[edstrelow]

I am going to stop using the term 'resonance' as the key term because that is I suspect only part of the problem.
 
Wikipedia's definition of "resonance" states :
 
" In physics, resonance is a phenomenon that occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency."
(bold added) 
 
I think that we are not just dealing with a "specific preferential frequency" problem.  Energy of a wide range of frequencies flows from the drivers to the earcups.  This is Newton's third law. Certainly if this energy  triggers specific resonance frequencies this may cause even greater problems, but I suspect that problems of sonic degradation occur even because of the non resonating frequencies.
 
My feeling is that the fundamental problem that one tries to solve with damping is getting rid of energy in the earcups, whether or not anything is actually resonating in the earcups.
 
This I have changed the heading of this thread.

 

[saidentary]

  I am going to stop using the term 'resonance' as the key term because that is I suspect only part of the problem.
 
Wikipedia's definition of "resonance" states :
 
" In physics, resonance is a phenomenon that occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency."
(bold added) 
 
I think that we are not just dealing with a "specific preferential frequency" problem.  Energy of a wide range of frequencies flows from the drivers to the earcups.  This is Newton's third law. Certainly if this energy  triggers specific resonance frequencies this may cause even greater problems, but I suspect that problems of sonic degradation occur even because of the non resonating frequencies.
 
My feeling is that the fundamental problem that one tries to solve with damping is getting rid of energy in the earcups, whether or not anything is actually resonating in the earcups.
 
This I have changed the heading of this thread.

Technically correct (I think) but I suspect that the meaning of "resonance" inferred by the readers of this thread is more generic.  That is, "resonance" is used more loosely to refer to unwanted vibrations that cause audible degradation of the intended signal.  These vibrations occur at multiple frequencies, and not just the "resonant" frequency of the driver enclosure. 

 

[richard51]

I think that the earcups are complex vibrational and resonant systems and are coupled to the  vibrational and resonant systems of the drivers,hence they resonate....The damping process trials (experimented  with the listening device of the ears and experienced by the ears) is optimized by the  use of the sorbothane with varied thickness, duro,form,  to maximize some vibrations and frequencies and minimized some others ... why ? because resonance are not always musically bad...Because resonance is also  «the intensification and enriching of a musical tone by supplementary vibration».
 
Hence,«Resonance can be a good or a bad. Musical instruments are designed to take advantage of resonance to increase volume or control its timbre. When the strings of a violin, for example, are bowed, the sound resonates within the body, which is the hollow part of the instrument, and thus becomes a bit more amplified for us to hear»  The same thing for an earcup of headphone apply, sorbothane is only a means for finetuning the resonance desired and eliminate the non desired one...In other words the earcup play an important active role in the restitution of the sound or in his destruction, sorb mod is only the possibility of optimization of this positive function, like the form and content of the living room play a part in the listening experience of the sound of speakers...All object, and all systems of objects vibrate, some vibration are not desired some other are desired....2 objects or systems if coupled resonate , some resonance must be damped to some degree, some to another degree, some other not....I am not an engineer this is only my 2 cents, if someone can teach me i will listen...best regards to all of you ...thanks to Edstrelow for this interesting thread ...

 

[edstrelow]

Grado has now joined Sennheiser in dampening earcup vibrations.  I picked up a catalog from Audio Advisor today and I see a Grado SR80e  ad saying:
 
" the SR80e  has...a new polymer to damp resonant distortion in the plastic housing.... The way the SR80e's new driver and plastic housing move air and react to sound vibrations virtually eliminate transient distortions. " 
 
   Looking at their website I see that Grado has introduced a third series of headphones, called the e-series which use a vibration absorbing material.  "Grado's proprietary SpaceBlack Polycarbonate is engineered to absorb excess energy and reduce secondary impulses, for a clearer tone."
 
In the same catalog, Sennheiser HD800 is still touting anti-resonance in its headband as they have for some time:
 
"...while the sandwich-material, anti resonance headband... utilize(s) advanced technology from the aerospace industry."
 
The Grado blurb is right on point, the earcups vibrate  and need damping.  I am interested to see that Grado see the problem as reducing transient distortion. We definitely need an explanation of how earcup vibrations degrade sound. I had certainly not thought of it as problem mostly affecting transient response. So this may be a helpful clue.   Also possibly easy to measure with square waves.
 
    But what about Sennheiser using the headband for damping?  I would have been sceptical about applying damping so far away from the drivers and earcup, except that I found a similar issue some years back  with the Stax SR007A  
 
 http://www.head-fi.org/t/671314/stax-sr007-resonance-problems .
 
