Arcam rBlink Bluetooth D/A processor JA Visits Arcam
I got comfortable in the center chair. I was visiting British manufacturer Arcam in their new facility, a few miles north of Cambridge, and product manager Andy Moore had set up a modestly priced but potentially good-sounding system in the company's dedicated listening room: KEF R300 speakers driven by the Arcam FMJ A19 integrated amplifier, which had impressed Stephen Mejias in the January issue. The source appeared to be Arcam's FMJ D33 D/A processor, which I reviewed in February 2013, connected by USB to a laptop running JRiver Media Center.
I closed my eyes, and Moore played a track from the soundtrack to one of the Batman movies. The soundstage was wide and deep, and the orchestral sound was detailed and uncolored. This was an unfamiliar room, system and recording, but I was impressed by what I was hearing. I opened my eyes and saw that the laptop wasn't being used. I turned to Moore to ask what we were listening to, and he pointed to his iPhone 4S. "I'm streaming audio to the Arcam rBlink with Bluetooth!"
Yessitting atop the D33 was an rBlink. Sam Tellig had reviewed this $249.95 Bluetooth-connected D/A processor in the December 2013 "Sam's Space." I have expressed my reservations about Bluetooth's lossy audio codecs many times in Stereophile, most recently in that same issue's "Letters," so it is an understatement to say that I was gobsmacked by what I was hearingespecially as, unlike some Android phones (see http://tinyurl.com/qhxjv3o), iPhones and iPads don't have the potentially superior-sounding aptX lossy codec, but use AAC at 128kbps (iOS6) or 256kbps (iOS6+ onward). (Because a Bluetooth wireless connection has insufficient bandwidth to handle uncompressed two-channel audio data of CD quality, which requires 1411kbps, some sort of data compression is necessary to stream audio via Bluetooth (footnote 1). Low Complexity Subband Coding (SBC) is the default codec in the A2DP Bluetooth profile.)
"It gets worse," laughed Moore. "I was streaming the file from Spotify."
Now my face was even redder. Spotify's Premium service, which was what Moore was using, uses the lossy Ogg Vorbis codec running at 320kbps. I've written before about the sonic dangers of cascading lossy codecs, ie, where one encoding/decoding cycle is followed by another. To encode a datastream, a codec breaks it down into blocks of variable size; when the results of two or more codecs are cascaded, it is extremely unlikely that the timing of each of these blocks will coincide. As a result, transient information that might occur at the intersection of two blocks can get spread out in time and sound.
My experience suggested that Arcam must be doing something special with the rBlink's Bluetooth circuitry. Rather than buy ready-to-use OEM modules, Arcam is a Bluetooth licensee and is thus able to use the latest Bluetooth chipset, to which they apply their own dejittering technology. Their use of aptX is probably helped by the fact that aptX developer CSR is based nearby, and the two companies' engineers sup their warm English beer in the same pubs. The DAC chip is the Texas Instruments PCM5102.
Perhaps I shouldn't have been surprised by my experience at Arcam. Stephen Mejias reported, in his November "Entry Level" column, how impressed he'd been with music streamed from Ms. Little's iPhone to the NAD D3020 amplifier. But I needed to audition the rBlink in more familiar surroundings. I asked for a review sample and, in the opposite of my standard practice, ran it though my usual suite of measurements before I did any listening.John Atkinson
Footnote 1: A primer in Bluetooth audio transmission can be found here.