Holy Crap! The New Stax Omega Looks fierce! (Stax SR-009)

[arnaud]

Amen to that, Andy. Who wants the hassle of returning $5K cans, let alone sending them to Japan!

You've found a good reason to sit patiently for another couple of months, that's good for your sanity . In the eventuality there was a problem when you receive yours though, it's not like shipping back a 70+ lbs amplifier. Would cost at most 100USD to ship it back insured and take no more than 3 days... In regards to 5kUSD you'll have spent on it, it's peanuts... Turnaround would also probably faster than going through a dealer and notoriously proactive distributor ...

Just saying, it's not like you got a choice anyhow...

arnaud

Edited June 3, 2011 by arnaud

[Currawong]

Having run them through a 007t for a few days now, I can definitely say they'll be worth the wait. I haven't compared them directly to O2s yet, but suggesting they are the Omega I revisited is probably not far off. FR is, as others have said, more like your classic Stax rather than like the O2s. Detail and resolution are other-worldly. I don't need to turn the volume up nearly as high as with the O2s, suggesting they are more sensitive, but that is possibly as much the relative amount of treble and the mostly jazz and classical I've been listening to as anything. Their impedance is 20kOhms lower. I haven't tried music with deep bass yet or tested how much the cups resonate playing loudly. I just noticed though, checking specs, they are a bit heavier than the O2s.

[screaming oranges]

I think the delay is because they're radioactive now... which means they should be self-powered! No need for an amp!

Oh wait, still need to get music to them somehow...

[HeadphoneAddict]

I'm afraid the Japanese will have to abandon ship and shrink wrap their island in lead to protect the rest of the world.

[jgazal]

Is it necessary to apply some kind of special coating to the anodized aluminum ear-cups on the SR-009?

I was trying to understand electrostatic charges in anodized aluminum and I have found this reference:

Electrically Conductive Anodized Aluminum Surfaces

Marshall Space Flight Center, Alabama Wednesday, November 01 2006

Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephone-exchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge.

These coatings are highly adherent, transparent, and relatively inexpensive.

The electrical resistivity of a typical anodized aluminum surface layer lies between 10¹¹ and 10¹³ Ω.cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly . preferably to<=10⁹Ω.cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma.

The electrical resistivity of the nanocomposite can be tailored to a value between 10⁷ and 10¹² Ω.cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines.

At present, the electronics industry uses expensive, exotic, electrostatic-discharge-suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

This work was done by Trung Hung Nguyen of EIC Laboratories for Marshall Space Flight Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Materials category. MFS-32092-1

This Brief includes a Technical Support Package (TSP).

Electrically Conductive Anodized Aluminum Surfaces (reference MFS-32092-1) is currently available for download from the TSP library.

http://www.techbrief...nt/article/1159

Edited July 21, 2011 by jgazal

[blubliss]

Group buy: I contacted Elusive Disc today and asked them to try and get an update, will post when I hear back.

[chinsettawong]

Is it necessary to apply some kind of special coating to the anodized aluminum ear-cups on the SR-009?

I was trying to understand electrostatic charges in anodized aluminum and I have found this reference:

As far as the ear-cups, I'm sure that Stax is using anodized aluminum for making them. In this case, I do not think that they want to discharge electrostatic charge, but they want to insulate the ear-cups from any possible electrical leakage. You certainly don't want to get an electric shock when you wear them.

Wachara C.

[jgazal]

As far as the ear-cups, I'm sure that Stax is using anodized aluminum for making them. In this case, I do not think that they want to discharge electrostatic charge, but they want to insulate the ear-cups from any possible electrical leakage. You certainly don't want to get an electric shock when you wear them.

Wachara C.

Dear Wachara, thanks for your reply. Perhaps I did not understand the electrostatic charges yet. Please help me to better understand how it works.

I believe anodizing still insulate the listener body from the stator/diaphragm/amplifier circuit. I think you are also saying that.

Nevertheless, I thought electrostatic was an imbalance of positive or negative charges in the surface of materials (but with extremely high voltages and almost no current), mainly when such materials are not conductors:

(...)

"Static" electricity appears whenever two dissimilar insulating materials are placed into intimate contact and then separated again. All that's required is the touching. Chemical bonds are formed when the surfaces touch, and if the atoms in one surface tend to hold electrons more tightly, that surface will tend to steal charged particles from the other surface immediately as they touch. This causes the surfaces to become oppositely "charged"; they acquire imbalances of opposite polarity. One surface now has more electrons than protons, while the other has more protons than electrons. When the surfaces are later separated, the regions of opposite charge-imbalance also get separated.

For example, when adhesive tape is placed on an insulating surface and then peeled off, both the tape and the surface will become electrified. (...)

(...)

http://amasci.com/em...con.html#eleven

My hair is not a conductor and still will stand up with electrostatic imbalance. The Mylar does not seems to be conductive, but still becomes charged with the circuit bias, am I right?

As I understood (okay, understanding is not my strength...), such special coating does not reduce the anodizing insulation. It just avoid charge imbalances in the surface of the material. So its surface does not become electrostatically charged. Am I getting this wrong?

