Headfi forum with release and build notes

MrSpeakers headphone plug terminals 

Acoustic wool I used

Brainwaves earpads

Prices for Prusa i3 on Ebay

Other materials include a recycled Grado cable, spare bolts from my Prusa i3 printer (and obviously my i3 printer for printing, too) and Hatchbox black PLA.

I like the Hatchbox stuff, thus far it has proven to be affordable and reliable, even at low printing temperature (180 degrees is all I got).

One side, stock t50rp. Otherside, Open alpha.


So:  Before I get into the build details, the bottom line is this is the definitive overhaul to complete in terms of t50rp mods.  I started with a refurbished mkiii,  and hated the crazy EQ spike at about where hihats generally reside.  This was not a subtle issue, and would give me a headache quickly.  From modding with the stock cups, I found denser damping=worse issue with treble and less bass.   Think of it like a bass trap- I used essentially felted wool, which in its raw form killed all frequencies except for the strongest… …Which in this case was about 2.8khz to give a rough estimate.  Ouch!  After googling around, I discovered Dan was using cotton balls as the primary damping material, with a thin layer of dense acoustic mat of some kind to line the cup (helps mostly I think with leakage control and resonance from the actual plastic and flat surfaces on the cup itself).

Damping the Alphas:

I already had this fancy acoustic wool, so I figured I could make some “wool balls” by separating the dense wad into fluffy pillows.  I’d say I aired on the side of less dense- at this point I was printing my Alpha cups, and the space in there is huge, leaving ample space to layer up some of these wool balls.  I did not feel the need to line the cups with a damping mat of any kind, because my wool seemed to kill noise and reflection already like nobody’s business.

Printing the cups and other parts:

…Painless, except on the inside of the cups there is a dip where the headband arm is mounted.   For no particular reason, I printed both cups without supports- but not without a large amount of “PLA spaghetti”  and the occasional emergency “duct tape the PLA spaghetti wad to the bed so it can have something to build on…”


Firstly, these sound nothing like the stock t50rp.  AT ALL.  the low end goes quite low with not a huge amount of distortion, the mids are wide and spacious, and the treble (including the significantly tamed-down spike) is springing and provides nice “pop” and sparkle.  These headphones are a pleasure to listen to- I’ve been doing Art Blakey and Coltrain lately because the reproduction of the jazz bass is superb,  Couple that with the expansive space where the sax and piano reside, these make a nice way to relax at the end of a day (which is how I have been relaxing each evening since I made them).  Obviously, we still have some fundamental setbacks.  The Fostex driver is unbelievably inefficient.  It takes much care to juice these properly (I like them through my e12 portable amp actually,  because I can crank the input volume on that with very little distortion for quite a bit).   Additionally, there is a limit to how much detail we can siphon out of the driver; this uber mod definitely maxes out the clarity and definition this driver can provide.  For example, the successor to this headphone when it was made commercially by Dan/MrSpeakers is the AEON (still in preorder mode at the time of writing)- a completely in house design trickling technology down from the company’s acclaimed ETHER headphones.  I am actually lucky enough to have had a few hours to play with them and chat with the inventor (Dan)- quite simply, the clarity and silkiness of the AEON demolishes the notion of clarity with my Open Alphas.  THAT SAID an $800 carbon fiber headphone invented from the ground up by Dan (who maintains the highest regards even from competitors (ZMF, even hifiman reps) as the most dedicated headphone creator) is obviously not really competing against a headphone a made for <$300 INCLUDING the 3d printer and donor headphones…. 🙂