HD650 KISS mod

Discussion in 'Modifications and Tweaks' started by purr1n, Dec 6, 2016.

  1. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Sorry, I may be being a bit thick here. I was asking about the small ports in the outside part of the plastic baffle Do you mean the silver screen surrounding the driver (don't think anyone has taken this out)? Do you mean the stock front foam?
     
  2. bigfatpaulie

    bigfatpaulie Tried to screw other friends while playing victim

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    Haha. No worries, I just thought it pretty funny. I can sort through the mods and make do.
     
  3. Dino

    Dino Friend

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    Not too weird. I remember posts from people having different numbers of foam discs under their spider. Mostly three - but not always. There was even speculation that Sennheiser might have used this as a tool to tune the sound of the drivers.

    I searched the word "foam" in http://www.superbestaudiofriends.org/index.php?threads/sennheiser-hd650-love-appreciation-thread.44/ but could not find these posts. Maybe it was in another thread or maybe I didn't spend enough time researching.
     
  4. kittenuwu

    kittenuwu Acquaintance

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    currently chaining for a 4 IV ditto atm too, just can't bring myself to do the whole 40+ in one sitting.

    I think there may have been an additional tweak to the HD650 recently. I bought my pair just a week or so ago from Amazon, and the rear foam only broke down to 2 discs, not 3. I saw some other replies in the main HD650 thread saying the same thing. This makes me wonder whether Senn came to the same conclusion you did re: 3 vs 2 foam discs... but maybe they just changed the thickness of the disks for ease of manufacturing or something. Seems like a weird area to mess with just to streamline manufacturing though.

    Either way, I'll give it a shot with one disk (not folded in half) covering the hole sometime later. I really liked the changes to the sound that taking the rear foam out brought, don't wanna totally reverse it.

    Was the foam being pushed into the hole just to ensure that the foam was tight enough around the inner radius that there weren't any large gaps for air to move through? If this is the reason, I'll try just laying a single foam disk over the hole and securing the edges with dynamat.
     
    Last edited: Dec 6, 2016
  5. Storytime

    Storytime Rando

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    Wow, this came at the perfect time--I'm literally in the middle of my mod, and was about to toss the foam disks! Gotta try this new version out. Thanks so much, Marvey

    One quick question about a point you made:

    Do you think the quarter mod would be worth it on a ZDS?
     
  6. purr1n

    purr1n Burned out

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    Try it without first. Depends on driver tube. if you feel you need more treble, start with a nickel.
     
  7. purr1n

    purr1n Burned out

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    On the foam discs, I just checked with this HD650, and it only has two. Another interesting thing: the 6XX and this latest HD650 has higher third order distortion in the bass than an earlier pair that I owned and performed the mods on. The foam discs don't change the distortion properties, but I am wondering if the drivers might be a bit different too.
     
  8. Yeskey

    Yeskey Friend

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    I threw the KISS mod on one cup and measured the results. Note that I use Sorbothane as an alternative to dynamat because Sorb's application is easier and dynamat is messy imo, but the results looks promising. the AKG foam is an AKG240 foam insert cut into an oval, dime modded, and fitted in place the stock pad.

    Range is -36 to 0 for emphasis
    RED: Stock front Foam + Sorbothane Dampening Ring
    YELLOW: AKG Front Foam + Sorbothane Dampening Ring
    BLUE: Stock Front Foam + KISS mod (Sorbothane Dampening)
    GREEN: AKG Front Foam + KISS mod (Sorbothane Dampening)
    [​IMG]


    Don't have Red waterfall for now, but I'll update later.

    GREEN: AKG Front Foam + KISS mod (Sorbothane Dampening)
    [​IMG]

    BLUE: Stock Front Foam + KISS mod (Sorbothane Dampening)
    [​IMG]

    YELLOW: AKG Front Foam + Sorbothane Dampening Ring
    [​IMG]

    Here's what mine looks like: (Oh no the pic's so large)
    [​IMG]
     
    Last edited: Dec 7, 2016
  9. GettingBuckets

    GettingBuckets Almost "Made"

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    That's definitely interesting. I went from the coin modded AKG 240 foam to the original stock foam because I felt like the 240 foam smoothed the upper region a bit too much, but maybe I need to retry.

    On a different note, any alternatives to the foam discs for the rear? Mine are long gone and destroyed.
     
