I've got a pair of SR-Lambda Pro headphones recently and I love them. Right nw I've got them hooked up as follows:

Wadia 23 RCA>Denon AVR-100>SRD-7 Pro>SR-Lambda Pro

I've also heard these out of Hirsch's ES-1 and the 007t amp. The ES-1 trumps all of them of course.

Overall they're the clearest sounding headphones I've heard. Vocals are warm but well articulated, the highs are sparkling and fast. The bass is full and rich but does lack the speed of a dynamic headphone at times...but it can go quite deep on some recordings (Thievery Corporation).

I don't think I've ever been sucked into Paul Galbraith's recording of the Bach Sonatas and Partitas for violin before like these cans suck me in. It's magical....I felt like I was back in music school sitting a few feet away from a buddy playing classical guitar at his recital. I closed my eyes and I was there.

I realize that I'm in the honeymoon phase, but I've never had a hard time putting cans down to go to work, do housework, go to slepp..etc. like I do with these. I don't want to stop listening to them. I' listening to them right now as I type.

I also picked up the SR-84 combo; called the Lambda Jr. by Stax (SR-4 electret energiser and SR-80 Electret headphones). These are a nice little find as well. Good office rig. Set up as follows:

iPod>Sonic Impact T-amp>SR-4>SR-80

Good little combo. Overall retains the same house sound, clear and crisp with more muted bass and less speed overall. But in a pinch they would make a neat little portable rig...can be battery powered since the SR-4 doesn't plug into the wall.

So what's your Stax?

The Marketing

The Review

No USB-C audio? am dissapoint.

An apple airpod max pro 2 ultra or whatever they are called rival?

Well, it has the premium pricing, vs the XM6 (relatively) pleb version.

I have a pair of Stax SR-007 e-stats - a 007 Mk 1 (s/n 71169) for which I made a new pair of diaphragms last year (long story, will make another post just about that here on HC soon) and a 007A (s/n SZ2-1636). In the last few days I've been noticing that the pair of metal arcs on the head assembly of my 007 Mk 1 makes a slight ringing sound transmitted to the drivers when I move my head, especially when these arcs are touching the headband. I don't recall them doing that before, but maybe I just wasn't paying attention. This ringing sound disappears if I either touch the arcs with my hand or reposition the unit so that the arcs no longer touch the headband. However, the latter doesn't last long and not allowing the arcs to touch the headband sometimes brings about problems of its own, like e.g. loud ringing whenever the arcs are accidentally tapped. This Head-Fi thread briefly discusses the arc tapping issue and also (mostly) the possibility of the arcs resonating with the driver sound itself (with potential ensuing problems like parasitic crosstalk and overall distortion), but I'm a bit distrustful about the latter hypothesis because it implies an unlikely design flaw by Stax.

Anyhow, I'd like to know if there is something I can do to prevent the arc ringing when my head moves besides keeping the arcs from touching the headband (e.g. adjusting the arc screws, etc.). It's important to point that my 007A doesn't have this problem. I don't know why, but what I do know is that my 007A has a tighter fit on my head than my 007 Mk 1, so I don't know if the different behavior is due to e.g. different tightness in the arc screws or just that the arcs are pressed harder against the headband due to the tighter fit and because of that the arc ringing just disappears.

Any hints on how to deal with this problem are welcome!

Stax noob here. I'm fairly new to electrostatics, but I did do my research before upgrading from my SRM-3. I managed to snag a 717 in what seems to be extremely good condition for around 670 USD a couple months ago. I've been really enjoying it, but I want to make sure the thing will last. I've read several times now that the electrolytic caps are a concern with aging Stax amps, and I want to know if they are any parts that need to be replaced in my unit in the near future. I'm also interested in making upgrades if possible and converting my unit from 100V input to 120V, but those are less of a concern.

I cracked the amp open and pulled of the decorative PCB on the transformer to take a couple photos of its innards (attached below) in hopes that it may provide some indication of the level of work required to perform any of the tasks mentioned. I have some experience with soldering and some fairly basic knowledge of electrical circuits and the like, by my skills and knowledge are geared predominantly towards medicine and dentistry, so I would greatly appreciate any help or resources on how to perform the maintenance/mods, some direction as to where I can take the amp if i can't do it, and a rough estimate of the cost.

Thanks in advance to whoever is willing to read this!

Now the plan was always to do something with the 009's to improve them but there was always something better to do.  Well with surgery pending a couple of months ago, I finally had time to do something not too taxing.  First off I needed a donor set and here is where that came in:

I got these three years ago and they just sat there in a box.  Too many parts missing with no spares available, three out of the four dust covers were trashed and I took off the arc to rescue another 009... so a pile of parts with fucked up drivers.  The plan forward was clear though, the drivers needed new dust covers, new diaphragms, a way to mount the cable and finally some way to attach the earpads which wasn't 009 levels of stupid.  Now none of those parts could be reused or they simply weren't there so time to do some designing.  I still suck at 3D design but practice makes perfect... or it should in theory.    

