Why are we so insistent on electrostatic speakers? Well, first of all, there’s the question of sound quality.
But a particular sound isn’t yet a wave motion of the air; it doesn’t yet get the eardrums vibrating. But a created sound about to come into being does the rounds of the neurons and the synapses. It dances around loftily or stealthily in the cranial universe of the composer or the performer. STAX earspeakers trace this sound. The method employed in this connection has to be electrostatic, because delicate sounds must not get lost. Delicate sounds are important elements of textural recreation. The main issue faced by pure audio is its re-creativity capacity. The question is how to convert the delicate opening wave patterns that determine tonal quality faithfully into air vibrations. This is the principal merit of electrostatic speakers. This is the only system that has the potential to recreate the most minute nuances with complete accuracy. SR-007 MK2 is the flagship model that aims to achieve the peak among STAX electrostatic speakers. They possess strong drive power in respect to the diaphragm due to the provision of an area in which there are no holes whatsoever on the outer ring of the electrodes (fixed poles) that were completed after an extended process of design and productions of prototypes. They succeed to the new generation units that realize a high degree of linearity in the aperture area. After attachment to a thick insulated resin case, they are fixed to a strong aluminum machined enclosure and shut out unwanted vibration. The cable is designed with the most appropriate structure for transmitting signals to the electrostatic transducer, and use is made of STAX original cables employing high-purity PC-OCC conductors that achieve outstanding sound quality due to their extreme thickness and low capacity. The new product SR-007 MK2 features improvements to the connecting area between the unit and the cable and achieves further improvements in transmission capacity and reliability. The mechanism unique to the SR-007 series whereby the enclosure and the ear pads rotate independently of one another makes it possible to achieve a positioning that exactly fits the ear shape of each individual listener. Where do the music of the spheres and the vibration of the cosmos begin and end?
Setting a section without any holes whatsoever on the perimeter of the electrodes makes it possible to achieve a deeper and more dynamic expressive capacity. There is strong drive power in respect to the diaphragm, and a high degree of linearity is achieve in the opening section too.
As is the case with ordinary speaker systems, the sturdiness of the enclosure is important for earspeakers. After enclosing the sound-producing unit in a thick insulated resin case, it is fixed to a solid metal enclosure. All unnecessary vibration is excluded.
A structure is adopted whereby the enclosure and the earpads are able to rotate independently. This enables positioning that exactly fits the shape of the ears.
An original cable developed with the aim of achieving an even higher level of reproduction is provided.
The conductors make use of high-purity PC-OCC. Outstandingly high sound quality is achieved through the extreme thickness and wide and low capacity.
Specifications of SR-007MK2 Electrostatic Earspeakers
●Type: Push-pull electrostatic open-air type headphone
●Frequency response : 6 to 41,000 Hz
●Impedance : 170 KΩ (at f = 10 KHz)
●Capacitance : 94pF (including cable)
●Sensitivity : 100 dB / 100 V r.m.s. at f = 1 KHz
●Bias voltage : 580 V / DC
●Left & Right Channel identifications :
Left (L) and Right (R) indicators are provided at the cable en trance points on the Earspeakers.
The left channel cable is marked with a solid Line.
The right channel is marked with a dotted Line.
●Ear pads : Real leather (Lamb) used on a part coming into contact with the skin.
High-quality leather used for the surrounding part.
