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Anyone wanna know what's inside a RE252? Plus - modding opportunities!

  1. a_recording
    Hi guys!
    Long story short, out of curiosity I took a bit of a risk today and decided to see what was behind the rubber silicone in the HiFiMan RE252s. Specifically, I wanted to find out if the rubber enclosed another enclosure, whether the 252 was actually ported, etc
    Now before you kill me for taking apart a perfectly good pair of IEMs, I did this in the hope that with the collective minds of Head Fi having a look inside, maybe there would be opportunities for modifying the original design. I bought the RE252s during the $99 sale a while back, and they really have been collecting dust in my collection for a while (quite literally - that black rubber loves dust!) amazinly because the form factor was a little uncomfortable, and of all my IEMS the RE252 was the odd one out for not doing anything particularly spectacularly. However, I do think its a really competent IEM and there is a lot of potential in that incredibly detailed and smooth 9mm driver.
    WIthout further ado, here are my findings:
    It may be a little difficult to see from these pictures, but here are the important details:
    The silicone rubber actually just encloses an empty area. But actually, the drivers and hard plastic enclosure are SEALED. With the silicone removed, the RE252 sounds to me more or less the same. 
    That's right - there's no dramatic drop off in bass, apart from the decrease in total weight reducing bone conduction a little. That means that the RE252 actually just has a 9mm driver in a very small sealed chamber - this may go someway explaining its somewhat bass light sound, as there is not much air it can actually move around.
    Now without strain reliefs and exposed wiring, of course the earpiece is too fragile to use consistently this way. The fact remains though, that the 252 has the potential to be an extremely light and comfortable IEM with a different housing - perhaps something that the RE262 will introduce.
    Now, this little experiment is obviously non reversible, so now I'm at a loss as to what to do with these. I'm throwing it open to you guys to suggest any other inquiries I could be making into the little chamber, or any suggestions of how I could find a new housing for these little hermit IEMs. (Maybe I could combine this with the knowledge from some of the DIY custom housing threads that are floating around :)
    Or, also feel free to smack me for the part-destruction of a pretty great IEM. Your call!
  2. DervishD
    I would kill you for destroying a pair of 99$ phones[​IMG]... because you should have presented me with them! [​IMG][​IMG]
    Well, now that you've removed the rubber cover, the next logical step is to port them. Drill a tiny hole in the hard cover to see if the basses improve, and increase hole size step by step.
    Knowing where the port can be drilled may make for a very good and easy mod on those phones. The rubber is easy to drill, and the only real problem is where to do the hole, as you cannot see if you're hitting the driver. With the rubber removed, it's easy to spot a good point and anyone will be able to do the same with a fresh pair (that is, with the rubber cover intact).
    Good job, and thanks for sharing your crime [​IMG]
  3. a_recording
    I would have thought porting would *decrease* the bass? I only say that because of my experience with the Sony EX-85 bass mod, where you blocked up all the ports and then slowly used a pin to open up small ports to reduce the bass...
  4. DervishD
    I didn't mean to increase the basses, only to improve them, make them sound a bit more airy. In my very reduced experience and expertise, light basses with good soundstage do sound "stronger" to me, with the same effect, so to say, of a subwoofer, adding body to the basses. That's why I suggested porting them, because port should increase the soundstage, but I may be utterly wrong!
    As porting the drivers will be irreversible, you should try other non-destructive mods first. Don't ask me which ones, I'm not much in modding [​IMG]
  5. okur


    Oh really?! [​IMG]  I do know it doesnt have any. So I'm curious abot how it's gonna drop off??
  6. a_recording


