Flying high in a CIEM Lear jet? Lear are neither the first nor last manufacturer of custom in-ear monitors aka CIEM. One of the first in fact was Jim Harvey of JH Audio. He’s had loyal customers for many years already. Then Unique Melody showed themselves from the Far East and big players like Westone and Ultimate Ears got involved. Today I know of more than 20 firms who serve this sector and plenty of new ones are in the wings. What’s more, today we have CIEM with 3 drivers, 4 drivers, 6, heck even 8 or 12. Crossover points can hit 5 to create 6-ways. Cuantos más mejor? The more the merrier? I’m not sure. Except there seems to be a trend.


Lear stands for listen & learn everything. Acoustic & audio revolution. They were first established in The People’s Republic of China in 2008. Their first product was an in-ear earphone called the Lear LE-01. In 2009 ownership was transferred to Hong Kong’s Forever Source Digital labeled "one of the most well-known professional portable audio products retailers in Hong Kong". Just one year later they had launched their first FMS-01 portable headphone amplifier to become what they believe the first and only company to have their custom earphones 100% researched, developed and fabricated in Hong Kong. By 2012 they announced the FSM-02 portable amp which sold out in 3 months. This was followed by the market’s first 5-driver CIEM which became very popular with headfiers.

The nomenclature BD4.2 stands for 4 Balanced armature and 2 Dynamic drivers per channel and represents their latest reference effort. It comes in two version, one a universal fit called LUF-BD4.2, the other a custom called LCM-BD4.2. Either way, this model has quad balanced armature drivers (2 for the mids, two for the treble) plus twin 6mm moving-coil woofers with adjustable outputs. These drivers are organized with a 3-way crossover plus quad-bore loading with metallic tubes and acoustic low-pass filters. The end result is one of the more advanced in-ear designs available. More on this anon.

Nearly all CIEM require routine instructions to place an order. Their makers require your ear mould impression which should be generated by an audiologist. The precise process can differ. Some manufacturers want your face relaxed during this procedure. Others want your mouth fully opened, some want it fully closed. Lear specify an impression that should reach deeply into the second bend of your ear canal for best results. Once done, your impressions are sent to them. You also pick the color, design and artwork. If everything is peachy, you should receive your custom-fit in-ear monitor a few weeks later, in Lear’s case with adjustable bass. My LCM-BD4.2 arrived in a watertight Otter Box with a cleaning tool and cleaning fabric, a mini screwdriver for the bass adjustment and a soft furry carrying pouch. The BD4.2 is crafted from acrylic shells with a vent hole and mounted potentiometer for the bass adjustment.