SPL M/S Master 1020 Manual Download Page 14

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M/S Master

SIDE section

Control Elements

-/+ FILTER

The „-/+“ knob controls the only actual effect on the M/S Master: a shelving filter meant to
boost or attenuate low and mid frequencies in the Side signal. The frequency range below
the given cut-off frequency is equally boosted. Use the LOW RANGE push button next to it
to set one of two possible cut-off frequencies, in order to define the frequency range to be
processed (see the next section).

Low and mid frequencies up to 2 kHz are very important when it comes to signal positioning,
that is why the filter is set to affect this specific frequency range. As mentioned before, for
frequencies up to 1.5 kHz it is time differences that define localization. Like any other filter,
the „+/-“ filter affects signal phase, which results in time shifts. An increase in intensity
results in an increase of the influence on the perception of the stereo image according to the
scale (attenuation to the left, boosting to the right).

Thus, filtering of low and mid frequencies increases the correction and shaping possibilities
with the on-board elements of the M/S Master. At the same time, the integration of an EQ in
the Side insert broadens even more the possibilities to make selective frequency processing.
The „+/-“ control is therefore a good complement to the STEREO WIDTH setting; the combina-
tion of both provides a wide and effective variety of processing approaches.

LOW RANGE

Use the LOW RANGE push button to set the cut-off frequency of the „+/-“ filter. When
engaged, the cut-off frequency is set to 800 Hz so you can process the low frequency range.
When disengaged, the cut-off frequency is set to 2.2 kHz, which means that the „+/-“ filter
processes all frequencies below 2.2 kHz.

FILTER OFF

Use this push button to disengage the „+/-“ filter. By disengaging the filter, the processing is
done solely on the Side signal encoded directly from the original L/R signal. Thus, the actual
L/R stereo image, ambience, etc. can be accurately appraised and processed if needed.

FLOAT OFF

FLOAT refers to a signal created from L/R that is mixed with the Side signal. Actually, in
addition to the L/R signal, from where the M/S encoding is created, a part of the L/R signal
(reduced in level) is attached to the Side signal. This is done as a parallel process, i.e. it is not
added to the encoded signal. This portion accounts for 10% at the most.

Mixing the FLOAT signal with the Side signal has two major advantages:

1. It avoids the risk of having a negative phase correlation ratio.

2. The less substance the Side signal has, the easier and safer the processing is with the

FLOAT signal.

In relation to 1:

Even extremely wide stereo images remain mono compatible. In this case,

FLOAT extends the bandwidth, so a compromise between mono compatibility and stereo
image is easier to reach.

In relation to 2:

If the original Side signal is made up of ambience or pad sounds, processing

can be very difficult. The risk of extreme settings is quite high because it is very hard to iden-
tify sonic differences clearly. Thus, the FLOAT signal provides a good sonic reference – even
if only during processing. After all, the FLOAT signal can be turned off anytime (once you are
done optimizing settings, for example).

Engage the FLOAT OFF push button to listen only to the Side signal created from the M/S enco-
ding.

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