[mechgamer123]

 
I have the 252S, replacing the wall wart with a fully regulated supply improves the performance when driving the SR-Lambda series(207,307,407,507) and the Sennheiser HE-60. It will drive the SR-009 if the volume is not turned up too high.
 
The linear amplifier part in the 252S is almost identical to the 323S except is current thru the stages is reduced. The 323S is like a simplified version of the KGSSHV.
The 252S does not use load resistors, it has an active current source like the 323S and KGSSHV, quite a nice design.
 
It also does not have any heatsinking so increasing the bias current will overheat the amp.
Replacing the cheap electrolytics in the 252 with high ripple Panasonics and Nichicon polymer caps will really wake it up.

Wow, thanks for providing so much useful information about STAX amplifiers! I am curious though, are there any major internal differences between the SRM-212 and SRM-252?
 
Also, are there any schematics for good 12V linear power supplies you would recommend using with the 212/252?
 
Which capacitors would you recommend replacing and where are they on the PCB?

 

[b0bb]

  Wow, thanks for providing so much useful information about STAX amplifiers! I am curious though, are there any major internal differences between the SRM-212 and SRM-252?
 
Also, are there any schematics for good 12V linear power supplies you would recommend using with the 212/252?
 
Which capacitors would you recommend replacing and where are they on the PCB?

I only have the 252, from pictures it looks like the 212 uses the Toshiba dual FET, that is obsolete now.
 
Below are the before and after pictures of the SRM252s.
 
Before picture is stock except for the fuseholder

 
After Picture

 
Notes:
1)The Nichicon FP Polymer 39uF caps are on the low voltage side.
 
The high voltage mods should be carefully considered before any attempts given the potentially lethal voltages
2)The Panasonic EE Caps are  on the High Voltage side
3)Metal tops of Panasonic caps are LIVE, do not touch when powered, a electric shock is always a risk around these.
4)The cans remain live for about a minute after power down, always check with a multimeter before touching the cap with hands or the soldering iron.
 
Power supply is a China Made Ebay Cheapie.
This is the Linear Technology LT1084 adjustable regulator, schematic can be found in the appnotes and datasheet from Linear Technology.
I am not sure if I would recommend it, the thing looks nice and some what well built but there is a bit of work to bring it up to scratch.
 
Specific fixes
1)Ground wire to chassis, visible in the picture below
2)Reverse the connection polarity for the STAX
3)Add load discharge protection diode, this is a normally reverse biased diode connected between the output and input terminals.
This prevents the regulator from blowing up when the load tries to discharge current back to it, if the regulator dies the voltage to the STAX amp will rise, if it is more then 17-18V it can blow up the amp.

 
Another view

 
Protection diode.

 

[Evshrug]

Finally! Found a convenient setup that powers my SR-X within the limited space on my desk, while connecting to all my sources:


Using the Stax again for the first time since getting the HD700, WOAH the Stax is on another level of sound quality, clearer and overall brighter than the Sennheiser. Now, something must be done for these on-ear headphones and their cloth-on-metal ear"pads." Any suggestions?

 

[cucera]

Just buy new pads from Stax US they enhance the bass which is their weak point.

 

[Evshrug]

Does Stax still sell SR-X pads, for a 40 year old model? The pads look clean with minimal wear, they're just literally like cloth on top of the headphone enclosure.

 

[Ali-Pacha]

Yes, they do : 
http://www.audiocubes2.com/product_info.php/manufacturers_id/18/products_id/142
https://www.staxusa.com/parts/ear-pads/stax-sr-x-earpad.html
 
You can google translate this to have the full scope and ask you official dealer : http://www.stax.co.jp/information/Service-J_2014-08-20.pdf
 
Ali

 

[Evshrug]

Thanks a ton!

 

[electrostatics]

I often see the old SR-303 show up for cheap (looks like a good entry can). Is there a huge sonic difference to the newer SR-307 or 407? Or just a small refinement?

 

[vansaint]

Hi all,
 
I just Purchased my first Stax consisting of a SRM-T1S and an SR Lambda Signature from Buyee.jp.
 
Or i hope i did.
 
I did not know what type the headphone was as the listing said it was an SR-407, but even with my minimal knowledge i could tell it wasn't and looking at the few pictures listed on Buyee it looked like a lambda pro.
 
I bought it anyway as it was a really good deal, used (category C) but working for 52800 yen which is approx 440 US.
 
Even then i was slightly skeptical.
 
It wasn't until i looked at the actual listing on Yahoo auction Japan that i saw a larger set of pictures and saw the start of a S and an I on the shoulder that i knew it was a Signature
 
Now i feel a bit more skeptical about this. 
 
Is it the real deal, did i get lucky?, did the seller really think it was a 407 as they had no idea or have i been set up?
 
Only time will tell i guess.
 
Has anyone had a lot of experience with the Japanese sites and can give me any feedback?
 
This was my first purchase using this route.
 
I also found the same item on rakuten with the full set of pictures.
 
It's listed as sold which is good, but i am wondering why the price was a lot higher.
 
 
http://item.rakuten.co.jp/yasukukaeru/o1145063/

 

[gefski]

Hi all,

I just Purchased my first Stax consisting of a SRM-T1S and an SR Lambda Signature from Buyee.jp.

Since the big "wallet bite" to get into Stax is the amplifier, my opinion is that this amp (if problem-free) by itself is worth $440 U.S. Therefore, the cans are free and may be just fine, and the door is open for you to get any Stax cans you want later.

I'm no expert but I'm surprised I don't see a voltage selector on the back though. Maybe someone that knows can weigh in.

 

[vansaint]

I've read that for this amp you can change the voltage but you have to do it internally.

 

[n3rdling]

Usually underneath.

 

[vansaint]

Thanks for that

 

[miceblue]

Steve Guttenberg at CNET published a review for the SRS-2170 last month. My sonic impressions pretty much mimic his:
http://www.cnet.com/news/new-kings-of-clarity-stax-sr-207-headphones/

The thing you have to understand about transparency, or clarity, is that it's all relative. That is, you might think your headphones are perfectly clear and clean, until you hear a pair that's way ahead of what you have. That will surely happen when you don a set of SR-207s; the clarity gains won't be subtle. There's so much more detail, but I wouldn't characterize the sound as bright.

So the SR-207 model is perfect? No, play the Black Keys' raunchy blues rock at maximum volume and the tables turn: the SR-207s' bass oomph comes up short, and dynamics lack the kind of impact you get from an Oppo PM-1 or Grado RS-1e. Again, those two models can't touch this one for clarity. I'm not saying the SR-207s can't rock out or make bass, they absolutely can, but they're not for headbangers.

I can't really say much about the higher volume thing, but my guess is that the amplifier might be a choking point for the SR-207. The measurements of the SR-207 look quite good on Innerfidelity, except for the roll-off at 30 Hz.
http://www.innerfidelity.com/images/StaxSR207SB2217.pdf

 

[020Assassin]

I have a Grado SR325iS as my primary headphone (and I built a ZennJazzGrado wooden headphone with Sennheiser PX 100 II drivers), but when I had a chance to buy these for 325€ shipped (about 15€ shipping), I couldn't resist:
 
Unused Stax Lambda Nova Basic set in original packaging:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 
 

 
I've given the Stax its own dedicated Tivoli CD player.
 
Pros: Amazing sound, easily the most detailed headphones I've ever heard, making me discover my music all over again. Comfortable fit and solid but not too heavy weight.
 
Cons: Fragile built, lack of portability, slightly warm and sweaty when wearing for hours on end. Also, when you take them off you need to hang them on a stand, because hanging them around your neck is not an option...
 
I'm very happy!