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STAX SR007 Resonance Problems?

Mar 17, 2015 at 5:05 PM Post #31 of 53
edstrelow said:
 

soren_brix measures the arc resonance at about 150 Hz. That 's quite audible, as a fundamental tone that's a few keys below middle C on a piano. ( see thread on damping Stax)

"Attached a FG to one channel and swept through the lower fq's <200Hz.
Sounds like the arcs resonance is close to 150Hz.
What I noticed the most is that somewhere between 150-200Hz and below there is a clear resonance present in the opposite channel.
Putting the clamps on, or even just damping the arcs with a hand is enough to remove the resonance."


 
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If I have indicated that I did a measure of the arc resonance I am sorry. I used the FG to find the approx at which fq by ear - just like tuning a guitar :-)
 
Mar 26, 2015 at 9:57 PM Post #33 of 53
Evidently Sennheiser had a similar problem with the metal headband used with the HD800.
 
This is from their webpage: "Metal headband with inner-damping element"  http://en-us.sennheiser.com/dynamic-headphones-high-end-around-ear-hd-800  Even mentions "minimum resonance."
 
The HD 800, like the Stax SR007 uses a metal band across the top (well Stax uses 2 bands.) Sennheiser seems to have recognized the problem this causes and used their own damping system. Stax only used a leather cover.
 
This you tube video shows the headband in more detail: https://www.youtube.com/watch?v=vlA84jbTkxk
 
There appears to be quite a damping under the band. Could it be sorbothane?
 
Thanks Arnaud for bringing this to my attention.
 
Mar 30, 2015 at 7:18 AM Post #34 of 53
edstrelow said:
  Evidently Sennheiser had a similar problem with the metal headband used with the HD800.
 
This is from their webpage: "Metal headband with inner-damping element"  http://en-us.sennheiser.com/dynamic-headphones-high-end-around-ear-hd-800  Even mentions "minimum resonance."
 
The HD 800, like the Stax SR007 uses a metal band across the top (well Stax uses 2 bands.) Sennheiser seems to have recognized the problem this causes and used their own damping system. Stax only used a leather cover.
 
This you tube video shows the headband in more detail: https://www.youtube.com/watch?v=vlA84jbTkxk
 
There appears to be quite a damping under the band. Could it be sorbothane?
 
Thanks Arnaud for bringing this to my attention.
Click to expand...

"Metal headband with inner-damping element" - Seems like two metal bands are tied flat together.
 
"The HD 800, like the Stax SR007 uses a metal band across the top (well Stax uses 2 bands.) Sennheiser seems to have recognized the problem this causes and used their own damping system. Stax only used a leather cover."- No, it's divided into three parts: (Cup) - Plastic - Metal - Plastic - (Cup)
 
"There appears to be quite a damping under the band. Could it be sorbothane?" No, the black blocks on the arc is hard plastic.
 
Adding sorbothane to the arc's will damp the resonance, but certainly not remove it. I have removed the leather, and wasn't shy applying sorb.
But it didn't really improve anything, so off it went and the leather is back on.
My experience is that the resonance is due to the arc material and the tension applied for giving it the shape.
 
The HD800 arc doesn't appear to have any resonance.
I have tapped all over and it is dead all over.
You can get a very short ringing tapping on the mesh, but it is short.
That also is true if you adjust the arc not to touch the head and/or if you removed the headband.
 
Mar 30, 2015 at 5:08 PM Post #35 of 53
Originally Posted by soren_brix /img/forum/go_quote.gif
 
 
"There appears to be quite a damping under the band. Could it be sorbothane?" No, the black blocks on the arc is hard plastic.
This is from Senn's ad on Amazon:
 
"The headband consists of a sandwich design in which a metal layer is covered with several layers of plastic. The high-tech plastic possesses incredible attenuation characteristics and ensures that oscillations are not transmitted to the headphone mountings."
 
Maybe they have found a stiff plastic to use instead of sorbothane.  If it's that good, maybe you shoud just make headphone parts out of this stuff?
 
Adding sorbothane to the arc's will damp the resonance, but certainly not remove it. I have removed the leather, and wasn't shy applying sorb.
But it didn't really improve anything, so off it went and the leather is back on.
My experience is that the resonance is due to the arc material and the tension applied for giving it the shape.
As regards the Stax 007, I did not stick sorbothane to the band directly, because I didn't want to remove the leather covers and I doubted that it would work just stuck to the leather because the leather is somewhat loose.. What I did was to create a clamp and that definitely does work. Cucera mentions damping the 4070 which has a band similar to the 007 "I damped the Headband like your 007. "
 
The HD800 arc doesn't appear to have any resonance.

