Madrigal Imaging N38 User Manual

Page 29

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 set-up 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 Nº38 solves this dilemma by virtue of a specially designed surround
sound processor interface. When you select the “ssp” alias for a
particular input on the Nº38, the output level and balance controls are
defeated and the preamplifier operates in unity gain mode, passing
through whatever signal enters that input without changing its volume
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
correctly integrate a surround sound processor with a preamplifier,
sending the processor’s Left and Right outputs through the Nº38 (and
on to the power amplifier for the main front speakers). Since the
output level of these channels cannot be changed by the Nº38 while
in “ssp” mode, the preamplifier cannot corrupt the careful calibration
of the processor’s output levels. And since the video sources are fed
directly to the processor’s audio input(s) at a line level, input
calibration cannot be disturbed by the preamplifier.

Note: the Nº38 will not allow an input with an “ssp” alias to be
selected during initialization, since allowing a line level signal to
pass through unattenuated at start-up presents a potential
hazard to your loudspeakers.

Surround sound

processors should not

be in a tape loop

Surround sound processors

and the Nº38

Wiring Diagram with a

Surround Sound Processor

Ctr

Listening Room

MADRIGAL AUDIO LABORATORIES

display

intensity

monitor

record select

balance

inverted

polarity

mon

standb

PREAMPLIFIER

Nº 38

mode

mute

video 1

video 2

video 3

video 4

Surround Sound Processor

Sub

Surround Power Amplifier

Center/Sub Power Amplifier

Main (Front) Power Amplifier

Ctr

Sub