Stax SR-207: Back to the basic

Disclaimer: This unit has been generously provided by my good friend, Danganronpa. And this is what I call a Southern hospitality, thank you very much! In order to minimize the linear error in the low frequency range, measurement has been carried out with acoustic leak minimized, by using a silicone putty as a sealant.

Although SR-207 is STAX's cheapest entry model, it is still a part of SR-Lambda series, which has a great heritage and legacy in the history of headphones. And since all of the current Lambda series models from SR-207 to SR-507 share very similar technical specifications, this entry model indeed deserves a good look as well.

PRO:  A well-extended flat frequency response & clean transient characteristic. Without a doubt, SR-207 exhibits a good electroacoustic behavior within its entire frequency spectrum just like any other Lambda series models; Thus, it can be considered to have a great economic value.

CON: A slight channel mismatch above 1 kHz & inverted polarity. Again, a good acoustic seal is vital for sound reproduction below 100 Hz. It is such a shame that the cable is not replaceable.

ON SECOND THOUGHT #1: Above data clearly shows the difference between Professional, Signature, and SR-207: As expected, compared to the other two, SR-207 is further damped by a few decibels in the treble for less harshness with its lower/higher ends further extended. Here's a rule of thumb for STAX headphones: The more recent the model is, the wider the frequency bandwidth becomes.

ON SECOND THOUGHT #2: Just like any other Lambdas, SR-207 turns into an accurate diffuse-field synthesizer when it is equipped with STAX ED-1 equalizer. The simulated result is of a slight downward-tilted diffuse-field characteristic, which is more suitable for general music listening as some listeners find the true diffuse-field target of Professional to be overly bright and harsh.

ON SECOND THOUGHT #3: A free-field analysis has been carried out at various locations within the frontal volume of the housing using an accurately calibrated microphone. The test result suggests that the entire surface of SR-207's diaphragm is not behaving uniformly just like any other Lambda series models, if not worse. The frequency response magnitude variation occurring at the polarized resonance frequency, 180 Hz,  indicates the diaphragm's stiffness has been slightly increased from that of the classic models.

ON SECOND THOUGHT #4: Just like the other Lambdas, this headphone is also far from the Olive-Welti target. A substantial amount of equalization is required to match Harman's target response.