Driver unit for Earspeakers
SR-303 Classic

■ The joy of pure balance amplification 

The operational principle of the electrostatic condenser type is based on a system whereby plus and minus output signals are input by push-pull into two electrodes sandwiching a diaphragm with a high level of accuracy and equidistantly, resulting in the vibration of an ultra-thin membrane through the repulsive force and suction force of static electricity, which is then converted into sound. The balance method, which is considered to be the ideal for amplification, is thus extended to speakers. The electrostatic system entails input by balance, output by balance, and sound conversion by balance, and, in realizing all these features, constitutes the perfect balance system. It is the only system that makes it possible to listen to sound in the ideal manner permitted by the balance system. The new SRM-007tII is our flagship model of a driver unit intended exclusively for earspeakers characterized by their wide range, high dynamic range and outstanding operating features with full allowance made for SACD and other new-generation high-density formats. The ultra-light polymer film, only a few microns thick, realizes unprecedented response and a high degree of resolution. Since it is driven on all sides, there is almost no partitioned vibration and there is no phase distortion. Nor is there any imbalance in the sound quality of the unit or distortion caused by the network. Electromagnetic distortion also does not occur. It opens up on the world of high sound quality that is the mark of headphone listening, a world characterized by the absence of need for large output, the high degree of freedom permitted by the use of high sound quality elements for use with small signals, and the even balance between left and right unaffected by acoustic conditions in the listening room. 

■ Features 

●We’ve taken another look at circuit constants and achieved a higher grade of reproducibility for SACD and other new-generation audio formats.
●Consists of a pure balance amplifier in which the XLR balance input does not have to pass through a transformer, an inversion amplifier, etc.
●Makes use of a simple two-stage amplification structure based on rigorously selected low-noise FET. The load resistance makes use of non-inductive coil resistance manufactured by Dale, thus realizing straightforward properties that take advantage of the features of vacuum tubes and outstanding sound quality with a high level of clarity.
●The output stage is designed to lower impedance by using a rigorously selected high voltage dual triode (6FQ7 type) in parallel connection, which has resulted in an improvement in dynamic range especially in the high frequency.
●The heater power source for the vacuum tube makes use of a power circuit of the DC ignition type using an electrolytic condenser and a high-speed Schottky barrier diode, bringing about further improvements in the SN ratio.
●Makes use of a large-capacity power transformer and capacitor.
●Equipped with one XLR (balance) input system and two RCA (imbalance) input systems, meaning that there is a total of three input systems.
●In the case of the RCA input, switching with the earth side ensures that there is almost no interference between devices.
●Use is made of a high sound quality quadruple volume unit which makes possible XLR input as well as all kinds of line level analog voice inputs.
●The RCA terminal “Input 1” is equipped with parallel output terminals and enables input throughout. Connection with other pre-amplifiers and recording decks, etc., is also possible.
■ Specifications
●Frequency response DC-100 KHz / +0, -1.5 dB SR-007 or SR-404 Signature, when using 1 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
●Number of inputs RCA×2, XLR×1 (balanced)
●Maximum output voltage 340 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 55 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 4.7 Kg
●Vacuum tubes 6FQ7/6CG7 type x 4
The standards and external appearance of this unit may be changed without prior notice in order to make improvements.

Copyright (C) 2007 STAX Ltd. All Rights Reserved.