Shure SRH440 'Foam plug' mod

Discussion in 'Headphones (full-size)' started by stuntmanfranky, Nov 20, 2009.
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  1. KimLaroux
    You're saying they don't isolate outside noise well enough? That's something. Of all the headphones I tried at the last meet, these have one of the best isolation. Did your pads get hard? If they got too hard to sqwish on your head, there's probably air gaps between your head and the pads.
     
    I guess I should try reinstaling the plugs. I've been using, and enjoying, these without the plugs for months now. Maybe it's time I revisit their original sound. And I still haven't tried cutting a plug in half and using one half into each speakers. It could prove to be a good compromise. 
     
  2. PFULMTL
    I guess I should say that I work on a shrimp boat in the Gulf. Imagine The Deadliest Catch, but less deadly. These do block the sound of water, half the engine noise, birds, and prevents brain damage from loud squeaking sounds. Headphones just aren't for my music, but it's also to protect my hearing.
     
  3. KimLaroux
    A couple of weeks ago I reverted to stock. I placed the foam plugs back inside the drivers. The first word that came to mind when I heard them was "clean". With the foams, they simply sound cleaner. They can reproduce just about every sounds, without stumbling over when it gets fast paced. They have less bass, but not by much. The bass is still there, it's just not satisfying. They have "thump", as is usual with closed cans, but they don't extend bellow that.
     
    This tells me Shure knew what they were doing when they added the foam plug in there. My next experiment will have the goal of finding a middle ground. I'll have to gather different types of foams and try them. I considered cutting one of the stock foam in half, but I've discarded this option when I tried the foams again. I don't feel it would be a good idea to loose the option of reverting to stock damping.
     
    This promises to be an interesting experiment. [​IMG]
     
  4. KimLaroux
    Sooo... I got bored of the lack of bass, so I moved to another experiment. I removed the plugs, and replaced them with smaller, lower density foam cubes. I had packaging foam laying around, so I cut small cubes from it, a bit smaller than the stock foams.
     
    This creates an in-between state. The idea is to allow more air to flow, but not all of it. It worked very well! The headphones have more bass than stock, but they aren't bloated like they were without any plugs. It's satisfying with every type of music. Without the plugs, hey could not handle fast bass like the kick drum in Metal. The bass was out of control and drowned the midrange. With the low-density foam, they have a more satisfying bass response without ruining the balance of the headphone. It's an overall pleasurable sound.
     
    I used packing foam because this is what I had on hand, but a piece of cheap cleaning sponge would do as well.
     
    Claritas likes this.
  5. MasterMech7777
       It is kinda funny you discovered something by accident that many many audiophiles have used for years (when sealed box size limitations are out of your control). I will do my best to explain what is happening, and that is a not an "Illusion" of bass you are hearing.
     
       OK first of all the air doesn't flow freely in a sealed can setup. The woofer is actually compressing the air inside the "can" in your headphones. If you have too small a "can" the bass will sound very stiff flat and muted. The air inside the inclosure is compressed under some amazing pressures (It has to do with the speed at which transducers operate). The compressed air generates heat (molecular collision and all that fun stuff), that heat causes the air to "stiffen up" (heat causes the molecules to become excited. In their excited state they take up a lot more room, so your speaker "sees" less air space and becomes flat. Of course the opposite effect happens when the speaker is driving outward and is decompressing the air inside the box. Main reason many Sub-woofers push out of the box further then when they drive inward.
       Now here comes the fun part of this long winded explanation. When you add filler (polyester fibers work best in my experience) it absorbs some of that heat and reduces the rapid movement of the air molecules inside the headphone enclosure. Thus acting like a larger box, less heat = more "relaxed" the air is. Theoretically it can be as much as 40%, that is optimal number and many factors affect this process. Stuffing and Idiabatic/Isothermal effects( http://www.arcavia.com/kyle/Equations/Stuffing.html ). This effect only works on sealed boxes, open air Headphones would not benefit from this.
       LunaticGTX460 happened to accidentally do this in his experiment. By adding the cotton to the enclosure, he in essence allowed the speaker to "see" more air space. That is why he is hearing more bass. Of course by removing the sealing film he in essence created a ported enclosure, and those produce "tuned" bass. The port allows the speaker to move more freely but it reduces the over all bass response, except for a very limited bandwidth. That is the main reason the overall bass was reduced.
     
    I hope my explanation helped. I think, minus removing the resonance film, adding small amounts of polyester fill to the "box" if the headphone and making sure it is well sealed may result in a nicely "tuned" bass. Of course you can play around with the amount of fill you add. Too much can have a reversed effect, so play around and see what you get.
     
  6. dhruvmeena96
    Ok heheh....
    This foam plug disscusion is too hot

    Shure inserted foam plug to absorb 60hz peak bass without heating the voice coil(open cell foam)...clay, blutak mod heats up the voice coil

    Just thought of mod which can help u all in this condition...

