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Damping Mechanical Energy Distortion of STAX and other phones with SORBOTHANE and other materials.

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  1. richard51

    I apologize it is my bad.... 1 cm also for me I wrongly wrote 1 inch....
     
    nick n likes this.
  2. edstrelow Contributor

    Why would speakers be different from headphones?
     
  3. chrismini
     
  4. chrismini
    Hello Richard. Remember me, Chris?
     
  5. richard51
    salutation Chris.... I hope all is right for you my best to you...
     
  6. skwoodwiva
    I have plenty of insoles, shall I put one in the blender?

    IMG_20180331_183514610.jpg
    Water helps

    IMG_20180331_184045981.jpg

    IMG_20180331_184811125.jpg IMG_20180331_193725324.jpg IMG_20180331_193738200.jpg IMG_20180331_193722821.jpg
     
    Last edited: Mar 31, 2018
  7. skwoodwiva
    Imitation is flattery!
    Good thread
     
  8. skwoodwiva
    @edstrelow
    Can you see how the heel pad, by just hugging the magnet, acts like one of those massive building weights opposing / absorbing back movement.
     
  9. Maxx134
    I have seen it all now.
    Exterior modding actually funny but in a cool way.

    I don't deny your results though.

    I have used sorbothane inside cups over dynamic drivers with some success with bass,

    but for resonance control, I would rather dampen than absorb,
    so I like dynamat type material,
    yet they add more weight than sorbothane.

    Sorbothane is a tricky material for me to get most out of.
    I still use sorbothane,
    but in tension, not in an "at rest" state.

    In my experience ,their best performance are done in either a "slight comprehension", or a "slight expansion" state.

    I never posted about it before but its cool the ways it has been chosen to be used here.
    So hat's off to you guys.
    :)
     
    Last edited: Apr 22, 2018
    richard51 likes this.
  10. richard51
    I use the sorbothane now mostly inside the He 400 .... and some between the headband to isolate the 2 cups.... I dont put in on the exterior cups anymore.... More practical to put it inside .... On My AKG 340 though I mostly put the sorb at the exterior around the cups compressed with elastic band because for this can it is more easy... Great results....
     
    Last edited: Apr 30, 2018
    Maxx134 likes this.
  11. edstrelow Contributor
    Maxx134 Looks like the outside of my Stax SRX 3 which I covered the same way. I cannot stress too much that covering the pieces with 4 layers of electrical tape magnifies the damping effects. hat is the principle of constrained damping.
     
  12. edstrelow Contributor
    I have not been too active of late, essentially because I have achieved my goal of getting effective damping of my headphones and loudspeakers and I have thus been doing less experimenting. Now it is just a matter of waiting for the rest of the audio world to catch up. Here is my headphone line-up, Stax SR007, Stax Lambda (404 and LNS) and Sigma (Pro and 404.) [​IMG] You can see a lot of damping on the outside of these phones, especially on the headbands. It came as a surprise to me that placing damping material on the bands would be effective, but as we know, Sennheiser figured this out years ago and is doing it now on its best dynamic phones and very likely to its stats as well.

    I have converted fully over to 70 duro sorbothane. I prefer to use the thickest sorb I can find, generally maxing out at 1/2 inch. The 3M self-stick is effective but not available on 1/2 inch sorb for which I have been using very expensive Lord 7650 glue, which came recommended by Sorbothane. The gluing matters a lot. You can hear the difference in sound as the glue cures (for 7650 that is a week or more, although it sticks well after an hour.) In fact even the tape cures over several hours.

    You will also notice that I am using fairly small pieces.\ of sorb. This has been one of the more interesting findings in this forum and several others agree that you get the best results if you use small pieces, eg. an inch or less in dimension. This was counter intuitive to me and why it works, I still don't understand.

    On top of the sorbothane I have also been adding 4 layers of electrical tape on the top (i.e. unglued side), thus turning the damping process into "constrained damping." I swear this doubles the effect of sorb. Possibly this article helps. https://en.wikipedia.org/wiki/Constrained-layer_damping

    I have also been sticking sorbothane mounted as near as possible to the drivers.[​IMG] Irrespective of Sennheiser's choice, I see no reason to let vibrations loose in the system and it seems a better practice to dampen them as close to the drivers as possible. This somewhat blurry shot shows small 1/4 strips, not yet covered with 4 layers of tape on the Sigma set-up. The Lambdas are treated similarly, while in the SR007, the sorbothane is stuck to a metal plate inside the earcup.

    Finally, I have been working on my speakers. This shows placements around my Polk SDA 1's. I have tried various thickness and the like over the last few years. I believe all of these are 70 duro, although some are no the 1/2 inch sorb that I recommend. Also some have only 2 layers of constraining tape, 4 is significantly better than 2.
    [​IMG]
    What does one gain by such damping? A huge improvement in sound quality. I have been to a fair number of audio shows and have heard nothing of this order of magnitude since I was exposed to me first electrostatics, many years ago. And of course damped stats gain hugely as well. The gains of damping on sound quality are in several dimensions:

    1) Dynamics, the attack and detail are much enhanced. I recall when I first realized with my early experiments that I was involuntarily tapping my feet to the rhythm. The treble detail, such as triangle, attack on strings, tremolo is much enhanced.

