DIY Planar magnetic heapdhones in details

  1. Garuspik
    Nice joke :wink: No, I've spent many hours finding rigid but ligtweight materials that aren't afraid of shock impacts.
    I have the biggest effective area of diaphragm ( ~50 sq. cm) and very massive double sided magnet structure. 14 pcs of 85*3*3 mm magnet blocks in each cup. Headphones won't be lightweight, but my target is 500 gr. Magnets itself weight ~200 grams.
     
  2. GREQ
    Did you have any success with single sided magnet structures?
    Or does that require a more complex type of magnet or trace design?
     
  3. Garuspik
    It's require exactly same circuit. Just remove one side of magnet structure.
    Sure I've made some experiments. Differencies are:
    - Lack of dynamics
    - less sensitive
    - double sided structure deliver much better punch and transient attack
    - minus 200 gramms :wink:
     
  4. GREQ
    Sounds similar to my experiment with the Audiotronic AHP66 (almost identical to Akai ASE-50) after taking out one magnet (since it's one magnet per side).
     
  5. chinsettawong
    Have you tried using other type of magnets? Perhaps you can find something with lighter weight and less magnetic force, but you can use thinner spacers to compensate for the lower efficiency. I remember you use 2 mm spacers. What if you can use 0.5 ~ 0.6 mm spacers?
     
  6. Tjj226 Angel
    This. Try a rounded cobalt bar magnet.
     
  7. WallofHooligans
    Bigger spacers also equals bigger bass characteristics though, so changing that could change the way they sound in another way. It could also change some of the soundstage qualities, but not nearly as much as the distance of the driver from your ears could. Still, worth a try.
     
    Garuspik likes this.
  8. Garuspik
    Exactly, my design moves a lot of ear. To do so I need big spacers. Benefit - big dynamic range and good bass extension.
     
  9. WallofHooligans
    Well, there are other ways to achieve similar results, you don't have to keep the spacers as far across. You can mess with the bass venting on the earpad side of the cans. If I remember correctly, reducing the size of the hole(s) in the baffle might help.
     
  10. Garuspik
    We have only one honest way to achieve good bass - move a lot of air. Yep, what you're talking about can be compared with bass reflex system in loudspeakers. But have you ever compared bookshelf speakers with bass reflex and big closed box speaker? Both can have 40 hz -3 db, but impression is totally different.
    That's a main principle of my design - big headphones that move large amount of air. In comparison with hifiman and Audeze I've managed to construct much bigger membrane in same size of cup.
     
    cskippy likes this.
  11. WallofHooligans
    Well, that's probably all true, but the difference here is in headphones, and not different sizes of speakers. Ask any fostex mk2 modder how to get better bass out of their cans, and they will give you a plethora of options that don't involve creating a thicker spacer between the driver and the magnet...

    But actually, if you want to increase the amount of air being moved by the driver, without modifying the housing at all, you should try corrugating the driver.
     
  12. GREQ
    There is an immediate problem with comparing this DIY project with the Fostex T50/20 mkII lineup, and that is that they are based on different principles.
    In this project, the open-back design absolutely requires the largest possible diaphragm to push the most air possible.
    This is something I can confirm with my experiences with the HE-500 and NAD RP18 and lots of modding, pad rolling, etc...

    But with a closed-back or semi-closed back design (Fostex T50 mkII), the kind of bass you're getting is a completely different quality.
    I've modded the T20mkii (semi-closed like T50 and for all intents and purposes almost identical) and the T40mkii closed back, and the quality in bass compared to large-diaphragm open-back planars is poor.
    Not to say that the sound quality from these headphones is bad - they can still be modded to sound incredibly good.
    The best you can do with these (IMO) is get deep, but very tight bass, that doesn't go very loud.
    As soon as you tease out more bass volume, it goes boomy, ruins the tonal balance and you lose overall objective sound quality.
    The flip side, is that often this kind of sound can also be desirable and extremely fun :)
     
  13. Garuspik
    WallofHooligans, when you're modding something you're limited in options and can only change acoustic characteristics of housing of the driver. I'm not a modder, that's a standalone project without any single factory made part.
    I made such thick spacers because tension of the diaphragm isn't too strong. I've made numerous variants, listened to them and measured and finally have chosen optimal tension. And if spacer is below 2mm diaphragm will hit magnets.
     
    cskippy likes this.
  14. GREQ
    Ooh.. sounds like some nice excursion there.
     
  15. WallofHooligans
    I still believe corrugating the driver should yield a better middle ground. You can corrugate and then tension the driver more.
     
    Garuspik likes this.

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