We want the diaphragm to become electrostatically charged, but we want the earcup to stay neutral. But with no special coating, anodized aluminum will become charged if it has "intimate contact" with other insulating materials. If such charge is enough to cause imbalance at the stators and diaphragm, I do no really know. If an engineer put a electrostatic voltimeter at that earcup and he says it has low voltage, then I will be fine.

There are two types of insulating materials. One type becomes positively charged and the other type becomes negatively charged. What type anodized aluminum is? Diaphragm is positively charged. If anodized aluminum becomes negatively charged, then an imbalance might occur when the AC signal turns the external stator positively charged, right? Is it strong enough to pull the diaphragm? I do not know. I am just trying to understand how it works. This is my not very reliable reference:

The following list shows you the triboelectric series for many materials you find around the house. Positive items in the series are at the top, and negative items are at the bottom (compilation of a few Internet sources)

Air - Very positive

Human hands (usually too moist, though) - Very positive

Leather

Rabbit Fur

Glass

Human hair

Nylon

Wool

Fur

Lead

Silk

Aluminum

Paper

Cotton Neutral

Steel Neutral

Wood

Amber

Hard rubber

Nickel, Copper

Brass, Silver

Gold, Platinum

Polyester

Styrene (Styrofoam)

Saran Wrap

Polyurethane

Polyethylene (like Scotch Tape)

Polypropylene

Vinyl (PVC)

Silicon

Teflon - Very negative

The relative position of two substances in the triboelectric series tells you how they will act when brought into contact. Glass rubbed by silk causes a charge separation because they are several positions apart in the table. The same applies for amber and wool. The farther the separation in the table, the greater the effect.

http://www.ambergoods.ie/electron.htm

There is other question I am trying to figure out. Suppose I have a plastic earcup. It is an insulating material. It might become electrostatically charged. It will be a positive charge or a negative charge? That charge is higher or lower in voltage that the electrostatic charge in the anodized aluminum earcup? If charges are similarly low, then the anodized aluminum would not need that special coating. This must be the most plausible hypothesis.

Am I saying something really wrong?

Edited July 22, 2011 by jgazal

[jgazal]

One additional thought.

Suppose you were an Stax engineer and such potential imbalance was really derived from the earcup electrostatic charge.

At first I thought a route to earth would help. But it is difficult to add a ground pin to pro connectors. And how to implement such earth connection? If you reach the inner part of the earcup, it would become a pole whenever the stator apply a magnetic force into it, would not?

So the mentioned ground should touch only the surface, so the anodized insulation keeps its integrity. But again, if such anodized coating is not a conductor, is an earth connection able to discharge its whole surface?

So I start using such earspeaker on dry weather and then the earcup surface touches other insulating materials. The earcup gets charged. Suddenly the imbalance leads the diaphragm into the stators and the diaphragm discharges. Lower volume occurs.

I thought time and humid air was enough to discharge the earcup and bring things back to normal.

So if I were an Stax engineer I would take the following procedures: 1) replicate a dry environment, with air conditioning, carpets, wool clothes (is Japan dry during winter? I bet it is not dry during Monsoon…); 2) see if such earcup becomes charged (the electrostatic voltmeter); 3) calculate if such charge is able to affect the stator/diaphragm system; 4) if yes, apply anti-static coating to the aluminum anodized coat (more cost).

Chances are there is no problem using aluminum anodized earcups without such anti-static coat.

I am just thinking about that possibility.

There is still the micro dust hypothesis. I do not have any idea how to prove this alternative hyphothesis...

Sorry for the long post.

p.s.: These subject reminds me Hindenburg (hydrogen). Winds blows and the airship is charged (charge is static). It was connected to the post of the ground winch with wet mooring lines. Then possibly "static" electricity/current (controversial).

[chinsettawong]

Hi Jgazal,

First of all, I'm not an EE. All I can tell you is from my experience making my own electrostatic headphones.

You might have been confused about the earphone's drivers and the cup. The purpose of the earcup is simply to hold the driver in its proper place. Since you are dealing with high voltage, you want to make sure that the high voltage will not be able to do any harm to the person who wears the headphones. If you look inside Stax headphones, you would see a plastic enclosure holding the driver rigidly and tightly together. This is also made of plastic which is a good insulator.

I can't speak for Stax, but my guess is that Stax has changed the earcup from plastic to aluminum because it simply looks and feels much better. I don't think it has anything to do with electrostatic discharge.

Wachara C.

[spritzer]

Aluminum has much better resonance properties compared to any plastic so that's why it is used. The SR-Omega uses a resistor based CT to ground the metal frame but the later models do not.

[arnaud]

Aluminum has much better resonance properties compared to any plastic so that's why it is used. The SR-Omega uses a resistor based CT to ground the metal frame but the later models do not.

I believe the main driver for using aluminum is the looks of the finished product (fine machining) more than anything else.

In particular, although it's true that an aluminum part has much more rigidity than most plastics of same shape, hence resonances pushed higher up, they're also much less damped than those of any plastic, which makes aluminum potentially less desirable...