Now first off, dust covers and diaphragm holders.  These are easy to do as PCB's but materials, thickness, films used etc. are all large variables.  Here are my first drivers, actually using the third batch of diaphragms as I slightly tweaked the dimensions once I started test fitting:

Those familiar with the stock drivers might spot the bias connection is very different.  I had to spend a lot of time cleaning the stock drivers, as they had been open for who knows how long, but this first test was successful.  Fully balanced drivers and no noises from them at all so they are as clean as I can get them.  The dust covers are 2um mylar-C, just lightly stretched (hence the slight lines visible) and the main diaphragms are also fairly loosely stretched 2um mylar-C, then heat treated and given a coat of fabric softener.  

The drivers are easy to align but one major part of this project is to find all the correct o-rings used to assemble these and in the right grade.  When I had waited a month for a large shipment just for the one size I needed to not show, I even bought some stupid expensive examples locally.  That got me here:

All new screws used to get the drivers into the housings.  You can see how beat up the aluminum housings are but hey, fine for a project like this.  Now there was the next difficult bit, the cable entry:

On the stock set it is a plastic guide which sits in those holes, the cable fits in that and the whole assemble is screwed down.  Now the stock cable I had was not perfect so instead of making my own version of that... I just used a standard Lambda cable.  A L500 was going to die for this set anyway (as I needed the arc) so why not use that cable.  Here is my solution for that:

This is 3D resin printed and is the second revision.  First was just to check for hole size, alignment and if it was fouling on anything but it was way too shallow.   This version still had to be sanded a tiny bit but it fits nicely.  I did make a 3rd and 4th version which is incoming to clean up the design a bit and give me some more internal room.  The earpads above are simply stuck on with some blutack so more on that...  

For the earpad mounting, there two problems there really.  None of mounting hardware was included and anybody who had changed the 009 pads knows just how fucking stupid that mounting setup is.  I also wanted to use non Stax earpads (not paying 300$+ for pleather crap) so here is what I came up with:

Same idea really but I added a spacer between the plate and the driver housing so there is room to slide the lip of the earpads underneath it.  The two layers of the PCB sandwich are visible there (along with the production number as I forgot to have it removed) and it works nicely.  I could have made this from aluminum but it wouldn't have cost roughly 4$ then...  

This is the fitment with some random test earpads and standard 1.6mm PCB's.  Works just fine and I can't find any issues with baffle seal... quite the contrary really.  

So here we are, the MA-009  

This set of earpads has already been replaced and it takes a matter of seconds to swap them over.  What a novel feature...  

Now what was the true goal for all of this, well besides having some fun doing something new... make a set of 009's I would actually want to sit down and listen to.  Now this project is far from over but here is something novel... a SR-009 that has some actual bass output.  They are still forward sounding but it has been diminished by a large extent.  I can use these for hours quite happily, even at my usually higher volume levels.  

The decision to use 2um mylar was to try and tame that forward edge and it has been partially successful.  A stock set of 009's is terrible on most music I try them with, this one is mostly good with just some tracks which show how bad that stator design really is.  There is this slight forward sheen over everything and it simply has to be the stators as the rest of the headphones has so much in common with the 007 overall design.  

Now the major issue is driver stability as the left diaphragm really likes to get stuck to the stators and I have to open up the driver to get is back on song.  I might have gone too far in sealing them up but I wanted some bass dammit!!    I will make some more test diaphragms and see if I can make some which can handle the pressure of going on the head energized while giving the sound I want.  For now I'll just use this pile of parts to make some music...  

So to end off... if anybody has a set of 009's with blown drivers that are collecting dust... hit me up and I might want to buy them.    

1. Models and nomenclature

The Stax SR-Sigma panoramic earspeaker was introduced in 1977. There have been 3 versions officially released and 1 after-market version commissioned.

1. The original low bias, grey grilled 1977 Sigma model (bias voltage of this model being 230V or “Normal”). The driver used was later recycled in the very successful Stax Lambda Semi-Panoramic earspeaker. The first release Sigma had a fabric coated, round bodied cord that connected the earspeaker to its amplifier/transformer.
   
2. Later versions of the normal bias Sigma (1987) used a lower capacitance, flat black cable that was recycled back from the (then) current Stax SR-Lambda earspeaker.
   
3. The later Sigma Professional (1987) version introduced the 580V Professional driver then used in the Stax SR-Signature earspeaker. This earspeaker had black grilles, lower capacitance chocolate coloured cables, and a chocolate coloured headband, compared with the original black cables and headband.
   
