HD650 KISS mod

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

  1. purr1n

    purr1n Desire for betterer is endless.

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    TEMPLATE UPLOADED!

    All art, instructions, material selections and information in this post and following posts (collectively the "SuperBAF HD650 KISS mod") are covered by the Creative Commons Attribution-Sharealike 4.0 international license. Any derivative work may be sold as long as instructions and art are distributed freely and correct attribution (mention of the name of the mod, SuperBAF, and a link to this thread) is maintained.


    HD650 KISS Mod
    (Keep It Simple Stupid)

    MATERIALS LIST
    1. Dynamat Extreme
    2. Creatology Adhesive Foam
    3. Foam disc (included with HD650, 3 per side after peeling them)
    TOOLS NEEDED
    1. Needle nose pliers
    2. Scissors
    3. House keys (use to prop open the grills from the side)
    This is going to be my definitive HD650 mod guide. Yes, there is already a dedicated HD650 mod thread here: http://www.superbestaudiofriends.org/index.php?threads/sennheiser-hd650-love-appreciation-thread.44/

    And an index to the mod variations and forks here: http://www.superbestaudiofriends.or...ve-appreciation-thread.44/page-63#post-100789

    The reason I am doing this because I have gone through it all and distilled the knowledge to something SIMPLE while finally reaching all of the the goals I originally set out to achieve. I love making things simple and cutting out all unnecessary BS. This mod addresses a minor side-effect of the original set of mods with the spider and back damping foam removed: a slight increase of a few db in the mid-bass. I don’t really find this slight increase in bass necessary. In fact, I kind of wanted to reduce it to HD600 levels. In essence, I wanted an HD600, but without the HD600s minor emphasis around 2-3kHz (which seems to drive @Hands crazy), and with the HD650's more refined character.

    Frequency Response Differences: Stock, older HD650 mod, KISS mod
    HD650 mods.png

    Note that differences are exaggerated with compressed Y-axis.
    • GREY = STOCK
    • ORANGE = HD650 original mods with front damping removed, rear damping removed, spider removed, an damping material applied on magnet
    • GREEN = KISS mod HD650
    Finally, the removal of the spider secure the foam (and magnet) down might result in the magnet falling off. It turns out that depending upon temperature or related atmospheric conditions, the magnet can actually fall out of the housing. This mod works with the friction fit and makes sure the magnet stays on. I originally thought the magnet might have been glued in and that the removal of the spider wouldn’t affect anything, but it turns out I was wrong. Be sure to press the two Dynamat side-strips covering the magnet / housing down with some minor pressure for a secure fit.

    Here is a picture of the KISS mod. The red Xs mark all the items that are UNNECESSARY or have a minimal affect. I would not bother with them. Out of all of the tweaks, the biggest improvement to the HD650 will be the application of dampening materials to the magnet. Only the application of the Dynamat / Creatology sandwich on the locations marked in the green Ys are necessary. I also DO NOT perform the quarter mod as I did not find it necessary running this out of the Jotunheim.
    20161206_074631.jpg

    Note that I am no longer using a donut on the magnet, but instead two large strips. This is for two reasons: 1) Keeping the cuts simple; 2) Making sure the magnet stays on the frame.

    The Creatology layer of the sandwich with the Dynamat Extreme is not necessary. It was done for two reasons: 1) Cosmetics; 2) Ease of marking and cutting through the Dynamat and its sticky gunk. The Creatology Foam part of the sandwich tends to help clean up the gunk on the scissors.

    One of the foam discs is folded in half into a crescent shape and applied directly on top of the magnet cover the hole. I used dabs of the Dynamat gunk to secure it in place (alternatively super glue might work). Be sure to lightly press a part of the foam (about 1/2 mm of it) into the hole of the magnet. It doesn't need to be perfect, but the foam does need to be flush / very slightly inside the hole. DO NOT get any gunk into the magnet hole and have it fall onto the driver membrane. Make sure the Dynamat does not cover any part of this hole. The driver really needs to breath, otherwise you will end up with something sounding like a Grado.


    Here are some additional notes for this mod.
    hd650 mod step 1.png
    hd650 mod step 2.png
    hd650 mod step 3.png
     

    Attached Files:

    Last edited: Dec 6, 2016
  2. zerodeefex

    zerodeefex SBAF's Imelda Marcos

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    Zomg, wait, did you just make an HD600++? f**k, going to get this done ASAP.
     
  3. Serious

    Serious Inquisitive Frequency Response Plot

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    So this time around you did go for additional back vent damping? I used to run my HD600s with a relatively open felt behind the magnet opening to reduce the bass to modded HD800 levels, but I felt it hurt clarity, openness, transient response, etc. The positive side-effect is that it also seems to almost completely eliminate the 5kHz resonance when done right.

    Another thing to try (which is hard to capture with coupler measurements): Put the right kind of felt underneath the pads. Seems to work relatively well in reducing the 3-4kHz emphasis. The right pads are important for good sound.
     
  4. AMW1011

    AMW1011 Friend

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    Kind of looks like an HD580's frequency response to be honest. I don't object to that one bit.
     
  5. purr1n

    purr1n Desire for betterer is endless.

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    The back venting is effectively two layers (one layer folded on itself) of the original three layers of foam. Without any damping, mid-bass is at its highest. I thought I would get stock HD650 levels, but it turns out to be a tiny bit less than stock HD650 levels, which is perfect, and as @AMW1011 said, kind of like the HD580, which happens to be my favorite Sennheiser out of the "6X0" series. My suspicion is that pushing the foam into the hole a slight bit helps reduce the bass from stock levels, while having only two layers helps with transient response. But again, I really do feel the main difference here is damping and securing the magnet to the frame. This really seems to improve the speed, focus and microdetail.