●Cable : 2.5m, PC-OCC, wide, low capacitance cable
●Weight : 365 g (Body) , 512g (Including cable)
●Operating temperature range: 0 to 35
●Humidity range for use: Less than 90% (without condensation)
New vistas for the non-feedback output stage
The first performance feature required of audio equipment is the capacity to convert air vibrations into sound waves so that the slightest signal can be appropriately heard by the ear. This means that an essential condition of the vibrating medium, i.e. the diaphragm, in the speaker which constitutes the system of conversion from electrical signal to air vibration is that it needs to be as light as possible. Divided vibration, which is unavoidable in the case of point drive, is possible, as is also ultra-miniaturization if total drive is possible. Moreover, if headphones are used, there will be reduction in the mass of air that needs to be driven, creating a more ideal situation. The electrostatic (condenser) type is the system that comes closest to this ideal. STAX refers to speakers of this type as “earspeakers” and has continuously sought for the ideal form. Since a dedicated unit is needed for drive purposes, the development of such units is equivalent to the pursuit of high sound quality in the electrical signal system. The matching drive system and the amplifier system are used for driving electrostatic speakers, and in the case of amplifiers it is possible to build circuits by means of vacuum tubes. In the case of electrical signal systems too, it is generally known that sound quality varies extensively depending on the circuit configuration, parts, etc. Which should be selected? There is also the element of musicality that needs to be taken into consideration when determining the sound that is the be-all and end-all of audio. The new SRM-727II employs semiconductor output drive stage and non-feedback (NON-NFB) output stage for the first time ever in a STAX driver unit. A pure balance DC amplifier configuration is used for the large current emitter follower Class A output stage. A significant increase in dynamic range especially in the upper frequency has been achieved. A high level of sound purity is achieved through the simple two-stage amplification circuit with low-noise FET input stage. This is a brand new driver unit that opens up new vistas for the sense of mass and textural expression supported by a virtually unparalleled degree of resolution, a natural sense of openness, and a powerful power section.
●The electrostatic method is a playback method which involves the installation of drive electrodes on either side of a high-polymer film diaphragm with a thickness of only a few microns into each of which a plus signal and a minus signal are fed. This means that XLR connection with a pure balance output CD player makes it possible to listen to the original sound permitted by the balance system without a conversion circuit.
●The output stage has been incorporated by newly developing a non-feedback (NON-NFB) large current emitter follower Class A amplification circuit. This makes it possible to achieve a much more vivid and dynamic sound quality.
●The emitter follower at the output stage makes it possible to achieve lower impedance. A major expansion in dynamic range in the upper frequency has also been achieved.
●DC amplifier configuration without the use of a coupling condenser.
●A high sound quality, low noise FET is used at the input stage with a simple two-stage amplifying circuit. A natural and pure sound quality with high information quantity is realized.
●When connecting your favorite attenuator or pre-amplifier, a direct switch that avoids duplication of the volume unit is included.
●Careful selection of parts with high consideration on sound quality, performance, and the environment.
●In order to avoid magnetic distortion, the chassis is made of aluminum materials, thereby contributing to purity of sound.
●Amplification is set at a low level, thereby facilitating subtle adjustment of volume during XLR input and when using high-output CD players, etc.
●Parallel output terminals (RCA) are included to enable the signal to pass through.
●A new panel face has been designed with rounded corners and a silver brushed finish.
●Earspeakers of PRO bias (5-pin) type can be used.
●Control functions are restricted to the volume, and the input uses a single selecting system between RCA or XLR. This is a drive unit for exclusive use with earspeakers with emphasis placed first and foremost upon purity.
●Frequency response DC-115 kHz (SR-007 or SR-404, when using one unit)
●Rated input level 200 mV / 100 V Outputs
●Maximum input level 30 V r.m.s. / at Minimum volume
●Amplification 54 dB (x 500)
●Total harmonic distortion 0.01% / 1 KHz, 100 V r.m.s. output SR-007 or SR-404 Signature, when using 1 unit
●Input impedance 50 KΩ / XLR balance 50KΩ×2
●Input terminals RCA×1 or XLR×1 (balanced)
●Maximum output voltage 450 V r.m.s. / 1 KHz
●Standard bias voltage DC 580 V
●Power voltage 120-240V ±10%, 50 to 60 Hz (adjusted for your area)
●Power consumption 46 W
●Temperature range for use Between 0º and 35ºC, max. 90% (no condensation)
●External dimensions 195 (w) x 103 (h) x 420 (d) mm (including VR knob and pin jack (20 + 10)
●Weight 5.2 Kg