4. A later version, the Sigma/404, was a Sigma rebuilt with high bias SR-404 drivers and their corresponding very low-capacitance cables.
   

2. History and conception.

The Sigma earspeaker design was the result of a complete reassessment of how headphone sound is perceived. Up until that point, listening to headphones or speakers were considered completely different experiences. Headphones were designed to inject sound directly into the ears with as much sound isolation as possible between channels and also from the external environment, reflecting their communications genealogy. The drivers were parallel to the pinnae (= ear flaps) and either intra-aural, circum-aural or supra-aural.

Speaker listening has the drivers at a great distance from the ear canals and sound produced has to traverse a great number of direct, reflected and partially absorptive pathways before arriving at the ear canal, allowing much more modification of the sound as well as left and right channel blending. The drivers are also in front of the listener and perpendicular to the plane of the pinnae.

Naotake Hayashi, the genius behind the original Stax company, decided that one of the differences between speaker and headphone listening was a result of that very isolation and direct aural injection inherent in the design of all prior headphones. He decided to make a headphone that would actually sound like listening to speakers in a partially reflective/absorptive room. The genius lay in his actual recreation of a room around each ear – a revolutionary concept that has never before or since been replicated. Each earcup was meant to approximate a partially absorptive and partially reflective series of surfaces for the headphone driver (now in front of each pinna and perpendicular to them, as per speaker listening) to bounce sound off and then into the ear canal. In other words, the direct injection principle was thrown out the window and now the drivers were only heard after firing sound into the ear canals via a reflection - and some absorption – from an internal lining of mineral wool. I am guessing that the ear speaker cages had to be constructed pervious to air, rather than designed with a solid body, for weight considerations (viz. a solid body construction would have been too heavy for comfortable wearing). Possibly there were also enclosed cavity effects to deal with if the headphones were sealed. Indeed, weight has been one of the main complaints levelled at the only enclosed Stax design, the Stax SR-4070 Monitor. The mineral wool lining of the cages, apart from reflecting and absorbing sound, much like a normal listening room, also provided some hermetic sealing of the cages allowing reduced front to back sound cancellation around the periphery of the drivers. In other words, the drivers could have bass (the lack of which has been a criticism of the relatively similar design AKG K1000), but not as much as if a solid body had been used. I am guessing that a solid body Sigma had been tried and discarded due to comfort and sound considerations, so a compromise between weight of the headphones and sound quality as well as bass extension was reached.

3. Comfort.

The Sigmas, although bulky and laughably unfashionable, have been engineered to be exceptionally comfortable on your head. It is literally easy to listen for hours without your pinnae contacting the metal inner grille of the drivers (Lambda series) or the earpads themselves (SR-007). The small listening cavities of those 2 phones also leads to sweaty ears, which is far less apparent with the Sigma series.

4. Sound.

a. Low bass and bass.

The sound of the Sigma always has slightly reduced very low bass because of some residual front-to-back driver cancellation through the mineral wool earcup lining, but beyond that point, the earspeaker’s sound is very hard to fault compared to what one is used to. The bass that is present, until the very low bass roll-off, is of excellent quality. Certainly there are no bass instruments that move back and forward in the soundfield, nor do they completely disappear as they descend the scale, as I heard with the Jecklin Float Electrostatics playing, for example, Tony Levin’s descending Stick run during Projekct One’s “Live At The Jazz Café” Track 3. On the Jecklins, Tony appears to walk out the studio door as the run descends to subterranean levels. On the Sigmas, he’s in the studio and hasn’t moved a muscle.

b. Midrange.

The reproduction of vocals comes as close to free of sibilant emphasis as possible. This is truly what you hear in live, unamplified music. Particularly realistic are piano and voice – the smoothness of the sound is just as relaxing on replay as it is live. Indeed, after attending a piano concert in a relatively reverberant wooden hall, the Sigma/404s got the extreme dynamics of the piano without any of the brightness at higher volumes that the Lambda Nova Signature exhibited. This exquisite piano reproduction is unique to this headphone, in my opinion

c. Treble

The later substitution of the 580V “Professional” bias drivers (either the Lambda Signature or the Lambda 404 headphone driver) to replace the original “Normal” bias driver, along with an upgrade of the original headphone cable, allows a reduction in the marked high frequency roll-off and a flatter extension in the very bottom-end reproduction compared with the original low bias Sigma. In my opinion, there are no drawbacks from this modification whatsoever and the top end sounds both smooth and evident, rather than smooth and rolled off as in the original Sigma

d. Correct volume level.