This was where I originally got started on the damping problem because I could hear a sonic improvement from damping the SR007A headband with sorbothane. However I should note  that this is only a problem in headbands that are tightly fastened to the earcups something the SR007 and HD800 seem to have in common.
 
However, as best I can tell, the new megabuck Sennheiser HE 1060 electrostatic has a similar headband to the SR007 and HD800.  So is its  band also damped like the HD800?  And if so, is merely damping the band sufficient to get rid of audible problems of earcup vibration or is it merely a halfway step?   To me, the way to test that would be to add bits of sorbothane and see if there is any additional benefit.
 
Still no sign from Stax that they are dealing with the problem, even with their new 500 and 700 Lambdas.

 

[edstrelow]

The Stax SRX III Mk 2 pro just seems to get better as I add more sorbothane to the earcups. Listening to it with my old SRM1 Mk2 Stax amp, it is now probably the most detailed and subtle phone I have ever heard.  The downside is  a slight harshness, which it had before the sorb mods and which I suspect is caused by the old, thick driver material.  Remember this is a 1970's headphone.
 
 

 
You can see that I have essentially covered both the plastic and metal portions of these phones with 1/8 inch 40 duro sorb pieces.  However, not every Stax phone I have worked on sounds good with lots of sorb.  For example I ended up removing some from my Sigma/404, Sigma Pro and SR003 to get rid of some bass boom. The SRX does not seem to show such a boom although it is no bass monster either so maybe it doesn't matter for  phones phones that are somewhat bass-shy at the outset.
 
I will be trying some comparisons of different sorb damping arrangements using the extra set of metal earpad holders shown at the right.  These can be swapped over in about a minute. I intend to use the current  version as my comparison and then compare the effects of changing the materials, thickness, duro etc. on the spare pads.

 

[arturo71]

This is a great thread. There is my experience so far:
 
I modded my Stax Lambda 404 as on pg 1 of this thread with sorbothane duro 30 1/4 thick. The change of sound was immediate and to me an improvement. Tighter sound, more focused image, slight increase of bass (probably related to the frequency cutoff of the sorbothane). A clear improvement. To be clear: it did not turn the Lambda into an Omega or something else but into a better class of Lambda. As a bonus I put some pieces of sorbothane as feet of my mac mini and under the shelves of my rack, clearly reducing vibrations/resonances (whatever you call it). Overall one of the best bang-for-the-buck upgrades I have experienced.
 
Then the other side of the coin: driven by my first successful experience, I tried the same with my Sennheiser HD600. This is a phone I thought may benefit from the mod because of this veiled sound of theirs I thought might come from resonances. There I had some problems: there was no much space left inside the ear cups so I had to put many small pieces of sorbothane, and the 2 sided tape I used would not glue them well. They were coming off all the time. Worse, I perceived no change/improvement in the sound. Eventually I reversed the mod. No hurt done and I am happy I tried.
 
Then I tried with my Stax 007A. I detached the earcups and glued pieces of sorbothane as explained in this thread, but then I failed miserably to put the cups again! The sorbothane (plus the two-sided tape) was too thick to put the ear cups back. So I reversed the mod. I ordered self-adhesive, thinner sorbothane and I will try again.
 
Best,
 
Arturo

 

[cpt000]

Am getting the Mikros 90 and it responds to the sorbothane mod.
 
Can anyone spare about 12 small pieces of sorbothane? Will pay for cost and shipping. Please PM me...thanks.

 

[richard51]

something i want to say about sorbothane and something very important that has been already observed by Edstrelow... I think that the glue of the sorb pieces takes time to paste and merge completely with the surface... the sound improvement will be continuing after  weeks... it is my experience...I have no other explanation why my he 400 sound so good now after all these months  with the sorb mod. i had made no other change in my gear...
 
p.s. the he 400 had  painted metal cups, this is probably why the adherence process take longer that in plastic cups, with the painted metal ...the betterment is there in the beginning but not apparently completely and optimally manifest in the first days and weeks... this is my only explanation for this puzzle... i must say that i have listen very little to my headphone for the 2  last weeks....hence my discovery of this  evident and completely imprevible  improvement...it is like the sound opened up more drastically...I am going back listen all the cd i know most for the last 2 days...wow

 

[edstrelow]

  something i want to say about sorbothane and something very important that has been already observed by Edstrelow... I think that the glue of the sorb pieces takes time to paste and merge completely with the surface... the sound improvement will be continuing after  weeks... it is my experience...I have no other explanation why my he 400 sound so good now after all these months  with the sorb mod. i had made no other change in my gear...
 
