Owner`s manual

Using Surround Sound

Processors

The Nº32 Reference Preamplifier incorporates a special surround

sound processor mode which makes it uniquely capable of integrating

the highest performance audio with surround sound—that is, a dual-

purpose music and movie system. In order to better understand the

value of this design, it is essential to understand a bit about the nature

of a surround sound processor.

One obvious and fundamental difference between stereo listening and

multichannel listening is the number of channels that must be con-

trolled. When listening to two-channel stereo, one must have a two

channel volume control so both speakers increase or decrease in vol-

ume in concert with one another. Similarly, when listening to six- or

eight-channel surround sound recordings (whether movies or music),

one must have a corresponding six- or eight-channel volume control.

This simple fact has made combining a high quality two-channel

preamp with an outboard surround sound processor extremely diffi-

cult over the years. In fact, until the Mark Levinson Nº38 was intro-

duced in 1993, it was virtually impossible to combine the two and have

the system work reliably well.

the SSP must not

come after the preamp

Dolby Pro Logic decoders incorporate a form of Dolby noise reduction

similar to the Dolby B one finds in cassette decks. This form of noise

reduction is level-sensitive. That is, Dolby noise reduction intentionally

treats strong signals differently than weak signals. In order to operate

correctly, the signal strength of the source must be “calibrated” to the

expectations of the Dolby noise reduction circuitry. (It is for this rea-

son that one finds “Record Calibration” features on better-quality cas-

sette decks.) It is therefore inappropriate to feed a surround sound de-

coder with the variable output of a preamplifier. Were you to do so, ev-

ery change of the volume control on the preamplifier would cause the

Dolby circuitry to mistrack. In extreme cases, severe distortion can re-

sult as the Dolby circuitry overloads.

the SSP must not

come before the preamp

The next logical alternative might be to use the surround sound pro-

cessor ahead of the preamplifier, sending its Left and Right outputs

through the preamplifier as a selectable Source. Sending the Right and

Left Outputs from a surround sound decoder to a pair of inputs on a

conventional preamplifier is also inappropriate, since any change of the

preamp’s volume control would then throw the carefully calibrated