Some interesting findings about Stax electrostatic stators - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th September 2011, 06:26 AM   #11
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

its the trasducers proximity to the ear channel that boosts the bass up to sufficient levels. Measured free-air the amplitude response probably shows a falling response below ~100Hz. So even for low bass-frequencies the excursion may remain small, especially with a such a large transducer as the Stax.
The array of small dots allows for a distribution of resonances and lower Qs of these and secures a proper d/s. The diaphragm movement on a macroscopic level is closer to translatory than bowed. This should also allow for higher possible SPLs.
Manufacturing -even if we donīt know the howto yet- was probabely much easier and cheaper than glueing multiple spacer dots and results in smaller dots, hence less īdeadī capacitance/diaphragm area.

jauu
Calvin
  Reply With Quote
Old 26th September 2011, 05:00 PM   #12
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
That was my next question "if those are supports for the Diagphram ot not ?" if so then I understand the design.


jer
  Reply With Quote
Old 26th September 2011, 07:17 PM   #13
oshifis is offline oshifis  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
They prevent the diaphragm from sticking to the stators at high SPL (clipping).
  Reply With Quote
Old 27th September 2011, 04:29 AM   #14
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
I'll try putting some silicone dots on the diaphragm and see if it will make any difference in sound. I agree with Calvin that this is a lot easier to do than making the micro spikes.

On the other hands, I do not think that these spikes actually touch the diaphragm. I agree with Oshifis that they are there only to prevent the diaphragm sticking to the stator. I've actually tried to tension my diaphragm using mechanical tension and hand stretch tension techniques. Mechanical tension tends to be too much for these headphones as the bass isn't as good. When I do hand stretch tension, it's a lot better. So, with low diaphragm tension and spacer to diaphragm width ratio of 1:143, my guess is that these spikes help the diaphragm sticking to the stators.

Wachara C.
  Reply With Quote
Old 27th September 2011, 07:58 AM   #15
diyAudio Member
 
Join Date: Apr 2005
Location: Utrecht
If the spikes won't touch the Mylar than I think you would hear a rattling sound at higher levels when the Mylar starts to touch the spikes. So these spikes must always touch the Mylar ( and otherwise they could be simply omitted).
While silicon dots offer some great insulation I wonder what these spikes can offer at this point. Of course the voltage requirements are much lower
I own some stax myself for several years and these things work great
__________________
drs M.J. Dijkstra
  Reply With Quote
Old 27th September 2011, 08:31 AM   #16
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
I've just opened up the driver again to check if the spikes touch the diaphragm, and no, they don't. I wish I have a tool to measure the height of these spikes.

Wachara C.
  Reply With Quote
Old 27th September 2011, 02:18 PM   #17
Nevod is offline Nevod  Russian Federation
diyAudio Member
 
Join Date: Nov 2007
Send a message via ICQ to Nevod
Very clever things they are..
Usually when diaphragm hits the stators, there is still lot of unused displacement - often about half of what is achieved when all the diaphragm hits the stators.

Standard support points which touch the diaphragm increase resonance frequency at same tension level, but they do allow to reduce tension and still not touch the stators.

These supports both do not increase resonance frequency and allow reduced tension. When the diaphragm deflects too much it first hits the supports, which seem to be round so this does not produce sound, and is mechanically divided into regions. So in the conditions where with an conventional stator a diaphragm would hit the stators at center of the driver, while it would barely move at edges, with such a dotted stator there would be the whole diaphragm would be deflected almost equally while not touching stators anywhere.

That's how I see it. Would be a PITA to diy though, sadly.
  Reply With Quote
Old 27th September 2011, 03:53 PM   #18
diyAudio Member
 
Join Date: Jun 2011
Quote:
Originally Posted by chinsettawong View Post
I wish I have a tool to measure the height of these spikes.

Wachara C.
Hello,

You can often make measuring devices from stuff around the house. For example, you can make shims from pieces of paper stacking then up until they are the same height. For instance, you could measure the height of a ream of paper and then divide by 500 to find the height of a single sheet. Also you could use the geometry of triangles to "amplify" the height to an easily measurable level.

Umm, but don't you have a CNC machine? Couldn't you make a set of gauges like a small inverted U?

As to the purpose of the spikes, I don't know. But independent of what their purpose is, they will introduce non-linear behaviour to the membrane resulting in something akin to soft limiting - so distortion as high deflection. It would be different if they always touched the diaphragm.

I do not know about them stopping the membrane from sticking to the diaphragm due to electrically generated negative compliance. All I have read has put the mechanical compliance of the membrane due to tension quite high. Whether it is as high as the 3.5 ratio used by Quad, I do not know. Has anyone on the forum experienced a membrane sticking to a stator in Stax phones under normal circumstances - at any level? It would be noticable because the sound would cut out. Of course, this argument could be shot down if you find this particular model is aberrant. Will it be a future design feature or a dead end?

Also, from the photo you supplied, the stator design should preclude the diaphragm being influenced by the thin film behaviour of the air trapped between the membrane and the stator so that one is out.

I can't see how they would affect the behaviour of the primary membrane resonance (apart from the non-linear bit) as this is purely a function of mass, compliance, and damping none of which is altered, at least at reasonable deflections. As to the higher order modes in the membrane, even if the spikes could affect them, I hope the modal deflections are not large enough to contact the spikes - that would be really bad.

Nope, short of tracking down the designer and making him talk, I don't think you will ever know for certain. Another Stax mystery!

Regards,
Bob
  Reply With Quote
Old 2nd October 2011, 09:45 AM   #19
210 is offline 210  Germany
diyAudio Member
 
Join Date: Dec 2010
Location: Here
Regards Wachara! Very interesting spikes. No spikes between the outer three holes/rows, and in the middle row they are three holes apart, else just two. Maybe the spikes do a little disloading of the diaphragm when touched. Could you measure the resistance between spikes and stator with a multimeter (probably in the megaohm range) ?
__________________
You know that's it: receive and transmit (Peter Gabriel
  Reply With Quote
Old 2nd October 2011, 04:16 PM   #20
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
Hi 210,

The Stators are coated with powder coating, I think. I don't have a high voltage resistance meter on hand. So, sorry about that.

I've been thinking about these spikes. Will they be beneficial if we were to put them on full range electrostatic speaker stators?

Wachara C.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Attenuation circuit findings Fe208e sigma adamt Full Range 0 22nd June 2010 02:20 AM
Interesting old Philco electrostatic tweeter peace brainerd Multi-Way 0 8th March 2010 10:56 PM
UltraLinear in toroidal parafeed, my findings. Shoog Tubes / Valves 2 4th February 2006 07:58 PM
Stators MrPin Planars & Exotics 10 12th January 2006 03:06 AM
Stax electrostatic headphones npdang Swap Meet 0 21st October 2004 07:33 AM


New To Site? Need Help?

All times are GMT. The time now is 10:52 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2