In addition to tools, instruments, and a service manual, a test tape is necessary if you wish to "calibrate" your recorder.
Test tapes come in "all shapes and sizes", so you must know what you want.

Above is a test tape from MRL
 

Remember: Never buy a "copy" of a test tape. It is NOT possible to copy them on a recorder as all errors on that recorder will be added to that tape.
A test tape is made on a special recorder and usually comes with a diagram showing the exact levels on that tape.

Besides, as you will see here, test tapes are recorded "full track" covering all of the surface of the tape.

1. First, we must know which tape width we use. For example 1/4 inch.
A recorded tape has "tracks" (invisible of course), for example 2 tracks like the figure below.

 

A test tape however, is recorded to the full width (se below), so it doesn´t matter how many tracks the playback heads have
on your recorder.
The tape can handle anything from an old "mono" head, to a 4-channel head.

2. Next, we choose which speed we will use. 7,5 ips for example.

3. Third, we must decide on Equalization.
The most used standards are NAB or IEC. Sometimes the recorder has switches so that you can choose
what equalization it will be used for. In other cases, it is manufactured for a certain equalization.

4. Magnetic energy (fluxivity).
This parameter tells us how "strong" the magnetic fields are on the tape when we record.
A look in the operating manual for the recorder tells us what fluxivity the recorder is made for.
Some recorder might have a switch to select between 2 fluxivity levels.
There are a number of standard fluxivities in the world. The reason is that tapes have developed over the years
and can handle stronger and stronger magnetic fields.
 

Fluxivity	Level	Standard	Frequency
320 nWb	0 dB	European studio standard, IEC, CCIR, DIN	1000 Hz
250 nWb	-2 dB	NAB elevated level	1000 Hz
200 nWb	-4 dB	NAB operating level	1000 Hz
185 nWb	-5 dB	NAB standard reference flux level	700 Hz
150 nWb	-7 dB	NAB standard 1965	400 Hz

250 nWb/m is a common standard for studio use, especially in the US. Here in Europe, you will often find
320 nWb/m. (On the Tascam 52, there is a switch to choose between 250 or 320 nWb/m).
According to MRL, the European 320 level is actually 285nWb and not 320, which makes only a 1dB difference from 250nWb. MRL call that level G320 (G for Germany).
 
 
 

TASCAM 38

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