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Beyer DT880/DT250 hybrid

Discussion in 'Headphones (full-size)' started by mdr30, Nov 7, 2010.
  1. MDR30
    Let me introduce a sweet sounding, balanced and universal headphone.
    A few months ago I bought a DT250 (€12) with a broken yoke to use for spare parts for my regular pair. It turned out everything else was in working condition. The cable came in handy for my DT48, but what to do with the drivers? Much later I remembered that I had a pair of old non-working DT880 lying around somewhere. A bad deal from German e-bay – the DT880 and two portable CD-players for €45, nothing working. Someone had poked inside the cups, ruining the drivers that probably were burned out. Would the DT250 drivers fit? There was only one way to find out…
    As I’ve never opened a pair of DT250 before, and haven’t seen it dismantled, I carefully unscrewed the baffles. The drivers looked similar to the DT880s for sure, I just had to figure out how to remove them.
    Wasn’t so hard. First I unsoldered the cables, then removed the soft glue locking the driver:
    I turned the driver anti clockwise a few millimeters:
    As you can see the drivers are similar, close to identical. The DT880:
    The DT250:
    Same size and same diaphragm. The old DT880 drivers were probably 600 ohms, the DT250 drivers are 80 ohms. There’s also a difference in the shape of the holes in the driver frame, but that probably doesn’t affect the sound much. [Edit Aug 2011: it does, it's a 100-200 Hz bass increase with the DT250 drivers.] The diaphragm has a slightly sticky feeling, with the typically structured surface.
    I had to remove the three pegs on the circumference of the drivers however, as the old DT880 drivers were just squeezed and locked in place. No problem with a small, sharp file. When securely in place, I fixed the drivers to the baffle with three dabs of hot glue:
    I wanted a straight, not coiled cord, so took a 3,5 mm interconnect cable from Thomann (€2.50) and cut it to the preferred length. The hardest part of the modification was to force the somewhat too large diameter cable through the rubber collars in the cup. Some lubrication did the trick. Different sizes of hot shrinking tubes were used to fit the cable in the cable lock of the cup and finally to the driver terminations. Then the baffles clicked into place, with pads from an old Philips headphone.
    The first version DT880 is very simple – a few plastic parts, a soft headband, decorative but fragile aluminum grilles, thin paper on the inside of the cups and a piece of felt covering the outside of the baffles. The yoke's joint to the headband often cracks on the old DT880, as it had on my pair, but some super glue gel (clamped over night) seems to work:
    Cheap and plastic it may look, but the sounding results are stunning. Much work must have been put into the construction and tuning. I guess the felt in front of the driver dampens high frequency resonances and makes for a smooth treble (I wonder if this is a special wool blend), resulting in a distinct and transparent sound throughout the whole spectrum:
    I don’t think Beyer exaggerated when they claimed to have created “electrostatic” reproduction from a dynamic headphone in 1980.  I mean the driver is still produced basically unaltered to this very day!
    I haven’t been able to compare my 80 ohm DT880 to the latest 600 ohm version, but these old, light, properly burnt in and comfortable cans are more than satisfying. In fact they sound great.
    (3,5 mm plug with 1/4 adapter)
    Listening from Clip+, D2+, Technics portable CD-player, Millennium HP1 headphone
    amp, music from baroque and classical/romantic/modern to 1950s/1960s jazz, Sinatra, Burt Bacharach, Steely Dan, Zappa, Eno, rock, Jaga Jazzist, easy listening etc.
  2. Zombie_X Contributor
    Very nice!! I never tried the DT250 before and this mod makes them sound a little enticing [​IMG].
    Any chance you would be willing to loan them out at all? I'd like to ass them to my comparison thread on beyers.
  3. MDR30
    I live on another continent so it's a bit difficult for me to let you loan the headphones.
    One advantage with the 80 ohm drivers is that I can use the DT880 with my mp3-players. Not bad.
  4. AncientWsidom
    That is so cool! very impressed...
  5. Amarphael
    great work man, photos too. electrostatic-like you say... i'm intrigued. How's the bass going?
  6. markanini
    The DT250's seems to have a very smooth responce in all measurements I've seen, ie less peaks and dips so from that perspective I see what Beyer are getting at. The 80Ohm and 250Ohm are worlds apart, though. The 80Ohm have subdued highs and eleveated bass, the 250Ohm are extremely flat. Curious that the drivers are a direct fit in the 880 cups. Thanks for sharing.
  7. Grev
    Did you measure the diameter of the driver?
  8. MDR30
    44,8 mm diameter, diaphragm effective 40 mm.
    I'ts true that the 80 ohm DT250 has fuller bass, but the treble - both in my hybrid and the original version, is not lacking. Graphs:
    The 250 ohm version has a slightly rolled off bass and is probably quicker (like the 600 ohm DT880) which makes for cleaner highs. It's also possible to tune (decrease) the bass of the DT250 driver by covering some of the 12 holes at the back of the driver with tape - the DT880 has 8 holes.

    The bass is fuller than the original DT880, making for a warmer balance. It starts singing at 30 Hz.
    I've since I started this thread acquired several headphones, including the original 600 ohm DT880 from the 1980s. These days I listen more to the AKG K500 and different orthos. The DT250/880 hybrid is a fine headphone, warmer and more immediately appealing than the DT880. It's not as ethereal as the DT880, but it doesn't have the 10 kHz sibilance issues of that headphone either.
    I initially used old Philips velour pads, softer and flatter, which in some ways was the best solution. Experimenting with Beyer's own velour and pleather pads is worthwhile.
  9. MDR30
    Someone asked me about the headband strap: it's available from Beyer, costs 5 euro and - together with fresh earpads - makes an old headphone look like new. Upper one new (no logotype), lower one old.
    And in place.
  10. eimis
    So the red marking indicates positive terminal?
  11. eimis
    ...Yes, it does. Interestingly, every DTxxx driver has different polarity, seems like they check polarity once the driver is fully assembled. And they don't always mark it on the driver, so I use my bench PSU limited at 50mV and 1mA to determine driver polarity. If the diaphragm moves outward, away from the magnet - your PSU polarity matches driver polarity.

    I got an old beatup DT770 600Ohm and put their drivers in my DT990 LE. They sounded incredibly fast with deafeningly loud treble and quiet (sub)bass. Then I put a few layers of toilet paper which tamed the highs but made it sound unenjoyable overall.
    Then I put DT250 250ohm drivers in the DT990 without any paper, just the black DT990 filter. The main characteristic sound of DT250 remains, with more treble, less but faster & higher quality bass, maybe a little recessed mids, wider soundstage and without the closed-in feel. It's actually a pleasant sound. And the bass does go very low, 30Hz is audible and doesn't sound distorted.

    This makes me think that Beyerdynamic could easily use the good old DT990 enclosure and put some nicely voiced driver in there, with that pleasant FR curve for example and create an affordable audiophile can. But nobody's enthusiastic enough...

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