What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





McIntosh XRT 18 loudspeakers


The McIntosh XRT 18 system produces sound uimages that are amazingly life-like. You'll hear stereo images that have depth and space dimensions that are so realistic, so satisfying that you will feel aware of the dramatic emotional intensity of your first experience of live music.
When you first hear the XRT 18's you will be amazed by five outstanding characteristics:
Transparency of sound
Coherence of sound imaging
Definition of musical instruments
Musical balance
Musicality of expression
Absence of typical loudspeaker sound
The core of the concept of the XRT 18 system involved not only the usual guidance from years of experience and the intuitive vision of a new possibility, but in this case it centered, as well, around a one and only choice from hundreds of possible cones, suspensions, magnets, agnetic assemblies, crossover network components, enclosure volume, stiffnes and geometry. that one critical choice is an optimized interrelatedness which yields, via computer modeling, the extra smoothness of the time and energy response fields which has eluded researchers for decades.
This miracle of sound recreation does not happen by accident. To reproduce the power, the clarity, and the pure musical expression of a triple fortissimo it takes a lot of individual speaker mechanisms. the XRT 18 distriubutes  the power over 32 tweeters, two midranges and two bass mechanisms. All of these must be coordinated in time and intensity to achieve the uniformity of sound images, wide, deep, accurate, realistic and satisfyimng. How we combined all of these radiators in the correct combination of pairs of radiators, controls of energy and time is the story of the XRT 18 system.

The voice coil assembly is joined directly to the rigid cone. It moves in the magnetic field of an oversized magnet and magnet structure. This voice coil assembly is centered and suspended in the magnetic field by a special cloth spider. The compliance of the spider is controlled by the careful impregnation of the cloth with phenolic resins. Diligent engineering decades of experience and continuous testing determined the selection of the right mass of the cone assembly for the ideal match of the energy capability of the magnetic structure. The cone and voice coil assembly is attached to the speaker basket with the centering spider and a critically formed closed cell urethane surround which is coated with a proprietary sealant.
The six inch mid-range was designed to complement the frequency range of both the twelve inch woofer and the one inch dome tweeters. Construction is very similar to the woofer except the mass and size of moving parts are greatly reduced to accommodate the higher frequency range. The rear of the mid-range is acoustically isolated from the woofer so that it cannot be driven by the back pressure wave of the woofer.
The one inch high frequency domes are made of a specially formulated textile. each dome is attached to a copper wire voice coil wound on a high temperature form. The assembly is centered and suspended in the magnetic field by a special surround. Both dome and surround are  coated with a proprietary material to make an air tight seal. The surround is connected  to an intermediate ring which is fastened to the magnet assembly.

Specifications
Frequency Response:  20 - 20,000 Hz
Reference Output Level:  86 dB (SPL) 1m/1W
Maximum Power:  150 watts of contiuous power (the system is capable of up to 500 watts program peaks)
Recommend Power:  As little as 30 watts may be used for smaller rooms and lower listening levels.
Fuse Protection:  system is protected by a 3 amp fast acting main fuse. The tweeters are protected by a 1=1/4 amp fast acting fuse.
Impedance:  8 ohms nominal
Crossover Frequencies:  350 Hz and 1500 Hz
Speaker Sizes (diameter):
Woofer :  305 mm (12 inch)
Mid-range :  152 mm (6 inch)
Tweeters :  25,4 mm ( 1 inch)
Cabinet Construction
The bass cabinet and high frequency column frame are made of 48 pound density fiber board with genuine walnut veneer exteriors. The finish  is a 23 step process including 6 hand applications  of oil-sealer with intermediated hand sanding and rubbing operations which enhances the full beauty of the walnut.
Cabinet Dimensions:
Bass Cabinet (W x H x D):  445 x 691 x 298 mm (17-1/2 " x 27-7/32" x 11-3/4")
Tweeter Column (W x H x D):  267 x 1456 x 413 mm (10-1/2" x 57-5/16" x 1-5/8")
System Weight:
Bass Cabinet :  28,6 kg (63 lbs)
Tweeter Columns :  13,2 kg (29 lbs)
Total Stereo System Shipping Weight:  98 kg (216 lbs)

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