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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 5th Aug 2018, 7:33 pm   #21
ianj
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Default Re: Dolby introduction on cassettes

The earliest cassette with dolby I have is a 1974 Polydor label one, the best sounding musicassette I have is 10cc greatest hits on Mercury label with dolby B ; bright & sparkling sound. Some dolby musicassettes sounded very dull.
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Old 5th Aug 2018, 9:51 pm   #22
jamesperrett
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Default Re: Dolby introduction on cassettes

Quote:
Originally Posted by TIMTAPE View Post
People occasionally ask if there is a digital Dolby decoder available today.
I've recently started using the decoding on U-He's Satin tape emulation software. It seems to work well and it means that I can concentrate on getting a good flat transfer initially and worry about noise reduction at a later stage. It works for Dolby A and Dolby B as well as various flavours of Dbx. I compared the software Dolby A with my hardware decoder and it seemed identical on listening tests (though I've not done any measurements yet).
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Old 5th Aug 2018, 11:05 pm   #23
TIMTAPE
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Default Re: Dolby introduction on cassettes

Thanks James. Yes I've seen the UHE Satin mentioned on the other forum.

I've not used a software decoder but have ingested Dolbyised cassettes with hardware decoding done later, looping the signal out and back into the DAW, but at the start or end of the digital recording, I inserted some some new "Dolby level" tones, not from the tapes because they had none, but derived from the playback machine's own internal calibration, or a Dolby level calibration cassette. It at least gave me some sort of benchmark as to where to later start trying to "decode by ear", even though the tape itself may be astray a couple of db's - or more- at 400Hz. I found the less guesswork involved the easier it was.

I feel the principle of the "Play Trim" control on some Yamaha and NAD cassette decks was a good one. It wasnt a pre decoder level control but a pre decoder treble boost or cut. I feel that the two best tools for attempting good decoding are both a level control and some sort of treble control, for in my experience, often it's more the inaccuracy in the treble frequencies, from 1kHz upwards, than overall level, that causes the decoder to mistrack.

Do the Satin decoders have any sort of indication as to what is "Dolby level" for them?

Tim
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Old 6th Aug 2018, 1:20 pm   #24
wd40addict
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Default Re: Dolby introduction on cassettes

https://sourceforge.net/projects/dolbybcsoftwaredecode/

Seems fairly effective as a B decoder, the biggest difficulty is setting the Dolby level by ear in multiple trial runs. A continuously variable 'play trim' type knob would be easier.
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Old 6th Aug 2018, 3:24 pm   #25
TIMTAPE
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Default Re: Dolby introduction on cassettes

Thanks for the link WD. Not surprised he's having trouble with a Dolby C decoder. It's more sophisticated than B especially in the encoding.
The official Dolby website used to have some great technical articles explaining the various NR types but I cant seem to find them now.

I was thinking today, the sliding band(s) used in B,C, SR and S can be visualised as a bit like a mexican wave moving left and right, often many times a second. It's very different from its professional predecessor, Dolby A which seems more like four DBX units all working independently, but it was invented before DBX.

Tim
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Old 6th Aug 2018, 10:16 pm   #26
jamesperrett
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Default Re: Dolby introduction on cassettes

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Originally Posted by TIMTAPE View Post
Do the Satin decoders have any sort of indication as to what is "Dolby level" for them?
I asked exactly the same question of the developers at

https://www.kvraudio.com/forum/viewt...?f=31&t=494747

and the answer seems to be to line up the Dolby tone to 0dB on Satin's meters (for Dolby A). I still haven't got round to sending them the results through my 365 unit though.
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Old 7th Aug 2018, 3:16 am   #27
TIMTAPE
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Default Re: Dolby introduction on cassettes

Thanks James. I havent dealt with Dolby A tapes but interesting thread. There would need to be some good headroom above the tone's level I'd imagine.
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Old 7th Aug 2018, 8:38 pm   #28
jamesperrett
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Default Re: Dolby introduction on cassettes

Yes - Satin allows you to set your reference level relative to 0dBFS.
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