The 3-position lever switch sets the conversion level to - 6 dB, 0 dB, or + 6
If you convert a L/R stereo signal with 0 dB, the phase correlation of the stereo
signal determines the output level. With a typical stereo mix you will get a
little less than + 6 dB on the M output, while the level of the S is lower, depending
on the base width of the stereo image. The higher output level of the M channel
reduces the headroom. To maintain the original headroom, set the level to - 6
dB when the matrix is used for L/R to M/S conversion.
Converting from M/S to L/R with a setting of 0 dB results in approx. the same
levels of M, L, and R. This is the standard setting.
The level of M/S conversion is not standarized; you may experience different
levels if you are using the TM131 with other units for format conversion. To
maintain a sufficient headroom and dynamic range, check the levels. Use a mono
signal with identical in the and right channel and the level of the M output
to get an idea of the conversion level. Some units produce 6 dB gain; if this
is the case you need to set the gain - 6 dB if you use the TM131 to re-convert
from M/S to L/R.
The TM131 L/R - M/S Matrix can be used to convert a common L/R
stereo signal to the M/S format or to convert a M/S stereo signal to left-right
stereo. No switching is required.