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

[spritzer]

You really need to make it to Mafia sanctioned meet.

[jgazal]

Suppose I have four parameters:

1) The lowest frequency the transducer is able to reproduce:

SR-007 = 6 Hz and SR-003 = 20 Hz

2) Mylar diaphragm area (estimative)

SR-007 ~= 78,95cm2 (8cm*pi^2) and SR-003 ~= 19,73cm2 (2cm*pi^2)

3) Air volume inside the chamber former by Mylar and your head (variable - estimative on average human being):

SR-007 ~= 150cm3 and SR-003 ~= 30cm3.

4) Maximum gap between stators (reference is 0mm at rest position - estimative)

SR-007 = +/- 0,5mm and SR-003 ~= +/- 0,2mm

5) Bias voltage - 580V

6) Power - 100V rms

Are we able to calculate the Mylar diaphragm maximum excursion when reproducing the lowest frequency? How much variation (in %) SR-007 and SR-003 offer? Are them equal (SR-007, more air driven, but larger diaphragm area and higher excursion; SR-003, smaller diaphragm area and less excursion, but less air driven)?

I am starting to understand why Stax prefers sealed dipoles instead of open baffle.

+ Mylar diaphragm area and - air volume driven = lower frequencies and less excursion.

Less excursion = less inter modulation distortion (IMD).

Less excursion = smaller holes = lower reflections (still trying to understand which frequency range has the worst reflections; mid-range or high-frequency; guess mid-range).

If the ratio between air driven, diaphragm area and excursion is similar, then both would have similar IMD (let's say between 20 Hz and 1khz tone we would have less harmonics or equal number of harmonics with lower volume).

Things I do not understand:

a) Why one would like to increase peak to peak voltage or bias voltage to insane levels if such parameter might increase inter modulation distortion? It seems to me that a different transducer with a larger area is more effective (more bass and less excursion). Okay, I see that more power has beneficial side effects, but might not be used just to increase frequency response at cost of IMD.

Why Stax Sigma, which had the highest volume driven, had the lowest bias (230V) and the lowest gap? Is not that bad for low frequencies? How much excursion one would need to reproduce 30 Hz if the volume of air driven inside the chamber were 400cm3? Such excursion would increase IMD too much?

c) Why it is said that the electrostatic diaphragms are the lightest thin on earth so it would increase fidelity? I do understand that such Mylar diaphragm does not have any inertia and avoid hysteresis, because there is no voice coil and magnet with a heavy paper cone. But as I see, when bias voltage is applied to the Mylar diaphragm, it should behave like a stiff material. Why there is any difference between diaphragm thickness if such environment (high voltage) make them act as an stiff material (just imagine touching the diaphragm when a 6 Hz tone is being reproduced; my guess is that you won't be able to press the diaphragm as it will push your finger off). So my guess is that it does not matter the weight of the diaphragm, but its BENDABILITY/PLIABILITY, thus the higher slew rates needed to reproduce high frequencies (20Khz) are readily molding the thinner diaphragm (i.e. 1.35 micron). With thick diaphragm there is less bendability/pliability. Can someone explain why weight is so important instead of bendability/pliability?

Best regards,

Jose Luis

p.s.: Sorry about my long post and obscure reasoning. I try to be clear, but usually I get lost...

[John Buchanan]

Force = mass x acceleration. For the same force applied (same bias), if the mass increases (thicker diaphragm) the acceleration decreases (slower response)

[mypasswordis]

And hysteresis increases with increase in mass as well. You don't want a flexible wobbly diaphragm, a stiff one is much better at reproducing the signal without introducing distortion. Both lowering mass and having stiff material raises the resonant frequency of the system.

[jgazal]

2) Mylar diaphragm area (estimative)

SR-007 ~= 78,95cm2 (8cm*pi^2) and SR-003 ~= 19,73cm2 (2cm*pi^2)

This is wrong.

SR-007 ~= 50,26cm2 (pi*4cm^2) and SR-003 ~= 3,14cm2 (pi*1cm^2)

Just trying to check if you are following the calculation.

Force = mass x acceleration. For the same force applied (same bias), if the mass increases (thicker diaphragm) the acceleration decreases (slower response)

Thanks for the input. You shall be right. I would like to see dimensional analysis. The difference in mass (1,35 micron to 2 micron) does really change acceleration? I think the pressure inside the chamber (air driven by the diaphragm) has a stronger influence. Just my guess...

[jgazal]

And hysteresis increases with increase in mass as well. You don't want a flexible wobbly diaphragm, a stiff one is much better at reproducing the signal without introducing distortion. Both lowering mass and having stiff material raises the resonant frequency of the system.

