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Headphones, Impressions

Modding the T50RP: voice transplant

A lot have changed since the last time I posted my mods for my dear Nami-chan (the T50RP). As a recap, here is what I did before:

  • filled the baffle with  newplast
  • lined the back of the cup with Akasa paxmate plus acoustic damping foam
  • I did said I tried cotton in the cup, but didn’t like it.

But I did add back cotton, only less compressed and to a lesser volume than before. IIRC it is somewhat 2 or 3 balls of cotton teased apart, instead of 5 balls before. But I wanted to try something else. Here’s what I did.

This time around, I wanted to use a reflex dot and some other damping material directly behind the drivers. Seeing that I don’t have much time and nearby resources to do crazy experiments, I just took whatever scrap I have at hand and shove it into the cup. Of course, being the anal person I am, I don’t just throw anything and everything, I do based on the things I learned while doing this personal project.

So first of is the reflex dot.

Just some normal adhesive-backed disc used to protect furniture. This particular one measures around 15mm in diameter.

The other materials I used are this:

I really do mean scrap. :D Once I have more time and resources I will try and emulate what I achieved in this mod with more accessible material so that others can try it too.

And mostly it will be stacked like so:

The caveat here is that all of my evaluation is based on what I hear and feel. I wish I have that FR measurement kit, but I challenged myself to build one myself, so that can be a long time coming.

Without further ado, here’s the results.

First up, just the reflex dot behind the driver. This one is constant on all the other configurations. To me it cleaned up the whole spectrum, now it’s more controlled. It also put the mids a little bit more forward, to my liking. I didn’t stop here, since I wanted to try what the other materials do. And because the mids is a little bit too forward and shouty, even for me.

  • Config 1

Portapro pads + HD414 foam + felt ring ear side. I just put the damping materials, stacked with the “back” towards my ears.

Basically it destroyed whatever instrument separation it has before, and the sound signature turned out all jumbled up and mixed around. Whatever that I managed to hear though is that the bass are more forward and prominent, and very textured and detailed. The mids are quite prominent too, but not as much as the bass. But when the track gets busy with various other elements sounding off, it gets buried. The highs diffused, cymbals sounds shimmery and almost without energy to my ears.


  • Config 2

Portapro pads + felt ring ear side. Same as the above, but just took out the HD414 foam out.

Instrument separation isn’t stellar, but a little bit better than config 1. It’s also turned out less mixed up than config 1. Bass and mids are basically the same. Highs though sound less shimmery, more focused, clearer than config 1, but still not to my satisfaction. This config also seems to have increased focused air pressure. By the end of the second time of my test song, my ear drums are slightly fatigued.


  • Config 3

Reflex dot + felt ring, cup side.

This one increased bass impact, but uncontrolled and incoherent. Strangely enough, I heard that it’s not boomy. But since the overall sound becomes not musical, uncontrolled mess, I didn’t listen to it long, so it might just be boomy after all.


  • Config 4

Portapro pads + HD414 foam + felt ring cup side (driver > stock white > reflex dot > hd414 foam > portapro > felt ring)

"front" side away from the driver

This time around, instrument separation better than all 3 before. It’s good, but not great. At least now it’s coherent and not mixed up. Bass are still forward, prominent, very textured and detailed. Mids are quite prominent, and not as hamstrung when a track is busy. Highs now sounds clear, sparkly, but easily overpowered by mids and bass. Overall, this is much better, but I still have a few other ways to stack it. I’m on the right direction at least.


  • Config 5

Portapro+hd414+felt ring cup side (driver > stock white > reflex dot > felt ring > koss portapro pads > hd414 foam)

I just reversed the sides.

This one is just so much better. Instrument separation better than both before, bordering on great now, now coherent and not mixed up, have better layering and imaging. And this time, I noticed soundstage.  Bass are forward, prominent, very textured, detailed. Mids are quite prominent, now can keep up when a track is busy, better than config 4. Highs sounds clear, sparkly, can now almost keep up with mids and bass. Can still be overpowered, but I guess that the highs in that song or track are just mastered that way.

Like I said, I seem to perceive better soundstage than previous configs. In fact, this is quite easily one of the first time that a song’s soundstage truly shown effortlessly. Of course, my music library are mostly modern production, and I used a crossfeed implementation, but this perception is very new to me. And come easily too without the need to strain to hear/perceive it.


  • Config 6

Portapro + felt ring scrap +reflex dot cup side (driver > stock white > reflex dot > felt ring > koss portapro pads).  The same as config 5, but without the HD414 foam.

Instrument separation is less able than config 5 but most definitely are better than 1 through 4.
Overall mostly almost the same as config 5, but without the effortless percieved soundstage and less able instrument separation.It’s still better than configs 1 to 4.

  • bass>=mids/vocals>other

In the end this is what I’d arrange the configs:

config 5 >= config 6 >> config 4 > config 1 >= config 3 >>>>> config 2

Of course, the materials used it slightly less orthodox and quite inconvenient for others to replicate. Like I said, I will try and emulate this setup using other more easily acquired, and “logical” material for others to try out, if they like. Currently I am, as you might have guessed, using config 5. Various info regarding the comparisons and my thoughts on the foams:

  • used the song “Howl” by Florence and the Machine (320 kbps MP3) for comparisons of all the config.
  • HD414 foam seems like open cell foam, hair strands can stab/pass through quite easily. Koss portapro pads seems open cell, significantly less open than the HD414.
  • felt ring is made from IKEA furniture feet protection discs, only I cut off the adhesive. It’s what I believe to be stiff felt, around 1mm thick approximately.
  • for all of the above, it seems that the bass is the one that makes the mids overpowered. Can easily be tuned by closing the bass port from the outside of the cup.
Hopefully someone would be interested enough to try this setup.

About fEast91

A foreign student who happens to like manga/anime and headphones.


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