T-PEOS H-100K

It was July of 2012, when T-PEOS of South Korea introduced their flagship model, H-100. A hybrid of balanced armature & dynamic drivers, H-100 was targeted for users who prioritize fidelity and accuracy.

In order to accommodate such requirement, T-PEOS teamed up with Goldenears.net, and tuned the IEM to precisely match Goldenears' proprietary target curve, which was a modified diffuse-field response that I do not approve of, especially due to the bloated bass.

And inside the box, included a certification card indicating the proof of performance assessment done by Goldenears. Now the question would be, could this certificate really prove its worth?

PRO: The overall sound is very reverberant, making H-100K one of IEMs with the widest staging.

CON: Overly bloated & undamped bass. Harsh high frequency peaks at 3 kHz and 10 kHz, giving a tonality that is close to a resonating hollow tin can, or "honky" signature. In addition, the 2nd-order harmonic distortion at 5 kHz is quite audible.

ON SECOND THOUGHT #1: A great news for the users who have small ear canals; as the insertion depth becomes shallower, the tonality gets more linear due to the half-wavelength resonance shifting towards 7 - 8 kHz region. Interestingly, this acoustic impedance interaction somehow acts like an insertion-depth compensator, resembling the D2CA resonator of Sennheiser IE800, and equalizes the harsh peaks above 7 kHz. Regardless, it is just an absolute shame that nobody has been able to notice this effect until now.

ON SECOND THOUGHT #2: Surprisingly, the mid-high linearity greatly improves with additional serial resistance, preferably higher than 64 Ω.

ON SECOND THOUGHT #3: Additional acoustic damping effectively tames harshness in the mid frequency range, but it should be noted that the overall bandwidth decreases as well.

ON SECOND THOUGHT #4: The rear vent only works as a depressurizer, and the true acoustic vent is located at the bottom of the unit, where the strain relief is. Sealing both of the vents yields about -5 dB of damping at 20 Hz, which is essential for better bass reproduction.

ON SECOND THOUGHT #5: In conclusion, T-PEOS H-100 is an IEM left with a lot of room for improvement, but neither the manufacturer nor the certifier acknowledge the true potential within. Moreover, the IEM fails to fall within the target curve when measured in high resolution(1/24 oct); what could have possibly gone wrong?

Below is the result of my modification effort with the combination of a complete seal of the vents + a 100 Ω adapter + shallow insertion:

So, is the certification really worth the hype? I highly doubt it.