The Sigma/404 really shines a light on just how successful Mr Hayashi’s earspeaker design concept really is. Another bonus I have noted with these earspeakers is that it seems to be relatively easy to dial up the “correct” volume of sound – they just sound “right” at that point. Although this is not unique for these phones, I haven’t heard a headphone with such a pronounced “correct” volume level for a track. The bass and treble just seem to be in perfect balance with the midrange only at that volume. Peter Walker of Quad was a great proponent of the “correct” volume theory apparently.

e. 3-D sound.

Then there is the seemingly increased 3D space that these headphones portray – the sound stage seems to be actually in front of the head, with some front to back space, compared with the usual line-between-the-two-ears imaging. This is something I’m not as good at hearing, so I will leave it to others to give their impressions.

These differences allow greater appreciation of albums that were mixed for speakers in the standard control room, because that is exactly what the Sigmas replicate. I would guess that apart from very low frequency roll-off, these earspeakers could be the greatest and most accurate magnifying glasses for mixing evaluation ever made.

5. Associated equipment needed.

I have found the SRD-7 Pro or SRD-7 Mk 2 will do an admirable job of driving these very power hungry monsters with a good power amp pushing them. If you wish to drive them with a direct drive electrostatic amp, I would suggest, at the very least, using any of Stax SRM-717/SRM-727/SRM-T2, Kevin Gilmore/Spritzer’s revamped T2 or the Blue Hawaii SE/Solid State Electrostatic amps. They are all powerful enough to drive these and the SR-007 Mk1/Mk2 series. The Lambda series are far less power hungry, despite using the same drivers as the Sigmas. Distance from the ears and absorption by the damping material may both account for these efficiency differences. The volume control levels for the Sigma/404 and SR-007 Mk1 I once owned were identical for the same reproduced volume – i.e. they seem to be equally inefficient - compared with a Lambda Nova Signature.

6. Credits.

Finally, one has to admire a designer who actually truly said nay to any marketing considerations. These phones are laughably big and ugly, but if they were anything else, could they sound as good? Thank you, Mr Hayashi for not listening to the form-over-function naysayers, and I bet there were plenty of those in Stax board meetings in 1976/1977

Lastly, I would like to thank Edstrelow for the inspiration to upgrade my Sigmas to Sigma/404s – something I did on faith and have never regretted it for a minute, and Webbie64 for making me realise the error of my ways when I briefly thought about selling them.

7. Postscript - Stax Sigmas high bias earspeakers compared – Pro vs Sigma/404.

The 2 Sigma high bias phones essentially differ in 2 main physical ways.

1. The headphone cable used for the original Sigma Pro was the same as the one used on the Lambda Signature – not as wide as the one used for the Sigma/404 hybrid, which were first seen on the Lambda Nova Signature.
   
2. The drivers are different also – the Sigma Pro uses the reported 1 um Lambda Signature driver, whilst the Sigma/404 uses the (2 generations) later 1.35 um drivers first seen in the Lambda 404.
   

Otherwise, the shells of the 2 earspeakers, apart from minor colour variations, are identical. The Sigma Pro driver appears to be very slightly more efficient than that of the Sigma/404.

In my set up so far, the two have been compared through the Studer D730 -> Apogee Mini-DAC -> Audio Research LS5 Mk2 -> Studer A68 -> Spritzer Pro SRD-7 bias + transformer box.

As seems to be the order of the day, the results are not what I expected. The Sigma Pro is far better than its reputation suggested and even bests the Sigma/404 in a couple of areas.

Firstly, the deep bass is slightly more evident and the mid bass is much tighter and slightly less resonant in the Sigma Pro. Bass drum has slightly more punch rather than smeared thud. This has been one of my only criticisms of the Sigma/404.

The midrange is about the same with both, but the treble is slightly more evident with the Sigma Pro. It’s close to a line call there, however.

As for dynamics – the Sigma Pro does dynamics somewhat better than the Sigma/404. The Lambda Signature driver/cable just sounds a little faster than the 404 driver/cable. This tends to alleviate some of the complaints about a mushy low end of the Sigma series.

The original Sigma low bias was far too rolled off at the top end in particular, despite the magical Sigma midrange being present there. It appears that either the Signature or 404 driver implants are a successful remedy to this, and give a phone that had huge promise a push into reference territory.

In summary, despite every single report to the contrary, I’m loving it! Flame suit on, hearing aid batteries fully charged LOL. Stax SR-009? Who cares?

Here are the phones list 

Sony R10 (Hard to find), Sr-4070, ZMF Verite, Focal Stellia

Any suggestion so far?

