[astrostar59]

  Anyway, final payment for my BHSE 2 months ago, it should be here soon...by Justin's standards 

 So I don't care about those lesser amps 

Ali

IMO having heard the BHSE against my KGSSHv they are not far apart. I could be happy with either. The KGSShv (Sanyo) is warmer than the BHSE which helps with the 009s and kicks harder in the bass. The BHSE has the magic midrange of tubes. Choose your poison....
 
Personally i have lost patience with power amps and tubes as I had some problems and I don't like the yearly cost of NOS tubes which are required to get the best out of the BHSE. It sounds too bright with the stock Mullards. I can't justify £600 a year TBH, would rather buy more music with that.

 

[zolkis]

Personally i have lost patience with power amps and tubes as I had some problems and I don't like the yearly cost of NOS tubes which are required to get the best out of the BHSE. It sounds too bright with the stock Mullards. I can't justify £600 a year TBH, would rather buy more music with that.

 
OT. I had that issue with my cj power amp too (consuming an octet of tubes every few years), got fed up and tried a large number of vintage and modern and experimental SS amps, but I realized I am a tube guy. Modern SiC, GaN and GaAs transistors get closer, but still IMHO one can more easily make good sound with tubes (ask Spritzer how many hours has he put in fine-tuning the Carbon). OK, the Carbon is ready and everyone says it's good, so feel free to go for it, but I'd just like to say that I don't have that tube wear-off issue any more with the auto-biasing PrimaLuna, nor with my other (modern) tube amps. After a few years of trying various tube makes, I ended up using Valve Art tubes nowadays, they sound good and last long. They are doing something right on their production line.
 
I didn't say this to deflect anyone from SS amps, but just to provide a complementary view .

 

[martin778]

Can someone check the build date of my 006TS and SR-407 based on SN?

 

[oogabooga]

I think the oldest SRM-006t had one NORMAL bias port, if that's of any help to you.

 

[martin778]

It's not the T or the TII but the tS which was introduced with the SRS-4170 package from around 2011.

 

[alpinemart]

Has anyone tried the Stax SRM-353X with the SR-007II? I wonder if Stax has improved the SRM-353X in comparison with the SRM-323S, but the power appears to be similar.
 
I've owned a SRM-727II previously and it didn't pair well with the SR-404; the treble was exceptionally harsh despite using EQ and the overall sound quality was analytical rather than enjoyable. However, lesser amps are apparently not suitable for the SR-007II and, unfortunately, I can't afford a BHSE, KGSShv or similar third party amp. Any advice most welcome!

 

[Pokemonn]

  Has anyone tried the Stax SRM-353X with the SR-007II? I wonder if Stax has improved the SRM-353X in comparison with the SRM-323S, but the power appears to be similar.
 
I've owned a SRM-727II previously and it didn't pair well with the SR-404; the treble was exceptionally harsh despite using EQ and the overall sound quality was analytical rather than enjoyable. However, lesser amps are apparently not suitable for the SR-007II and, unfortunately, I can't afford a BHSE, KGSShv or similar third party amp. Any advice most welcome!

for me 727 tend to sound harsh, i recommend to audition used stax tube amps. they sound warmer and smoother and enjoyable. and you need to use EQ in treble too.
but in term of resolution, stax tube amps are not good IMO.

 

[goobicii]

I saw on one forum I rather not mention that some dude put these pads https://www.amazon.ca/Brainwavz-Replacement-Hybrid-Memory-Earpad/dp/B00ZGGG3KY/185-4029103-2290361?ie=UTF8&tag=vglnk-ca-c584-20 on his Stax SR-007 Mk 2.5 (SZ3)  and it completly flatened out the U shaped freqency response....
 
if you look at innerfidelity measurements,tyll measured about 4 009s and 2 007s and they all have this little weird U shaped freqency response,its only little bit,its pretty subtle,I know 007 and 009 probably arent first things when you think U freqency response,fostex TH900 and Abyss are U shaped much more,but still,the stax have it.Its like small midbass hump and louder upper mids.
 
after using these new pads the freqency response seems so much better! its now flat from 1000hz all the way to 60hz and then very gently rolls off,it also boost the hole in lower treble on 007...... this just looks fantastic! I think tonality is biggest complain about stax 007 and 009,this fills up the midrange and fixes the bass hump and on 007 fills the treble hole,did anybody tried it?

 

[zolkis]

I have only tried the Brainwavz leather pads (flat, 30 mm high, 110x90 mm outer and 70x50 mm inner diameters).
Warning: they are oval, and the shorter diameter is too small, so makes it a very tight fit on the 007, kind of heavily stretched.
 
It does sound slightly better on the 007 than the black Stax EP-007 pads. However, on other headphones (such as the TH900), the Stax pads sound better.
 
But on the 007 the 009 pads sound still better, and my modded 009 pads sound much better.
 
Measurements are not giving things justice, since they are usable up to a few kHz, at least with the rig generally used by hobbyists (miniDSP UMIK-1 + REW + DIY coupler); nevertheless when used comparatively, they give an idea.
 

 
As seen above, the Brainwavz leather pads have less midrange dip than stock 007 pads.
When compared to my modded 009 pads, the difference in sound is bigger than in measurements (especially in bass where the 009 pads are much better sounding than comparative measurements would tell):
 

 
A few notes:
- The bass drop below 50 Hz in form of a step is a coupler thing, not noticed on my head when doing a frequency sweep: using slightly bigger pressure of the pads on the coupler make it flat, but since that is hard to control, I stay with the step.
- The treble raggedness is mainly coming from measurement setup limitations. It gives an idea, and more or less matches with my subjective evaluation, but take it with some reservations.
- The impulse response is slightly better with the modded 009 pads than with the Brainwavz, which is slightly better than the stock 007 pads.
- Distortions are almost the same, the 009 pads have slightly less distortions on odd harmonics than the others, but compensate with more on even harmonics, so while the THD is nearly the same, the 009 pads will sound slightly fuller and more musical.
 
