STAX SRS-2170 / SR-207 Earphone System Measurements

Discussion in 'Headphone Measurements' started by purr1n, Dec 27, 2016.

  1. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend
    Joined:
    Sep 24, 2015
    Likes Received:
    34,768
    Dislikes Received:
    53
    Trophy Points:
    113
    Location:
    Calabasas, CA
    STAX SRS-2170 / SR-207 Earphone System Measurements

    The STAX SR-2170 system consists of an SR-207 headphone and SRM-252S amp. This is an electrostatic headphone system, which means that we cannot use a phono jack on a stereo or iPad to play music from these headphones. The cost of this system is about $700 (in the USA) if obtained grey market via eBay. STAX's distribution gets more and more horrific the farther we get from Japan. I am not sure if the Needle Doctor (USA) even carries STAX anymore since STAX is such a pain in the ass. But the nice thing is that the system includes an amp that does the job quite well. It's not like we have many available choices.

    Also, USA service for STAX is craptastic. Not only is service impersonal, but expensive. STAX USA tends to dick around with customers and try to decline service as much as possible, finding weak reasons to do so. In other words, they bend their backwards to make sure we are NOT taken care of. Personally, I think the guy running STAX service in the USA is lazy. Or maybe it was an idiot room position given to someone who was related to one of the STAX founders. I was quoted near $2000 for a driver repair on a SR-007. Fortunately, the lower end STAX seem to be more reliable, but it should be noted that more than half of of STAX gear I have purchased has failed. This includes an SR-009, SR-007 (dead drivers) and SRM-323 (rca jacks). I have heard of many SR-009 and two other SR-507 failures (my SR-507 did not experience any issues.)

    Here is a picture. The amp uses a 12VDC 0.5 from a watt wall wart. This was a Japanese spec, so a voltage converter was used to drop 120V to 100V. A 120VAC to 12VDC wall wart would be a more suitable solution.
    20161227_124513.jpg

    The SRS-2170 sounds super clean, with only a hard time reproducing sub and low bass before 50Hz or so. For most music, particularly of natural instruments, there shouldn't be a an issue. Bass tends toward a softish bouncy quality commonly heard with thinner diaphragm planars. Mid-bass (60Hz to 200Hz) is much clearer than almost any dynamic. Treble was fast, refined and exquisite. The MrSpeakers line of planar Ether speakers has this quality, but STAX presentation still wins out in terms of refinement, smoothness, naturalness. I actually prefer the treble of the SR-207 to that of the more expensive SR-507, which was tizzy. (SR-507 could be described as boom and tizz).

    The one thing that stood out and really bothered me was the midrange bump. The folks here who bitched about the midrange bumps of the Focal Elear or to a lesser extent the Utopia are going to hate this bump. It's so excessive that it's not even recording dependent. It permeates through all recordings. The bump has a side effect of slightly creating a dip in the lower mids / upper bass, result in a loss of body or on occasion a colder presentation.

    I attempted to get as good a seal as possible for the measurements below. I added a piece of non-leaky high density foam to better simulate how the funky earpads conform to the head. A weaker seal will increase amplitude of the bass peak and move the resonant frequency higher. We can get a pretty punchy fun sounding 90-100Hz emphasize if we wanted.

    STAX 207 Frequency Response (0db line = 100dbSPL)
    STAX 207 FR.png

    STAX 207 Distortion (at above levels)
    STAX 207 L HD.jpg
    STAX 207 R HD.jpg

    I re-measued the left driver several times to confirm the worse measuring sub to low bass distortion. Bass quality from 60Hz to near 160Hz is better than that of the HD650. We can easily hear this too. The sub bass roll-off is more sudden with the SR-207.


    STAX 207 CSDs
    STAX 207 L.jpg
    STAX 207 R.jpg

    Thanks to @Mikoss for this item. Loaner program?
     
