Vintage Stax Headphone Measurements and Comments
Sometimes my job is quite humbling. Like when headphone enthusiast yaluen decided to ship me a dozen headphonesmany very rare and collectablefrom his collection for measurement. For example, the Stax SR-1 was first produced in 1960...only four years younger than I! I have to tell you it's rather scary to hook up a headphone of that vintage and put it through the torture test that is my measurements system. And too that end, you'll see in the measurements that I didn't run the 100dBspl distortion test...I just couldn't bring myself stress these lovely old headphones to that extent.
I've put together a little .pdf booklet with all the measurements in it so that you can view it as you read the quick comments from yaluen and I. Enjoy!
Stax SR-1 (1960)
yaluen's notes - Stax's first headphone with 6 micron diaphragms which was released back in 1960. These went through a few revisions as Stax honed their manufacturing expertise. According to various catalogues and manuals, Stax gradually increased the bias voltage the SR-1 was designed for from 150v to 200v to 230v "Normal Bias" by improving stator insulation. I think this particular one is a late production pair since it has SR-3 pads whereas earlier units had hard foam pads (think Grado).
Tyll's notes - Very light caliper pressure. Took me forever to figure out which ear was right and left. The only marking is a a red thread in the woven strands of the cable going to the right ear.
When I press on the headphones to position them on my head I can sometimes hear a frightening thunky noise, then some distortion, then a little pop, and then it clears up. I assume this is the diaphragm getting pushed against the stator, getting electrostatically stuck to it, and then releasing. Scared the crap out of me.
Sound is rather thin with little bass response below about 120-150Hz. Midrange through presence region is surprisingly well balanced but a tad laid back. Treble is a bit wonky with 4-8kHz suppressed and 10kHz+ a little too accentuated giving cymbals a little more tizz than tang.
Pretty amazing that a headphone this old sounds this good. It's pretty obvious why audiophiles of that era with an interest in headphones bought Stax: Even this very first model is significantly better than the dynamic headphones of that era.
Stax SR-3 (1968)
yaluen's notes - As I understand it, essentially an improved SR-1. At this point, Stax has perfected the design and manufacture of the SR-1 drivers which they put in this new model. Ad copy states Stax also implemented a filter to improve balance, bass response, and localization. Perhaps this is referring to the grey part of the baffle? And the aforementioned new leather over-ear pads for better comfort.
Tyll's notes - Slightly snugger fit. It does seem to have slightly better bass response and a more neutral mid to treble transition. Balance in the treble region is better; cymbals are still a bit breathy but do have a more satisfying fundamental tang. Yeah, these are surprisingly listenable.
Some of you Stax experts may be able to comment more authoritatively on this, but is does seem to take a little while for these to fully charge up. At first I hear quite a bit of distortion as I raise the volume, but slowly and surely I am able to play them louder and louder without obvious distortion. These do not have the clunky noise problem that the SR-1 had when pressing them to my ears.
Stax SR-X/MK-3 Pro (1985)
yaluen's notes - Last of the SR-X on-ear series, resolution was Stax's focus for these models. Interesting to note the SR-X MK-3 was marketed as 迫真派 (true to life) and the SR-5 that was being sold concurrently as 敘情派 (emotive).
Tyll's notes - These are an on-ear headphone. Comfort is a bit wonky as they wobble around some with head movement. Measurements are pretty stellar, but don't sound nearly as good as they measure. They do have pretty good tonal balance, but I hear them as somewhat hard and agressive 2-6kHz. Bass extension is much better than the previous two models.
Stax SR-Gamma Pro (1985)
yaluen's notes - Same drivers as the SR-X MK-3 Pro but over-ear and in open cage enclosures.
Tyll's notes - Bass extension is better than the SR-1 and SR-3, but does sound somewhat loose and indistinct. Low-treble sounds a bit veiled, upper mids seem hard to me. Not a very comfortable listen.
Stax SR-Lambda Signature (1987)
yaluen's notes - 1 micron diaphragm, thinnest film used by Stax in their drivers. Airiness is its calling card.
Tyll's notes - Much better bass extension than previous open modelsmeasurements show roll-off begins at 50Hz. As yaluen indicates, treble region is pretty nicely behaved in these cans, but the upper-midrange is shouty and somewhat uneven and colored.