The first thing I discovered is that the 'nano-technology' used by hifiman actually comes from the covering used by indoors aircraft model enthusiasts，the name is OS film and it is still available on ebay or https://www.indoorffsupply.com/shop/os-film-25ft-roll-1

the driver of the hifiman estats is completely glued which is similar to the early stax lambdas,  but hifiman glue is significantly worse...after opening the driver i found that they only use OS film for their dust cover, the diaphragm is another PET film ~ a little bit thicker but with much better strength. In order to repair the diaphragm, I found a seller on Alibaba who can provide samples of Toray PET film with thickness below 2 microns at an acceptable price，and use the inner tire stretcher to stretch the film like any other diy estats ，Then test it with a 10" subwoofer and minidsp umik-1 to find proper F0.

       conductive coating is another serious problem，I've tried quite a few methods including antistatic agents like licron crystal, ANTISTATIK100，floor cleaner，carbon-based coatings such as graphene, and alcohol-soluble nylon, even tried nano-silver wire solution and metal evaporation...Some of them are sensitive to humidity, some arcs，some are ridiculously expensive, some have uneven surface resistance distribution, and some are sensitive to temperature changes. Yah~ finding the proper conductive coating is the most difficult part especially for a layman. unexpectedly, I tried to search for hifiman patents, hoping to find something useful... here's a patent showing that they used some kind of metal oxide nano particles as conductive coating for their estats. emmm，very interesting...🙄 By consulting with chemistry professionals, I decided to try a solution called ATO (antimony doped tin oxide), there are many antistatic agents I have used before have ATO ingredients though. I got some ATO alcohol solution at concentration around 10~15%, it works really well, and coating appearance is somewhat identical to hifiman diaphragm!

The last thing is to repair stators. hifimans probably use #150~300 brass mesh and solder their edges to a 2mm thick aluminum base plate PCB board, then glue the rest of middle part. I've tried tensioning those brass mesh with embroidery frame and manual screen stretcher，but it is not tight enough to stretche brass mesh in this way, the mesh itself is too strong to tighten it up... then I found some brass sieves with different meshes on taobao and these machined copper screens are perfect for making DIY mesh stators...

after everything's ready，i desoldered OG brass mesh, cleaned the copper foil, applied low temperature solder paste, and carefully soldered the new brass mesh with a heat gun. 

During the process of repairing shangri la jr, I started planning to make some bigger mesh stator estats... of course，the target is its big brother shangri la SR😈I received a set of the first batch of shangri la sr made in 2016，here is the headphone inside，yap~inherited the tradition of hifiman with such horrible workmanship...😱 however，SR sounds not as technical as the X9000 though，but with more pleasant and passion. SR uses 3mm thick aluminum base plate PCB instead of 2mm on JR version，2 black things in the middle are to prevent the diaphragm from attaching stators，The D-S gap is around 0.7~0.8mm(thickness of glue included) which is identical to JR version，active area is close to 6400mm² ，that is pretty large diaphragm size for a commercial product though，but less 5300mm² of area on stator allows air to pass through.

I tried to use the 3mm FR4 board as mesh holder at first time，however，mesh stator disassembly is not an easy job...therefore，I changed to use 1.5mm brass plates as the mesh holder and glued the copper mesh to it , brass mesh is also replaced with higher # red copper mesh for more convenient adhension. I spent most of time adjusting the tension of the diaphragm and finally found the tension needed for F0 similar to OG SR ,the clone driver has a slightly enlarged diaphragm(6839mm²) ，0.73mm fr-4 pcb spacer， and everything is screwed to the housing cover.

The frequency response of clone and SR are generally similar，but the sensitivity difference between the two is about 1.5dB actually，SR is more diffused...clone one sounds a bit more clearer. SR has obvious recession between 1-2kHz，it may be caused by a sealing problem in the space between the driver and the earcup.... It's unlikely to be solved without EQ, but it doesn't sound as bad as it looks from the graphics.

one more thing...

Every shangri la must have a throne , so I made one for my mutation🤣

Time for some impressions of this rare beast.    The Icelandic distributor has a set on loan and they carved an entire afternoon out of the schedule for me to try it and do some comparisons.  I showed up with the HE90 I built from spare parts, Aristaeus, Carbon amp and a port modded SR-007Mk2.  Since they were using the built in dac on the HE-1, I just plugged both amps into as well to equalize the comparison. 

Over all, I like the build quality of the headphones.  Imagine a HD800 built properly and you are pretty much there.  The leather earpads are super nice and the headband has nice extension to even fit my large melon.  I don't think they are super comfy though as they are fucking heavy (550gr) and all of the pressure is on the top of the head.  The Stax 4070 is just about as heavy but far more comfy due to the suspended headband design.  The earcups get a bit warm due to the internal amps but only about 5-7°C above ambient.  The cable is also pretty nice and not microphonic at all but more on the amps etc. later.  