    Last edited: Dec 27, 2016
    Lyer25, Scubadude, ultrabike and 7 others like this.
  2. Serious

    Serious Inquisitive Frequency Response Plot

    Friend
    Joined:
    Sep 28, 2015
    Likes Received:
    1,139
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Munich
    Oh nice, will be interesting to compare against my SR202 and SRM212 measurements when I post them. Hint: I'm happy that you also measure higher D2 than good dynamic headphones. According to the specs this shouldn't be the amplifier.
     
  3. sorrodje

    sorrodje Carla Bruni's other lover - Friend

    Staff Member Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,641
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Dijon / Burgundy / France / EU
    For the Seal, things are pretty simple. On the head (at least on mine) a well sealed Stax "farts" when you push it towards the ears and even when you move it. on the coupler , the Stax should fart if the seal is OK .

    When the seal is OK on the head , you can try to pull a bit the cups and the loudness effect / bass boost is obvious as it is in above measurements. Even a slighlty broken seal produce a bass hump and a loss of extension.

    The 1 khz bump pervades the whole Stax family. IMO it's exactly what haters call the sound of plastic and nothing else. I'm allergic to this bump I hear as shouty and I was sensitive as well to Focal's emphasis @1khz :) . But at least Stax headphones offer something I love in their effortless sound hence my love/Hate relationship with the Stax Sound. The SR007 and the Lambda NB exhibit a bit less of that 1 khz shout in my experience.

    I completely agree with the low mid depression as well. It contributes indeed to the lack of body and the kinda ethereal nature of all Lambdas.

    My 2 cents.
     
    Last edited: Dec 28, 2016
    anetode, n3rdling and Serious like this.
  4. gepardcv

    gepardcv Almost "Made"

    Contributor
    Joined:
    Nov 20, 2015
    Likes Received:
    158
    Dislikes Received:
    0
    Trophy Points:
    43
    Location:
    San Francisco, CA
    I'm traveling and so don't have access to my stuff (including the 207) so I can't verify at the moment, but I wonder if the 1k peak can be EQed out a little bit. I'm also a bit more sensitive to the bass roll-off of the 207 than the graph indicates. It sounds too light in low frequencies (like some pipe organ registers).
     
  5. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend
    Joined:
    Sep 24, 2015
    Likes Received:
    34,768
    Dislikes Received:
    53
    Trophy Points:
    113
    Location:
    Calabasas, CA
    The 1.5kHz bump seems more pronounced on the 207 more than the others I've heard from 307 to 507, 007, and 009. I figured something's gotta go for the entry level. Will give EQ a try.

    I wish STAX would get their distribution and service together for the USA. Thought Edifier would have helped them fix this by now. Hard to give something like this a wholehearted recommendation, at least in NA, without these things in place.
     
    Last edited: Dec 28, 2016
  6. Serious

    Serious Inquisitive Frequency Response Plot

    Friend
    Joined:
    Sep 28, 2015
    Likes Received:
    1,139
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Munich
    Dunno if the SR207 is similar to the 202, but I use a -3.8db high shelf at 1150Hz (Q1) and an extra -4db Q2.0 EQ filter at 9kHz in JRiver when I use EQ. I find it very bright tbh. I also like to reverse the polarity in software with the STAX.
     
    gurubhai likes this.
  7. sorrodje

    sorrodje Carla Bruni's other lover - Friend

    Staff Member Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,641
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Dijon / Burgundy / France / EU
    IME , all lambda ( almost all Stax axtually) exhibit that 1 khz emphasis ( I'd say between 2 and 4 db emphasis) sometimes it's mitigated by some other FR charactertics ( warm tone for the 007 , whole High mids elevation for the 009 , better bass for all omegas ..) but it's still there. IME the 507 I owned and the 307 I heard was exactly like your 207.

    As @Serious told above , the two hot spots of a lot of Stax are 1 khz emphasis and a peak somewhere in the treble. it will maybe sound strange but the point I dislike the most on my 007mkII was the disjointed treble resulting from the overall laid back high mids and treble + the treble peak . it's the first think that popped up when I heard the 007mkI at @Ali-Pacha's place the first time.

