SETTING LISTENING MODES
ABOUT THE S170'S LISTENING MODES
The S170 preamplifier offers seven distinct listening modes, tailored for different types of recordings or program material.
MONO
All output is directed to the center channel; low frequencies are directed to the subwoofer if one is present in the Speaker setup
Mono mode is best selected for monaural recordings originally produced in single-channel format, including classic films and historic music recordings. It ensures a stable, clear monaural presentation with correct bass management.
STEREO
Stereo recordings, whether in PCM/digital or analog form and wither surround-encoded or not encoded, are reproduced as recorded; multichannel digital recordings (Dolby Digital and DTS) are reproduced via the left- and right-front channels only, as Lt/Rt (left/right-total or "downmixed") signals.
Select Stereo mode for listening to stereo recordings when you do not wish surround-sound to be in effect, or for multichannel recordings when only two-channel playback is possible (or desired).
DIRECT (DOLBY DIGITAL / DTS SOURCES ONLY)
Multichannel digital recordings (Dolby Digital or DTS) are reproduced via only the channels employed in the original recording. For example, a "5.1-channel" Dolby Digital 3/2/1 recording will reproduce via the front left-center-right, surround-left/right, and subwoofer speakers (plus surround-back speaker(s), if any); a Dolby Digital 2/0/0 recording will reproduce via only the front-left and -right speakers (and the subwoofer if these were set to "Small" on the <Speaker setup> OSD menu, and so on.
SURROUND 6.1
Multichannel digital recordings (Dolby Digital or DTS) are reproduced via the full suite of front, surround, and one or two "back"-channel speakers, plus subwoofer (if any). If Dolby Digital EX/DTS ES encoding is present in the original recording its logic is used to derive the back channels; otherwise, the S170 preamplifier derives a single surround-back channel from the left/right surround channels.
DOLBY PRO LOGIC
Surround-encoded recordings (and stereo recordings that are not encoded ) are reproduced with Pro Logic Dolby Surround decoding, with output to left, center-, and right-front channels and a single monaural surround signal sent to both surround-channel speakers, plus a subwoofer (if any). The surround channel's response is rolled off above 7 kHz to discourage localization of surround-speaker locations in DPL mode.
Pro Logic mode is best reserved for surround-encoded recordings intended for Dolby Surround or compatible-system reproduction. These include most films on videotape and many on LaserDisc, television/cable programming produced for surround-sound, and most older LaserDiscs. Most DVD recordings, even those that do not exploit multichannel surround, include a Dolby Digital and/or DTS soundtrack in 1- or 2-channel modes; where available, this will usually deliver better performance. With rare exceptions, NAD's proprietary EARS listening mode will produce superior results from stereo music recordings than will Pro Logic.