    2) tonal accuracy, you get more overtones and instruments and voices sound more real.

    3) Spatial imaging on headphones is much enhanced. Instruments and voices are localized better in space and the spatial field becomes wider. This is presumably because of the damping of opposite channel signals across the headband (i.e. crossfeed.) Basically, if you mix left and right channel signals, you will get less stereo. Sorbing reverses that trend. If you go back some pages you will see where Mitchell actually measured the mechanical crossfeed from one earcup to another, i.e. he could detect and measure the left channel in the right earcup or vv.

    4) Removing garbage sound. Volume goes down in my systems after sorbing. I generally will turn up my Stax headphone amps about one notch after damping of the phone. This is what I expect if the sorbothane is getting rid of some of the signal. Once early on, I quickly removed sorb which had been stuck on the front of my Sigmas, while listening to them. The sound level suddenly jumped about one amplifier notch. But what you heard was a sort of weird ambience added to the signal. That at least is how my brain interpreted it. That I suspect is the sound of the buzzing in the system caused by the mechanical vibrations.

    What are the basic physics here? At the outset we have Newton's rule that for every action there is an equal and opposite reaction. That's what is pumping mechanical energy into the earcups and speaker cabinets. However, energy does not just die, it has to be converted to some other form of energy. Sorbothane claims it converts mechanical energy to heat, thus getting rid of it that way. If you don't get rid of this energy it either causes the earcups/speaker boxes to vibrate, or what I think is more likely, feeds energy back into the drivers, thus messing up the driver's operation and rubbish sound is being added to the music. Presumably this rubbish energy still dies fairly quickly, i.e. in the milleseconds range otherwise you would be hearing sound on your phones/speakers after the music stopped. Sorbothane damping merely accelerates the process.

    I am very happy where I am in this exercise. I have great sound probably in the top 1% of high fi systems and at very little cost. I just laugh as I see the rubbish being talked about super costly systems, knowing that whatever the merits of such systems they are almost all suffer the major distortion that I am eliminating in mine and that they are not. And yet I suspect I have not got the absolutely best results even now. I have been struck that the sound just keeps getting better the more damping I add. I am guessing that I haven't got the full benefit especially on low frequencies, where according to Sorbothane, thicker sorb, eg. 1 inch or more works best. It is difficult to add 1 in sorb to most headphones, except on the headband. I suspect I may add some to the back of my speakers to see.
     
  13. Maxx134
    I do not dissmiss your methodology or results at all, but I like to try clarify some points.

    Sorbothane was designed to work under pressure, or tension.
    I see most usage here without pressure or tenion, which is good to know it still works.

    I thinking your taping was good for adding pressure to the sorbothane.


    But your link is a bit different.
    Constrained damping works by use of different density materials, like what Dynamat does.

    Both work great and you have shown very interesting results in the usage of sobothane methods.
    Thanks for showing this.

    I used sorbothane as well with success.
    It deserves to be suggested for its benifits.
     
    Last edited: Jun 4, 2018
  14. richard51
    My testimony is the same ...A system without vibration does not exist....
     
  15. edstrelow Contributor
    Re: sorbothane under pressure. I have been on this problem for a few years and there is even one earlier thread just dealing with the Stax SR007. I have talked a couple of times with technical reps as Sorbothane who gave me some pointers but had little to specifically discuss about speakers and headphones. Often it is used in industrial applications, as footers for equipment but it has to be carefully tailored to the weight of the object and the frequencies needed to be damped. Vibration damping is a big deal to mechanical engineers and I have discussed what I have been doing with a half a dozen, and they they all seemed to understand and agree with the approach. I do recall talking to one of the Schitt designers who acknowledged the use of sorb to dampen circuits in some of their equipment. To my mind this problem is one of the last frontiers of audio.

    My first efforts used clamps on the sorb but over time I found I used little pressure to get the best sound. Then I started just sticking the sorb on using the self-stick or other glues and it seemed that I was still getting good results and I stopped playing with clamps. Still later I used electrical tape to hold some in place on headbands, by wrapping the sorb to the band. I liked that even more, and finally realized that simply covering the back with tape gave as good result as wrapping. I got the term "constrained" damping from Mitchell who did the measurements of mechanical crosstalk on headphones. That does not imply pressure, just a wall of sorts on the back of the material.

    There's a lot of basic physical measurement needed here to understand the phenomenon and to determine the best methods of damping. I would like to see measurements of the amount of vibration in earcups and speaker boxes and then a concerted effort to dampen it to non-existence. Then I want to hear what non-vibrating speakers and phones sound like.
     
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