    1.Ok remove the foam plug

    Optional. Paste a 3M micropore(or any porous) tape on vent.

    2.get a more open cell foam(1/2 inch thick and 1/2 radius to magnet base) and paste it on back

    3. Paste dynamat or blutack(thin layer) on remaining area of magnet

    4. Paste dynamat or blutack(thin layer) on inner side of baffle(wall connected to driver).

    5. Get a akasa paxmate plus and paste inside the cup

    6. Fill the cup with surgical absorbent cotton roll[(equal weight)first unlayer all and then layer it again so that u can make them loose]

    7. Now roll shure 840 pads, but before that get a legging cloth, fine meshy cloth and tightly paste on dispersion plate(between earpad and speaker driver). This will reduce chuffing treble noise and clean up treble with 0.5db loss

    8. This is regarding the shure 840 ear pad. Cut a foam in same shape as earpad with 2inch thickness(memory foam is best) and put it beneath the earpad)

    Ok guys now u can alter this mod according to urself, just i will share the science behind this

    The foam shure inserted was for cutting down bass for better quality as it absorb bass reverb and resonance. Pasting at back of magnet will do the same thing but having bigger and more open foam will give the driver some air to breath, this will make the mids and treble transition smooth and tight.

    3m transpore tape is for those who are sensitive to bass, reducing airflow

    Blutack or dynamat adds weight to base so the driver is incapable of producing rocky motion resonance(bad bass resonance) and produce only medium frequency and treble resonance which is partially absorbed by the foam(reducing bass resonance to zero)

    Akasa paxmate plus at back of driver absorbs these medium and high freq resonance(not completetly but 1000x better than stock.

    Filling loose cotton will. Trick the speaker to large cabinet producing pretty deep and tight bass.

    Now going furthur deep in science

    As the sound reflect, paxmate will make the reflection irregular due to rough foam surface and will go miltiple reflection inside the cotton reducing back wave significantly by 50db

    The remaining air particle (still having energy) then have to pass through foam on the vent plus apply force on front baffle to create overall resonance which is quite immposible due to dynamat or blu tak

    Ok sorry for english, the back wave will have difficulty through foam

    And u will only get front sound without any driver or headphone distortion plus flat till 15hz and then steep roll off. Without any decay at any spectrum

    I thought of earpad mod as sound became damm to tight and large but didnt gave me the sence of spaciousness

    As in my term there are 3 types of sound placing

    1. Sound image-placement of sound
    2. Sound stage-distance of sound
    3. Sound scape-audience perspective or 360 sound at every axis

    So it gave the best image and stage but lacked the scape.

    So distancing the driver(inserting foam) from ear gave a small natural decay to center mids and center high mids and increase the scape( alittle bit hollow to make phantom sound experience)

    Guys thanks a lot that modder do exist to dynamics tooo

    Because i was fed up with orthos and want to do something innovative to dynamic community(limitation to sq but sounds great if done propey)
     
  7. dhruvmeena96
    Mastermech 7777, man i rock in explaining(if everbody gets the point of larger surface area and air molecule trap) but kimLaroux dont use polyfill inside headphone as they are not subwoofer and dont move that air, so i am suggesting loose cotton.... hehehe
     
  8. Zounds
    Thanks so much for the SRH440 mod suggestion.   Could you make your instructions a bit more clear?     A pic maybe?     How's the treble response?   Thanks very much.
     
  9. dhruvmeena96

    can you post the pics of your m50....i want to do it with m50x but have not opened it yet.

    Is it the centre hole when we open it. Well i want it to open up as they sound intimate. Will this ruin the SQ or improve it
     
  10. dhruvmeena96
    well sire....i want to ask that if i remove foam, is there any increase of resonance as the foam is inserted there to damp any resonance in the beginning.

    Well is it worth it.

    The proble with my m50x is 120hz dip which make bass boomy(it is flat but 4dB to 6dB 120hz dip make bass sound boomier and looser) and a 5dB 2k peak which make sound a little intimate, engaging but at sacrifice of soundstage.


    If these two issues are solved....m50x can throw any head phone out of the water.

    Well i am using hm5 pad with 32hz equalised to be 9dB up just to compensate sub bass..
     
  11. dhruvmeena96

    sir how much boomy bass is reduced and how much soundstage improved. Is it worth removing as per calculation

    If fundamental tone is 331hz then resonance overtone will go to 4160hz. So if 120hz is fixed by this, it will raise 2khz making it sound little forward. But if the back felt is doing its work perfectly after removing the foam plug.....then it is wortg for me.


    So i wanna ask, that does it improve depth as i am satisfied with the width.

    If it does imorove bass linearity

    Please answer these question sire...


    Is it worth on m50x
     
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