    Fortunately for me , Sennheiser made E-Stat headphones I like more than any Stax. Not to mention FrankenMilos HE90 clone.
     
    Last edited: Dec 28, 2016
  8. Kattefjaes

    Kattefjaes Mostly Harmless

    Friend
    Joined:
    Sep 5, 2016
    Likes Received:
    4,737
    Dislikes Received:
    39
    Trophy Points:
    113
    Location:
    London, UK
    The expense and hassle of getting stats and their amps repaired when they cark out is what has consistently put me off the idea. It's a shame, I do enjoy the airy, ethereal sound of the Signatures that I sometimes use. Edifier could have a bit of a winner on their hands if they made Stax less of a bear to deal with.
     
  9. mypasswordis

    mypasswordis Rando

    Joined:
    Jan 20, 2017
    Likes Received:
    5
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    US
    Could someone investigate how much pads have to do with that 1-2kHz peak? I might have a hypothesis about it in relation to the different pads Stax have used over the years, but if you can provide unbiased proof it would be better. The original Lambda NB/Pro/Sig have different pads to the SR202/303/404 variants, which are obviously different from the new lambskin pads like on the 404LE and I believe the newest generation Lambdas also have different thinner pads. That peak is what some HFers have gone on and on about over the years (the infamous Stax "etch"), and personally I don't have that much of a problem with it except on the SR009 and 404LE. I have not heard the newest generation Lambdas.

    Like sorrodje said, pad seal is everything when it comes to the bass so it wasn't sealed properly in the original measurements. Subjectively, all of the Lambda variants I have ever heard have good bass extension.
     
  10. Serious

    Serious Inquisitive Frequency Response Plot

    Friend
    Joined:
    Sep 28, 2015
    Likes Received:
    1,139
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Munich
    Pads have a lot to do with this. See my HE60 pads measurements here (with SR-202):
    http://www.superbestaudiofriends.or...sr-202-srm-212-measurements.3608/#post-107520
    The HE60 pads are tuned for less 1kHz than most other pads. Not sure how other pads work, but I think all of the STAX pads have the 1kHz bump. The depth and the specific side-wall damping and inner foam of the HE60 pads work very well at killing that 1kHz hump. The HE90 pads, although larger, could also work or maybe the HM5 pads (no idea).
    I really can't emphasize enough how much I preferred the HE60 pads to the STAX pads. Made the tonality go from terrible to very good, while also drastically improving the comfort.

    I could not get a good seal without pressing on the cups (or maybe using rubber bands). Still, the bass extension wasn't super bad with the seal I typically got. The HE60 pads inherently have a less than airtight seal, but they also conform better to the head. You can't get the flatline bass extension that you can get with the STAX pads, but the seal also had less variability for me. I got a better seal with the HE60 pads.
     
    Lyer25 and mypasswordis like this.
  11. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend
    Joined:
    Sep 24, 2015
    Likes Received:
    34,768
    Dislikes Received:
    53
    Trophy Points:
    113
    Location:
    Calabasas, CA
    I wouldn't say that it was sealed improperly because I can show you a measurment where the SR-207 was truly sealed improperly. The measurements reflect the seal on my own head and how I hear things. The SR-207 pad material is kind of hard and non-comforming. This contributes to the difficulty in getting a good seal. The measurements reflect a seal that can be realistically obtained on my head, not an idealized one on the measurment rig, which I could have easily provided.
     
    Last edited: Jan 21, 2017
    Ardacer and Serious like this.
  12. mypasswordis

    mypasswordis Rando

    Joined:
    Jan 20, 2017
    Likes Received:
    5
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    US
    Fair enough. Some of the pads from the older Lambdas are soft and I believe they have slightly more cushion as well. Seems like the earpads could potentially be the cause of both the bass resonance and the small upper midrange peak for some people, especially given Serious confirming that using an HE60 earpad gets rid of that upper mid peak.

