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Sunday, July 14, 2013

Ultimate Ears Universal In-Ear Reference Monitors

Disclaimer: This special version of Ultimate Ears Reference Monitors has been provided by James. My blog would've been long gone without my friends' continuous support, THANK YOU!

In a collaboration with Capitol Studios, Ultimate Ears developed this custom IEM for studio engineers. The manufacturers claim that the IEM has been meticulously tuned to be flat, in order to match any type of professional recording/mixing/mastering conditions.

PRO: The interchannel matching here is much better than that of the custom version.

CON:  Unlike what the specification states, the UERM does not cover up to 20 kHz. Its impedance characteristic varies greatly over the entire frequency spectrum- making the IEM hard to be driven effectively.

ON SECOND THOUGH #1: Insertion depth-related issue is pretty much negligible.

ON SECOND THOUGH #2: Even a source impedance of 33 Ω radically changes the tonality of UERM. Adding any amount of resistance to is not a good idea.

ON SECOND THOUGH #3: As the IEM's acoustic output impedance is quite high as is, a sheet of micro-fiber handkerchief only yields a few dB of attenuation. A foam plug seems to do a better job here.

ON SECOND THOUGH #4: Both data are measured at the reference plane. The difference between the custom version and the universal is quite big as seen above, which is most likely caused by the difference in damper location/insertion depth estimation. Such interunit mismatch caused by manufacturing error is a practical limitation, of which virtually all of custom manufacturers are struggling with, and there is simply no solution for it.

ON SECOND THOUGH #5: When compared against the Olive-Welti compensation target, UERM's sub-bass goes missing, suggesting its frequency response is not up to the "reference" quality, contradicting the claims made by Capitol Studios and Ultimate Ears.

ON SECOND THOUGH #6: This is what I said in the previous article: "Is it just me, or the frequency response of the UERM really resembles that of good old Triple.Fi 10 Pro?" Since James has provided a scratch pair of TF10 as well, I simply cut the IEM open for modification, and matched its frequency response to that of UERM here.

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