My Super Janky "HD850" mod

Discussion in 'DIY' started by tommytakis, Mar 23, 2021.

  1. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    Had some free time since ETA Genesis design is mainly finished so I thought I go back to my unfinished "HD850" project, which was mainly inspired after @Bill-P showing that it can be done.

    I think the most challenging aspect was figuring out how to fit the damn drivers into my design because of its diameter changing every few millimeters. What I came up with is a converter ring that holds the drivers in a uniform depth so I can easily just push the drivers inside my 3d printed housing.
    [​IMG]
    For the enclosure, I took what I learned from working with @E_Schaaf and made a Genesis-like enclosure that uses similar techniques for the front. For the rear, I had some really dense foam cutouts for fostex TH900 mod that Ev gave me long time ago and somehow ended up fitting it quite well along with good sonic improvements. This is a very rough prototype so had some printing issues but doesn't bother me since it's just aesthetics and this will most likely be a one-off thing I do for fun.
    850 inside.jpg
    Bill actually shared one of his STL files for his older iteration of the mod for me to tinker with. It's super clever how the driver just clicks into place, but I didn't like how I am stuck with using only HE90 pads. So I made a pad ring that can fit most circular pads in the market. I'm currently using the pancake pads for its linearity in treble. I've also made my enclosure to fit any 6x0 headband for convenience sake since I have 2 pairs of Senns that I keep in my daily rotation.

    OK so how does it sound?
    hd850 .jpg
    Chacha's miniDSP EARS I'm borrowing right now is fickle and is choosing not to work with me so this is mainly subjective impressions but brief because... well it's my mod so feels weird talking about it myself. Maybe Ev can measure it for me some day, not a high priority though.
    - tonality wise, it's closer to 6x0 now than the hd800 since I removed the drivers from the cursed enclosure. No idea how it'll actually measure, just how I hear.
    - good dynamics, a little lacking on the sub-bass department like typical openbacks, but better than hd800/800S. macro- and micro- contrast don't feel lacking. I might keep this janky pair as a complement to ETA Genesis.
    - clarity is a step or two above 6x0
    - staging feels more natural than hd800 but if you're a big fan of headstage, hmm maybe you'll be disappointed. I would say it lies closer to 6x0 staging but not 3 blob-y. Sometimes instruments can come a little close but who cares, it's headstaging lol
    - overall resolve feels competent, at least source revealing. Sounds great with SW51+ where I found the hd800 lean and still kinda bright with sw51

    I'm no professional modder so not sure how far I'll get with this mod, but since bitch-ass Sennheiser won't make HD850 so I guess I'll keep working on this myself.

    Thanks for reading through my rambling nonsense, I'll try to post updates regarding this whenever I can. :) I had ZERO experience with CAD, I just kinda learned as I went, so I'm sure anyone can do this with a little 3d printer and a computer. If any SBAFers want some pointers from me, just ask away! I'm always happy to help out
     

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  2. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    Modded hd600
    [​IMG]
    Modded hd580
    [​IMG]
    HD850-Jank v1
    [​IMG]
    Ok some rough measurements, figured out how to used ARTA thanks to @E_Schaaf and @rtaylor76
    (SBAF Comp-R with miniDSP EARS)
    I'm having trouble getting a good seal rn so bass gradually rolls off like this. Really not this bad when you hear it. I already made some revisions for the next version to get better seal

    [​IMG]
    I blame this odd shape of the drivers :(
    [​IMG]
    [​IMG]
     
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    Last edited: Mar 23, 2021
  3. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    [​IMG]
    @E_Schaaf suggested I try using denser foam in the front and make the driver distance closer by 1.5mm (6.5mm -> 5mm) so that will be my next goals
     
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  4. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Nice work!

    You mean the diameter of the round part of the HD800 driver housing isn't perfectly round? Or it has cutouts for the mounting screws or something.
     
  5. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    Tyty, driver housing
     
  6. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Wow, that's kinda bizarre that the driver housing is not round. I guess they wanted to make it difficult for people to DIY with them :p
     
  7. E_Schaaf

    E_Schaaf MOT: Upscale Audio; recovering HFM addict

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    all the cool kids run em naked! They are round, they just have this plastic bit that's unremovable so Tommy had to build around it. This bit is what's ruining the front seal and killing the bass but rev 2 should be fixed per the last images in the post above.
    upload_2021-3-23_21-8-42.png
    Just another angle
    upload_2021-3-23_21-9-2.png
     
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    Last edited: Mar 23, 2021
  8. 7seven

    7seven Rando

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    Can the naked driver still be reinstalled back into the plastic driver grill/housing?
    like without needing glue or anything?
     
