Stax SR-009S Electrostatic Headphone Review

[gnarly]

The problem with the old Lambda's is that they have a nasty bite somewhere in the midrange/HF range, it's difficult to describe but if you listen to, let's say high end AKG's or Sennheisers and then put the Lambda's back on, you will notice the high frequency sounds a bit 'etched'.
Still, I heard the Lambda Pro's on an SRM-1/MK2 Professional and it's shockingly good when you consider the year it was released.

Yeah, i think i might have the same impression of the Lambda's, as I've ended up using them with a default bell cut at 2200Hz, maybe -4dB, moderate bandwidth.
Kills a bit of an unnatural bright edge i think....

 

[BALKAN_RAKIA]

This is not a headphone you take to hip hop party but for a more refined level of music listening.

Stax turn hip hop into this -

 

[pablolie]

I should note that this headphones back radiation into the room was the loudest I have heard. So @solderdude may be right that some room interference may be in play here.

Is that a "feature" or another weakness in the un-EQd "design"? I know and accept there is a bit of a cult around Stax, but a spade is a spade and the uncorrected measurements are a mess. And now there is room correction needed on top?

 

[pablolie]

Stax turn hip hop into this -

Is this website being renamed after the obvious discrepancy between measurements and subjective perception? Now classical music sounds better with distortion that only gets better at an unhearable and ear-damaging 104dB? Stax doesn't turn hiphop into classical. Classical is a genre that mandates accuracy and stage like no other. Preferably at sound levels that don't damage ears.

 

[amirm]

Is this website being renamed after the obvious discrepancy between measurements and subjective perception?

There is no discrepancy. With speakers, we measure both on and off axis and attempt to characterize what a speaker might sound like in a room. With headphones, we don't do that. As a result in frequencies where wavelengths get small enough relative to cup size, we don't take into account those reflections and their sonic effect. I have always said that speaker measurements are 70 to 80% predictive of listening results and headphones are 60 to 70%. Here, measurements were super powerful in getting the tonality right with EQ. They were just insufficient to characterize some elegance in the soundfield perception.

 

[pablolie]

There is no discrepancy.

Very respectfully I beg to disagree. I think you'd have put the panther piggy in there if it was another brand. The uncorrected measurements are simply horrible and there is no way around it.

 

[Soria Moria]

All the talk about ‘driver farts’, having to avoid humid environments, avoiding dust, limited driver excursion and needing a specific type of amplifier makes me never want to get an electrostatic headphone unless this estat ‘magic’ is proven real somehow.

 

[amirm]

Very respectfully I beg to disagree.

Disagree with what? Measurements showed response errors which were directly used to develop EQ. Once EQ was in place, then the headphone sounded great. What is the discrepancy in that?

 

[SDC]

Had 009 and 007ta. I'll personally rate it poor.
Limit of maxSPL and being bass shy.
Danger of high voltage damaging the diaphragm.
To me does were not acceptable at such price...

And the biggest problem, AS of STAX is horrible.

DCA makes great headphones with good bass and perfect after service. They can't be in the same 'golf' category...

 

[pablolie]

Disagree with what? Measurements showed response errors which were directly used to develop EQ. Once EQ was in place, then the headphone sounded great. What is the discrepancy in that?

If a $5k product *begs* for *major* EQ, in my opinion it is a flawed design. This frequency response out of the box in a $5K product is a joke, and I doubt there has been much worse on this website:

You *did* mention in your conclusions you wished they'd done a better job for "out of the box" sound. To me - I think that is a mandatory requirement to command the price tag. I did mention I was sorely disappointed when I got my Stax stuff back in the day. And I wonder how many people that use the headphones go and EQ them for accuracy.

Again, my point is made respectfully. I know there is a a Stax cult out there, and all my posts on this website show I completely approve of personal choices.

 

[Maiky76]

While technically, to get Harman type bass, your proposed EQ in the bass seems logical I would not recommend it.
The Stax headphone will not sound quite good with this kind of EQ in the bass.
Amir's EQ is about the max. it should be given.
This EQ will eat up 9dB of headroom giving about 100dB SPL peaks for bass notes. In such case you could only use it at moderate volumes.
Electrostat's Achilles heel is large excursions in the bass due to the high mechanical tension of the membrane to prevent 'sticking'.

