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resistor man
10-17-2001, 06:28 PM
There was a discussion sometime ago about de-coding dbx encoded tapes. Of course, I sold all my dbx units and now I need to decode a tape. Naturally. Anyhow, I was wondering if anyone has done any messing about with this problem...
Kihoalu
10-22-2001, 02:35 PM
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Hi Res - Yes I was fooling with this idea some time ago. Even though I have dbx units, I know it is better to digitize first, then process. Fortunately dbx is simpler than Dolby to decode. The posts should still be on the site here, but as I recall, the decode process is to do logarithmic expansion at a 2:1 rate and then to apply de-emphasis (both low and high boost). The trouble is that the control channel also has band limiting which is different on dbx Type I and Type II. I have digitized some tapes but I have not yet done the work to do the de-coding. Being lazy, I was hoping someone else would come up with a plug in or even a script to do this and then post it.

...Good Luck

...K
resistor man
10-22-2001, 11:31 PM
HAR! Well, if I fool around and manage to get it sounding OK, I'll post it.

Thanks for the answer...
Kihoalu
10-24-2001, 04:26 PM
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Oh Yes- you must use RMS level detection to do the 2:1 log expansion from, but CEP does all that just fine. What attack & decay time s to use?? - I think that is discussed in previous posts - but I intend to measure it with my equipment once I get off my arse on this project. Trouble is - I am doing eight or ten other projects at the same time - and this one (with the dbx decode) is just for archiving some old but fine material that is slowing dying on R-R tape.

...K
resistor man
10-25-2001, 04:02 AM
Originally posted by Kihoalu:
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- and this one (with the dbx decode) is just for archiving some old but fine material that is slowing dying on R-R tape.

...K

Yeah, that's what's happening here... trying to put together an anthology CD for a friend of all his albums from the 80's. The Maxell and TDK reels play like new, but the Ampex requires baking... did you know you can use a food dehydrater for that chore? 5hrs. at 135 degrees with the same amount of cooldown time does the deed, usually. Anyhow, thanks for the info.