    My conjecture other than pad thickness and compliance is materials. I think for whatever reason leather (on the more expensive Stax models) is causing a more pronounced upper mid peak compared to vinyl or whatever it is the other pads are made of.
     
  13. Serious

    Serious Inquisitive Frequency Response Plot

    Friend
    Joined:
    Sep 28, 2015
    Likes Received:
    1,139
    Dislikes Received:
    0
    Trophy Points:
    113
    Location:
    Munich
    That could very well be the case. The material definitely plays a big role and the more closed and reflective materials seem to get more of the upper mid hump. With something like the SR009 it might be a good idea to put some foam on the inner pad walls.
     
  14. Shinwami

    Shinwami Rando

    Banned
    Joined:
    Nov 13, 2016
    Likes Received:
    11
    Dislikes Received:
    11
    Trophy Points:
    3
    Location:
    Okinawa
    Marv, where's your measurement of Stax SR009, 007 and some other Stax (with these latest test gears)? Cheers
     
  15. Scubadude

    Scubadude Almost "Made"

    Joined:
    Jan 23, 2016
    Likes Received:
    182
    Dislikes Received:
    1
    Trophy Points:
    43
    Location:
    Pretoria, South Africa
    Thank you for these measurements. I picked up an NIB SRS-2170 set during the week and I am quite astounded by how good is sounds. I don't find the rolled offextremities / mid emphasis offensive. Actually I much enjoy it ... About like HD650 with better bass, speed and clarity. Damn good for the money this is. Actually it is just damn good.
     
    capetownwatches likes this.
  16. Kattefjaes

    Kattefjaes Mostly Harmless

    Friend
    Joined:
    Sep 5, 2016
    Likes Received:
    4,737
    Dislikes Received:
    39
    Trophy Points:
    113
    Location:
    London, UK
    Beware, it's a gateway drug.

    The novelty factor of the delicate, detailed spacious sound is pretty huge, though isn't it? Glad you're enjoying it. Some of those small entry-level sets offer surprising bang for buck, and can be more enjoyable than you'd expect.

    It's different tradeoffs, there is no such thing as a free lunch, but after years of different permutations of dynamics, it can be an eye-opener.
     
    Last edited: Sep 15, 2018 at 4:56 AM
    Scubadude, Ardacer and dubharmonic like this.
  17. Ardacer

    Ardacer needs to read more, post less

    Contributor
    Joined:
    Oct 15, 2017
    Likes Received:
    284
    Dislikes Received:
    1
    Trophy Points:
    63
    Location:
    Croatia
    Yeah. I invite people, friends that have no clue about audio to my home all the time. Family friends, friends of friends etc. I always let everyone listen to all my gear and I don't tell them about it beforehand. Estats always win, always sound "most realistic" except for one dude that really got a boner for hd800. I'm not excluded, it's probably the best sound for me pesonally. Bass is nicer on planars, that's about it.
    One guy likes them so much he makes lists of what he'd like to listen on them and comes visit from time to time.
    (sr-l700 on srm313, Ojneg didn't like them, some friends here didn't like them, I adore these.)
     
    Scubadude likes this.
  18. Kattefjaes

    Kattefjaes Mostly Harmless

    Friend
    Joined:
    Sep 5, 2016
    Likes Received:
    4,737
    Dislikes Received:
    39
    Trophy Points:
    113
    Location:
    London, UK
    If you get a better, possibly non-Stax amp, you'll be shocked how much nicer those L700 will sound- they scale far. Something modest and solid state with a CCS will get you quite far, if you don't want to spend a fortune.

    (Yes, I'd love a BHSE or a KGSSHV, but for my modest needs, a little prototype Mjolnir Octave 2 is sounding remarkably nice and surprisingly linear on my humble L300-LE. I am becoming a bit a neutralhead facist, I fear, but can live with this option :))
     
    gepardcv and Ardacer like this.

Share This Page