p.s. the he 400 had  painted metal cups, this is probably why the adherence process take longer that in plastic cups, with the painted metal ...the betterment is there in the beginning but not apparently completely and optimally manifest in the first days and weeks... this is my only explanation for this puzzle... i must say that i have listen very little to my headphone for the 2  last weeks....hence my discovery of this  evident and completely imprevible  improvement...it is like the sound opened up more drastically...I am going back listen all the cd i know most for the last 2 days...wow

I definitely agree with your observation that the sound can improve markedly as the bond gets better. I have noticed this in several of my phones too. When I first started trying sorb damping I realized that I at least had to wait overnight after sticking some on before deciding if I liked the effect or not. But I agree that there seem to be  long term effects too. What you will notice is that the bond is much stronger after a few weeks and months and that it  can be harder to remove the sorb.
I should also note that I have had one phone, the Sigma, where the sonic effects got worse over time. The phones started sounding to bassy and boomy until I removed some sorb and finally got a  nice tonally balanced  sound.
I keep meaning to do some comparisons with different types of bonding material using these on  my interchangeable covers of my SRXIII but I just I just don't seem to have the time.  I would like to try superglue, since this is just about the strongest and fastest setting glue available.

 

[richard51]

  I definitely agree with your observation that the sound can improve markedly as the bond gets better. I have noticed this in several of my phones too. When I first started trying sorb damping I realized that I at least had to wait overnight after sticking some on before deciding if I liked the effect or not. But I agree that there seem to be  long term effects too. What you will notice is that the bond is much stronger after a few weeks and months and that it  can be harder to remove the sorb.
I should also note that I have had one phone, the Sigma, where the sonic effects got worse over time. The phones started sounding to bassy and boomy until I removed some sorb and finally got a  nice tonally balanced  sound.
I keep meaning to do some comparisons with different types of bonding material using these on  my interchangeable covers of my SRXIII but I just I just don't seem to have the time.  I would like to try superglue, since this is just about the strongest and fastest setting glue available.

thanks that confirm my experience....but now with the completing of the gluing process adherence i am astound by the transformation of my he 400.... thanks very much to you....

i understand NOW what you have already said with your Stax experience about the sorb mod.versus a stax amp  upgrade... I know now that no amp can do that to my he 400 ....except the sorbothane... i cannot thank you too much....i will wait for your reviewing different gluing process....

 

[edstrelow]

I  got a nice result sorbing a cheap earbud phone with pieces of 1 mm sorb.  I have never liked any regular dynamic phone since I went electrostatic many years ago, but some of the earbud and IEM phones have impressed me.  These  current phones are a no-name brand that came with a recently purchased Tecsun portable radio.  When I tried them out on the headphone amp of a Sherwood CD player, they seemed fairly decent although a bit limited in air, bass and treble.  So I tried attaching some small pieces of 1mm thick sorb.  The self-stick on the sorb didn't stick to whatever these were made of but 3M 80 adhesive did the job.  You can see some excess which I will remove after the bond is more secure in a day or so.  The benefits were obvious right away, better dynamics, more  air and sparkle to the treble. Still not much  help with the bass.   Probably just not much there on these phones.  Still a sweet improvement for an expenditure of about 10 cents.  
 
This makes the point again that there are serious design issues with most headphones, relating to the vibrational characteristics of the enclosures.  Hopefully with Sennheiser using viscoelastic damping on their HD 800 (and I would assume their new super phone) and Grado coming up with a proprietary plastic to dampen vibrations there will be a gradual move by manufacturers to deal with the damping issues.
 

 

[Hutnicks]

  I  got a nice result sorbing a cheap earbud phone with pieces of 1 mm sorb.  I have never liked any regular dynamic phone since I went electrostatic many years ago, but some of the earbud and IEM phones have impressed me.  These  current phones are a no-name brand that came with a recently purchased Tecsun portable radio.  When I tried them out on the headphone amp of a Sherwood CD player, they seemed fairly decent although a bit limited in air, bass and treble.  So I tried attaching some small pieces of 1mm thick sorb.  The self-stick on the sorb didn't stick to whatever these were made of but 3M 80 adhesive did the job.  You can see some excess which I will remove after the bond is more secure in a day or so.  The benefits were obvious right away, better dynamics, more  air and sparkle to the treble. Still not much  help with the bass.   Probably just not much there on these phones.  Still a sweet improvement for an expenditure of about 10 cents.  
 
This makes the point again that there are serious design issues with most headphones, relating to the vibrational characteristics of the enclosures.  Hopefully with Sennheiser using viscoelastic damping on their HD 800 (and I would assume their new super phone) and Grado coming up with a proprietary plastic to dampen vibrations there will be a gradual move by manufacturers to deal with the damping issues.
 