Amp itself...well it is just fucked up.  I get that they were trying to cater to some nouveau-riche people who just want something expensive but the wank factor is off the charts.  I also have serious doubts about what's hiding in that nice marble shell... 

As for the headphones them selves... well the drivers look pretty much identical to the HE90 units and the few pictures of them that exist, point to that.  I wanted to rip off the earpads to check further but people get antsy with something this expensive...    One worrying thing I noticed though is that both sides of the drivers have porous dust covers.  They look identical to the woven nylon found on the HE90 and well...I would expect solid covers. 

Now for some actual impressions.  As I said above the HE-1 dac was the source for all the amps.  To that you have to turn off the headphones so no direct comparisons were possible but I know how both systems should sound so not a big problem there.  The source feeding the HE-1 was a Macbook Pro running itunes but I bypassed that with my own FLAC files and player. 

There are some major changes compared to the older system, this one can do bass and isn't as horribly colored either but over all...I was not impressed and the system never made me really interested in the music.  It doesn't engage like a good 007 system can, where I sometimes just sit in awe even after owning a set for all these years.  Here, it just doesn't pull me in.  This is clearly a midrange issue as there just isn't enough presence there. 

First off the major issues are the bass, treble and the soundstage.  Let's start with the bass, it has this annoying hump to it sort of like the old Lambdas.  I'm not sure if this is the mosfet driver (could be, the Cavalli crap boxes have similar issues) or the headphones but it is a clear coloration and once you notice it, just annoys the fuck out of me.  Now on some tracks it wasn't as noticeable but always lurking in the background none the less. 

Next up is the treble...which is both subdued and bright at the same time.  I know plenty of people complain the 007's lack sparkle and with the Mk1 this was mostly true but they could be bright if the source called for it.  The HE-1 manages something different, the treble is just flat and boring but then it suddenly bites hard.  Now I was listening at higher levels but still nothing super loud, only about 12 o'clock on the dial.  This also wasn't like the upper midrange bite of the 009's, more lower treble fizz but the source material didn't call for this.  I'm so used to listening to SR-X Mk3 Pro drivers now (which are pretty much the gold standard for treble) as they are in my DIY headphones and nope, nothing like this.  I suspect the amp is a huge influence here too but no way to verify that... 

Last major issue, the soundstage.  Many will know my stance on the old HE90 where it sounds like you are listening to some people playing in dense fog and you can't quite make out where they are.  This time around it is much improved but the lack of pin point accuracy is still apparent.  The soundstage is also a bit too far away for my liking and it just doesn't throw the same huge headspace the 007's can.  This also affects the midrange and the whole "disconnected" feeling I got from the whole system.  I once reached for my phone as I was just a bit bored listening to it. 

Over all I like that Sennheiser built this but they really should have spent more time on the electronics.  I don't think there are any improvements to moving the amps to the cups over something like the Carbon where I can burn 50+W as heat and overcome the small capacitance in the cable.  Next post will discuss the tech specs of the system but I'll end with another picture of it all... It was really dark in there and I suck at taking pictures... 

Now for some technical discussion.  I found the specs in the back of the manual and it turns out the bias is 650VDC and the amps run at +780VDC.  This makes this more than compatible with Stax so I see no issue with removing the internal amps and rewiring one of these for Stax use.  I have been asked to that before but I'm really hesitant to mess with something this expensive. 

That said, moving to proper amps which are not just the HEV70 rehashed can only be an improvement.  I've never found any mosfet device with sufficiently low Cob to work in this role so I truly don't get what Senn were thinking. 

Some other info, the entire amp only consumes 40W per the user manual which doesn't leave a lot for the actual amps.  So we have 8 tubes running with heaters plus all the motors in there.  HV supply for the tubes, another for the output stage and well...not a whole lot of power to spare here.  Compare that to the BHSE, Carbon or even the T2.  All of them use far more power and it is just for one goal, to power the headphones. 

I also played around with the amp and I could swear that the volume control feels like a RK27.  No way to know but how it felt when moving to the extremes...it was just like a RK27.  Now as a proper volume control aficionado... ... they all feel a bit different.  TKD feels nothing like a P+G or a RK50...  Until somebody opens one of these up, take it how you will.  It is also clearly a volume pot and not a chip or some other setup. 

You want to like, but don't. Mine is a q701 I bought used 12 years ago real cheap. Cheap because it

smelled like an ashtray. Pulled it apart and cleaned it well, and did the bass port mod. I don't like the

sound. Put it away and then tried it out again  when I changed DACs and amps. I still don't like it.

I'm trying real hard to make myself get rid of it. It's hard to be a horder.

