Ultimate Ears UE900: Take two

Since my review in 2012, there has been a rumor that Logitech have tinkered the internal configuration of UE900, thus nullifying the result of my analysis. In order to figure out what the hell is going on with Logitech, I bought a brand new pair of UE900 at my own expense.

PRO: Please refer to my previous analysis in 2012.

CON: Please refer to my previous analysis in 2012.

ON SECOND THOUGHT #1: Yes, UE900 from 2014 outputs a lot more mid to high range response compared to the 2012 one.

While such change does slightly better treble in stock configuration, it has a drastic impact on my "recommendation". No, UE900 with a 100 ohm resistor doesn't sound as linear as it used to be.

ON SECOND THOUGHT #2: As far as insertion depth goes, please refer to my previous analysis in 2012.

ON SECOND THOUGHT #3: While everything else remains the same as the 2012 analysis, the resonance at 8 kHz(λ/4 resonance of the tweeter) is heavily emphasized with added resistance. The treble response is not at linear, and requires extra amount of effort to tone the peak down.

ON SECOND THOUGHT #4: Even with different kind of acoustic dampers, the problematic resonance still persists. And please note that UE900's stock damper is located in the middle of the bore, so extra care is required when removing it. (If your UE900 comes with a pair of white dampers, you should definitely have a real problem with the annoying peak at 8 kHz as can be seen here)

ON SECOND THOGHT #5: As far as the working principle of the pinhole bore goes, please refer to my previous analysis in 2012.

ON SECOND THOUGHT #6: Since the previous modification method doesn't work anymore, here's something different: First, block the pinhole bore and puncture a smaller hole with a needle. Second, remove the stock damper, insert a piece of earbud foam(1 mm X 1 mm X 1 mm) to the far end of the bore, and equip a 2200 Ω red damper(the stock damper may be reused) on top of the foam. Make sure the red damper is situated in the middle(stock location) of the bore. Finally, a pair of Sony MH1 sleeves(also compatible with Sony hybrids / Phonak stock / Shure EA510) are needed to fine-shape the frequency response above 10 kHz.

Users may add extra resistance, perhaps a 33 Ω resistor, to further make the sound flatter. This time, UE900's reference target is Sony MDR-EX1000 without the peak at 5.5 kHz, but with extended treble, and the result is stunningly good.

ON SECOND THOUGHT #7: While in stock configuration, UE900 of 2014 doesn't even closely match any reference targets.

IN CONCLUSION: This is headphone modders' worst nightmare come true, and I have absolutely no clue why Logitech have made such decision. UE900 can still be nicely tuned, but it turns out to be way more difficult than how it used to be.