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7.1     Special Considerations for ADAT and Digital Media Users:

Digital signals must be kept below 0 dB. That is the absolutely highest value the digital to analog converters can measure. The resultant clipping is horrible. It is good to keep your signals as close to zero as possible though. This will help keep the wide dynamic range of digital. 44.1 kHz samples the signal every 22.68 microseconds. The signal is measured and a value is assigned. If the peak is at 0 dB, then you have 65,536 possible values for your signal to be measured. (This is by converting the number of bits in binary). If you record at -6 dB, there are only 32,768 possible values to be assigned to your signal. You'll end up losing some of the dynamics.

An effective menthod to avoid distorting your digital recorder is to use a hard knee limiter set to -2 or -3 db.  This will prevent ANY signal from exceeding the setting and distorting the tape.  You can also have a compressor set with a 4:1 or lower compression with the threshold a little lower than the threshold of the limiter.  Try to BARELY flicker the compresors gain reduction meters.  If there happens to be a loud peak, it will get compressed slightly before limiting, and it will sound a little more tolearble than the transition straight to hard limiting.

Alesis ADAT's are sometimes known to eat tapes. Here are few recommendations to limit this as much as possible:

  1. Use only high quality tapes. Some brands seem much better than others for longevity.

  2. The hotter it gets, the more likely your tapes will get eaten.  

  3. Don't enter transport commands quickly. The machines get confused easily. Let the machine finish whatever command you tell it to do before issuing another command. If you want to cancel the command, press stop only once. Pressing stop a second time starts the disengage command.

  4. Some tape brands require more stretching than others. If you stretch only once, the tape may have a little more stretching to do, which may not become a problem until after 50 hours of play. Stretch new tapes at least twice before formatting.

  5. Keep your machine clean. Very clean. Follow all routine maintenence recommendations.

7.2    A Few Notes on Tape Recorder Maintenance:

Audio recording equipment needs constant care and maintenance to record and play optimally. The equipment owner should clean and degauss (demagnetize) any tape recorder on a regular basis. I clean my heads EVERY TIME I record. You should also get a good rubber cleaner to clean the roller, the head cleaner doesn't work well for this. I always use a swab, not a cleaning tape.

It's also important to occasionally send your deck to have the bias and azimuth set properly. This helps to electronically optimize the way the deck records. It is possible to calibrate your deck at home, but I'm not sure how to do it. I'm recapping my ocilliscope soon, so maybe I'll experiment and I'll be able to fill you in later. Until then, check with your equipment manufacturer for a technical manual for your recorder. Having the deck set right really helps the sound, especially with cassette-based recorders. A small change in the azimuth will really effect the high end response. When you set the bias, make sure you send a sample of the tape type you prefer. They will set the deck for that brand, and you'll need to continue using that brand to achieve the best results. Note that most manufacturers recommend a high bias (Type II, Cr02) tape - keeping in mind that cheap tapes will deposit gunk on your heads.

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