Beginning Electrostatic Headphone Measurements

Big thanke to Klutz Design for the cool CanCans headphone stand on which to display great headphones.

In a rather shady headphone forum out there on the interweb (that will remain unnamed) lives a group of gentlemen who call themselves: "The Stax Mafia." In recent weeks, having become aware of my work measuring headphones, they've "requested" that I make some measurements of electrostatic headphones.

I just couldn't resist. (I don't want to wake up with a goat head on the pillow next to me.)

Beginning Electrostatic Measurement Program
These fine gentlemen (and I use the term rather loosely) have begun to ship me a rather expensive, and glorious, array of gear to measure. The first arrivals have been the stunning HeadAmp Blue Hawaii electrostatic headphone amp, Stax SR-007 headphone, and the new --- and particularly spectacular --- Stax SR-009 headphone.

Over the last few days I've set up the gear and modified the normal headphone test in order to run these cans through a series of measurements to add to InnerFidelity's collection of headphone measurements. Today, I've taken the first set of preliminary measurements, and will be communicating the results to the gentlemen in question.

Once any modifications required to the testing procedure are achieved, and approval is received, I will be moving forward with their request to measure and review some of these extraordinary headphones. (Listening tests will be done with composer's music who's last name end in "i" or contain "cc" only.)

For your viewing pleasure, here are the first two preliminary sets of measurements.

The Stax SR-009

Click on graphs image to download .pdf for closer inspection.

The Stax SR-007

Click on graphs image to download .pdf for closer inspection.

I very much look forward to further tests and completing this commission in a timely manner.

(If I don't post within the next couple of days, start looking for me ... likely in a large vat of liquid nitrogen, or in little pieces baked into a quality pumpernickle. Wish me luck.)

Stax SR-009 and SR-007 web pages.
Maker of exquisite headphone amps, HeadAmp.

inarc's picture

Interestingly, the SR-007 measures better than the SR-009.

Limp's picture

A second there I thought my eyes deceived me, but the 007 measurements really do look prettier in many areas!

RudeWolf's picture

I think we are not alone in here....

tubefan kt88's picture

these awesome headphones measure and look very very good! i wish i could have one of these, so sweet!, i hope you post the hearing impressions on these Tyll!!! Good luck

dalethorn's picture

Lots of people were saying the SR-007 was too dark and the SR-009 would be brighter. Are the graphs switched?

donunus's picture

The 009 square wave has a sharper rise time which would result in a brighter sound even though the constant sound with pink noise of the 007 seems brighter. People normally complain about brightness during the attack of instruments which is why people find the 009 to be brighter sounding IMO.

Limp's picture

It's all there in the 300Hz square wave.
The rather significant overshoot of the 009 signalizes its bright nature.

dalethorn's picture

Sounding a bit brighter but not actually being brighter? I like that idea, even though I don't exactly know why. I see below where Tyll says he agrees, but I can't tell from the context what the agreement is. That the 007 is better or worse than the 009? I was under the assumption that he wasn't going to say right away.

donunus's picture

Think of it this way... A constant shaking of a shaker for example will sound brighter on the 007 while an instant hit of some cymbals will be brighter and more shimmering with the 009. I don't know how much brighter though since the square wave and the Frequency response work alongside each other here and I would have to hear the cans myself to know for sure.

gurubhai's picture

the 009 has considerable more energy than 007. I suppose that gives it a brighter sound compared to 007.

wnmnkh's picture

Maybe Tyll made mistake and the graph got swapped, or 007 seems better on technical side.

Tyll Hertsens's picture
Nope. No swap on the data.
wnmnkh's picture

Following Ultrasone Edition 10 review, it seems you are making yet another stir at that shady forum again. :P

screaming oranges's picture

As there are different variations of the 007, I think the charts should state which variation the measurements apply to since info on the web states they are voiced differently. As to the 007 vs 009, the findings are very interesting so far... can't wait to hear about personal opinions on comparative performance on human ears.

wnmnkh's picture

Tyll's taste on sound, I think Tyll will say 007 is better (or at least better balanced sound.)

Tyll Hertsens's picture
Agreed. I thought about that, when I do the official tests I'll put the serial number and any rev evel up on the graphs.
khaos's picture

The Omega 2's FR lookas looks quite a bit like the LCD-2's FR (this one

svyr's picture

007 kinda reminds me of

hmph... muust find good close HP...

Tyll Hertsens's picture
I recently had the pleasure of visiting Smeggy and listening to his latest revs .... O.M.G! They're very good. Thunderpants have my highest recommendation.
svyr's picture

expensive and probs not light because of the wood though :( . That kept me from ordering a pair.

Tyll Hertsens's picture
They seal better and sound better than the D7000 to me. That puts them right in the mix, in my mind.
svyr's picture

I didn't like stock D5000, or mmoded D5000, or stock D7000. At all. Plus the pivot joints on those are flimsy be design (even the manual says not to handle them by the cups)

Unfortunately that's not the point.
I don't doubt T50RP smeggied sound good, and seal well (since denon just has your ears wobble in giant cups :D) ...

What I'm worried about is above. Specifically.

Aside from that I'm worried the wood is not properly dried (I've seen at least one cracked cup from presumably that.) Although smeggy said, he'd replace the cup if it happened to me.
and I'm also worried about the smeggied T50RPs being a hand-craft job. He admitted not measuring them, so YMMV...

Those + the potential weight issues and somewhat suspect comfort w the headband make me pretty UN-willing to put in $7-800 (incl stax pads)

Limp's picture

Comfort and build quality are absolute non-issues with the Thunderpants. The headband systen he uses is the best one I've ever come across, distributing the moderate weight very evenly across your scalp. Don't worry about this.
They are however rather large and cumbersome. This added to the fear of ruining the exquisite woodwork, they're far from ideal as a travel set.
(/OT endorsement)

mobbaddict's picture

My Thunderpants sounded nothing like the O2, they were much more mid-centric. They certainly didn't sound like those measured by Tyll though, no way they had so much bass (and yes they were made by Smeggy).

plin's picture

Both, but especially 009 have impressive THD measurements!

DaveBSC's picture

I knew you were getting an 009, but wasn't aware that you had an 007 sent in as well. As has already been stated, please clarify whether its a MK1 or MK2.

Looking forward to the video report on these.

julian's picture

As I said in the other forum, I think mk2's measurements are more interesting. There's a kind of extramural dispute "stax mafia vs. stax engineers" about o2mk2's superiority.

Furthermore it's the current model, mk1 is discontinued.

Tyll Hertsens's picture
It's a Mk 1 ... it was borrowed from a private individual.
Jazz Casual's picture

Tyll, is there any likelihood of you measuring the more affordable Lambda's such as the SR-507 and SR-407?

Tyll Hertsens's picture
Measured a bunch yesterday, I think a 507 is among them. But yes, I'll be doing more.
Jazz Casual's picture

You bewdy!

meng-609's picture

May I ask about how to choose 009's amp?

I want to buy DAC M1, but I don't know how to choose my amp.

I plan to buy liquid lightning and order Blue Hawaii (as you know, BHSE need take long time for waiting), but someone told me M1+LL is not fit and Kgsshv is better. However I can't find where I could try what kind music I like. 

Could you please give me some advices?