    I will try to repeat this experiment on the HD6XX, but not anytime soon. Headed overseas again. If anyone knows of any good xiao long bao places in Dubai, please let me know.
     
    Last edited: Dec 6, 2016
  6. Psalmanazar

    Psalmanazar Most improved member; A+

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    Measurements look a lot better than the original mod. I tried @Ryu 's pair of HD 650M last weekend and it was just too bassy and the cleaning up/"hardening" of the bass just made it worse. Also the 11-12 ish khz recession even worse with cymbals which is my main complaint about the stock HD 650 treble.

    HD 580 and the black felt HD 600 have the best balance of bass to treble but sound too veiled to me compared to the modern silvery iterations. Brand new HD 650s with clamp and new pads are still my favorite overall as I can only really tell the bass levels ABed as the amount of bass is more dependent on the age and wear of the earpads than headphone model. I really want to try to the KISS mod.
     
  7. chakku

    chakku Friend

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    Any CSDs/Distortion comparisons?

    Looks like I've got something new to try when my 6XX arrive
     
  8. Serious

    Serious Inquisitive Frequency Response Plot

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    @Psalmanazar Just try replacing the back foam with a few different materials. As you can see in the measurements, it makes a big difference how much it obstructs the vent/how far it goes into it. Very easy to mess up channel imbalance that way. In this case it's all personal preference. Even though I'm a neutralhead and hate the emphasized mid-bass response of even the HD600, I still preferred leaving the vent open, at least with no extra dynamat on the magnet. I will have to try again with some dynamat on the magnet, but those mods won't turn the HD6X0 driver into the HD800.

    @chakku CSDs will most certainly look better. FR looks smoother. Distortion will be the same at the same level, which means it will be less as the bass levels are reduced. In that case it's a matter of how we look at the measurements. Against the harmonic frequency as a reference, the distortion will probably look the same.
     
  9. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Might not be as good as the original. My wife says the one in Qingdao isn't the same, maybe cuz they ship stuff over from Taiwan fearing the mainlanders will steal the recipes.

    I've got something similar with 1 layer of slightly more open foam stuck to tar on the inner circumference of the Dynamat donut, not flush against the magnet, but sealed fairly tightly to the Dynamat. Do you think this makes a difference (the not flush part)? I'll try inserting another small disc of foam underneath and see how it sounds.

    This is what I have now but without the hole in the foam.[​IMG]
     
    Last edited: Dec 6, 2016
  10. purr1n

    purr1n Desire for betterer is endless.

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    Very cool. I am close to it.
     
  11. bigfatpaulie

    bigfatpaulie Tried to screw other friends while playing victim

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    Step 1 - "Finally, the removal of the spider and..."

    Hunh?
     
  12. Yeskey

    Yeskey Friend

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    Alright where in the world did I put those foam disks?

    edit: Found them, but apparently I only got two foam disks per driver.. Weird.
     
    Last edited: Dec 6, 2016
  13. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Covering the baffle ports didn't have a significant effect?
     
  14. Merrick

    Merrick A lidless ear

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    Crap, I think I threw my foam discs out. I've currently got the damplifier donut on there.
     
  15. purr1n

    purr1n Desire for betterer is endless.

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    Ravi might be writing down step by step instructions. Step by step instructions are super time consuming and I might not have the time.

    Nope. I'm not even sure they are really baffle ports, at least ports that actually breath through. The ports would seem occluded by the screen and then the pads. I'll double check the procedure with the HD6XX.
     
  16. shipsupt

    shipsupt Admin

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    Marvey, any chance you can lay a stock 600 FR on top of this one for a comparo? I know you're bored and have nothing better to do!
     
  17. Serious

    Serious Inquisitive Frequency Response Plot

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    Actually I think those are the main reason why no screen will give you less bass. With the stock foam covering them it will probably not have as much of an effect.
     
  18. purr1n

    purr1n Desire for betterer is endless.

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    Nope. I would need to go to EC labs, steal Craig's HD600, put new pads on them, measure them, take them back to the lab so Craig doesn't get pissed. Then I have to perform final evaluations on the Holo DAC. Then I got some other secret audio shit going. I have to finish the Batman Tumbler Lego tonight. And I need to level up my Pokemon in 3DS and finish off the final four so I can start breeding 5 / 6 IV Pokemon so my son and I can duel each other with more powerful Pokemon. I have never lost to him in any of our official duels, but he is getting better. Eventually he will outsmart me strategically or not make any errors to beat me. He already knows the type strength / weaknesses chart a lot better than I do. Then I need to buy two other preamps to compare against Freya. I need to ship my Nikon for a banding issue that was caused by their last repair job. I need to find my passport too. Then finally I would like to sit down and listen to my records for pleasure, rather than for this site. And I need to start the small Fostex driver speaker builds.
     
  19. shipsupt

    shipsupt Admin

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    I don't get it, sounds like you have the time?

    If figured you might already have 10 different stock 600 measurements that you could grab. No worries, I'll do it the old fashioned way!
     
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  20. purr1n

    purr1n Desire for betterer is endless.

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    Hmm. Let me check.

    Take with grain of salt because HD600 pads were worn. Also taken years ago.

    BLUE = HD600
    GREY = HD650 KISS
    HD600 vs KISS H650.png
     

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