STAX SR-Λ (Lambda) Series

 The SR-Λ (Lambda) series have such pleasing sound quality because its diaphragm is oblong, instead of round, as in the SR-Σ Series. This shape approximates the elliptical shape of the outer ear so that you use your entire ear to listen to the sound, just as you would in a natural listening situation. In fact, the diaphragm is actually larger than the average ear's dimensions to take full advantage of the outer ear's response characteristics. The result is fuller low range response along with the uncolored mid and high range response typical of electrostatic reproduction.

The design approach of the SR-Λ Series won various prizes and especially the SR-Λ Signature is called "The best Headphone in the World".

 SR-Λ (Lambda) Normal + SRD-7sb

Stax introduced the SR-Lambda in 1979. still a worthy product in its own right, it has also served as the foundation for the most important earspeaker innovations since then. And in one respect it has not yet been bettered - the earpiece.  This designencloses the outer ear, housing an angled oblong diaphragm larger than the average ear's dimensions. The radiated sound is then captured by all parts of the outer ear and conducted to the eardrum - just like listening in any normal situation. The brain perceives a spacious sound field outside the listener's head. How unlike the typical headphone, whose earpiece crushes the outer ear, not permitting it to do its job, while the small dynamic speaker injects the music unnaturally into the ear canal.

SR-Λ (Lambda) Professional

Daimler Benz provided the impetus for the SR-Lambda Professional (1982) when they requested a unique earspeaker to analyze car noise. Stax achieved the desired low-frequency response by increasing the electrode gap and the polarizing voltage. These changes also created side benefits - the Lambda could now play louder than before, and with increased efficiency and less distortion. Until the advent of the Signature, the SR-Lambda Pro was the best earspeaker Stax  knew how to make; it remains a product second  to one only.

 The SRM-1 Mk2 Professional was designed to drive the SR-Lambda Pro or other earspeakers dirctly. Its pure class-A circuit eliminates audio transformers and coupling capacitors for detailed, natual reproduction. Like the SRM-T1, this unit can be connected to the tape loop of a preamplifier, or run directly from the line-level source - CD player, tape deck, tuner or mixing console - resulting in a remarkably simple and elegant signal path. It has output sockets for one Professional Series and one standard earspeaker.

 The SR-Lambda pro earspeaker can also be powered through the SRD-P portable energizing adaptor. It employs high-power IC's and Professional bias-voltage circuitry to extract the earspeaker's capabilities. The SRD-P operates not only on a household power source but also on batteries, allowing remote use for high-quality monitoring of location recordings. Its RCA input trminals enable direct connection to line-level outputs (as with the SRM-1 Mk2 Pro); but it also has a mini-jack input for use with portable cassette decks or mini CD players.

The SRD-7 Professional energizing adaptor connects to the speaker taps of a power amplifier, enabling one to enjoy Professional Series earspeakers  over whatever equipment one already owns. It contains advanced features like LC-OFC wiring and audio transformer windings, and an all-aluminum chassis to eliminate magnetic distortion. This adaptor is a particulary viable alternative to the direct-drive earspeaker amplifiers if one has made a major investment in state-of-the-art. Preamps and power amps.

SR-Λ (Lambda) Signature + SRM-T1

Surpassing the SR-Lambda Pro - probably the most widely acclaimed audio component of recent years - was a formidable task, but that is what the SR-Lambda Signature has accomplished; any superlatives not expended on the Lambda pro may now be safely employed. Two material changes are largely responsible. The Signature's transducing diaphragm is only one micron thick, a reduction of one-third from the Lambda Pro. And the signal cord is made of PC-OCC cable, specially cast from oxygen-free copper to preserve phase integrity through large linear-crystal-line structure.

A standard-setting earspeaker requires an amplifier which performs similalry - the SRM-T1.  this two-stage driver unit incorporates dual FET's and twin 6FQ7/6CG7 triode output tubes, thus combining transient speed with the smoothness and dimensionality sophisticated audiophiles have come to expect from vacuum-tube amplification. The SRM-T1 can accommodate both Pro Series and normal earspeakers.

The Signature System is urgently recommended for discerming audiophiles seeking the ultimate in musical information retrieval.

SRM-T1 Tube Driver 

Frequency Response:  DC-20kHz, +/-1dB

Gain:  60 dB

Harmonic Distortion:  0,02%

Input Impedance:  50 k Ω

Input Level:  100 mV

Maximum Output Voltage:  330 V RMS (1 kHz)

Bias Voltage:  230 V DC, 580 V DC

Power Requirements:  100 - 240 V 50/60 Hz

Dimensions (W x D  x H):  7-3/4" x 15-1/4" x 4"

Original Box (W x D x H): 18" x 9-1/2" x 5"  (+1 lbs)

Weight:  10,5 lbs