STAX SR-Σ (Sigma) Series

 Stax electrostatic earspeakers are widely used by the best recording studios and broadcast stations in the world. The simple reason for this is that these earspeakers deliver unsurpassed sound quality and the most accurate high fidelity reproduction possible. The general advantages of headphones over speaker systems are:

The acoustic conditions of the listening room do not affect the sound.

The diaphragms do not have to move much air (there is little load) therefore they can be made lighter to improve transient response.

There is no danger of acoustic feedback (howling) to the turntable.

The diaphragms are very close to the ears, so it is easy to pick up small musical details.

 The advantages of electrostatics over conventional headphones are:

The several micron thick high polymer film diaphragm is so light that it can respond accurately and instantaneously to the tiniest signal fluctuations.

There is no magnetic (hysteresis) distortion since no magnets or voice coils are used.

Electrostatic drive ensures uniform control over the entire diaphragm surface so there is no partial vibration or the cone breakup seen in dynamic type headphones.

 Stax (SR-Σ) Professional Series

The Stax professional series earspeakers have originally been developed for Daimler-Benz, the world-famous West German automotive manufacturer. They feature a wider electrode gap realized by a increased bias voltage (580 V). This resulted in a distortion-free bass sound along with a incredibly pure mid and high frequency range.

 The SR-Σ (Sigma) and Σ Professional are completely new kind of earspeakers developed over a long four year period. Their innovative design lets you enjoy more natural ambience reproduction than is possible with simple headphones. The diaphragms are placed forward away from in a normal music listening environment. The outer ear is not pressed, so the entire ear interacts naturally with the sound. Furthermore, a carefully designed cavity is employed to produce resonance characteristics simulating those occuring in a hall or room. All this results in a panoramic sound field without the feeling one has with conventional headphones that the sound is centered within one's own head. The employment of comfortable lightweight materials and a biomechanically engineered headband also contributes to the non-fatiguing pleasure of listening to music with the SR-Σ and SR-Σ Professional.

Stax SR-Σ (Sigma) System -

The Stax SR-Σ Panoramic Imaging Electrostatic Earspeaker design is a successful attempt to recreaqte a natural, realistic sound field from a headphone format. Headphones were originally designed for picking up Morse Code in communications, not recreating a musical sound stage. Until the introduction of the Stax SR-Σ, no headphone manufacturer paid much attention to ambience and its effect on musical imaging.

The SR-Σ earspeaker design locates an oval shaped electrostatic transducer in front of the ear at 90° angle to the ear. This does two things to improve the image perspective to the listener. First, by using an oval shaped transducer that is larger than the outer ear itself, the SR-Σ allows the outer ear to naturally channel the waveform into the inner ear. This allows the sound to reach the eardrum in the most conventional way. Second, the transducer is located in front of the ear, not over the ear. This removes the image perspective from within the listener's head and places the image in front of the listener. The SR-Σ transducing elements are positioned ideally in terms of the natural perimeters and auditory path of the ear. The result is optimum spacing for music in relation to the ear. The SR-Σ gives natural sound with none of the tight, sealed-in feeling, or the diminished scale sensaations conveyed by ordinary headphones.

Specifications SR-Σ [SR-Σ Professional]

Type:  Electrostatic / Push-pull High Bias

Frequency Response:  25 - 38,000 Hz [30 -35,000 Hz]

Sensitivity:  94 dB [98 dB]

Impedance (10 kHz):  122 k Ω [143 k Ω]

Maximum Output:  103 dB

Earpad:  Soft artificial leather, replaceable

Cord (low-capacitance):  2,5 m; 6-strand  6-pin plug [5-pin plug, PC-OCC]

Weight (without cord):  391 g [395 g]