Stax SR-Alpha Pro Excellent (1989)
yaluen's notes - Same as the Alpha Pro but with PC-OCC cables and revised pads designed to conform to the contours around the ears, sounds very similar to the Alpha/Gamma Pro but sub-bass extension is audibly improved. I really like the tonal balance of these. Vs other over-ear Stax, bass has a more immediate presence (tradeoff of textural nuance unfortunately), less accurate but has what I think is the most natural and satisfying kick out of the Stax I've heard. In fact, its overall presentation is more upfront which I guess is to be expected given its smaller construction and how much closer the drivers are to the ears. Makes for a different kind of listening experience, less grand but super engaging. Perhaps my favourite Stax headphone.
Tyll's notes - Very light, comfortable, and stable on the head. I'll echo some of yaluen's word's here: This is a very enjoyable headphone. I can understand why he says the bass seems to hit hardit does relative to most of the other cans here. The emphasis at about 80Hz is a goodly sized bump, but bass does drop off rapidly below. The bass also suffers from some distortion; this will often draw more attention to the bass giving it subjective emphasis. And he's right that it looses "textural nuance" as a result.
Presence rises a bit less steep that many of the other cans here, and the peak at 3kHz is a conservative 10dB. The result is a substantially less agressive headphone than most of the others. Treble is also fairly grain-free. On the down side the treble tonal profile is just a bit uneven and down quite a bit in the top octave. I hear it as inoffensive, but lacking in resolve and nuance...maybe a bit boring, but definitely not annoying.
Stax SR-Alpha Pro w/Yax1 Pads (1989)
yaluen's notes - Same as the Gamma Pro but I've installed these aftermarket pads. These pads caught my attention because they're contoured similarly to the Excellent pads but are deeper. Bass doesn't seem to hit as hard as the Excellent however.
Tyll's notes - Boy, looking at the measurements I would have thought I would have preferred these over the Alpha Pro Excellent...but I don't. Somehow they're harder and more shouty sounding, but I really don't see that in the measurements. I wish I had time to play with some EQ back and forth to nail it down, but I'm going to guess that I really need the 3dB Harman bass boost to take my attention away from the other end of the spectrum and even the score. These also seem to be a tad more piercing.
Stax Lambda Nova Signature (1994)
yaluen's notes - Followed the SR-Lambda Signature but the two are about as different as you can get with Lambdas. The LNS is towards the smooth and intimate end while the Lambda Sig is more nimble and airy.
Tyll's notes - Looking at the measurements you really wouldn't think there'd be too much difference between these and the Lambda Signatures, but there is...at least in terms of what the listening experience is like. Objectively they're clearly of the same family, but a bit of added warm and an ever so slightly smoother treble can make a significant difference in listening pleasure. Looking at the measurements it's quite clear the LNS not only has better bass extension, but significantly lower distortion as well.
Stax 4070 (2001)
yaluen's notes - Closed-back monitor, commissioned by NHK for broadcasting applications. I haven't spent much time with this one but my first impression was its dynamics was the most compressed I've heard out of a Stax headphone.
Tyll's notes - These are big, heavy beasts, and to make things worse, the self-adjustable strap seems to let the headphones droop down farther than desired. Really not very comfortable at all.
FR measurements show a fairly good plot with the presence region between 800-2kHz rising somewhat too fast and the peak at 3kHz about 5dB too high. Yeah, despite having a well controlled bass and a pretty well behaved mid- and upper-treble, the hot presence region steals all the attention with a swift centerpunch right between the earballs. I'm not sure about yaluen's "compressed dynamics" comment, but I sure as heck can't turn these up too loud, and I can't really concentrate on anything but it's shouting presence.
Stax SR-L300 (2016)
yaluen's notes - The entry model in the newest Lambda series dubbed "Advanced Lambda" which feature significant redesigns, most noticeably new angled baffles. I've written up a comparison against the SR-202 in this post.
Tyll's notes - Phew, what a relief after those 4070s. Introduced just last year, these are the youngsters of the group and, one would hope, the recipients of all those years of learning. At $430 they're also the least expensive of the current line-up.
I guess I find these a pretty nice compromise. Bass has good extention to 50Hz, and fairly low distortion. Presence region is nicely balanced, and treble tonality seems good, but for a slightly hot mid-treble and a somewhat more troublesome tendency to be grainy in that area. Still, for $430 and having just listened to 56 years of Stax headphones, I'd say these are nice.
Makes me think I need to get the whole current family in here for a listen.
Thanks ever so much, yaluen, for sharing your lovely collection!