Saturday, February 12, 2011

Home-Brewed Alternative to Dolby

HiFiCollector Community Member, Tony sent in this very creative way to create home-made noise reduction in vintage systems. Thanks Tony!
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I read your piece on the AKAI integrated amp and tuner (2650 & 2450), and it reminded me of my first ever hi-fi cassette deck, the AKAI GXC-36D, which didn't have Dolby. I have attached a scan I found online, showing this deck, and it's more expensive and Dolby-equipped relative (which I couldn't afford at the time!). The GXC-36D had a very satisfying solid feel to it - you know, the way that any good piece of kit has a good, well-made action with no "play" in the controls, in this case the keys and the lid of the cassette tray.

However without Dolby, it was quite hissy, but I found a way around it.

I used to have a basic Wharfedale Linton system (re-branded Garrard turntable, Wharfedale receiver and speakers) and the receiver had a pair of bridging plugs between the pre-and power-amp sections, at the rear along with all the usual connections. So by disconnecting these, I could use a couple of spare leads to connect the tape deck to the output of the pre-amp, then the output of the tape to the power-amp input.

This meant I could boost the treble of the recording with the pre-amp controls, then turn it back down on playback. Instant customized Dolby! I had to be careful not to saturate the treble frequencies, but it worked well. As the sound went via the tape deck it was easy to monitor too. Of course, I caught upgrade-itis and the system was replaced piece by piece, and the bridged amp eventually went. I wonder how tapes produced by this method would sound like to my more experienced and therefore more critical ears if I could do it again now, with the same gear?

I suspect that the roll-off with the treble control might be different to a dedicated and calibrated Dolby circuit, and the overall quality might not be as good.

One last important item: In order to play the tape back, I had to re-bridge the amp and connect the tape deck to the tape input as usual - otherwise, the tape output would go directly to the power amp section and would have NO volume if you, or any other HiFi Collectors get the chance to try this technique, please remember this for the sake of your speakers - not to mention your nerves.........!

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