Mark Levinson 380 - Integrating SSP with N°380

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the decoder out of adjustment, changing the volume of the Left and
Right speakers while leaving the Center and Surround speakers unaf-
fected.
One could attempt to restore the proper balance by marking a “cali-
brated” point on the preamplifier’s volume control and then using only
the Pro-Logic decoder to adjust the volume of the system, but this
method is both crude and imprecise, yielding inconsistent performance
at best.
the SSP must not
be in a tape loop
The last remaining alternative would seem to be to insert the decoder
“within” a preamplifier by hooking it up in a tape loop. Unfortunately,
this setup returns the Left and Right outputs of the decoder to the
preamplifier, where they can be inappropriately changed without
changing the Center and Surround outputs. It is therefore inappropriate
to place surround sound decoders in a tape loop.
It would seem that there is no way to properly integrate a surround
sound processor with a preamplifier for a high quality, dual-purpose
system.
the SSP & the Nº380 The Nº380 solves this dilemma by virtue of a specially-designed sur-
round sound processor interface. When you select the ssp name for a
particular input on the Nº380, the output level and balance controls
are defeated and the preamplifier operates in a “unity gain” mode, pass-
ing through whatever signal enters that input without changing its vol-
ume in any way. In fact, the display indicates that a line-level signal is
being “passed through” unchanged by showing “LINE” in the display.
Thanks to this design innovation, it is possible for the first time to cor-
rectly integrate a surround sound processor with a preamplifier, sending
the processor’s Left and Right outputs through the Nº380 (and on to
the power amplifier for the main front speakers). Since the output level
of these channels cannot be changed by the Nº380 while in “ssp” mode,
the preamplifier cannot corrupt the careful calibration of the
processor’s output levels. And since the audio portion of audio/video
sources are fed directly to the processor’s audio input(s) at a line level,
input calibration cannot be disturbed by the preamplifier.