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

  1. a_recording
    Just so I get this right, is the suggestion that if I made a small port for the driver, the bass response might actually improve? Or just the bass speed?
  2. mvw2
    Well, you'll do one of two things.  Opening up a sealed enclosure, untuned, very leaky, will raise the Q of the driver + enclosure.  What this will do is raise the roll off point but make the roll off shallower.  If you run a tuned port, i.e. a device that holds a column of air that can actually resonate, then you won't have the early run off like a leaky box and will extend the frequency response down lower, although there will be group delay on the bottom end due to the port using the 180 out of phase rear sound waves.  Also for an in-ear configuration, the port would need to exit into the nozzle and into the ear to work.  The port is a resonator and the driver nearly stops moving air at peak resonance.  Basically around the tune frequency the port is the device making a lot of the sound.  You can't just feed that into the outside world.
    Most all of the IEMs simply using porting to create an aperiodic enclosure.  The benefit is they can use smaller enclosures with higher Q drivers, gaining low frequency sensitivity in a smaller package.
    So, basically the good way to make this work right is to do a custom mold with a dual port nozzle.  The main port would be the front exit of the driver.  The second port would be the tuned port for the enclosure.  Think of something like the Triple.Fi 10 earphone but running a single driver out just one of the two ports.  The second port is simply a path of specific diameter and length into the enclosure to tune the low end.  That's pretty much the only way you'll make it work.
  3. winds of change
    [​IMG] OMG poor little baby... 
  4. a_recording


    You certainly sound like you know what you are talking about XD however, I don't think that is within my abilities at this point. I've ordered some of that Radian ear plug goop though, so hopefully I'll be able to make strange customs out of these 252s!
  5. a_recording
    UPDATE: Hey guys, in case anyone was curious, I did go ahead with the Radians custom earplug mold stuff. The process was actually pretty quick and painless - first I balled up the goop and smothered the earbuds with it EXCEPT for covering up the aperture. I pushed it into my ear with the nozzle pointing to my ear canal. (It's probably good to have an idea of where the nozzle is pointing before you cover it with goop. I played music through them while I did this, so I had a good idea of where the sound was coming.) Then I followed the instructions, smoothing it in my ear and leaving for 10 minutes.
    After 10 minutes I took them out, and actually, I applied a little more goop right on top of the nozzle (wanted a slightly more secure fit) and pushed them back in. (Don't put too much more otherwise it will go straight into your ear canal.) Then I waited another 10 minutes, took them out, and got a small drill bit and manually twisted through the ear canal part of the plug until it reached the nozzle. You have to go very slowly, otherwise you'll end up with the drill bit straight through the nozzle.
    Without further ado, here they are:
    While they aren't going to win any design awards looking like forlorn punctured slugs, they are really very very comfortable. The sound is still the same old RE252 sound as far as I can tell.
    If I had to do it again I would have removed the RE252 filter, pushed a hard tube the diameter of the nozzle into the RE252 nozzle and moulded the goop around that nozzle, then removed it afterwards so I could get a cleaner finish and skip the drill bit step. However, I was a bit impatient and didn't really have any tube like that around.
    This is definitely something fun to do, and not as scary as it sounds :D
  6. goodvibes


    Exactly right about the Q and roll off and that It's a vent and not a port. It will increase bass and lower the resonance point until it gets too large where it just sounds less controlled and the bass rolls as it looses back resistance and approaches its lowest in use resonance point. I'm not sure this is aperiodic with an infinite size as the second chamber. The resonance point will change but probably still be well defined but that's splitting hairs. I wouldn't know what to call it other than perhaps infinite baffle as it gets very open but even this is a bit off as there's a front chamber of your canal.
    All this could be manipulated but something designed for a sealed enclosure should work this way. A completely open back design could be optimized for bass with mechanical resistance built into the driver. Just adding as I'm sure you know this.[​IMG]
    It would seem that you couldn't support enough air mass in a front port in an IEM but it's an unigue environment with some built in front resistance so perhaps it could work. I'm sure there's some good science here. The rules don't change but the environment is quite unique.
    I would think it pretty odd for the op's driver to be completely sealed in that capsule and still have decent low bass. Usually there will be a hole somewhere.
  7. DervishD
    Good job with the "custom goo"! I'm trying to find it in Spain, just to make a test. I don't know which phones I would "goo", though...
    Thanks for the photos, the advice and the review :)

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