Stax SR-009 Channel Imbalance Trouble / Driver Problem?

Jun 2, 2011 at 8:03 AM Post #47 of 933
This is a bit of a worry, as I only just received mine and I was #5 on PJ's list. However, they are far from the first headphone manufacturer to have issues with a new model.
 
Jun 2, 2011 at 2:39 PM Post #48 of 933


Quote:
I have an SR-009 on order through Woo Audio in New York and received the following e-mail from Jack earlier today:

"We received a news from STAX. About 12% of SR-009 developed noises due to microscopic dust between the stator and the film. A decision made by June 27th that all shipments are stopped. STAX is currently revising the design and solving the problem. Shipment will resume within 60 days.
 
I am sorry for the bad news. I will keep you updated.
 
Sincerely,
Jack"

I don't understand the date reference but the rest is crystal clear.
 



Or, in other words, back to the drawing board.
 
"noises due to microscopic dust!" Really? Just words to make the problem seem small.   The problem(s)  is more than just noise, some owners are complaining of a loss of signal.  That's not a dust issue.
 
I assume we will find out some day what the real problem is and it will be interesting to compare that knowledge with this release.
 
 
 
 
Jun 2, 2011 at 4:08 PM Post #49 of 933
 
Quote:
Or, in other words, back to the drawing board.
 
"noises due to microscopic dust!" Really? Just words to make the problem seem small.   The problem(s)  is more than just noise, some owners are complaining of a loss of signal.  That's not a dust issue.
 
I assume we will find out some day what the real problem is and it will be interesting to compare that knowledge with this release.
 
 


Well, there may be two different problems - the dust contamination problem and whatever it is that's causing the loss of signal.
 
 
Jun 2, 2011 at 5:25 PM Post #51 of 933
Why do people always assume the manufacturer is lying?

Going by Gu Sensei's description of the issue with his pair, it seems they still can't make the cable and wiring properly.
 
Jun 2, 2011 at 11:57 PM Post #52 of 933


Quote:
Why do people always assume the manufacturer is lying?

Going by Gu Sensei's description of the issue with his pair, it seems they still can't make the cable and wiring properly.



The 007a has no problems so far but when it comes to SR009 , such problems crop up.
 
 
Jun 3, 2011 at 1:33 PM Post #54 of 933
I don't believe Stax to be dishonest about this but the distributors certainly have been in the past.  Let's all remember that this is the third new model release in the last 10 years that doesn't go too well.  The 4070 chassis wasn't quite well thought out (as in it restricted the swivel action of the cups so fit was an issue for many people) which is why it was quietly replaced in 2002 with a new model which fit everybody.  Fast forward to 2007 and most of the first SR-007Mk2 units were defective and returned for replacement.  That wasn't the end of the matter though as a new revision quietly surfaced which is supposed to have fixed a lot of the Mk2's issues. 
 
As for the issue at hand here, I'm just not buying "micro-dust" at all.  If the dust is so small that it got past the Stax QC (these drivers are assembled in a clean room) then they must be very small indeed.  The D/S gap on all Stax Pro bias units is 500 micron so the dust must be a good percentage of that to cause any issues.  Then we have how dust issues in a driver present it self, lots of odd noises are given and even wild oscillation but never lost signal. 
 
Jun 3, 2011 at 3:45 PM Post #55 of 933
 
The only information that's worth considering is information coming directly from Stax or from customers who actually tried the product. Stories coming from US distributors trying to explain why they can't ship product should be taken with a grain of salt (or dust
wink_face.gif
) in my view.
 
 
Jun 3, 2011 at 10:04 PM Post #57 of 933

 
Quote:
maybe the disphragm is collapsing and sticking to the stator? That can explain why pushing the cup will make the sound normal again (air pressure pushing the diaphragm off the stator).
 
 



I have made many ES headphones, and I think that Stax is pushing its headphones a bit too hard.  From what I have heard, the SR009 is more efficient than SR007.   They must have made the D/S gap smaller than SR007 - yet keeping the bias voltage the same.  There is a big possibility that the diaphragm might randomly collapses to one side of the stators.
 
Jun 3, 2011 at 10:13 PM Post #58 of 933
 
Quote:
I have made many ES headphones, and I think that Stax is pushing its headphones a bit too hard.  From what I have heard, the SR009 is more efficient than SR007.   They must have made the D/S gap smaller than SR007 - yet keeping the bias voltage the same.  There is a big possibility that the diaphragm might randomly collapses to one side of the stators.

 
That was my thought too (effect of small spacer and / or larger diaphragm), but Birgir says the diaphragm is nowhere near that flexible.
 
It's very intuitive but I thought it all made sense when put together:
 
1. Sensitivity has increased so indeed spacer might have been reduced.
 
2. I believe one of the specs is max SPL in the 120dB range or so (need to look this up but if I remember, Edstrelow mentionned this in one of the threads). Which I interpreted as some limitation to membrane displacement until arcing and what not occurs.
 
3. The hole at the center of the stator. Again, maybe very stupid idea but this gives you additional clearance (max membrane displacement is at the center) and maybe have been implemented to increase dynamic headroom.
 
 
 
 
Jun 3, 2011 at 10:19 PM Post #59 of 933
Also, if it was an issue with membrane getting stuck to a stator when there's too much (de-)pressurization during the fitting on one's head, I hope the solution won't be adding a vent like o2mkII to the detriment of SQ...
 
 

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