I see your point and I think it makes perfect sense for dynamic transducers.

But does that apply to electrostatic transducers with a polarized diaphragm?

I am not saying we should change Mylar for stiffer materials. I just think the mass difference between 1,35 and 2 micron does not matter. Its bendability/pliability seems to make a difference.

[mypasswordis]

I see your point and I think it makes perfect sense for dynamic transducers.

But does that apply to electrostatic transducers with a polarized diaphragm?

Yes?

1.35 to 2 micron is approximately 50% increase in thickness. Then multiply that by the area and density.

Just ask yourself, why would Stax start off with a diaphragm that was maybe 5 microns thick in the 60s and 70s and then evolve to its current 1.35 micron thickness today with better manufacturing techniques? To make their headphones sound worse?

[spritzer]

Well first off, the reason we have sealed baffles is because if they leak you have waves colliding and you loose information. With dipole speakers they try to extend the baffle as much as is possible and place them so that no direct reflections occur but the figure 8 dispersion and beaming help a lot here. With headphones we have the option to completely seal the front and back.

Thinner diaphragm=less mass. Less mass=less force needed to make said mass vibrate. The mylar is tight as a drum so the weak electrostatic forces don't have a hope in hell of moving it beyond slight vibrations. Now with less mass you also have other issues such as the inherent frequency of the system and diaphragm stability.

As for the issue of ever more powerful amps, it's not really the voltage swing we are aiming for, that just comes as a bonus with ever higher rail voltages which we need for higher slew rates. We never use most of this voltage which is the same that can be said about a B22 driving a HD800. More power than you'd ever need. First off one must remember how an electrostatic transducer behaves at said 100V and how current comes into play here. The sole purpose of designs like the T2 and BH is to give you 100V regardless of frequency and the load presented by the drivers.

[jgazal]

Yes?

1.35 to 2 micron is approximately 50% increase in thickness. Then multiply that by the area and density.

Just ask yourself, why would Stax start off with a diaphragm that was maybe 5 microns thick in the 60s and 70s and then evolve to its current 1.35 micron thickness today with better manufacturing techniques? To make their headphones sound worse?

It is true; there is a relevant increase in mass. I truly believe that 1.35 micron is better!

What I am trying to understand is how the membrane vibrates. A dynamic transducer has a pre-molded polymer and no matter the current applied it will sustain that form.

What I find interesting in electrostatic transducers is that the membrane is actually changing its form according to the voltage/current applied.

That's why I think bendability/pliability plays a more important role than mass.

In the end, we might be saying the same things. At lower frequencies, with higher excursions, bendability/pliability contributes more to the equation. At higher frequencies, with lower excursions, but really fast movements, mass makes more difference.

Well first off, the reason we have sealed baffles is because if they leak you have waves colliding and you loose information. With dipole speakers they try to extend the baffle as much as is possible and place them so that no direct reflections occur but the figure 8 dispersion and beaming help a lot here. With headphones we have the option to completely seal the front and back.

(...)

I am aware of waves with opposite phase cancelling each other, mainly at lower frequencies. I was thinking a baffle extension like the "acoustic bass lens" of Sony MDR-F1:

(...)

The sole purpose of designs like the T2 and BH is to give you 100V regardless of frequency and the load presented by the drivers.

Those are truly marvelous designs. I see why everybody likes them.

I am not going to keep up with my stubbornness. If everybody says mass is the relevant parameter, I will cope with that. Just starting in this world of electrostatics so I shall remain quiet...

[Wmcmanus]

Things I do not understand:

Everything in your post and those that followed it.

But that's Ok. I'll be interested in giving them a listen.

[jgazal]

Every time I re-read Notes on DIY Electrostatic Headphones by Chu Moy on Headwize I realize the vast majority of my doubts are already answered there. It is just me (who cannot capture all the subtleties).

[Craig Sawyers]

I does not seem a new Omega to me. This thing is a whole new better model. I think they are not going to discontinue the O2. This thing is a new flagship. Omega name was a reference to the circular stator, right? C32 (apparently the prototype code) might receive a totally new name.

I'm just catching up with the new and shiney thread - but I thought Omega was used for the last letter in the Greek alphabet - in other words the last word in headphones. Until the C32....

[luvdunhill]

Perhaps they'll use the "lost" letter instead, the digamma! (classics major geek FTW!)

[arnaud]

This site is such a mine of information, I should have read here before posting on head-fi! The information below is thus mostly old news for you guys, but I thought some listening impressions , however brief it was though, might still be welcome:

I went today to the fall headphone festival organized by Fujiya Avic in Tokyo. I only wanted to check out Stax's new prototype and Ultrasone's Edition 10.

