For those that find the HD650 too dark...

Discussion in 'Modifications and Tweaks' started by cskippy, Oct 11, 2016.

  1. cskippy

    cskippy Creamy warmpoo

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    Here are the mods that I've done, in addition to the coin mod and rear felt removal, based on @stratocaster mods from Changster.

    Felt ring (no change in frequency response but helped with distortion):
    [​IMG]

    White bloomy thing is the cotton nail polish removal pad and then there is some protective foam I pulled from the top of a mic box (different foam did make a noticeable difference in frequency reponse so YMMV):
    [​IMG]

    Stock vs modded frequency response:

    [​IMG]

    Stock Waterfall:

    [​IMG]

    Modded Waterfall:

    [​IMG]

    Stock CSD:

    [​IMG]

    Modded CSD:

    [​IMG]

    Subjectively they come across as more mid forward due to the reduction in the mid bass hump and the flattening of the 2kHz dip. However, they also sound faster because there isn't this bloat for lack of a better word presenting itself in every song. Another benefit of reducing the hump is that sub bass becomes more present as it's no longer tapering off at the same degree as the stock HD650. These still aren't perfect as I feel they are missing some sub bass and roll of the high end a little too much especially after 10kHz. They still remain the most speaker like headphone that I have heard and are only bested in frequency response by my modded HE-6. Imaging and depth remain largely the same however some things like vocals are pushed slightly closer due to the 2kHz flattening. I personally like this as I use these as my alternate reference headphones and want a totally flat sound for mixing.
     
    Last edited: Oct 12, 2016
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  2. Mdkaler

    Mdkaler Friend

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    Nice work!
    So the modded graphs are with the felt ring and white foam only and no other mods?
     
  3. cskippy

    cskippy Creamy warmpoo

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    Thanks for asking. I did do the coin mod and rear foam removal but still felt they were too dark. I updated the first post to include that.

    The easiest way to do this mod is to get the nail polish removal pad and some very porous foam to hold it in place. I'll add which nail pad it is when I can.
     
  4. Garns

    Garns Friend

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    Do you still have the spider in place?

    I ask as I tried your mod a couple of weeks back but with the spider removed, as on my pair, it seems that the nail pad fully seals the magnet vent, killing the bass entirely. I rigged something else based off this up that seemed to have good effects, but maybe I was doing yours wrong...
     
    Last edited: Oct 12, 2016
  5. Serious

    Serious Inquisitive Frequency Response Plot

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    You can reduce the mid-bass hump, 2kHz dip and 5kHz resonance by putting stuff behind the driver hole. Try something thinner if you lost all the bass. The problem is this also damps transient response. Personally I don't like what it does, but the graphs sure look nice. Due to the reduced mid-bass hump, the bass extension measures similarly to the HD800, but it doesn't sound as extended.
     
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  6. cskippy

    cskippy Creamy warmpoo

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    @Garns yes, I still have the spider in place.

    It really depends on the materials used. Even flipping the cotton pad as it has two differnt sides, one soft cotton, the other a mesh type material has an effect. I'll try and find an easily bought foam and nail pads to add to the first post so others can try.

    @Serious Yeah, I suppose it does damp the transient response some but I'm kind of over technical abilities if the sound isn't right. I have A/Bed back and forth and it's not significant enough to worry about. Plus, pair it with the Jotunheim and you still get lightning quick response.
     
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  7. Garns

    Garns Friend

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    Good, thanks - sounds like my cotton pads are different to yours, both sides have some kind of meshy covering. I may hunt out some others that are closer to what you describe.

    Your measurements look great - I am totally down with the project of getting the midbass a bit more even. Right now I have 1/2" open cell foam, in the same position you have, but cut to a smaller radius and with a hole punched through the middle over the rear magnet vent. So the vent still has a straight shot out the back. Like you, I hear a more balanced tonality (midbass certainly down) and I don't really perceive any loss in other departments.
     
  8. gixxerwimp

    gixxerwimp Professional tricycle rider

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    This reminded me I have "Life Saver" size foam rings from my initial modding attempts. I stuck them behind the driver hole, held on by the exposed bits of Dynamat tar. The mid-bass (and possibly bass overall) is slightly reduced but what I like even more is that the bass is much cleaner now and not as bloomy. Different low freq instruments don't wash out as much into each other.

    Prior mods: rear foam and spider removal, Dynamat Xtreme, nickel-size coin mod.
    [​IMG]
    [​IMG]

    Will try the felt ring on the back of the baffle and maybe rug liner again on the front side to see if it helps with the grain in the treble.

    I'm going to post about this in the Love/Appreciation thread, since that's where most of the mod talk is.
     
  9. cskippy

    cskippy Creamy warmpoo

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    Here is the pad that I've been using. It must be old as hell because I can't find it anywhere! I would just use a cotton facial pad and use as much as needed for your tastes. I would pull them apart, in half, and pull the cotton stuffing out so it was just the outside material. For this mod, I did use a full cotton pad but the driver could breathe through the sides since it wasn't a perfect seal. Any open cell foam should work as a holder, heck, the foam that comes with the box might be just right.
     
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  10. cskippy

    cskippy Creamy warmpoo

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    Here is V2 of the mod:

    Full mods are front quarter mod, rear foam removal, rear spider removal, HALF a cotton pad using the more porous side, Sennheiser stock foam inside box. This keeps more of the frequency response the same but attenuates the midbass bump down ~3dB. Different thickness of cotton attached to the pad would affect the quantity of bass attenuation. Too thick and it would kill the bass. Too little, and there would hardly be any effect. I would error on the side of too little and adjust to taste.

    [​IMG]

    Stock Waterfall
    [​IMG]

    Modded Waterfall
    [​IMG]

    Stock CSD
    [​IMG]

    Modded CSD
    [​IMG]

    Stock Impulse Response
    [​IMG]

    Modded Impulse Response
    [​IMG]

    I'll let more knowledgeable people chime in on this but I find the impulse reponses fascinating. It would seem that after the initial response the driver takes a while to get back to neutral. Modded Has an almost identical initial response but the overshoot after is less.

    For those that try this mod, feel free to share your impressions!
     
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