Model Information

[Tranquility Bass]

DAL Sigma
 





From the time of its introduction during 1992, the DAL SC-IV loudspeaker earned international acclaim in top audiophile magazines and among leading recording and mastering studios for its virtually flawless reproduction of complex musical sounds. Indeed, the SC-IV was Stereophile magazine's "1994 Product of the Year" and earned "best sound" awards at numerous audiophile shows throughout the world.

In keeping with its tradition of always pursuing means for improving its products and their performance, DAL introduced the SC-IV/A during 1998. It incorporated a new type of woofer (that made possible an on-axis response down only -3 dB at 20 Hz) and a much more complex crossover network (with nearly twice as many components as the SC-IV). The review of the SC-IV/A by highly respected Robert Deutsch in the November 1998 issue of Stereophile, confirmed that it represented a significant upgrade of the original SC-IV - and a "steal" at its recommended retail selling price.

Now comes the SIGMA-I, a loudspeaker similar to the SC-IV/A but with added complexity and sophistication. Although the SIGMA I uses the same tweeter, mid-range and woofer drivers as the SC-IV/A, that is where the commonality ends. The SIGMA I is larger than the SC-IV/A by approximately 1.5 inches in height, width and depth, by virtue of its double thick (1.5") walls. Also, seen from the front, the SIGMA I has a very attractive 3/4-inch, "quarter-round hardwood trim" that surrounds and "outlines" the SC-IV/A-size grill. Additional internal bracing also adds to the stiffness and acoustically inert properties of the SIGMA I's enclosure.

Further, the complex and sophisticated crossover network of the SIGMA I provides highly accurate reproduction of the most complex musical transients. This attribute is evident from an examination of its well-documented, measured and audible accuracy is without equal in the marketplace - except, of course, that of larger and more expensive DAL loudspeaker models.

The guaranteed performance specifications of the SIGMA I reveal such attributes as an incredible bass extension (-3dB @ 20 Hz), true +/- 1 dB amplitude Vs frequency response (measured anechoically at 10 feet on-axis), near-perfect impulse and step responses, ultra-low levels of non-linear distortion, true on-axis "time/space collimation"(TM) (pulse-coherency), inaudible cabinet diffraction, symmetrical radiation patterns, a very flat curve of impedance Vs frequency (that varies from about 3 to 7 Ohms, with very little reactance), broad vertical/horizontal dispersion and precise pair matching. DAL also performs 100% Q.C. testing of every speaker driver, sub-assembly and each assembled loudspeaker. Final on-axis measurements of frequency response, impulse response, step response, etc. of every speaker are made within one of DAL's two large anechoic chambers, under the direct supervision of a competent engineering staff, to ensure that every performance specification is met or exceeded before shipment.

Indeed, in a world where "flooby-dust" advertising and subjectively-based claims have replaced real, well-documented evidence of performance accuracy, the SIGMA-I offers proof of what today's most advanced loudspeaker technology can accomplish. And, it does so at an affordable price.


 

AMPLITUDE/FREQUENCY RESPONSE:	25Hz to 20kHz; +/- 1 dB; -3 dB @ 20Hz (anechoic).
EFFICIENCY:	Approximately 91 dB SPL at 1 meter for an input level of 2.83 Volts RMS
IMPEDANCE:	Nominal 4 ohms (min.=3 ohms; max.=7.5 ohms)
PULSE-COHERENCE:	Impulse response is equal to or better than most top-of-the-line CD players and Digital Processors.
RADIATION PATTERNS:	Precisely symmetrical in both horizontal and vertical planes
DIFFRACTION DISTORTION:	Virtually eliminated by the use of efficient sound-absorbing material. (US Patent #4,167,985)
DRIVERS:	-Two 10" Woofers (cast basket, high damping rubber surround)           -Two 5" Mid-Bass (cast basket, high damping rubber surround)           -One 1" composite textile dome tweeter.
CROSSOVER AND INTERNAL WIRING:	First order design. Biwire, biamp capability. High voltage, metal film capacitors. Precision machined wound, heavy gauge, high purity copper coils. CAD designed Mil spec fiberglass PC boards utilizing high purity copper traces. Internal wiring via individually isolated ultra pure, proprietary copper cables.
RECOMMENDED AMPLIFIER POWER:	Minimum of 100 watts/channel, rated into 8 ohms
RECOMMENDED LISTENING DISTANCE AND ROOM SIZE:	10 to 12 feet, on axis, in a room not smaller than about 15 feet by 24 feet.

 

SIZE:	72.75" H x 13.5" W x 19.5" D
WEIGHT:	250 lbs. (each)
MATERIAL:	Laminated layers of veneered MDF, varying in thickness from 3/4" to 1.5". The internal volume is optimally filled with high-quality, open-cell foam to achieve appropriate absorption and damping of internal acoustical energy.
FINISH:	Standard: light or black Oak.           Optional: Rosewood, Cherry or Natural Cherry.
GRILL:	Frame: Acoustically transparent, precision machined steel frame.           Cloth: Acoustically transparent black weave

Sigma Frequency Response






Sigma Impulse Response






Sigma Step Response






Sigma Spectral Time Delay Response






Sigma Impedance

[Tranquility Bass]