Professional Sound - Indepth

Upgrading the Dolby 363 SR by Barry Lubotta

As a firm believer in the superior sonic qualities of ½” analog versus DAT as a two-track mixdown format, I was excited several months ago to purchase a used Dolby 363 SR two channel noise reduction unit to complement our ½” machine. Since we already had Dolby SR on our 24-track recorder, I expected the same kind of performance when I wired in the Dolby 363. To my surprise, I found the sound quality of my tapes through the 363 somewhat disappointing. The problem was that the high end seemed to lose its sparkle and the soundstage shrunk. These less than flattering results made me question whether I was better off with or without noise reduction on our two-track machine. And then it struck me as to why I have seen so many used 363s offered for sale over the past few years – probably unhappy owners.

Now my short-term memory isn’t quite as good as it used to be, but there is nothing wrong with my long-term recall. And sure enough, driving home that night I remembered reading an article that appeared in REP magazine several years ago which dealt with modifications to the Dolby 363 SR. Later that evening I was knee deep in old magazines and had just about given up hope of ever finding the piece in question. Down to my last REP I scanned the index and there it was on page 62 of the May 1991 issue – “Upgrading the Dolby 363 SR” by Jim Williams. Seems like I was not the only one who found that the original unit was somewhat lacking. This excellent article described the less than exceptional parts used by Dolby in manufacturing the 363, and went on to give detailed instructions on how to modify the unit so that it would regain it’s clarity, transient response, and sparkle.

I contacted David Miller at Digital Ears in Toronto and asked him to perform the upgrade for me since I knew it was beyond my modest capabilities. When I dive into a piece of equipment, my philosophy has always been that I will either make an improvement or destroy the thing entirely, and in this case the odds seemed to favour the latter result. Dave and I discussed the mod and agreed that we could take the improvements one step further by replacing some capacitors and other ICs in the signal path. Since the Dolby 363s are no longer under warranty, there was no risk of alienating Dolby the company.

A week later David delivered the upgraded 363 and I plugged it in for a few days so the new components could break in. When I got around to recording music through the system, the improvement in sound quality was immediate and easy to hear. The detail and sparkle from my source came through unchanged, as it should have in the first place. I’d have to say the unit now sounds better than our 24 channel Dolby SR.

If you already own a Dolby 363 SR unit, you owe it to yourself to experience a significant improvement for a modest price. The cost of the mod was just under $400. Now the 363 can do the job it was designed for.

I find it surprising and disturbing that Dolby utilized such low quality audio parts in a device that was never cheap to begin with. By investing in this modest upgrade, you can play your part in keeping analog sound quality alive and kicking into the next century.

Barry Lubotta is the owner of Pizazzudio Recording Studio in Toronto, ON.

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About Andrew King
Andrew King is the Editor-in-Chief at Professional Sound. He is also a co-host of Canadian Musician Radio and NWC Webinars’ series of free music and entertainment industry webinars.
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