Installers often specify two-channel ceiling speakers to make their jobs easier when installing speakers in zones where both left and right channels must be routed to only one speaker, but inherentdesign flaws in conventional two-channel designs often lead to significant performance sacrifices.
â€œOur goal,â€ says Parasound president, Richard Schram, â€œwas to make a two-channel speaker which would sound identical to our C 65. However, this was easier said than done! We soon learned that the typical dual-tweeter, dual-voice-coil-woofer configuration had inherent flaws. With two tweeters, the mid and high frequencies from one tweeter reinforce and cancel the mid and high frequencies from the other tweeter, causing very jagged and fatiguing frequency response peaks and dips. Tonal quality varies immensely as you move around the room.
â€œThe basic problem with a two channel woofer voice coil,â€ continues Schram, â€œis that it weighs more than a conventional voice coil. This weight reduces the woofer’s sensitivity, while its frequency response and tonal balance vary drastically, depending on if one or two channels are connected. Also, its impedance is halved when its two voice coils are connected in parallel for a single channel.â€
To make a C 70 two-channel speaker sound like a C 65, Parasound uses an actual C 65 driver and crossover. Schram’s innovation is to connect the two input terminals directly to a special precision audio transformer with two 8 ohm primary windings and a single 8 ohm secondary winding, which in-turn connects to a single C 65 crossover. Signals from the left and right amplifier channels are safely blended to mono in this unique transformer.
This has several major advantages: First, Its load is always a gentle and consistent 8 ohms for both one- and two-channel configurations. In other two-channel speakers when the channels are connected in parallel, the resulting 4-ohm impedance leads to increased amplifier distortion, reduced dynamic headroom, increased its operating temperature, and a shorter operating life.
Second, the C 70 level stays the same whether one or both channels are connected. Now you can install two-channel C 70s and single-channel C 65s in the same system and know their levels will all match. The output levels of other brands of two-channel speakers will always be relatively lower with one channel connected, or higher with both channels connected.
Finally, the C 70 has the same excellent frequency response and â€œpoint sourceâ€ dispersion characteristics as the C 65. With other two-channel speakers, response is ragged and radiating patterns are full of â€œhot spotsâ€ and â€œnullsâ€ that make uniform coverage nearly impossible.
The C 70 is ideal for open spaces or for mounting near side walls. The 1-inch Ferrofluid-cooled soft-dome tweeter can be aimed up to 15 degrees off-axis for smoother in-room response and precise focus. The 6.5-inch Polypropylene/Mica woofer features an advanced Santoprene surround material that both improves frequency response linearity, and prevents the deterioration that occurs in conventional foam surrounds over time.
The Parasound C 70 two-channel ceiling speaker is currently available at a suggested retail price of $325 per pair.
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