RECOMMENDED BIAS SETTINGS
If You Are Using | Then Consider | Here Is Why It Is The Right Choice |
3M 226 | 3M 966 | 966 is the perfect choice with lots of benefits
has 6 dB less Print Through than 226 |
OR | ||
3M 996 | 996 is a step up to a +9dB mastering tape
has 3 dB less Print Through than 226 |
|
3M 806 | 3M 908 | 908 is the perfect choice with lots of benefits
has 5 dB less Print Through than 806 |
OR | ||
3M 966 | 966 is a step up to a +6 dB mastering tape
has 3 dB less Print Through than 806 |
|
3M 808 (For Nagra) |
3M 908 | 908 is the best Nagra tape ever manufactured
has 3 dB greater Signal-to Noise than 808 |
OR | ||
3M 966 | 966 is the best tape for Stereo Nagra
has 6 dB greater Signal-to Noise than 808 |
RECOMMENDED BIAS SETTINGS
MUSIC MASTERING TAPE (Highest Signal-to-Noise)
Tape# |
Speed |
Record Head Gap | 10 kHz Over Bias |
lps |
mils | dB | |
3m996 |
75 |
0.125 | 9 |
0.25 | 6.5 | ||
0.5 | 4 | ||
15 |
0.125 | 6.5 | |
0.25 | 4 | ||
0.5 | 3 | ||
30 |
0.125 | 3 | |
0.25 | 2 | ||
0.5 | 1.5 |
3M 966 3M 967 3M 250 3M 226 3M 227 |
75 | 0.125 | 7.5 |
0.25 | 5 | ||
0.5 | 3.5 | ||
15 | 0.125 | 5.5 | |
0.25 | 3 | ||
0.5 | 2.5 | ||
30 | 0.125 | 2.5 | |
0.25 | 1.5 | ||
0.5 | 1 |
GENERAL MASTERING TAPE
Tape# |
Speed |
Record Head Gap |
10 kHz Over Bias |
lps |
mils |
dB |
|
3M 806 3M 807 3M 908 |
75 |
0.125 | 6 |
0.25 | 4 | ||
0.5 | 3 | ||
15 |
0.125 | 3 | |
0.25 | 1.5 | ||
0.5 | 1 | ||
30 |
0.125 | 1.5 | |
0.25 | 1 | ||
0.5 | 0.5 |
BIAS SETTINGS Proper bias setting depends on the tape speed and the record head gap length. Smaller or narrower gaps require more over bias as shown in the table.
Record Head Gap Length |
Recorder Model Numbers |
0.25 mil (6.4 µm) |
All models except those listed in the 0.50 mil chart below |
0.50 mil (12.7 µm) |
Ampex AG440, 1000 (newer models), ATR 100 series, Otari 7800, 5050B(F), MKII-1 |
OPERATING LEVEL CROSS REFERENCE CHARTS
Maximum Recommended Operating Level | ANSI Level | DIN Level |
3M 966 | 520 nWb/m (+9 dB) | 570 nWb/m (+5 dB) |
3M 966/226/250 | 370 nWb/m (+6 dB) | 410 nWb/m (+2 dB) |
3M 806/908 | 250 nWb/m (+3 dB) | 280 nWb/m (-1 dB) |
3M 808 | 185 nWb/m ( 0 dB) | 200 nWb/m (-4 dB) |
Your desired operating level may be different from the reference fluxivity level on your reproduce alignment tape. If this is the case, use the chart above to normalize the operating level to the reference level found on typical reproduce equalization for optimum frequency response using the reproduce alignment tape.
Any combination of signal-to-noise and headroom can be achieved. Using less than the full signal-to-noise capability of the tape (by reducing the operating level) will result in lower distortion, less audible print-through and more headroom.
The reference (fluxivity) level of 320 nWb/m is commonly used in Europe. Due to difference in flux measurement techniques, this is equivalent to approximately 290 nWb/m when measured by American Standard Flux measurement technique as in this chart.
Desired |
Reference Fluxivity Level on |
||||||
ANSI |
290nWb/m |
||||||
ANSI |
DIN |
DIN |
320nWb/m |
||||
520 nWb/m (+9 dB) | 570 nWb/m (+5 dB) |
-9 VU |
-8 VU |
-6 VU |
-5 VU |
-3VU |
|
370 nWb/m (+6 dB) | 410 nWb/m (+2 dB) |
-6 VU |
-5 VU |
-3 VU |
-2 VU |
0VU |
|
290 nWb/m (+4 dB) | 320 nWb/m (0 dB) |
-4 VU |
-3 VU |
-1 VU |
0 VU |
+2 VU |
|
250 nWb/m (+3 dB) | 280 nWb/m (-1 dB) |
-3 VU |
-2 VU |
0 VU |
+1 VU |
+3 VU |
|
200 nWb/m (+1 dB) | 220 nWb/m (+3 dB) |
-1 VU |
0 VU |
+2 VU |
+3 VU |
+5 VU |
|
185 nWb/m (0 dB) | 200 nWb/m (-4 dB) |
0 VU |
+1 VU |
+3 VU |
+4 VU |
+6 VU |
PROCEDURE:
Determine the desired operating level.
Determine the reference (fluxivity) level of the reproduce alignment tape you are using.
In the chart, find the VU reading at the point where the values from steps 1 and 2 intersect.
When reproducing the reference level tone from the calibration tape, set reproduce gain so the VU meter reading found in step 3 is achieved.
EXAMPLE:
Desired operating level for 3M 806 is 250 nWb/m.
Reference level on alignment tape is 185 nWb/m.
The VU reading is -3 VU at the intersection of the column and row from steps 1 and 2.
Set reproduce gain so VU meter reads -3 VU when reproducing the reference level tone from the calibration tape.