Rugged deep response woofer
To meet the specifications for the Sp-39, Philips engineers were obliged to design a woofer which could meet four rigid acoustic requirements; deep bass response, high efficiency, impeccable fidelity, and rugged durability. The newly designed 8" cone woofer offers all these features.
In any system, a woofer must provide rich, satisfying bass. The Sp-39's woofer exceeds even he goals of fine speakers, however, reaching down to 30 Hz for full bottom. With a fundamental resonance frequency of 20 Hz, however, the driver also avoids the hollow, boxy tones so sften found in speakers of this size.
Construction of the cone is from fibre-filled pulp selected for its combination of strength and exceptional resistance to distortion. The driver itself is seated in a new high-compliance suspension.
At the heart of the woofer is Philips Feroxdure ferrite magnet and an all-aluminum voice coil. Feroxdure eliminates the need for massive unwieldy magnets which were formerly needed to create deep bass response. One light-weight Feroxdure magnet provides more strength than orthodox magnets of considerably greater size. At the same time, the aluminum wire-would voice coil, which minimizes mass, offers significantly less resistance to movement than the standard voice coil. And the all-aluminum bobbin radiates heat efficiently, one reason why this driver is so resistant to over-load; even at 40 watts (RMS) of power input, this woofer will stand up to stress.
Wide-dispersion midrange
The same design features which characterize the SP-39's woofer have been incorporated in the new 2" dome mid-range driver.
The same patented Feroxdure ferrite magnet and the all-aluminum voice coil ensures high efficiency and faithful reproduction along with surprisingly light weight. The power of this new driver is comparable to that of orthodox drivers much larger and heavier.
Normal speaker systems force the mid-range driver and woofer to share the same baffle. This design allows interaction between the woofer and mid-range driver which can result in severs distortion. The new Philips mid-range driver is acoustically isolated in its own anclosure. The mid-range driver is capable of operating a full efficiency even outside the speaker cabinet. Because of the directional nature of mid-range frequencies, the driver has been designed for wide dispersion. The total angle of dispersion is a full 120°
Special acoustically isolated tweeter
A 4" dome design, the driver features a 1" copper wire-wound voice coil and the patented Philips Ferodux magnet. The Feroxdure ferrite magnet packs considerably more power into the same size than orthodox magnets can offer; greater strength means faster response and cleaner sound.
Like the mid-range driver, the tweeter is sealed in its own enclosure, isolating the driver from the woofer which could cause distortion. The tweeter is capable of operating at full efficiency even outside the speaker cabinet.
Specifications
Speakers
Woofer : 8" cone-type
Mid-range : 2" wide-dispersion dome-type
Tweeter : 1" dome-type
Power Handling Capacity: 40 watts (RMS); 80 watts (peak power)
Impedance: 8 Ω
Efficiency: 96 dB at 4 watts (1 metre , T.H.D. 1,0%)
Frequency Response : 35 - 20,000 Hz
Crossover Requirements: 500 and 450 Hz
Crossover Network: 3-way 12 dB/octave parallel type
Fuse Type: fast blow protection
Dimensions (H x W x D): 22" x 13" x 10,5"
Weight: 45 lbs
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