HD250 Linear MK1

Discussion in 'Headphone Measurements' started by ultrabike, Apr 26, 2016.

  1. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    9,609
    Dislikes Received:
    19
    Trophy Points:
    113
    Location:
    Irvine CA
    @Cspirou visited and brought with him this collector item. These are not the somewhat easier to find HD250 Linear II but the original Linear MK1 from Sennheiser. These seem indeed a bit hard to find, and I think @Cspirou got a great deal out of them.

    [​IMG]

    These seem to be from the early 80s, and this goes to show that durability was not crap then. The pads are replaceable. The impedance I was told was in the 600 ohm range (didn't check) and the headphone cable seems custom and designed to be connected in parallel with other similar headphones. This may explain the need for high impedance. The sensitivity is also quite high as I was able to drive them to 90 dB with my 2i2 w/o going past 12 o'clock even with such a high impedance.

    They are a bit shallow in the cups and discomfort may arise if ones ears touches the insides of the cup. Pressure is not an issue, but these are rather old cans. Even so, seal was not too hard to attain.

    The sound it's rather balanced and isolates decently. These seem to be monitor closed headphones and they sound like such. I felt they were a bit edgy with some songs, but not too much. They are also somewhat warm and pleasant. However, they really shine with certain kinds of songs. Specifically, @Cspirou pointed me to some of his favorite tunes, and I felt these cans sounded fantastic with such material.

    Here are some further impressions from his majesty's site:

    http://www.head-fi.org/t/603099/sen...2-hd450-hd480-ii-hd480-classic-and-surrounder

    Anywho, here are some measurements:

    Frequency Response

    HD250Linear_fr.png

    Distortion Right

    HD250Linear_Dist_right.png

    Distortion Left

    HD250Linear_Dist_left.png

    CSD Right

    HD250Linear_CSD_right.png

    CSD Left

    HD250Linear_CSD_left.png
     
    slankoe, Dino, Cspirou and 3 others like this.
  2. Armaegis

    Armaegis Friend

    Friend BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    4,233
    Dislikes Received:
    2
    Trophy Points:
    113
    Location:
    Winnipeg
    Early studio headphone distribution amps were literally just a simple power amp with a whole bunch of jacks wired up in parallel off the output. A high power high temperature trim pot would be placed in front of each jack to control output. A high impedance headphone would be required in order to limit how much current was getting passed through the pot and to debatably get a more linear response from the pot depending how it was wired up.

    Of course, in situations where headphones are being daisy chained in parallel without individual pots on each, then yes you want a very high impedance on each headphone so that the resultant load isn't too low for the amp.

    600 is a nice big number, and also a holdover from the old radio transmission standards (pretty sure tube amps were part of the equation too since that's the era it was developed).
     
    Deep Funk, slankoe and ultrabike like this.
  3. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    Thanks for letting me watch! It was a really educational experience to see how the measurement process works and I'm glad to finally see how these measure.
     
    ultrabike likes this.
  4. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    Well there goes this pair. The right driver gave out. :( Not likely to find a replacement since these were discontinued in 1992. Good thing I bought these used for cheap.
     
    Last edited: Aug 29, 2016
  5. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    9,609
    Dislikes Received:
    19
    Trophy Points:
    113
    Location:
    Irvine CA
    Sorry to hear that @Cspirou. Is it something you can fix, like a loose wire or something like that?
     
  6. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    I'll need to investigate, hopefully it's a wire I can reconnect.
     
  7. Armaegis

    Armaegis Friend

    Friend BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    4,233
    Dislikes Received:
    2
    Trophy Points:
    113
    Location:
    Winnipeg
    ultrabike, Cspirou, Deep Funk and 3 others like this.
  8. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    These are still the best closed headphones I've tried so far. Not the most comfortable, but the pleather pads the seller is including might help with that.
     
  9. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    4,272
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    Vancouver BC
    Sold :D

    After some listening, will think about modding along the lines of @stratocaster 's tweaks to the mk2 (which is what got me interested in these in the first place).
     
    ultrabike likes this.
  10. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    4,272
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    Vancouver BC
    Yep, no shortage of ohms:

    [​IMG]

    The plug is Sennheiser's PX1 stackable-DIN thing, as in Fig 2 here (PDF). The cable is obviously original and has gotten really stuff and unwieldy, but luckily 6x0 2-pin plugs fit in the cup ends, and having a 2m HD6XX cable spare I've substituted that.

    Only had a quick listen so far, but I think they have possibilities. Bright in the treble, so will have a go at some front filtering; but the replacement pleather pads (Brainwavz, I think) put on by the previous owner seem to have eliminated the 200 Hz dip.

    Measurements are pretty rough. The bass roll-off is more a function of my 'head' geometry than reality, I'll need to play around with it a bit more to get it satisfactory. Ref at 80 dB because otherwise those treble peaks will clip in my system, and the poor little Nano BL didn't have a lot of room left...

    [​IMG]
     
    ultrabike likes this.
  11. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    Oh these need some voltage for sure. I find myself near max on weaker amps
     
  12. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    4,272
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    Vancouver BC
    Heh - yeah. Listening was on Magni (where these will live) on high gain. Nano is for listening from the computer and for measuring.

    Did you manage to fix your pair?
     
  13. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    5,695
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    Nope, i have one functional driver. I opened up the other one and it requires some surgery that I'm not skilled enough to do.
     
  14. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    4,272
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    Vancouver BC
    Been playing with these. The pleather pads they came with had a very hard ridge that became annoying after not very long, so I replaced them with Brainwavz large round velour ones - after which they started looking like ultrabike's measurement of Cspirou's stock pair. Here they are with an extra layer of 1/16" felt inserted in front; note the return of the formerly missing 300 Hz dip:

    [​IMG]

    Following @stratocaster , I experimented with rear port damping, removing the dual-tube plastic insert and replacing it with, eventually, 1 layer of thin open foam and 1 layer of felt. Here's the result, with the addition of 1 ply of toilet paper in front to further calm the treble:

    [​IMG]

    The drop in the bass isn't quite as extreme as it looks (head geometry), but is certainly more than ideal. It could probably be improved, but I was focused on trying to even out the mids as much as possible, and they're sounding pretty good now.

    Spectral decays left & right:

    [​IMG]

    [​IMG]

    I might work more on the bass port to see if I can bring back some low bass without funking up the mids too badly. Content to listen for a while now though.
     
    E_Schaaf, m17xr2b and ultrabike like this.
  15. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    4,272
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    Vancouver BC
    Thread necro 'cause it's Sunday morning.

    Shure SRH pads fit these too. They look a bit odd because they're oval rather than round, but with a bit of trimming of the skirt they go onto the plastic former/clip ok.

    SRH840 pad (pleather) in green, Brainwavz round velour pad in red. Other mods as described in post #14 above with the omission of the layer of felt in front of the Shure pad (there's already foam in them). Probably should include it though because...

    [​IMG]

    Right channel only because clumsy oaf broke the lead-out wires on L, so I can't give a useful subjective comparison. When both were working (post #14), I didn't think the bass rolloff was as extreme as it appears; my coupler seems to do this with closed-backs.

    The Shure pads also give a lower-treble spike vs stock pads on Fostex T50RP. Cannot recommend.
     
    spwath and Lyander like this.

Share This Page