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.