Note that I don't have much listening impressions because one literally only has seconds to sample the gear until the seat must be vacated for somebody else… Yet, one can at least get a very rough idea of the tonality of a headphone, probably not much more so notes below are only worth so much, you are warned …

...

Before listening to the new prototype, I had a brief chat with the Stax representative. Unfortunately I do not know who he is, but a very nice senior person. I speak a little Japanese but frankly not well. So please forgive if some of the following is inaccurate due to some loss in translation / foolish interpretation .

First, I asked when it was going to be out: first half of 2011 is the plan. Next, the price: 300k to 500kJPY. Third, a matching amplifier: yes likely, but not in the immediate future. So probably we can't expect an amp to be released at the same time as the new headphone. He did mention though that the current top of the line amplifiers from Stax can "drive this headphone without any trouble".

Next, I asked about the diaphragm: it is a new design. Something about a complicated manufacturing process because their are three layers assembled together by heating process. The thickness is higher than Omega 2 because while a light / thin diaphragm is good for transients, it is affected by "low" frequency resonances. This time around, it would appear that Stax has tried to achieve maximum stiffness (and damping, hence the multiple layers?) with the new diaphragm. Anyhow, it is a complex manufacturing process which I guess is driving the cost up.

Next, the frame: aluminum, much stiffer than Omega 2 frame. The weight is a bit affected but I did not feel the headphone was heavy at all. The frame thickness may change slightly in the final version but looks like the looks is pretty much set (I find it really beautiful, the Omega2 looks cheap in comparison, and well, it will be ).

Last: the name … Of course he did not say but this is a new series, beyond the Omega. The Omega 2 will remain on sale. When I asked about anniversary, he said that this is indeed a point as Stax is reaching 50 years in existence…

Now to the listening. Again, it was too brief but I could go for two rounds fortunately. I listened on the 727A, which is nice because it's also my own amp. The source was a Marantz SA-15 or something like that, not very high end.

Well, what jumped at me is that the tonal balance is quite different from the Omega 2, it seems definitely more tonally neutral while the Omega 2 has a warmer tonality on this amp.

The highs of the prototype are very present but absolutely not shrill or detached from the rest. Next, the bass is absolutely there but tight. In comparison the Omega 2 does feel like the bass could be firmer / more controlled (again on the 727A).

It does seem like the headphones are quicker sounding than the Omega 2, and dynamics are improved. Too short listening to say for sure though, some of this might have to do with the more neutral tonal balance.

Finally, the ease of drive: while I listen to the Omega 2 at 9-10AM at home, I was at 12-2PM with the new prototype. Mind you, the source might have an impact on this. My yamamoto D/A is a rather hot source.

Overall, I have to say I was very impressed. It feels very much like a step in the right direction based on this short listening experience. The price is going to be steep, but it appears Stax is trying to get the top seat for best sounding headphone in production!

[Beefy]

Nice first post!

How were the Edition 10's?

[mypasswordis]

Well, what jumped at me is that the tonal balance is quite different from the Omega 2, it seems definitely more tonally neutral while the Omega 2 has a warmer tonality on this amp.

But don't have $5k to spare. Thanks for the impressions, I'll definitely want to try it out at some point.

[The Monkey]

Welcome to the forum arnaud. Thanks for that information.

Now we just need the yen to collapse against the dollar.

[manaox2]

arnaud, could you perhaps steal a crate of these?

[Craig Sawyers]

Now we just need the yen to collapse against the dollar.

Well having just sprung for the 007 Omega2, and had all the softening up necessary domestically for a pair of headphones that are more expensive than any loudspeaker I've bought, I need to play the long game for the next 6 months or so to get an even more outrageous pair - I reckon a full thousand UK pounds on top of the 007 price. Or maybe I need to make a trip to Japan for some business excuse, and sneak them back in through customs.....shhhh.

Mind you the 007's sound glorious driven by a Blue Hawaii. I can hardly wait....

[cetoole]

Welcome to the forum arnaud. Thanks for that information.

Now we just need the yen to collapse against the dollar.

This sounds like a job for a joint venture of the east, west, and southern legal teams.

[The Monkey]

arnaud, could you perhaps steal a crate of these?

Yes, please. Just route them through Logan.

[n3rdling]

Thanks for the info arnaud

[morphsci]

That should be stickied as an example of a great first post.

[HeadphoneAddict]

Thanks for the nice post. I sure hope Stax didn't voice it for just the SRM-727, where it might sound "off" on the good amps.

[luvdunhill]

I'm pretty sure Stax doesn't "voice" things. Unless by voice you mean makes things that sound fucking awesome.