I have tapped all over and it is dead all over.
You can get a very short ringing tapping on the mesh, but it is short.
That also is true if you adjust the arc not to touch the head and/or if you removed the headband.
Would that seem to imply that the ""Metal headband with inner-damping element" is there for general damping of the whole phone?  Also  if the Senn band is as tightly linked to the earcups as the metal bands are in the 007, whether or not they ring, they could still transmit sound between the earcups, i.e. add to crosstalk.  That would give  a reason to put damping there there rather than in the cups.
 
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Mar 30, 2015 at 6:28 PM Post #36 of 53


i don't buy the magical plastic story, I think it's maketing BS

Yes, clamps works, but in my experience they damp but doesn't remove the problem, like a light finger tip on the arc does.

The HD800 is generally better built in comparison to the 007 imo, and there don't seem to be a need for damping anything ;)
 
Mar 30, 2015 at 7:21 PM Post #37 of 53
soren_brix said:
i don't buy the magical plastic story, I think it's maketing BS

Yes, clamps works, but in my experience they damp but doesn't remove the problem, like a light finger tip on the arc does.

The HD800 is generally better built in comparison to the 007 imo, and there don't seem to be a need for damping anything
wink.gif
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The only way I could tell would be to put some sorb on it and listen to what happens.
 
Mar 30, 2015 at 7:23 PM Post #38 of 53
I think we need a title for you Ed: Just sorbothane that headband already! or some thing similar :)
 
Mar 30, 2015 at 7:38 PM Post #39 of 53
arnaud said:
  I think we need a title for you Ed: Just sorbothane that headband already! or some thing similar :)
Click to expand...

I would be quite happy to leave this and let others investigate this matter.  All I wanted was to get a better sound for each of my phones by damping and that I have done.
 
The bigger issue is  whether  this phenomenon means anything to headphone design. I talked to an engineer from Schitt (they have an odd sense of humor) he told me that they were using sorb in their electronics. There can't be much vibration there, only transformer hum.   There's tons more vibration in a headphone. So should everything be damped with sorb, if so where and how.  As soren_brix says this isn't rocket science.  Well maybe it is if you really want to understand it, but trial and error goes  a long way.
 
I talked to a number of people at Canjam who had been working on similar lines of trying to reduce enclosure coloration.  One guy told me that there were a number of sorbothane type materials, some claiming to be better. Another showed me some nice little dynamics based on AKG's(?).  He had replaced the backs with wood and added some kind of soft copper to dampen the wood. They sounded very good. Another guy handed me an Audio Technica ATH-W1000X which was a bigger set, also with wooden cups and I gather fairly expensive. I added some thin strips of sorb on the metal part of the frame and it got rid of a lot of tizziness, added some bass and a bit better sounfield.  He listened for a bit and said "this is better" and rushed off to show his buddy.
 
So far, as best I can tell, only Sennheiser has figured out that there is a problem here and only with their HD 800. Who knows, maybe they really  found a magic plastic as they claim.
 
BTW I saw currawong  there.
 
Mar 31, 2015 at 9:19 AM Post #43 of 53

Discovered this thread recently and did a little test to see if there's anything to it.  If you want to duplicate this, it's a lot easier than fashioning sorbothane clamps.  I just put both hands on the metal frame and hold on with thumb and fingers, playing around with position and pressure while listening critically.  Opinion here is that there's no big change, aside from losing just a bit of the "air" of the 007s, possibly due to my arms being in proximity to the back sides of the transducers.  I tried keeping my arms out front, shifting positions ,etc., and am pretty much convinced this has practically no effect.  Now, is warm flesh as good a damper as sorbothane - IDK.  Do I care to pursue further - not really.
 
Mar 31, 2015 at 1:59 PM Post #44 of 53
downrange said:
 
Discovered this thread recently and did a little test to see if there's anything to it.  If you want to duplicate this, it's a lot easier than fashioning sorbothane clamps.  I just put both hands on the metal frame and hold on with thumb and fingers, playing around with position and pressure while listening critically.  Opinion here is that there's no big change, aside from losing just a bit of the "air" of the 007s, possibly due to my arms being in proximity to the back sides of the transducers.  I tried keeping my arms out front, shifting positions ,etc., and am pretty much convinced this has practically no effect.  Now, is warm flesh as good a damper as sorbothane - IDK.  Do I care to pursue further - not really.
Click to expand...

You are right warm flesh is not as good as sorbothane.
 
Mar 31, 2015 at 6:47 PM Post #45 of 53
I think Schiit is using sorb to damp tube microphonics, although who knows, maybe transformer hum too.
 
Re: damping headbands, I think it'd be more efficient to fashion sorbothane washers for the headband screws than to stick clamps on the headband.
 
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