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  9. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    HD850-jank v2
    -5mm driver distance
    - rear dense foam cell donut
    - fostex foam ring around the front
    - AP2k pads
    [​IMG]
    [​IMG]

    Using the dense fostex foam piece in the front along w revised design helped with the bass seal, and swapping to AP2k pads brought some of the uppermids up similar to 6x0 levels.

    As usual, big thanks to @E_Schaaf for the pointers!
     
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  10. Bill-P

    Bill-P Level 42 Mad Wizard

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    If you have time and would like to check it out, I can send my V2.99 over... (V3 doesn't exist because it's the other thing I promised I'd open source!) so you can have a reference. \/

    P.S.: that looks good! I should get around to printing out all of the stuffs I've worked on...
     
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  11. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    HD850-Jank V3.1
    - lighter/ more breathable front foam piece that was hand cut by @E_Schaaf
    - increased diameter from 71mm -> 75mm and added front circular vents (Similar to ETA Genesis)
    - There's a rear piece I still haven't printed yet, but already a major improvement in tonality, less pushed mids and more uppermids like Senn 6x0. Hopefully I can make that bass go straight down to 20hz w/ further revisions
    upload_2021-3-27_14-50-2.png

    @Bill-P said he'll send me his latest version of his mod soon so very excited to see how they compare!

    Some pad swap measurements: (Green is the diff pads)
    1. Pancake pads
    [​IMG]
    2. Random Circular velour pads from Blon headphone that no one wants to buy :(
    [​IMG]
    3. Perforated Leather pads from Accessory House
    [​IMG]
    4. ZMF Universe Hybrid pads
    [​IMG]
     
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    Last edited: Mar 27, 2021
  12. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    HD850-Jank V3.2
    - This is with the rear piece that just finished printing w/ a memory foam donut insert
    - swap back to the dense fostex front foam insert
    (also started doing 5db scale now as requested from 10db)
    V3.2 (green) vs. V3.1(yellow)
    [​IMG]
    [​IMG]
     
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  13. netforce

    netforce MOT: Headphones.com

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    Nice stuff Tommy! Glad to see the progress!
     
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  14. Taverius

    Taverius Smells like sausages

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    Nice work.

    I wonder where that 3k peak is coming from.
     
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  15. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Much of what I'm about to say, I can see you're already playing around with. But figured I'd share, just in case.

    In my experience, there is generally a tradeoff between bass extension and upper-mid response with this driver. More bass, usually more of a dip there. Treble may also suffer in terms of overall level and/or smoothness. (This is true to some extent with the HD6X0 drivers too, but their inherent design and enclosure get them closer to ideal right out of the gate.)

    The center of the driver, where the HD800S resonator sits, more or less acts like any other vented or breathable parts of a driver baffle you'll see on most headphones. You can cover this up to some extent to increase bass. You might be able to get away using this as your only baffle vent, but I imagine you'll have to find a mix of using this (somewhat or fully covered) and other baffle vents around the driver or under the pads.

    Otherwise, the usual tricks apply...more venting on baffle around driver, less bass. More breathable pads, less bass.

    My hunch is the HD800 driver will require a cup design somewhat like that of the ZMF open-back headphones. ZMF's open-back headphone are more semi-open, with something like a 70/30 or 60/40 split between open and closed. You get a lot of the benefits of an open-back, but the enclosure design isn't totally open. This also allows for strategic damping behind the driver or in the enclosure in general.

    That in mind, since increasing bass tends to mess with the upper-mids and treble, you may be able to counteract that through damping behind the driver.

    Another thing you could try is devising a headband and pad scheme that effectively turns the HD800 driver into something like a Grado or Porta Pro, limiting tuning down to the center baffle/resonator point and pads.
     
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  16. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    upload_2021-4-3_12-8-19.png
    [​IMG]

    HD850j v3.3 (green) vs. v3.2(pink)

    This is what I did in the rear with couple strips of micropore tape, and I really like how it sounds now. Eventhough more roll off according to measurements. Covering the rear hole definitely feels like the final piece of the puzzle I was missing. Thanks for the tip Tyler!
     
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    Last edited: Apr 3, 2021

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