    Now now Okur... it does have some bass. They are no DDM's though : P
  7. mvw2
    Lol.  I think it was Kostalax that did a similar mod.  He pulled the rubber off and added a metal rear housing from another IEM he had to make a more standard IEM design.  Frankly I like the RE252 desgin because it is nice and secure and does constrain the housing so you don't get any vibration.  The downside is fitment of course.  It pretty much forces the user to use a foam tip to add in compliance to let the rubber housing sit more naturally.  The foam tip allows the nozzle to sit off center from your ear canal if need be and also insures proper seal.  With a good seal, these are not bass light.  However, I do see some gain to stepping to a tuned, ported setup for the driver.  It could very readily get to 20Hz without a problem and a little tweaking of the enclosure size and tune frequency would raise and extend the bass like well. 
    The RE252,s biggest challenge is fitment and getting a good seal as well as comfort.  A major issue with this for many folks is the lack of bass.  It's not an earphone that is so easy about getting a solid seal, so I understand the comments.  Really, this earphone has a good amount of bass.  The frequency response is very flat although tilted slightly bright, but the bass actually doesn't roll off until under 50Hz.  The note thickness is a little on the thin side, so bass isn't as hearty as some earphones.  However, it does offer more impact of note than most earphones and does help maintain good, perceptible bass.  It's basically punchy but lean, but it NEEDS a good seal which doesn't happen easily.  The straight nozzle on this earphone also makes it sound the tip used doesn't go up the ear canal, so you're forced to use shallow insertion.  I ended up taking a Comply T-500 tip a size larger than I'd normally use, cutting off the end section to shorten it (or it just gets squished and blocks the hole), and using that as a shallow fit tip.  A decored Shure foam tip would also be a good choice.
    Don't be fooled by an earphone that doesn't do anything amazing.  As long as the earphone isn't doing anything wrong it typically means the earphone is simply doing everything correctly.  It's not something you really realize until you use other products and then go back to the earphone.  Every time you go back to it, it will impress you.  You start realizing how good it actually is.  There just isn't the wow factor in the start that some earphones have.  I will also note that the RE252 does scale with the quality of the input so a better source device and better source audio will let it sound better.  The RE252 is one of only a couple earphones I've used that scale so heavily with the quality of the information coming in.  They can end up sounding crappy just as easily as they can sound amazing, and it's pretty much all your fault. [​IMG]  The RE252 and UM3X are the only two earphones I've used that scale so much, and this does correlate to how revealing these earphones are.  Out of everything I've used, the RE252 have been my favorite.
  8. ethan961
    I'd send them in to have customs made out of them if they truly are sealed, or else I'd make my own customs out of them with that DIY method using home made custom earplug goop like that thread that's been posted a few times here in the last week or so. That would make them more usable than anything.
  9. rawrster
    You know..If you didn't like your RE252 you could have just sent them to me :p
  10. a_recording
    @mvw2 I agree with what you're saying. The truth is, that if I could have an IEM like the RE252, but with low end response that didn't roll off even at 20hz like the DDM, and with all its deep timbre-y goodness, I would be in heaven. I always got an okay seal with the RE252's, and I didn't find them hideously uncomfortable (hey, I tolerate the DDMs.) It's just that I've figured out with the CK90Pro and the DDM that I really do prefer a little bass punch, and I'm a little sensitive to sibilance.

    Yah I've been looking into that stuff, with the radians ear plug goop. That doesn't sound altogether too expensive or too difficult. There's one thing I did want to try and achieve though, which was an imitation of the "acoustic horn" on the CK90Pro by making the canal part of the plug open progressively wider. That's one way I can think of thickening up the sound. I'm wondering how I can do that without making the cored out canal part of the plug too flimsy. Most of the guides just seem to suggest cutting the canal part down till it gets to the opening of the IEM nozzle.
  11. a_recording


