Bryston SP 1 Series Instructions Manual page 26

In a commercial Theatre, you don't detect this because the
large number of surround speakers and the reflections within
the room prevent your two ears from receiving equivalent
signals.
The THX Decorrelation Circuit discreetly changes the time
and phase of one surround channel versus the other
preventing your left and right ears from hearing identical
signals, and helping to re-create the spacious and ambient
sound you experience in a commercial Theatre.
In Dolby Pro-Logic mode, with THX processing selected, the
Adaptive de-correlation is operative at all times since the
surround signals are entirely monaural.This proprietary THX
processing algorithm also works effectively in Dolby Digital
and DTS film playback modes.
Even though motion picture sound-track mixing engineers
now have the option in these formats to create different
information for the discrete surround channels these encoding
processes offer, a significant portion of the overall soundtrack
may still be monaural.The unique adaptive nature of the THX
de-correlation processing detects monaural signals, and only
operates when such signals are present.
You can safely leave the THX processing engaged for all
motion picture playback modes, with the assurance that the
processing will only affect the type of signals it is designed to
enhance.
5. Bass Peak Level Manager
To diminish the chance that your subwoofer will overload from the large
amount of bass, often present in the LFE channel the system uses a Peak
Management circuit which works with the data you supplied during
speaker setup to help match the subwoofer output to your specific
subwoofer's capabilities.
Please note that the factory default for the BLPM is -20 dB since the
capabilities of your specific subwoofer are unknown.
In the SP1 setup and calibration section above ,the final step you should
have performed was to set the BLPM for your subwoofer's specific
capabilities. If you have not does this you should return to the setup section
(see page zxx) and do this now.
6. Loudspeaker Position Time Synchronization
In an ideal world your theater space would allow you to be an equal
distance from every speaker you have installed.
Unfortunately most residential spaces do not allow this condition to exist.
The THX Loudspeaker Position Time Synchronization circuit allows you to
digitally adjust the apparent position of each speaker in your system for the
best multi-channel imaging and smoothest frequency response.
NOTE:
Both the Bass Management(#5 above) and Position Synchronization
(#6 above) settings are accomplished during the system setup operation.
Once completed they normally do not need additional adjustments unless
you change speakers or speaker positions.
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