Stax SRM-500T Earspeaker Driver Unit


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Mid class vacuum tube driver unit

A STAX custom-made low noise DUAL FET is installed on the first stage and the vacuum tube is installed on output stage. STAX continued to use the traditional circuit design which is perfect for the STAX vacuum tube driver and improved the power efficiency. These flow through to an overall sound quality improvement.

In addition to the conventional power transformer for the high voltage circuit, the newly designed power transformer with the winding for the low voltage circuit is installed in the SRM-500T. The low voltage winding enables to improve the power efficiency and achieve further power saving and better sound quality than the conventional vacuum tube output driver units such as SRM-006tS.

The RCA/XLR input and RCA PARALLEL OUT terminal are installed.

The new chassis which is more rigid than the conventional model is installed. The chassis has a hybrid structure using a lot of non-magnetic aluminum and further reduces the effect of the environmental noise factors such as vibrations. The inputs are RCA an XLR, the mutual exclusion inputs. The custom made concentric dual volume knob which is common to STAX products and RCA PARALLEL OUT functions are installed same as the conventional driver units.

The clear and highly transparent sound, a feature of the vacuum tube circuit and the warm and wide sound texture is maintained and the thickness of the low-mid range is brushed up. This is the new choice for the combination with the advanced lambda series (SR-L300/SR-L500 MK2/SR-L700 MK2).


  • Type: FET input + vacuum tube output hybrid DC amplification driver unit
  • Vacuum tube: 6FQ7/6CG7
  • Frequency response: DC – 90kHz (with one SR-009S)
  • Gain: 60dB
  • Harmonic distortion: 0.01% or less (1kHz/100Vrms output)
  • Input impedance: 50kΩ (RCA), 50kΩx 2 (XLR)
  • Maximum output voltage: 300Vrms (1kHz)
  • Bias voltage: DC580V
  • Operating temperature / humidity: 0 to 35 degrees C / less than 90% (non condensing)
  • Input terminal: RCA x 1, XLR x 1
  • Output: RCA parallel output terminal
  • Power consumption: 38W
  • Dimension: 195W x 102 H x 376 D mm (maximum protruding portion included)
  • Weight: 3.4kg

Due to the bespoke nature of our high-end music systems this product is not available to be purchased online. Please contact us for personalized service from one of our team of experts.