Well, if one spends that much on a type of devices with widely known limitations (not to say these are bad nor that they have no place on the market),
one should not be surprised to hit these limitations.

As @Ken Tajalli highlighted here, I try to warn the users...

Here is a different EQ that does not boost the LF beyond the boost needed to EQ the HF which does not seem to raise objections.
This results in a ~3dB improvement in the loss of dynamic range.

And one EQ religiously sticking to the amount of boost used by @amirm that yields another ~1.5dB in dynamic range compared the previous one.

 

[F1308]

Long life RED and BLUE.
Voted POOR.

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[soundwave76]

I have been waiting for this review, or just Stax in general. There really is something unique and special in the Stax sound in my experience. I had the L300 Limited and loved them.

 

[solderdude]

As with every product in life all of them have some strong and less strong properties.
With Stax the less strong things are:

• price (the biggest complaint)
• build quality (flimsy feeling and/or actual quality)
• comfort (some models are really not very comfy)
• certain aspects in the sound (without EQ)
• adjustability
• longevity

The positives are:

• you have something really different
• certain aspects of the sound which are really excellent
• conversation piece
• pride of ownership

What owners and non owners value above all other things actually determines what one thinks (or only suspects) about the actual headphones or the measurements.
For sure... price and build quality are the biggest downsides. For some certain sound quality aspects they have might be worth that though. Most can not look past this elephant.
Those that can easily afford these headphones without even making the smallest dent in their wallets might appreciate the differences in sound quality with some other higher end headphones. These same people generally are not interested in $ 50 IEM's that also can sound great.

Choose your poison.

 

[Vict0r]

Add a subwoofer!

 

[solderdude]

Add a subwoofer!

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SUBPAC lets you feel the bass by immersing the body in low-frequency, high-fidelity physical sound, silent on the outside. Ideal for music, gaming, & VR.

subpac.com

 

[Rja4000]

This is a unique headphone in that it goes from no distortion to severe distortion just a hair higher in volume. It doesn't gradually, or even non-linearly increase distortion. It just falls apart at a precise point.

Is there possibly an effect of the amp ?
I always wonder: those specialised amps use transformers, don't they, to reach the high voltage the membrane requires ?

So how much of the distortion is due to the transducers and how much is due to the transformers, especially at low frequencies ?

Just wondering...

Here 2 measurements of the Topping EHA5, from Topping Web page.
(But at what level is that measured ?)

 

[solderdude]

Is there possibly an effect of the amp ?
I always wonder: those specialised amps use transformers, don't they, to reach the high voltage the membrane requires ?

So how much of the distortion is due to the transducers and how much is due to the transformers, especially at low frequencies ?

Just wondering...

It IS the energizer that is the culprit here.
Until double the bias voltage is reached distortion will be low but increase a bit at larger excursions and at resonance frequencies as well.
With 580V bias voltage this is around 400Vrms (112dB)
The max voltage swing is reached at 118dB which is about 2kVpp (1kV positive, 1kV peak negative)
Higher voltages will add distortion and may lead to sticking or sparking and making holes in the membrane (depends on isolation and humidity).
Seeing that the EHA5 is limited by the amps which drive transformers and specs stating 2kVpp = 750Vrms it can reach the 118dB border.

 

[Ambient384]

Thanks!, but that would not be shown in the lower frequencies doing the THD test?

The bass at 20 ~ 50Hz is 91db. Adding 10db 100Hz low shelf or music that already reaches that naturally would bump up the bass to 100db.

 

[Veri]

Nice review and it confirms what I already experienced with Stax headphones many times before, that they are very responsive to EQ, astonishingly clean and distortionless. Actually the #1 best over ear headphone expirience for me was the original SR-Ω from 1993 equalised to Harman AE/OE 2013, the close second is the same but on the new omega (SR-X9000), simply uncanny level of clean and imaging, SR-Ω also has the most powerfull bass of all electrostats essentially negating the only historical weak point.

Can you still get a SR-Ω in good condition you reckon?