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Alesis ADAT - Affordable Digital Multitrack (part 9)

One day we’ll wonder why we put up with reel-to-reel analogue tape for so long. Here is a selection of classic analogue problems which the ADAT doesn’t have.


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Kiss your analogue problems goodbye

One day we’ll wonder why we put up with reel-to-reel analogue tape for so long. Here is a selection of classic analogue problems which the ADAT doesn’t have.

Reel scrape

Newcomers to the recording studio find this noise intensely annoying, although many engineers seem to be able to filter out it somewhere along the connection between the ear and the brain. No matter how well aligned your machine, no matter how flat the flanges of the spool, no matter how carefully you thread the tape, that irritating rasping sound comes back again and again. If you try to correct the problem by bending the flanges of the spool you’ll only make it worse, and you may be tempted to adopt the solution many continental Europeans do which is is to use spools without an upper flange. Be warned however that you have to use European tape if you take a screwdriver to your empty take up spool because the American stuff will throw its coils skywards when you fast wind.


Think of all the trouble you take to lay a nice clean signal down onto tape, and then consider what happens when it is deposited on the rusty metal particles of the tape’s magnetic coating. The result is that your lovely music plays back mixed with a random signal which is commonly known as tape hiss. Tape is a noisy medium, an order of magnitude noisier than high quality audio electronics, and tape rather than any other component of the recording chain has placed the limit on our achievements ever since it was invented. Things have improved vastly over the years, particularly with the various forms of Dolby noise reduction, but when you hear background noise on your finished recording, you can be sure that most of it is coming from the analogue multitrack recorder. Digital recording doesn’t eliminate noise, and really a digital multitrack recorder should have a resolution of at least 18 bits to bring the finished mix up to full CD standard since noise build up is inherent in any multitrack recording process, but the 16 bit ADAT provides a very noticeable improvement on what most of us are used to.

Modulation noise

Tape hiss is one kind of noise, due to the fact that the signal is recorded on particles of finite size. Modulation noise is something else, and arguably more annoying - noise that rises and falls in level with the level of the signal. Modulation noise makes a recording sound ‘dirty’ and is particularly noticeable if you are recording without the benefit of Dolby noise reduction. If you use dbx noise reduction, this has the effect (through a different mechanism) of making the modulation noise worse. Digital recording isn’t totally free of modulation noise, but at 16 bit resolution you would be really hard pressed to hear any.

By David Mellor Thursday January 1, 2004