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Tuesday, December 18, 2012

Suyama Fit Ear TO GO! 334

Suyama Dental Laboratory Co., LTD.(須山歯研), the manufacturer of Fit Ear branded custom in-ear monitors, is known for their expertise in dental prosthetics manufacturing in Japan. I was in that industry for a brief period of time, so I know custom IEMs are made in a similar way as prosthetics are made. Not sure whether they are aware of in-ear acoustics or not, but for a good fitting mould making, they should know what they're doing.

I have been previously rejected by Suyama for a review sample. 
I could've been much nicer with this review? :)

Earlier this year, they introduced Fit Ear TO GO! 334, the world's very first generic type IEM with 3-way, 3-units, 4-transducers driver configuration ever, for whooping 105,000 JPY.

With the most expensive price tag for a generic IEM, Suyama implemented some of ground-breaking technologies, developed by themselves in their 344. First of all, the transducer configuration is as following:

Tweeter: Knowles ED-29689 / Mid-range: Knowles CI-22955 / Woofer: Sonion 33A007

And perhaps the most intriguing effort would be the titanium-tubing high frequency bore, which is supposed to keep any type of acoustic intereference of CI-22955 & 33A007 away from ED-29689. Although it may sound great, the manufacturer, Suyama, has yet to explain the scientific principle behind this rather radical approach.

PRO: Nice built quality.  Good to finally see a custom-based IEM with the polarity all aligned.

CON: There is a channel mismatch in the lower frequency range, as much as up to 3 dB. Nothing big of a deal, if 334's price tag is not considered.

ON SECOND THOUGHT #1: Even though 334's tweeter unit is a Knowles ED-29689, the high frequency is well retained up to 3 mm away from the reference plane. Since custom IEMs' conventional insertion depth ends somewhere at this point, MH344's users might find this data useful as well.

ON SECOND THOUGHT #2: A 33-Ohm resistor should tame the bass nicely, while slighly attenuating the high frequency as well.

ON SECOND THOUGHT #3: While the titanium bore is acoustically isolated, it seems other bores are leaking, while retaining their own characteristics to a minimum degree, as shown above.

ON SECOND THOUGHT #4: Try to block one of the side bores (in this case, the lower one), and add a 100-Ohm resistor to your 334; a nicely tamed mid-range obtained. And the damper for the titanium tubing is merely of a 330-Ohm, so don't even bother with it unless less treble is desired. BTW I wonder whether Suyama actually acquired a proper authorization to use the triple-bore technology described on US8116502, patented by Logitech .

Special thanx goes to my friend, vAsurada.


  1. How would you compare it to UE900 and ER4? In terms of phase and frequency response?

    1. Phase control is quite brilliant, while maintaining quite realistic transient characteristics(big sound stage): bass-mid drivers are well joined together. Not as linear as ER4, but phase linearity doesn't mean much unless you need a binaural simulator.

      Frequency response is.. Well, I am not a bass-head.

  2. What do you mean when you say that the phase control is brilliant? And you also mention that the 334 had its polarity all aligned. What does this mean and how do you determine this from the charts?

    1. Drivers are soldered correctly, and no phase distortion&interchannel mismatch in the audible frequency range has been observed. (minimum phase is plotted)

      For further information, please refer to here:

  3. What's the difference between the phase curve on the impedance graph and the phase curve on the phase response graph?

    1. Hi Burr,

      Impedance phase: Above 0 degree, inductive reactance. Below 0 degree, capacitive reactance.

      Acoustic phase: Mixed phase response.

  4. 산미천님 핏이어 334 이 제품 성능이 어떠한가요?

    영어도 딸리고.. 초보라 파악하기가 힘드네요..ㅠㅠ..

    1. 성능은 딱 TDK BA200 급이라고 봅니다.

    2. 헉.. 그럼 k3003i 나 ie800 이 훨씬 낫나요..?

    3. 측정 결과와 제 감상에 따르면 그렇습니다.

  5. A nice read, thanks for the technical insights~

    Although I'm not really into making my own iems, I was quite sure the CI should be the woofer while the dual unit Sonion 33A007 should be the so-called "2 low-mid drivers".