STAX SRM-007t STAX SRM-007t Vacuum Tube Output Driver Unit

STAX SRM-007t Vacuum Tube Output Driver Unit for electrostatic earspeaker (5- & 6-pin) 

ORIGINAL OWNER
Unit is in working condition & cosmetically clean except for slight nicks on the side panels visible in the photographs. 

Features (from manual)

"The SRM-007t is a driver unit designed for the ideal driving of STAX electrostatic earspeakers. Vacuum tubes incorporated in the SRM-007t output stage provide transparent and clear sound different from that of solid-state drivers. The SRM-007t is equipped with standard, unbalanced RCA input connectors and an additional 2 sets of both RCA and XLR connectors (balanced input). These two input systems are switchable on the front panel.  Main features of the SRM-007t are as follows:

"The dual triode 6FQ7/6CG7, highly reliable and registible [sic] against high pressure, is employed in parallel output stage for low impedance and further transparency in high frequencies.

1. Direct drive system without transformer between the amplifier and earspeaker sections generates stable and high quality sound.
2. Simple two-stage amplifier construction with dual FET's in the first stage and twin triode 6FQ7 tubes having high dielectric strength in the second stage achieves the most natural and clearest sound reproduction making full use of the merits of vacuum tubes.
3. DC circuit (capable of DC amplification) which incorporates no output capacitors unfavorable to sound quality.
4. No magnetic materials such as iron and the like that have detrimental influence on sound quality are used for the chassis and electronic components.
5. Resistors and capacitors are carefully selected among those developed for quality sound reproducing CD players and Power Amplifiers.
6. Quadrupled double-spindle volume control realizes genuine balance input without transformer.
7. Two high bias earspeaker outputs are incorporated, besides a normal bias output for original earspeaker users. These output systems enable users to drive two sets of earspeakers of the STAX PRO series at the same time, as well as allowing the comparison of professional earspeakers with normal bias type earspeakers.
8. Two input system is switchable with the input selector on the front panel. Moreover, there are two types of connectors (RCA and XLR) provided for INPUT [2], and the connectors are of genuine balanced input (pin 3:HOT). (Refer to the Main Parts/Panel Nomenclature and the block diagram on page 4 & 5 respectively.)"
   

Specifications 

• Frequency Response:  DC~70KHz/+0, -1.5dB
  
• Gain:  60dB (Input 100mV-->Output 100V)
• Harmonic Distortion:  0.01% Inputs:  RCAx2, XLRx1 (balanced)
• Input Impedance:  50KΩ (50KΩx2 for balanced input)
• Maximum Output Voltage:  340V r.m.s. (1KHz)
• Earspeaker Outputs Bias Voltage:  230Vx1, 580Vx2
• Power Consumption:  55W
• Operating Temperature Range:  0~35°C
• Vacuum Tube Employed:  6FQ7/6CG7x4 pcs 

Accessories

• AC power cord
• RCA pin cable
• Owner's manual
• Original box