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





B&W DM-70


B&W DM 70 /Continental

Product Summary
The DM70 is new thinking on acoustical distribution pattern especially within the vitally important mid-frequency region of 400Hz to 5kHz, aiming towards exploring the advantage of an approximately spherical distribution pattern.
All units are designed and built within our factory to ensure maximum quality control and retention of the exclusive original design
The styling and general appearance has been designed to be acceptable in the world market, resulting in the Standard and Continental versions each available in various finishes.


 Technical highlights
A mid-frequency unit capable of handling input powers in the region of 35Watts RMS with distortion factors to the order of 0.5% or lower.
The bass radiator is capable of truly complementing acoustical distribution and power handling without occupying an unduly large enclosure volume.

 Electrostatic mid and HF unit
This is an eleven module doublet electrostatic unit covering all frequencies above 400 Hz. It's unique polar distribution pattern both improves stereo stability and increases the ratio of reverberant to direct sound. The pattern is virtually circular in a vertical plane through mid-band frequencies, providing a very wide, uniform arc.
Bass Unit
Bass frequencies are handled by a unit with a nominal 12 in (305 mm) piston diameter, chosen as being reasonably consistent with the enclosure volume to build a system with a resonance below 40 Hz , and a free air resonance in the region of 18 - 22 Hz.
The cone assembly consists of a laminated structure providing the stiffnes requiered to avoid break-up, and is additionallly braced and mass adjusted by small rectangular sections of synthetic rubber fixed at critical positions on the front face of the cone.
The massive magnet assembly ensures excellent damping and handling of transiants without hangover.

Bass Chamber
This is an infinite baffle type, with complex internalabsorbents making it almost aperiodic. Considerable attention has been paid to both finish and construction, the enclosure is acoustically inert, being built of 24 mm of 650 density chipboard and heavily braced.


B&W DM 70 Standard


Specifications
Type:  Stand-mount loudspeaker system
Acoustic Load: 
Bass unit : Infinite
Electrostatic unit : Free standing with removable pad to control rear radiation pattern
Drive Units:
Electrostatic mid & HF unit covering all frequencies above 400Hz
305mm piston diameter bass/midrange unit
Axial response:  90° arc horizontal within ±2 dB an axis response at all frequencies up to 15 kHz
Frequency Response:   50 Hz to 15 kHz, ±4 dB
Crossover Frequency:  Nominally 400 Hz
Total harmonic Distortion:  1,1% at 1 kHz
Sensitivity:  95 dB at 1 metre
Nominal Impedance:  8 ohms
Power Handling:  25 W
System Resonance:  40 Hz ±1% (System Q below unity in the order of 0,9)
Dimensions:
Standard Model
Height : 808 mm (including stand)
Width : 815 mm
Depth : 382 mm
Finish : Walnut or Teak
Weight:  50,8 kg (112 lbs)
Continental Model
Height : 820 mm
Width : 680 mm
Depth : 390 mm
Finish : Walnut and white
Weight:  36,3 kg (80 lbs)



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