I’ve now had the SR-X9000 here for over a week so time for a writeup... as my email inbox is full of people asking for just that. 🙂   First impressions were very promising, the build quality is superb, and those drivers are just a marvel to behold.  I do like the new replaceable cables even, though it is a bit of a copy of the King Sound setup, and they really should include a 2.5m cable and a 5m one, the 1.5m makes no sense to me.  The earpads might be a tad too big in terms of open area for their own good but they are well made and comfy.  That new arc design is also excellent, far better than the 009 mess.  The inspiration from the SR-Omega is clear but the build quality here is far, far better.  Same loose feeling fit too; they mostly just hang off the head with minimal clamping.  I really like how they drew inspiration from them, but I also have some issues with how that was executed… more about that later.  The system I’ve been using them in is my main rig, Denafrips Terminator DAC feeding a Carbon CC all being fed from my main PC. 

Now for the sound, these are clearly voiced in the same direction as the 009/009S but not as horribly colored as those two.  They sound open and lively with decent bass and the forward slant is there but far better than the predecessors.  I remember thinking… “these are what the 009’s should have been 11 years ago” so yeah, not bad at all.  For some recordings they really work but yeah… a few tracks in and the cracks began to show. 

A bit of a backstory, I’ve likened buying Stax to being in an “abusive relationship” for the last 15 years.  Back in 2007 they brought us the 007Mk2’s with all of their issues.  Sure, they could be fixed easily enough with some blutac but yeah it was a sign of things to come.  At CanJam it was confirmed there was a new version of the 007Mk2’s out and they were even worse (the Mk2.5 as we called them), the blutac helped but could not fix the terrible voicing.

Then it was announced a new flagship was incoming and the SR-009 landed in 2011.  Now we all remember the clusterfuck that was, drivers failing left and right and forward sound with pitiful bass response… yeah, I’m not a fan.  One bright spark was in 2014 when I got a new set of 007Mk2’s and they had clearly been changed for the better.  The port finally kind of worked and the voicing was more like the Mk1’s.  Then we got the limited edition 009BK (2016?) which I found to be a small improvement over the 009 but still that same sound and finally the 009S is 2018.  Less said about them the better, quickest I’ve ever sold one of my flagship phones there… 

That brings us to the present and since the wait for the SR-X9000 was so long, I had time to bolster my collection to compare against them.  I got a used set of 009S just to make sure I didn’t like them (that was still the case), a Voce (not arrived yet due to some shipping snafu’s) and finally the one I really wanted, a SR-Omega with early 007 Mk1 drivers.  I had a set a decade or so ago and it’s really the only set of headphones I truly regret selling.  I also got my final set of Audeze CRBN’s to compare against the new kid on the block. 

I had a lot of fun doing so and after a few hours I gravitated to a direct A-B test of the SR-Omega/007 against the X9000.  Makes sense as they are a similar idea, put a more modern driver into that same basic housing design.  That did reveal the two main issues with the X9000’s, the bright edge to everything which is just borderline annoying and more distracting than anything.   Second are the imaging issues… 

First off, the brightness, with the 009’s they were really intolerable, and I’ve never been able to just sit down and enjoy a listening session with 009’s.  It’s not that bad here but it’s always present.  Some tracks it just blends in and becomes part of the sound while on others it stands out and takes away from the immersion.  What makes it worse is that there is no logic to which tracks have that edge to them, bright ones which I would expect to have it… well it just blends in while darker ones have it.  Must be a resonance issue as there is so little damping here. 

Now with the imaging, I think Stax made a mistake having the outside screen angled like that.  On the SR-Omega it is perfectly parallel with the drivers but on the X9K, it is maybe 3mm further out towards the front.  This or some part of the driver structure might be the culprit for the odd imaging.  Let me clarify, they throw a large soundstage but it’s very much a “three blob affair”.  Nothing wrong with that really but it’s the front imaging which sounds off for me.  It’s all a bit to distant and boxed in while not being as focused as the 007 soundstage.  When you pick up on it, it becomes very apparent and distracting. 

As comparison, let’s take the SR-Omega and SR-007Mk2.  The SR-Omega throws a wide soundstage but it’s all a bit loose and diffused.  Now the 007’s (all of them really) have a much tighter, more focused soundstage which also does something unique, there are layers to it.  With the SR-X9000 it’s more like the SR-Omega (which makes sense) but more localized to the three blobs and the middle one has that odd boxed in effect while being a bit distant. 

Now other than these two things, these are well made and high performing sets, but these two things annoy me enough for them to not make my top/best ever list.  The SR-007’s are more laid back and “darker” but also more neutral and truer to the original sound.  The SR-Omega/007 is a more fun and looser version of that sound but those slight deficiencies just make them a welcome change, doesn’t make them any less neutral.  They simply act as a bridge bringing those two sounds together, absolute purity of the 007 with the more warm and loose nature of the SR-Omega. 

