Friday, April 10, 2009

Tips on Using Analog Tape

This post is a guest editorial by our highly experienced maintenance staff member.


QUESTION: What should I watch out for if we decide to record to analog tape?

So....if an engineer wants to record to analog tape today, here are some suggestions to make the session go off without a hitch.

First, the engineer or producer should estimate how many reels of tape they will need and ask the studio far enough in advance to order enough reels cut from the same batch for the entire project. Today, batches or production runs of tape are much smaller because of the lower volume of analog tape production. Therefore the acceptable deviation or inconsistencies between batches of tape can become more apparent if a project uses reels from different batches in the middle of a project.

Second, it is always good practice for the engineer and assistant engineer to check the alignments of tape machines PRIOR to recording music. It is quick and easy to send 100Hz, 1kHz, and then 10kHz DIRECTLY to tape (no inserts or effects between the oscillator and the tape machine) and look at the level on INPUT and then throw the machine into RECORD and look at the level coming back from tape in REPRO. All that matters is that the level on INPUT and REPRO are the same! You only need about 30 seconds or less of blank tape on each reel to just check the consistency of the batch(es). That is considered acceptable deviation between reels and what is not acceptable can be decided by the engineer, but at least there will not be any unpleasant surprises.

If you have no choice but to work with reels from obviously different batches, there are always options that will enable you to work around the inconsistencies. One option - for very minor differences - is to call the technical engineer and have them tweak the record alignment once you start working with the new, differing batch. For more serious deviations, the machine can be re-aligned and new tones can be printed on reels from different batches of tape. This latter, worst case scenario can be time consuming and bring the creative process to a grinding halt, which is why we recommend getting tape that has the highest probability of consistency (reels from a single batch) for your project.

Lastly, you should remember that the imperfections of analog recording (called "non-linearities" by electrical engineers) are the reasons people find analog appealing to begin with. By non-linearities I do not mean a high noise floor (hiss) and high-output tape slammed with signal. These are not examples of the limitations of the analog recording medium, but are symptoms of unintended use of tape. When you record to analog, you cannot expect the precision and consistency that today's digital recording systems boast in their technical specifications. The analog system should be relatively flat in its frequency response (+/- 1-2dB from 50Hz-15kHz) with a consistency of +/- 0.25dB between channels and a consistency of +/- 1dB between batches of tape.

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