Parasound Halo C1 Controller manual Using Unmatched Power Amplifiers

TECHNICALLY SPEAKING continued 61

Using Unmatched Power Amplifiers:

While it’s best to use identical amplifiers for all chan- nels, it’s sometimes more convenient or economical to use a mixture of amps, especially if you already have some. If you do, observe the following:

•Check with your amplifiers’ manufacturers to see which of your amplifiers do and do not reverse sig- nal polarity. Then reverse the output connections of the amplifiers that reverse polarity – and only those amps (i.e., connect their black terminals to the speakers’ red terminals, and vice versa). This will ensure correctly matched polarity from all your speakers. Otherwise, “imaging” (the sense of where sounds are coming from in the recorded soundfield) will be vague, and bass may suffer.

•It is not necessary that your amplifiers have identi- cal input sensitivity (a measure of the input level needed for a given output power), because any variations are automatically compensated for when you set up and match your speaker levels.

•Your amplifiers need not have the same power rat- ings, either. Low bass requires the most amplifier power to reach adequate levels for music and spe- cial effects. So your most powerful amplifiers should be used for your subwoofers (if they have no amplifiers of their own) and for speakers that you identify as “Large” during C 1 setup. If you have “Large” speakers in all channels, the front speakers should get the most power, then the sur- round speakers, and the lowest-powered amps can be used for the surround back channels. If you have a mix of “Large” and “Small” speakers, use the more powerful amps for the “Large” ones.

THX ® Processing

When THX modes are selected for an incompatible source or speaker setup, the C 1 will remember the selection and will automatically apply it when the setup is changed or when a compatible source is selected.

Pressing the THX key on the Master remote turns on THX signal enhancements that work in conjunction with most of the C 1 listening modes. (The excep- tions are those which generate surround signals from two-channel source material, such as Pro Logic, PL II Movie, PL II Music, Neo:6 Cinema, Neo: 6 Music, Natural, Party, Club, and Concert.)

THX processing has several parts and modes:

•Re-Equalization, which is patented by Lucasfilm, adjusts the frequency response of movie sound- tracks to compensate for the acoustical differences between home theaters and commercial movie theaters; without it, movie soundtracks would sound overly bright and fatiguing. It is applied to

the front channels and, in THX Surround EX mode, to the surround back channels, but not to the side surrounds. Re-Equalization is not used in the THX MusicMode.

•Timbre Matching compensates for a characteristic of the human hearing that changes the apparent frequency balance for identical sounds coming from different angles and directions. Because the main speakers are at the front and surround speak- ers are at the sides, this hearing characteristic would make voices and other sounds change as they moved from the front to the surround chan- nels, or vice versa. Timbre matching alters the fre- quency balance in the side surround channels to compensate for this.

•Adaptive Decorrelation functions with Dolby Pro Logic to add a greater sense of spaciousness and to enlarge the listening “Sweet spot.” It accom- plishes this by altering the mono surround informa- tion so that the left and right surround speakers receive different, rather than identical, signals. It does not apply when the surround channels already differ from each other, as is usually the case with such discrete digital surround systems as Dolby Digital and DTS.

•THX Surround EX decodes information for the sur- round back channels from signals matrixed into the surround side channels. It is not available for non- surround signals or for those which, like DTS-ES Discrete, carry back surround information as a sep- arate digital signal. To activate THX Surround EX, press the THX key on the Master remote while in Direct mode. (If “THX EX Enable” on the “THX Audio setup” menu is not set to “EX On,” you will have to push the THX key twice.) This mode is available only when the presence of at least one surround back speaker has been noted on the Speaker Setup/Size menu.

•Advanced Speaker Array (ASA), available only in sys- tems with dual surround back speakers, compen- sates for the effect of different speaker spacings on the size of the listening “sweet spot.” When it is active, two more modes become available:

–THX Advanced Cinema is designed for playback of 5.1-channel digital soundtracks over a 7.1-channel system.

–THX MusicMode is similar, but sends more sound to the surround back speakers and less to the side surrounds.

•Boundary Gain Compensation reduces excessive bass below about 35 Hz, to prevent the boominess that can occur when speakers with substantial