I feel I should also talk a bit about the new kid on the block, the Audeze CRBN.  Now I’ve had a few of them here, prototype units to the final production version and it really is the antithesis of the SR-X9000 is terms of fit and sound.  The CRBN is snug as it hugs your head with thick and supple earpads.  The sound is far more damped so it is darker but still very open and expansive.  Now they aren’t perfect, they have that slight issue with the midrange presence due to the heavy damping, but it is minor overall.  They are really what the HE90 could have been back in the day, more diffused than the 007’s but with proper bass.  Nice way to tie back the 007's were always being compared to the HE90 back in the day. 

Lastly, how are they to drive.  Well… as one would expect with a driver this size, they need a lot of power to behave.  That brightness will quickly get out of control, especially at higher volume levels when the headphones don’t have enough power behind them.  I’ve only tried them on a couple of amps so far so I’ll need more time with that, but I’d say powerful and neutral amps will suit these just fine.  

Conclusion/TL; DR

These are good but not as good as they could have been.  They are too forward sounding though not as bad as the SR-009, 009BK or 009S.  I crave neutrality over everything else, the headphones should just present the sound with as little an impact on it as is possible.  If they fail to represent a part of the spectrum, that’s fine but if they add something… then I have a problem with it.  The brightness and imaging issue does disqualify them due to that, but I will keep them around, nonetheless.  With some material they work well and plus I’m in a collecting mood… 😉   I'll probably add to review later on as I spend some more time with them. 

Finally, I’m going to be a bit cynical and think Stax are doing this sound signature on purpose and not for the obvious reasons.  This is exactly the type of sound which grabs you on a quick audition or impresses the useless audio reviewers out there who don’t know any better.  Back in 2002 the 007’s got no love at all as they are the definition of “unimpressive at first audition”, let along not many amps around at that time which could drive them.  Stax are clearly now trying to make money and not audio purist just trying to make the best product possible, nothing wrong with that, so I’m glad this wasn’t a complete hack job like the 009S. 

Anyone have hands/ears on yet?

some photos of them https://imgur.com/a/sFUOz0S

the website for them

https://www.eslabhk.com/

http://video.google.com/videoplay?docid=-100926089806656515&hl=en

These were made by Audiotec in France and aside from some brochures back in the say we know nothing about them.  There isn't even a model number on them or a left-right identifier.  They are quite big, roughtly the same size as the SR-Omega and the back of the fork is pretty much a clone of the SR-1,2 and 3 setup Stax used. 

Here are the earcups opened and these do have the honor of having a truly unique earcup design.  No screws as they use nails which are friction fitted.  Very secure assembly but an utter pain in the ass to disassemble... 

Not sure what is up with that baffle.  It made of the same material as really old PCB's but those traces don't go anywhere. 

Driver lifter out of its cradle and doesn't this look familiar.  Turns out that it's the same or very similar driver to the ones used in the Stax electret models.  Never seen one with the mineral wool damping pad being a part of the driver housing though. 

Same pic but showing a bit more of the green wool pad used on the back of the driver.  This keeps the driver in place against the baffle similar to the Magnavox sets but it's a far from ideal setup.  There is also very little to keep the back wave from colliding with the front and that foam around the driver is decomposing quickly. 

Showing the connections inside the cups.  The joints simply have fiberglass insulation pushed over them but not secured in any way.  Yet another thing that needs to be fixed... 

Here is the original 6 pin DIN connector.  Oxidized all to hell so I simply removed it. 

Now the important bit, how do they sound.  Well I don't have the original adapters so I had to make due with what I have at hand...    I knew that the stock transformers used with the Audiotec stuff had very high stepup ratio (1:65) so it was no surprise that the highly modified SRM-007tII didn't manage to drive these even at full volume.  I do have a few KGSSHV's here and they did a stellar job with a very balance sound signature.  The bass is a bit odd given the housing and all the colorations it adds but not bad at all. 

Finally here is how they look now but I'll do some further mods to them.  They really need a new cable and some baffle insulation...

Last but certainly not least, great thanks to Luc for giving me this set to play with.   

Both drivers are slanted forward and left one has less bass. Volume is slightly unbalanced but mostly noticeable for stereo music.

Should I risk it? Audio signature suddendly changed today and then it sounded normal again (that's when I noticed both drivers slanted forward. Left one was only slightly slanted now both of them fully are)

I've had the opportunity to try it and if you are a SR-007 person and not as into the 009/X9K, this is a fulfilling option. It does require considerable power, which the Stax mafia has been taking care of since ~2003

https://www.headamp.com/products/dan-clark-corina

Donald

This should be interesting…

https://www.nuanceaudio.com/en-us