Last October, we reviewed Fiio’s first wireless solution to the passing of the headphone jack — the BTR1 Bluetooth receiver. Though the BTR1 lacked support for AAC-encoded music files and its volume control had an unfortunately-placed two-step jump, we liked it very much and saw it as an excellent solution for those willing to go wireless, but unwilling to give up their favorite portable wired headphones. This time, Fiio’s back with a new entry in its Bluetooth audio receiver range, the μBTR. Compared to the BTR1, it’s cheaper (about half), smaller (about half), and less powerful (about two-thirds).
The “μ” symbol — pronounced “mu” — is a Greek character that is used in many areas of science and mathematics. Probably most relevant here is its use to denote a micron, or millionth of a meter. Though Fiio probably should have chosen a character that’s easier to Google (“μ” is nowhere to be found on standard keyboards), it’s a fitting name. The μBTR is very tiny, at just 55mm x 19mm x 9.1mm — about the size of two AAA batteries — and weighs a negligible 12.5 grams. It’s small and light enough to mount on a pair of over-ear headphones, assuming you don’t mind looking just a little weird in the process. It’s a very stylish device — smooth matte white plastic (Fiio says more colors are coming in the future) and a glossy acrylic faceplate replaces the BTR1’s black scalloped aluminum — an ultra-minimalist and attractive package. Starting at the top of the μBTR, we find a 3.5mm headphone jack, control buttons, and a USB-C charging port. A plastic clip is now permanently attached to the rear of the device, and on the front is a single multi-function LED and microphone.
Inside the μBTR is a Qualcomm CSR8645 Bluetooth chip paired with a Texas Instruments TPA6132A2 amplifier and 120 mAh battery. These are power-efficient components, as we got about the advertised nine hours of battery life on a charge, and were able to recharge completely in about an hour. Using the μBTR is just as easy as the BTR1, if not easier — one button handles power, pairing, phone calls, and Siri, and a rocker button handles volume and track controls. Its iOS integration is mixed — the μBTR’s battery status is reported on iOS, but volume is not linked; when connected, iPhone volume is controlled independently from the μBTR. Its buttons don’t have quite the same clicky feeling as the BTR1, but we can certainly accept a more plasticky feel at this price.
The μBTR specs are reasonable for this price, though it’s not punching that far above its weight class. Bluetooth 4.1 is supported, as are aptX and AAC codecs. in our testing, we got 30 feet of range without skips easily. The μBTR’s tiny amplifier puts out a maximum of just 20 mW of power into 16 ohms (10 mW into 32 ohms); not enough to power every headphone out there, but, in our testing, enough for IEMs or portable over-ears like the Audio-Technica ATH-MSR7. The μBTR has a frequency response of 20Hz-20kHz and THD+N of .05% (for perspective, the X7 MkII’s distortion spec is 0.0008%), and an IEM-friendly output impedance of 0.3 ohms. The μBTR’s noise floor is low enough that with 16-ohm or 32-ohm headphones, it was dead silent — none of the hiss we often hear with Bluetooth devices. Fiio claims that this device can sound better than wired; we’re not willing to go that far, as there is no lossless Bluetooth audio transmission. That said, like any good Bluetooth device, there are times when the μBTR might be indistinguishable from wired; the μBTR sounds at least as good as Apple’s Lightning Adapter in many cases. Though its lower power output potentially narrows its appeal, the μBTR offers a compelling value as an entry-level headphone jack replacement.
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