  10. Yeskey

    Yeskey Friend

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    I actually sent an email to sennheiser support asking whether or not they stocked foam disks before I found mine. Will get back to you if/when they respond.

    EDIT: Holding the foam disks to a light source, it looks like they're the same stuff as the foam earpads. Color, density, porous design, material, thickness etc. I know Senn Uk stocks earpads for individual purchase. So for those who lost their foam disks, Buying and cutting ear inserts might work.

    Here's the foam ear pad UK: http://headphonespares.sennheiser.co.uk/hifi-tv-headphones/hd-650/foam-discs.html

    Massive pics incoming because idk how to use my phone.
    [​IMG]
    [​IMG]
     
    Last edited: Dec 7, 2016
  11. zerodeefex

    zerodeefex SBAF's Imelda Marcos

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    Trying to source HD6XX or pristine HD650s for not too much moola. I don't have the foam disks and I want to stay as faithful to the instructions as possible.

    If anyone would be willing to trade my modded HD650s + some cash on my side for their stock ones, please let me know.
     
  12. Serious

    Serious Inquisitive Frequency Response Plot

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    Sorry, meant the foam. I think cutting out the part of the foam that goes over these holes will give you less bass and lower mids, but I haven't confirmed myself.

    Removing the metal screen will give you no bass. Besnia replaced it with cork and Bill-P has done a lot of weird mods, but no screen will definitely ruin your headphone and give you no bass. The same thing could be seen with the HD800, where no screen gives you a 6db/octave dipole cancellation below 2kHz*. I think the HD600 driver has a higher Q and might try to push through the cancellation a bit more, but it's also smaller meaning that the cancellation will set in at a higher frequency.

    *Actually the frequency should be higher due to the driver size (4kHz with the metal ring?), but I guess the measurements looked like that because the microphone was in the nearfield for those frequencies.
     
  13. zonto

    zonto Friend

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    How does effectively reducing the rear damping from three foam discs to two foam discs reduce the midbass hump? Solderdude measured stock rear foam and a doubling of the stock rear foam, and the latter is what reduced the midbass hump (and subbass extension).
     
  14. Serious

    Serious Inquisitive Frequency Response Plot

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    The foam is partially in the hole. Even if it was only two layers, they closed off the hole more than the 3 layers which were just sitting on top of the hole.
     
  15. zonto

    zonto Friend

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    Figured. Your comment about channel matching is extremely important then.

    Seems like a better option would be to pursue Arctic Cotton or similar that lays flush on the magnet. More consistent results that way.

    Edit: There also other considerations here. @Hands has stated he thinks the less behind the driver, the better. Though this mod effectively reduces the midbass hump, we should determine whether re-damping results in the loss of other subjective benefits of no damping like loss of grain/strain, openness, sense of space, etc.
     
    Last edited: Dec 7, 2016
  16. MikeD

    MikeD Acquaintance

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    This mod looks a lot like returning a modded 650 to its stock form.
     
  17. zerodeefex

    zerodeefex SBAF's Imelda Marcos

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    Removal of the spider, the back foam, and mass loading the magnet is definitely returning it to stock form.
     
  18. Garns

    Garns Friend

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    I agree. Finding the right material is important. My experience is that most things I tried putting behind the magnet hole reduced bass, but also low-level detail and freeness of the sound. The Arctic Cotton sounds interesting, if it is constituted so as to do the former but with less effect on the latter (as has been claimed)
     
  19. zonto

    zonto Friend

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    In @MikeD's defense, he didn't say the KISS mod was returning the HD650 to stock form; he said it was a lot like returning it to stock form. I agree. Really the only difference here is the mass-loading and rear damping foam being slightly depressed in the vent, given:
    1. the stock foam pad is being doubled up and at least some HD650 pairs ship with two foam pads instead of three;
    2. the spider cage's functionality as a foam damper holder and magnet keeper-inner is now being performed by the mass-loader; and
    3. no coin mod.
     
  20. zerodeefex

    zerodeefex SBAF's Imelda Marcos

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    Don't be a smart ass. Mass loading the magnet is a pretty different tactic from previous mods and the move closer to the hd580 jubilee/old HD600/HD580 FR is a substantial change in the character of the headphone.

    @Marvey can we get CSDs?
     

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