Madrigal Imaging Audio/Video Preamplifier manual Using the PAV

Setting the Volume

Home THX cinema

Dolby Pro Logic Surround

Stereo Surround

Using the PAV

There are, in effect, two volume controls in the PAV. When in either THX cinema or pro logic modes, the input level control should be used to compensate for dif- ferences between recordings, using its associated green LED as a guide. Adjust- ments to allow for personal preferences, late-night listening, and the like should then be made with the master volume control.

When in any of the other surround modes, the input level adjustment is signifi- cantly less critical and can be largely ignored (particularly if input level defaults were set up during installation).

When the THX cinema mode is engaged, both the Dolby Pro Logic circuitry and the proprietary Home THX audio processing circuits are in use. This is most ap- propriate for film-based program materials made since the mid-1970’s, which have in all likelihood been mixed in a standard dubbing stage environment. This set- ting will provide the listener with the most accurate reproduction of the majority of motion pictures available. In addition, many other video source materials are produced in Dolby Surround using the industry standard response curves, and are best enjoyed in the THX cinema mode. (Examples include Star Trek: Voyager and The David Letterman Show, which are mixed in an environment which emu- lates the dubbing stage used for film.)

Some program material does not conform to film industry standards, although it may still be Dolby Surround encoded. Music videos on MTV, for instance, are of- ten Dolby Surround encoded, but have soundtracks which are produced in non- film studios. In fact, a growing number of music CDs are mastered with surround sound. These sources and others which have surround encoding but which are unlikely to have been mixed or re-mixed in industry-standard production facili- ties should use the pro logic mode to avoid compensation where none is indi- cated.

When in doubt as to whether THX cinema or pro logic is more appropriate, lis- ten for a natural presentation of the treble. Films mixed for theatrical release ex- hibit an elevated treble region when played back on a home system with flat re- sponse. The THX cinema mode will correct this. Conversely, surround-encoded programs without this high frequency emphasis might sound dull or lacking in detail when (incorrectly) played in the THX cinema mode.

The stereo surround mode has been carefully designed to extract real ambience from your recordings rather than synthesizing something artificial that might be quite alien to the music itself. The ambient cues found in the program material are then used to provide appropriate information for the center and rear speakers. The front Left and Right speakers are left unaffected by this mode, allowing you to hear unadulterated stereo imaging with the addition of a genuine sense of hall ambience.

Since this mode is based on the recordings themselves, it is normal to hear some variation in the degree of the effect. Extremely “dry” recordings which lack any significant ambience may not sound significantly different than when in surround

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