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Thursday, March 21, 2013

Final Audio Design Piano Forte VIII: An electroacoustic outlaw

Disclaimer: Yet again, I should thank James for providing me with more than I could have ever hoped for.

Piano Forte VIII, also known as FI-DC6102SB, is one of Final Audio Design's flagship electrodynamic models. Originally designed to be completely sleeveless like any intra-concha earbuds, Piano Forte VIII is truly an unique IEM. As sleeves couple the acoustic transmission between the IEM and the ear canal together, with such sleeveless design, the radiation impedance caused by leak interferes the bass response greatly. However, according to the manufacturer, the IEM comes with their all-new cutting edge technologies that can negate all of the intereference.

However, there is absolutely nothing new about their claims, as such tweaking techniques can be seen on any IEMs from Sony MDR-EX1000 to the budget-priced Monoprice 9927. As their controversial Balanced-Air-Motion technology turned out to be a commercial gimmick previously, it is not very hard to imagine that they can also be complete bogus as well.

PRO: Both channels are extremely well-matched for an intra-concha earbud.

CON: Not only the IEM does not have any sub-bass, the frequency range from the mid and above is awfully disconnected due to peaks and deep-nulls. The tonality itself is like that of a speaker attached on an iPhone. As its sound quality turns out to be inferior even to that of Apple Earpods, it is quite evident Final Audio Design's tweaking techniques are nothing but hoax.

ON SECOND THOUGHT #1: Even with an air tight seal, the sub-bass is still missing, which is due to over-ventilation of the front vent. Changing insertion depth does not help either.

ON SECOND THOUGHT #2: While blocking the strain relief does not have any effect, closure of the front vent completely restores the lost sub-bass, even with a normal amount of leak. Combined with rear vent modification, it might be possible to gain some amount of low-frequency linearity at least to a reasonable degree.

ON SECOND THOUGHT #3: Additional acoustic resistance at the output of the IEM tames harshness caused by resonant peaks.

ON SECOND THOUGHT #4: Although there is no hope for this outlaw that defies the law of electroacoutics, it might still be possible to retain some linearity with careful modification even under a normal amount of leak. Thus, here is my recommendation for Piano Forte VIII users:
First, block the front vent & the large rear vent with a plastic tape, and puncture a pinhole on both of them. This will equalize sufficient amount of air pressure, effectively preventing from the speaker to be over-driven with bass. Second, grab a microfiber eyeglass cloth, and cut out two annular-shaped pieces with 3/16" in diameter. Third, insert the cloth pieces into the bore. This is what you'll end up with:

In order to minimize leak, a pair of small Monoprice sleeves has been equipped upside down. You may or may not need such sealant, depending on how the fit suits you. Since no destructive modification has been carried out, the sound signature is still retained.

While the sleeveless design is a brilliant idea for its independence from tight acoustic coupling, the execution done by Final Audio Design turns out to be extremely poor. I think we will be able to listen to IEMs without sleeves someday, but now doesn't seem to be the time yet.


  1. Two questions, one specific to this review, another more general:

    1. On the one hand, the response at the bass end of the FR is down off the charts. On the other hand, the distortion "at 100dB" is also high off the charts. The question is, how is this distortion response measured? Does distortion "at 100dB" mean 100dB@1kHz? ie if the response at 20Hz is 30dB down, does 10% distortion @100dB actually mean 10% distortion @70dB? Or are the phones driven as hard as necessary until they produce a true 100dB at 20Hz and then the distortion measured?

    2. I've been wondering, how important are narrow peaks and dips in the treble region to the listening experience? My reasoning is that
    a) we have poor tone discrimination in the treble region, possibly a hint that the ear doesn't much care whether a sound is pitched at e.g. 8kHz or 8.1kHz.
    b) From looking at spectrum of music in real time, it seems that musical and natural sounds are often wideband at high frequencies, meaning that a transducer with smooth treble response and a transducer with jagged treble response but roughly equal FR when smoothed across, say, 1/3 octaves, will produce roughly equal amounts of treble energy playing back musical and natural sounds (whereas the jagged transducer would produce a much different amount of energy at one of its peak frequencies compared to the smooth one.

    So, do treble spikes just look ugly on a graph? Is it fine as long as the smoothed response isn't elevated? How much smoothing is perceptually transparent? (or should I say, how wide a treble spike is perceptually transparent?)

    The reason I ask is because I'm planning to move away from pure tones to bandlimited pink noise as the signal source for my EQ calibration and am wondering how wide a band of noise to use.

    1. 1. 100 dB SPL @ 1 kHz, which is quite a common sound pressure level used in the industry.

      2. a&b: You should refer to textbooks focused on psychoacoustics, especially on auditory masking for further details. Chapter 19 on Sound Reproduction by Dr.Floyd Toole is a good start. Theoretically, the critical bandwidth of 8 kHz is around 900 hertz-wide, so the perceptual treble energy of a musical spectrum should be more or less the same. However, it is important to note that such estimation is quite vague, as even a high-Q peak at 8 kHz can easily be heard. (like that of shallow-inserted ER4) Moreover, as the frequency goes up, our sensitivity in discriminating intensity increases greatly:

      "How wide a treble spike is perceptually transparent?" Roughly estimated, below 100 Hz, lower than 1/3rd octave. Above 1 kHz, higher than 1/6th octave and up. I always stick with higher than 1/20th octave for FR & CSD to observe complex acoustic properties such as resonance and reflection.