In the current application however, I fail to imagine how the little inertial forces of the moving diaphragm can noticably excite mechanical resonances in the earcups.

In comparison to the motion and radiation of the driver itself, it's likely negligeable.

[spritzer]

Well first and foremost is the price of aluminum. It is dirt cheap and easy to machine. I also know Stax considered something else for the SR-009 but dropped it due to cost.

Edited July 23, 2011 by spritzer

[arnaud]

Well first and foremost is the price of aluminum. It is dirt cheap and easy to machine. I also know Stax considered something else for the SR-009 but dropped it due to cost.

What is this something else if not inappropriate to ask? Magnesium, carbon fibers?

[jgazal]

I feel better now someone replied. I thought I had written something so stupid that you were closing your eyes to my post… It happens to me all the time...

@Wachara: I am not an EE also and I admire your skills.

I am not saying aluminum is worst than plastic or vice-versa to the purpose you mentioned (hold the driver in its proper place). They might have their acoustical pros and cons.

But is it possible the ear cup surface (that is out of the circuit) to become naturally charged? Does that charge affect the circuit?

For instance, we would have both stators at peak (outer -450V and inner +450V), the diaphragm at +580V and the earcup with some charge (I do not know, let's say -300V).

The earcup charges could build up from touching other insulators (our hands, our clothes, the sofa, the firm molded foam at the wooden box etc.) and not from the circuitry. Well, is that possible? Or the earcup surface stays always neutral?

(...) The SR-Omega uses a resistor based CT to ground the metal frame but the later models do not.

@Spritzer: you are a living Stax encyclopedia (okay, Stax mafia member...).

Why they abandoned such metal frame ground? Does that ground keep the ear cup surface always neutral? Are there pictures available?

Edited July 23, 2011 by jgazal

[HeadphoneAddict]

They say, "there is no Stax Mafia", but if there was then The Stig would be sleeping with the fishes...

[spritzer]

What is this something else if not inappropriate to ask? Magnesium, carbon fibers?

It's not something I can discuss but there may be an SR-011 later on which may use it. Here's hoping...

@Spritzer: you are a living Stax encyclopedia (okay, Stax mafia member...).

Why they abandoned such metal frame ground? Does that ground keep the ear cup surface always neutral? Are there pictures available?

They were just worried about the aluminum being a conductor if something went horribly wrong. The SR-007 is a much better mechanical design so this can't happen any more.

[jgazal]

They were just worried about the aluminum being a conductor if something went horribly wrong. The SR-007 is a much better mechanical design so this can't happen any more.

Well, then my "static charge on the ear cup" hypothesis is useless. I better shut up my mouth and stop writting things I do not understand...

[TMoney]

Group buy: I contacted Elusive Disc today and asked them to try and get an update, will post when I hear back.

Did you ever hear anything back from ED? It looks like the Japanese sellers have some fresh supply (See price japan) so maybe there is some hope for the rest of us in getting our 009s soon.

[blubliss]

Nothing yet.

[arnaud]

Did you ever hear anything back from ED? It looks like the Japanese sellers have some fresh supply (See price japan) so maybe there is some hope for the rest of us in getting our 009s soon.

I confirm that there appears to be stock at the local dealers. At least, Audio Union had 2 units ready to ship as of last week end. It looks like Stax is being very very cautious with international shipments, which is understandable given the bad publicity and costs of shipping.

[purrin]

Nothing yet.

I'm sure it's not ED, but rather ED waiting on news.

I'll give it until October.

[TMoney]

ED just moved the date on their website back to 8/23. At this point October doesn't seem like such a bad guess.

[livewire]

Gonna make for some really nice "stocking stuffers".

(although I am hoping y'all get them earlier. Need some decent impressions.)

[Gu Sensei]

(I read the welcome message two years or so ago and have been lurking since. I finally joined up as I figured this would probably be the best place for information/discussion on the 009s but have held off posting until I had something substantial to contribute. I’ll briefly summarize some impressions but am guessing these frequency response measurements will be of more interest.)

As I have posted elsewhere, I have found them to be quite simply the most resolving, capable, and transparent headphones I have ever owned or tried. I have never experienced such precise imaging nor been able to so clearly observe dynamic shifts or soundstage differences in recordings. Everything sounds effortless. Probably, I am most impressed with just how voiceless these phones seem. Every other ‘neutral’ pair of headphones I have tried has had some character beyond simple frequency response variations that seems present going from track to track. I am at a loss to describe any sort of sonic voice the 009s are adding to the listening experience... except in one area; their treble response.

I do find the treble to be a bit troublesome and with their extreme resolution and clarity, issues with poor or bright recordings get exacerbated. I have been tinkering with equalization to smooth out the treble and pull it back. These graphs are very helpful to that end but I am completely new to this and hope some others will be equalizing and posting about the gear they are using with graphs of their adjustments.

Since their release, I have done the occasional google.co.jp image search for some frequency response measurements and finally found some. These were posted in this thread which is a discussion forum on Stax but I am not too clear on the methods for getting the measurements.

(not sure why but the measurements are not all being shown. clicking on them brings them up though)