Stax SR-Lambda Pro headphones John Atkinson

John Atkinson auditioned the Stax in May 1991 (Vol.14 No.5):

For this comparative review, I borrowed a pair of the Stax Lambda Pro "Ear Speakers," as well as a Stax ED-1 diffuse-field equalizer. The Lambdas were driven by their SRM-1/Mk.II direct-drive, class-A, solid-state amplifier, using a Meridian 208 CD player as source. As well as using each pair of headphones for my daily music supply, I did some paired comparisons, matching levels by ear using the 1kHz warble tone on the Stereophile Test CD.

I've used the electrostatic Stax Lambdas ($1200) on most of the recording projects I've been involved in over the last few years, finding their clean low frequencies and superb retrieval of midrange detail essential to getting an optimum recorded balance. It could never be said that these were dull-sounding cans, however, and as well as an elevated mid-treble region, which somewhat accentuates tape hiss, their sound can sometimes become a bit steely; some audiophiles attribute this to the solid-state amplifier. Certainly when the amplifier is first switched on, the sound is objectionably hard; it takes at least 30 minutes to warm up. Nevertheless, the ease of the Lambdas' sound, coupled with their spacious presentation of recorded acoustics and a comfortable fit on the head, make for a lot of long-term listening pleasure.

To judge soundstaging I used a number of my own binaural recordings as well as some CDs supplied by John Sunier of The Binaural Source. The Staxes threw a somewhat wider stage than the Grados, though both were still excellent. Neither gave me an image to the front of my head with central sources, though this is something I have never found a pair of cans to do, even with the Stax diffuse-field equalizer in the chain. (I understand that this has something to do with the fact that the headphones have to have the exact response of the listener's pinna for this to happen, and that this is something that can only be approximated given that it is different for everyone.) Instead, frontal sources tend to move in an arch over my head.

By comparison with the AKG K-1000s, the Stax Lambda Pros electrostatics could be heard to have more extended low frequencies, with an overall warmer midrange balance that emphasized the AKGs' residual nasality. Interestingly—and perhaps justifying the AKGs' design principle—the Staxes used with the ED-1 equalizer sounded similar to the AKGs used without, though the nod still has to go to the Lambdas for absolute midrange neutrality. (In this respect the Grados were better still.)

Auditioning the effect of the Stax ED-1 diffuse-field equalizer ($800) is awkward, as it takes a while to get used to its tonal balance; then when you bypass it, the music seems colored by its inverse response. (This is particularly disturbing with recorded tape hiss.) The equalization is perhaps a bit too extreme in the upper midrange: there's a degree of emphasis in this region, giving a slight "eee" coloration (heard as a complementary "aww" character when the EQ is switched out). Nevertheless, the ED-1 tames the forward treble of the Lambdas, giving a more relaxed, more musically natural sound overall, but still with some steeliness apparent. (It actually worked better with the Grados in this respect.)—John Atkinson

Stax Limited
US distributor: Yama's Enterprises, Inc.
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