Back to the past: dbx cassettes

I have a couple of old Technics tape decks, both which feature “dbx” compression. Most everyone who has used cassettes would have heard of Dolby, “dbx” was an alternative approach to achieving the same thing; tape noise reduction. Unlike Dolby, it worked across the full audio spectrum.

I recently found a stash of my old 80s tapes whose time for binning was well overdue. Amazingly, they still play very well! I would have thought they’d have faded to oblivion. I found a couple of tracks worth keeping.

Most of the old recordings are dbx encoded and I’ve found a neat way to make them more vibrant.

First I play & capture them with dbx off. This yields a very “flat” sounding recording because the dynamic range was squashed by the dbx encoder during recording.

I give a little low and high boost to the track, then gently denoise it. It still sounds “flat” because its dbx encoded. No amount of EQ can fix that.

Now I dont have a software dbx decoder, but one of my old decks (RS-M235X) has a “dbx disc” mode for decoding dbx encoded records. Those must be a rarity.

So I play the processed track back through the deck’s line in. It dbx decodes the cleaned up audio and I end up with a surprisingly better result than if I’d just played the tape through the decoder and EQ’d it after.