I have asked Brainwavz whether they would make pads on my specifications (slightly angled shallow pads, slightly bigger horizontal diameters than the HM5 pads), but they don't. Of course these are replacement pads on their own headphones, and they don't want to make money on pads alone.
 
Since the HM5 pads were not really good on the TH900 either (see this post), probably I am going to modify them myself, rather than throwing them out or selling.

 

[zolkis]

OK, I checked the "other" thread as well, and it made me think to try the hybrid version of the Brainwavz pads as well - that is the angled version. But I am skeptical about it being better than the 009 pads, which are perfect, and Stax has given up the 007 pads system for good reasons. But if one cannot get or doesn't want to pay for the 009 pads, these Brainwavz pads are cheap and very good quality. Now you have measurements about 2 versions (flat leather version here, and angled hybrid version on the "other" thread).

 

[lilbthebasedgod]

So have we ever figured out the thickness of the SR-009 driver?

 

[Drumonron]

  ...so not happy about the 007's?

No, I absolutely love the 007s and the 009s....but I love my HD800s, RS-1s, HD600 and HD700s, etc (see my profile for all my babies).
 
Truth be told, the SR007s were loved so much by me that I thought...my God - what's the SR009s like!
 
Listen, I think the Stax earspeakers are such elegant pieces that effortlessly and elegantly output music, that you have to explore that.
Regrets? No - the dividends continue to be paid over and over.

 

[zolkis]

  So have we ever figured out the thickness of the SR-009 driver?

 
Driver, or membrane?
The membrane is said to be under 2 microns thick (like with the 007 and other Stax headphones), but apparently it's a new type of material, not mylar.
http://www.theabsolutesound.com/articles/stax-sr-009-electrostatic-earspeaker-playback-54/
 
The HE1000 uses sub-micron thickness of membrane material.
Sennheiser said they looked into this and optimum thickness is about 2.4 microns, that they are using in the new Orpheus.
 
In fact it doesn't really matter without knowing the material, the elastic modulus and other things. What matters is summarized below.
 
Check this post (and thread):
http://www.head-fi.org/t/555908/stax-sr-009-channel-imbalance-trouble-driver-problem/60#post_7517321

  The tension of the diaphragm affects directly with its resonant frequencies (RF).  The higher the tension, the higher the RF.  Mylar is a typical material for making diaphragms.  In order to get the same tension every time, you need to make a mechanical stretcher.  You stretch the Mylar to your desired tension, then you glue it to the spacer.  
 
The normal and safe diaphragm width to spacer thickness is around 100:1.  For anything beyond that, you can either increase your tension or reduce the bias voltage.  That will again affect the RF.  It will take a lot of trials and errors to get everything just right.
 
As for Stax, I'm sure that they know what they are doing.  However, Mylar isn't very easy to handle.  Given its surface smoothness, it might just slip a little when stretching or gluing.  And that might cause some problems, IMO.   
 
Wachara C.

 
and this one:
http://www.head-fi.org/t/555908/stax-sr-009-channel-imbalance-trouble-driver-problem/60#post_7518345

  Since the diaphragms are using a new type of plastic (which we don't know what is) then that could be the issue.  I do doubt it though since nobody as experienced as Stax would mess up diaphragm tension or choose a material which isn't fix and forget like mylar.  You have to remember that once mylar is tensioned and heat treated then it will remain in that position for at least 50 years.  Why 50 years?  That's how old my still 100% functional SR-1 is and being the first electrostatic headphone, our best point of reference. 
 
For an electrostatic transducer to be linear and have vanishingly low distortion then the diaphragm has to be ruler flat and very tight.  The Stax units certainly are, you can make them "sing" simply by lightly blowing air on them.  Given how weak the electrostatic force is then it simply isn't possible for it to stretch or dislodge the film in any way. 
 
The max SPL limit of any electrostatic driver is set by the inherent voltage limits of the drivers and not excursion.  The voltage limit is normally around double the bias voltage which means the driver will start to burn up once it is surpassed.  Now with most of the Stax amps this isn't a problem since 1200V P-P is a lot of voltage and more than they could ever output.  Only a handful of the DIY amps can output at these levels so damaging the drivers isn't very likely.  Now with the normal bias sets it was a very different story and Stax did try a lot of different things to stop people from burning up the diaphragms.  Sadly none of them really worked... 

 

[edstrelow]

I pulled this off a 6-moons review

 ​

"I The new SR-404 Signature utilizes a new diaphragm only 1.35 microns thick as compared to the 2 microns of my former Lambda Pros and the 1.5 microns of the Lambda Nova Signature. "     http://6moons.com/audioreviews/stax2/stax.html

 ​

However I am not sure it's accurate.  I am sure I have read that the SNL is 1 micron  but my googling is not pulling this information  up.

 

[arnaud]

I'd be curious to hear what knowing the actual thickness of the SR009 diaphragm brings to the table, considering the fact nobody knows what material is actually used 

.
 
A driver is so many more parameters than just the diaphragm thickness, I am not really sure what one thinks can be inferred from knowing this actual property.
 
arnaud