

James, sorry for the lag...
I've got no original 'warble' tone at hand, nor the correct specs of how it should be like, but here's an old thread that should be applicable to this case as well:

http://www.kvraudio.com/forum/viewtopic ... 1&t=394533

You may download the zip and do 2 passes on the file: one with the A-type set to encoding, and another one with it decoding. Then compare real vs. software.
You could post results here or upload it somewhere (as wav, not mp3). Then we could grab it and inspect. Could be that we missed something in the first place. Simulating companders is a tough business.

[jamesperrett]

Hi Sascha - sorry, I've only just seen this. I've downloaded the file and will run it through the Dolby unit.

Cheers,

James.