Hi and welcome to RO!

Try the search engine. I remember a relevant discussion not too long ago.

Happy hunting!

Regarding the DBX noise reduction system. There were 2 types, type I and type II. Type I was the professional full bandwidth type. Type I I was the Prosumer version which was slightly bandwidth limited in the upper frequencies within the detector at 10,000 cycles, it still passed full frequency response as the process was only limited within the detector circuit. You first need to find out whether it was type I or, I I? If you're talking about something that was recorded on a Teac/TASCAM type machine, it was probably type I I? If it was a professional studio recording, then it was probably type I?

Now to the decoding dilemma. DBX was a companding system that utilized an infinite ratio compressor at 2:1, whose threshold started at about -80 DB with a preemphasis curve similar to vinyl disk cutting and FM radio, analog tape, i.e. the high frequencies were greatly exaggerated in the recording process. In playback, the process was reversed. That is to say, there is a playback deemphasis equalization curve that turned down the high frequency response by a reciprocal amount compared to the encoding and an infinite threshold expander at 1:2. Preemphasis and deemphasis already increases signal to noise ratios and has been used with analog disc recording, analog FM broadcasts and analog tape. This process alone increases signal-to-noise by over 10 DB. The compression and expansion can also widen the dynamic range by twice since they are utilizing a 2 to 1 and then a 1 to 2 companding process and thus increased the signal-to-noise ratio by about 30 DB. It is also very important to have as flat a frequency response within your system as possible (which Teac/TASCAM units never had, they were + 2 -3 when properly adjusted. This was magnified by a factor of 2 in the process and probably why most people hated the way it sounded? + 4 -6 that ain't flat!)

I think you could almost create the same thing in software but not exactly? I have some old masters myself and have been contemplating trying what you are going to attempt. I don't think it would be 100% effective as having an old DBX unit. I think my mentioned process could probably pass for archival purposes? Of course your best bet is to probably look for a used unit on eBay if people haven't already thrown them out? Again you have to find out whether it's type I or I I. It's rather passe' these days. I have not heard of any actual plug-ins that mimic the original process. Hey, maybe you should contact DBX?

Good luck to you on this endeavor and I would like to hear what your outcome turns out to be? (okay I sort of lied, a friend of mine gave me a type I, 4 track unit but my old masters are type I I originally)

Noisy old broad
Ms. Remy Ann David

JoeR wrote: Hi -- I'm new to the site, so if I'm asking a question that's been asked before I apologize, and apologize if I'm asking a dumb question.

I have a DBX encoded tape from the mid-70s that I need to digitize to save. Are there any plugins or software virtual modules that will decode DBX?

Thank you in advance and thanks for the expertise!!

JoeR

I don't know where you are located but we have the equipment to do the transfer for you. Contact me off list. Thanks