Novodio iHX: Yet another IEM from Widing?

Disclaimer: This pair is owned by James too!

Better known as a portable version of Widing ME-10EX, iHX is the very first IEM from the french company, Novodio. Compared to the original ME-10EX, Novodio iHX, which was released in January 2012, is of higher sensitivity and lower impedance. And most importantly it is way cheaper, priced at 39,90 €.

Perhaps the most distinguished feature of iHX is the proprietary 3D sound stage technology. Just like how a human HRTF works in a loudspeaker environment, a bit of signal from each channel is mixed into one another in order to create a natural stereophonic sound image, according to the manufacturer. In other words, they implemented an analog version of crossfeed into iHX. Since this kind of pseudo 3D simulation is usually realized by a DSP process, their approach is absolutely brilliant, only if the claim turns out to be real.

PRO: Lower distortion than that of the original. High frequency is well-extended up to 20 kHz.

CON: The problematic ringing at 4~5 kHz is now even greater, and the bass response is an overkill. The graphs can't even be plotted properly. And finally, the manufacturer intentionally inverted the right channel's polarity only, in order to achieve the claimed "3D effect"... Let me assure you: That is an audible acoustic disaster, not a "3D effect"!!! Shame on you, Novodio.

ON SECOND THOUGHT #1: Just like the original version, iHX is virtually free from insertion-depth related issues.

ON SECOND THOUGHT #2: Due to its lower acoustic output impedance, iHX is more susceptible to the effect from additional acoustic resistance than ME-10EX.

ON SECOND THOUGHT #3: Although the stock triflanges, or any long stemmed sleeves, definitely help taming the problematic ringing at 4~5 kHz, the ringing itself is way too strong to be compensated with sleeves.

ON SECOND THOUGHT #4:  Since the strain relief is acoustically sealed, the side vent is the only depressurizer on iHX. Blocking this hole attenuates the overall low frequency range up to 10 dB, but it is advised to leave a pinhole at least, to prevent damage of the driver.

ON SECOND THOUGHT #5: James asked a few question in regarding to Widing ME-10EX & Novodio iHX brothers when he shipped the items:

1. Do WIDING ME10EX and Novodio IHX share the same driver, just with different impedance?
2. Why does the Novodio's bass sound tighter (and closer to the WIDING) when I add 100ohms? Adding output impedance should have the opposite effect on damping, no? 

Answer #1: It is quite obvious that while the basic design philosophy is identical, the electrical design of their drivers is entirely different. Here's the comparison of some measurement parameters of both IEMs.

Widing ME-10EX VS Novodio iHX

Answer #2: Conventionally, though they require more power to achieve adequate sound pressure level, headphones with higher impedance are simply better in terms of electrocoustic performance compared to headphones with lower impedance. Not only they are free from impedance interactions, but also have less noise due to Ohm's law(constant voltage drive). And this, in fact, is more emphasized when headphones with same design have different impedance value, such as DT880 or RE262/RE272. However, it is just not the same with Widing ME-10EX & Novodio iHX brothers. Even if iHX is equipped with an additional 100 Ω in series, they are still very different from one another.

And adding resistance in between a headphone and an amplifier output decreases damping of the driver, resulting in frequency dependent attenuation. Thus, an additional 100 Ω on iHX should yield a boost of 0.6 dB at 4.8 kHz due to loss of damping, and that's about all there's to affect.

Impulse response compared between 0 Ω VS 100 Ω

Distortion compared between 0 Ω VS 100 Ω

CSD from 200 to 20,000 Hz compared between 0 Ω VS 100 Ω

CSD from 20 to 200 Hz compared between 0 Ω VS 100 Ω

Not only the distortion figure remains the same even with additional 100 Ω, time-domain characteristics remain unstirred. Moreover, the said tonal change, which James describes as "tighter" damping, has not been observed at all.