    I do like them - I just want to give birth to a magical creation the likes of which the world has never seen! :D 
  12. Photofan1986
    You are a criminal! But thanks, anyway :p
    I actually considered doing this when I could not get a good seal with them, and finally, cutting off the appendice was sufficient. Now, I wear them with the cable over the ear and I'm getting an excellent seal.
    Mvw2, as you, I really like those iems. Your description of them is spot on.
    I'm really looking forward to the new RE262 to see what goods Hifiman will bring to us. An RE252 with more bass weight would definitely be interesting!
  13. mvw2
    Yeah, the CK90Pro is neat in that it does actually get to 30Hz without hassle.  For a simple dual driver earphone, it is ruler flat and extended.  It's a balance that requires effort for most other earphones via EQing.  It can both get low and have good dynamic breadth.  The lack of dynamic compression on the low end may be an unusual experience for some though.  A lot of these brighter earphones are just too lean on the low end lacking some in body or lacking the excursion to maintain dynamic range into the lower octaves.  This starts to become obvious with the RE252 when toying with EQing and pink noise.
    An interesting test to play with is to use pink noise on an earphone.  If an earphone has a relative lack of capacity to play a frequency range well, it will show through when EQing.  There will be a lot less sensitivity to adjustments in that region.  This is also true through x-over points if they are not blending well.  For example, below 150Hz the RE252 starts to become relatively insensitive to EQing and there is less representation of a specific tone.  With an earphone that can play a 50Hz tone really well, you can bump that point up or down a few dB and you will hear a very distinct rise or cut of that frequency.  You will hear a 50Hz tone become dominant, clear and distinct.  With an earphone having trouble making a coherent note at that frequency, you get a relative insensitivity to EQing and a vague sense of that tone.  Under 150Hz, this starts to show through on the RE252.  It is a small sealed driver, so it might just be the size limitation and physical constraint on the low end.  There's sensitivity, but it's obvious that the note is not effortless and well defined.  The midrange and top end are outstanding though.  The top end also shares this characteristic.  For example with the Custom 3, the mid-treble driver used offers a relatively thick, textured note for a BA, and there is some natural roll off on the top end.  When EQing, I will find some insensitivity to EQing changes and a less coherent tone at the frequency I'm adjusting.  It shows some limitation of the driver being used and the limits of capability are heard through normal play.  You don't quite get that air and sparkle and sense of limitless extension that you would find in other IEMs.  For the x-over example, the UM3X is a good representation.  There's a moderate dip in the midrange that is from whatever tuning they do for the earphone.  There is a relatively sizable insensitivity to EQing over this region and a lesser sense of a coherent tone through these midrange frequencies.  It's probably a side effect of having multiple drivers playing through the same frequency range and there may or may not be phase issues with the x-over design.  In presentation the UM3X sounds a little "rough around the edges" and there isn't seemless coherency through the audible spectrum.  Other multi-driver earphones are flawless through the x-over ranges and whatever designs that are run just blend more seemlessly.  If done well enough, you shouldn't be able to even tell where the x-over point is at all.
    You might want to look at the Klipsch Custom 3 by the way.  If you want to try another dual driver BA but with a thicker presentation and actual texture to the note, the Custom 3 is one of the best examples.  It does naturally roll off on the low end, but it does respond well to EQing and isn't really mechanically limited.  It offers more detail and better sound stage than the CK90Pro.  You won't get quite the same extension and top end sparkle though.  The CK90Pro high frequency driver is pretty good on extension.  I might opt for the Triple.Fi 10 if I wanted something that could do both low and high with gusto though, but I'd EQ it to a flat response if I didn't want fun mode.  It's energetic, refined, and sweet, but it needs a little EQ massaging to get it really good.  The CK90Pro is balanced but it does fall short with a rather significant lack of micro detail.  It's missing a lot of smaller information, although I'm not sure why.  There are very few earphones that are incredibly balanced on their own.  The RE252 is perceptively very well balanced and even in presentation despite being slightly bright in tone.  The CK90Pro is the flattest earphone I've ever used.  The Custom 3 is very well balanced and just keeps improving with a little EQing.  The MTPG is very good, not perfectly flat but flat within a couple dB and very extended as long as you like a smooth, laid back top end.  A lot of other products out there need a bit of work to even out, good if you've got the EQing power, bad if you don't.
    I'm glad I've got a DBA-02 coming, but I still need to look at grabbing a Radius DDM to try out, that and the Panny HJE900, too many good things being said not to at least try them.  The two biggest earphones I'm waiting for though are the RE262 and the SA7.  I have high hopes.
  14. KimChee
    Yeargh! I never understand why people do this, or drop/smash/destroy type tests.  I've been known to take electronics apart myself, but it's been in a repair/dead type scenario.  I think I'd do something like Kostalex and put it in another (metal) shell.  I actually found the Re252s to fit quite well, and the rubber housing had kind of a suctioning effect and stayed in really well.
  15. ethan961


    I guess you were lucky enough to be able to use it how it was ideally designed to be used and fit. I can't (and won't) speak for it, but I suppose you can consider yourself lucky (or not misfortunate).

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