STAX / SRM007TA

Driver unit, dedicated to STAX headphones, vacuum tube driver unit

■Driver Unit
■For STAX headphones only
■Vacuum tube driver unit
■Frequency response: DC to 100 kHz / +0, -3 dB (when using one SR-007)
■Rated input level: 200 mV / at 100 V output
■Maximum input level: 30 V r.m.s. / at minimum volume
■Gain: 54 dB (500x)
■Harmonic distortion: Less than 0.01% / 1 kHz 100 V r.m.s. / when using one SR-007 or SR-404
■Input impedance: 50 kΩ / 50 kΩ x 2 when balanced
■Maximum output voltage: 340 V r.m.s. / 1 ​​kHz
■Standard bias voltage: PRO bias DC 580 V
■Power supply voltage: AC 100 V ±5%, 50-60 Hz (Voltage cannot be changed)
■Power Consumption: 55W
■Operating Temperature Range: 0-35°C
■External Dimensions: (W) 195 x (H) 103 x (D) 420mm [including VR knob and pin jack (20 + 10)]

■Weight: 4.7kg
■XLR Polarity
1: Shield
2: Hot
3: Cold (European style)

■Features
~From the manufacturer's website~
- The operating principle of electrostatic (condenser) amplifiers is that positive and negative output signals are input in a push-pull manner to two electrodes that precisely and evenly space the diaphragm (vibrating body). The electrostatic repulsion and attraction forces vibrate an extremely thin membrane, converting it into sound.
In other words, the ideal balanced amplification method is extended all the way to the speaker. The electrostatic type is a truly complete balanced system that achieves balanced input, balanced output, and balanced sound conversion, and is the only system that allows you to enjoy the original sound of the balanced system as it is.
The SRM-007tA is a flagship model of earspeaker driver units that achieves even wider range, higher dynamic range, and superior operability, with an eye toward new-generation high-density formats such as SACD. The ultra-lightweight polymer film, just a few microns thick, achieves exceptional response and high resolution. Full-surface drive minimizes split vibration and eliminates phase distortion. There is no inconsistency in the unit's sound quality or distortion caused by the network. There is no magnetic distortion. The lack of high output allows for greater freedom in using high-quality small-signal elements, and the ability to maintain consistent left-right balance is unaffected by room acoustics, allowing for the world of high-quality sound unique to headphone listening.

- Circuit constants have been revised to achieve even higher-quality reproduction of new-generation audio formats such as SACD.

- A pure balanced amplifier is used, eliminating the need for a transformer or inverting amplifier, even with the XLR balanced input.・A simple two-stage amplification configuration using carefully selected low-noise FETs is used, and the load resistors are DALE non-inductive wound resistors, achieving the natural characteristics and highly transparent sound quality that take advantage of the characteristics of vacuum tubes.
・The output stage uses carefully selected high-voltage dual triode vacuum tubes (6FQ7 type) connected in parallel to lower impedance and significantly improve the dynamic range, especially in the high frequencies.
・The vacuum tube heater power supply uses a DC ignition power circuit with large-capacity electrolytic capacitors and high-speed Schottky barrier diodes, further improving the signal-to-noise ratio.
・High-capacity power transformers and power capacitors are used.
・One XLR (balanced) input and two RCA (unbalanced) inputs are equipped, for a total of three inputs.
・The RCA inputs also have switchable earth terminals, virtually eliminating interference between devices.
・A high-quality quadruple volume control unit allows input of all line-level analog audio in addition to the XLR input.
The RCA terminal ""Input 1"" is equipped with a parallel output terminal, allowing input through-out. It can be connected to other preamplifiers or recording decks.