Inspired by this post and several converstations with NickN, I used your method on a pair of Sony Ericsson HPM 62 earbuds. These became my "go to" earbuds a while ago when I picked up a pair at a thrift shop and recabled them and was subsequently stunned at the sound staging and quality.
So cutting a couple of corners off a sheet of sorbo (thanks Nick) I stuck them on in a similar config to your pic and went for a walk. What was great bass before now was focused to almost perception and balanced with the new clarity of the mids and highs. Soundstagine seemed to jump out a kilometer in each direction. I was stunned and put it down to "new headphone syndrome"
Well it's killer cold right here and as I was on my way back one of the little triangles let go and fell of unknown to me. My immediate response was that something was wrong with a channel on the player. I just started laughing when I pulled the but out and found the sorbo had gone. Got home cut a new piece and just now have taken them off. Mobile, home system, this gets my seal of approval and thanks.
You guys just helped make a great product even better.

 

[edstrelow]

 
Inspired by this post and several converstations with NickN, I used your method on a pair of Sony Ericsson HPM 62 earbuds. These became my "go to" earbuds a while ago when I picked up a pair at a thrift shop and recabled them and was subsequently stunned at the sound staging and quality.
So cutting a couple of corners off a sheet of sorbo (thanks Nick) I stuck them on in a similar config to your pic and went for a walk. What was great bass before now was focused to almost perception and balanced with the new clarity of the mids and highs. Soundstagine seemed to jump out a kilometer in each direction. I was stunned and put it down to "new headphone syndrome"
Well it's killer cold right here and as I was on my way back one of the little triangles let go and fell of unknown to me. My immediate response was that something was wrong with a channel on the player. I just started laughing when I pulled the but out and found the sorbo had gone. Got home cut a new piece and just now have taken them off. Mobile, home system, this gets my seal of approval and thanks.
You guys just helped make a great product even better.

Good to get some supporting observations. Interesting about the bass, that I got little boost whereas you got a lot. I have just tried some little pieces of sorb on  an old Sennheiser IEM(I can't see the model #.) This phone was of much higher initial quality than the previous earbuds and had ample bass. Adding the sorb turned it into  such a bass monster that I could feel my skull vibrate. Obviously way too much bass and I will probably  cut some off or split them into smaller pieces, something I have noticed before to give a more balanced sound.

 

[Hutnicks]

  Good to get some supporting observations. Interesting about the bass, that I got little boost whereas you got a lot. I have just tried some little pieces of sorb on  an old Sennheiser IEM(I can't see the model #.) This phone was of much higher initial quality than the previous earbuds and had ample bass. Adding the sorb turned it into  such a bass monster that I could feel my skull vibrate. Obviously way too much bass and I will probably  cut some off or split them into smaller pieces, something I have noticed before to give a more balanced sound.

I am very tempted to run a strip on the ER4S. If anything needs a bass boost it would be them. I did try it on the B&W C5 and it cleaned things up a little but overall had much less effect than on the Sony's. The beemers suffered from slightly aritficial highs and the sorbo has calmed them down .
 
I have the Senni CX300 and CX270s. The 300 is an outright bass machine so that may well be the beast you have. They don't get much use here for that very reason.

 

[edstrelow]

 
I am very tempted to run a strip on the ER4S. If anything needs a bass boost it would be them. I did try it on the B&W C5 and it cleaned things up a little but overall had much less effect than on the Sony's. The beemers suffered from slightly aritficial highs and the sorbo has calmed them down .
 
I have the Senni CX300 and CX270s. The 300 is an outright bass machine so that may well be the beast you have. They don't get much use here for that very reason.

Yes, I think my Senn IEMs may be  the CX 300, that  sounds familiar. I keep them as a back-up to the, Stax portable when  I travel and it is too noisy for the Stax, mostly inside an airplane. Interestingly, they sound better this morning, there is still  a lot of bass but it is more listenable. I attribute this change to the glue bonding better overnight. I have noticed this before with other phones, that the sound may change somewhat over time after sorb is added. Generally the  sound gets better overvtime but at least one phone, the Sigma, got worse and I ended up removing some sorb to reduce bassiness.
 
One of the many things we do not understand about vibrations and damping of headphones is how adding a damping material such as sorb can INCREASE the sound levels at some frequencies. I have spoken with the technical advisers at Sorbothane a couple of times and they have told me that sorb does not attenuate much below 50 Hz.  So if it damps other frequencies , then the bass below 50 Hz would end up proportionately louder. However I think there may also be some positive feedback or low frequency resonance coming in here to, especially when the glue is not yet set. I seem to be hearing too much bass to be explained just by differential damping, which then goes away after the glue sets.