Stax SRM-400S


  •  All-stage FET Configuration DC amplification
  • Newly Designed Output Stage
  • Custom-Made Low Noise Dual FETs
  • Pair of RCA input terminals
  • Pair of XLR 3-pin input terminals
  • RCA parallel output terminals
  • 30W Power Consumption

Available on backorder

Stax SRM-400S

Stax SRM-400S

SRM-400S Electrostatic Headphone Amplifier

STAX is proud to introduce a new semiconductor driver unit SRM-400S as the successor model of SRM-353X. A STAX custom-made low noise DUAL FET is installed on First Stage and additional FETs are also installed on last stage. SRM-400S follows the design and the manufacturing method of the high end model SRM-700S, in which the amplifier high quality FETs are installed in all stages. The characteristics of the right and left FETs are measured strictly and the selected FETs installed in 400S are also featured in SRM-700S. In addition to the conventional power transformer for the high voltage circuit, the newly designed power transformer with winding for a low voltage circuit is installed in SRM-400S. The low voltage winding enables to improve the power efficiency and achieves further power saving and better sound quality than what was featured in older driver units such as SRM-353X.
Stax SRM-400S

New Chassis

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 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. All electric components are strictly selected considering the environment.
Stax SRM-400S

High Resolution Sound

SRM-400S presents the high resolution sound which is unique to the semiconductor circuit design and dynamic low range sound reproduction. From the lows to the highs, the frequency response is well harmonized throughout the entire spectrum. Not only for the combination with the advanced lambda series, SRM-400S is also ideal for the upgrading from the entry level SRS-3100. This is a promising new model which covers beginners to intermediates among the renewed driver unit line-up.
Specifications STAX SRM-400S
Frequency Response DC – 90kHZ (with one SR-L500 MK2)
Harmonic Distortion 0.01% or less (1kHZ/100Vrms output)
Maximum output voltage 400Vrms (1kHz)
Bias Voltage DC 580V
Operating Conditions 32 to 95 degrees fahrenheit @<90% humidity
Dimensions (H)4.0″ x (W)7.68″ x (L)14.8″
Weight 3.4 lbs
Similar product SR-009S
Weight 2 kg
Dimensions 25 × 25 × 25 cm


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