JVC UX-1 micro system Lab Report

Lab Report

Tested via its headphone output, and set to 2V/0dBFs, the UX-1's CD section may offer swift loading and track access but the audio performance is rather limited by the 14-bit Toshiba TD6710AF DAC and (analogue) minimum phase filter. The A-wtd S/N is just 81dB, low-level linearity is already –1dB adrift by –88dBFs while digital jitter – mainly data-induced in nature – is ~900psec. The frequency response is flat to within ±0.5dB from 100Hz-20kHz but shows a low bass roll-off amounting to –14dB/20Hz that carries through to the main amplifier outputs. JVC has included an 'Active Hyper Bass' feature that applies a +13.3dB boost at 50Hz but the response still remains –14dB down at 20Hz. While this rolled-off bass seems extreme by modern standards, it's less so when we consider the compact dimensions of the partnering UX-B1001 loudspeakers. Distortion, meanwhile, is relatively high at 0.3%/20Hz, 0.14%/1kHz and 0.9%/20kHz at maximum digital levels but reaches a minimum of 0.025% at –20dBFs [see Graph 2, below].

The partnering amplifier is rated at 2x11W/4ohm, albeit at a rather alarming 10% THD... Relaxing our standard 1% THD limit to 2% allows the UX-1 to squeeze out 2x6.5W/8ohm and 2x9W/4ohm, while there's sufficient 'headroom', and a maximum 2.9A current reserve, to accommodate 9W, 14.5W, 17W and 7W into 8, 4, 2 and 1ohm loads at up to 5% THD, respectively. I've already noted the amplifier's LF roll-off where distortion also climbs to a huge 33% (re. 0dBW/20Hz) before settling out at 0.028-0.24% from 100Hz-20kHz (re. 0dBW). Otherwise, overall gain is +23.7dB and the A-wtd S/N is only slightly below average at 83.1dB (re. 0dBW). PM


Dynamic power output vs. distortion up to 5% THD into 8ohm (black trace), 4ohm (red), 2ohm (cyan) and 1ohm (green) speaker loads. Max current is 2.9A


Distortion versus digital (CD) level over a 120dB range (1kHz, black; 20kHz, blue)

Power output (<2% THD, 8/4ohm) 6.5W / 9W
Dynamic power (<5% THD, 8/4/2/1ohm) 9W / 14.5W / 17W / 7W
Output imp. (20Hz–20kHz/100kHz) 1.35–0.39ohm / 0.59ohm
Freq. resp. (20Hz–20kHz/100kHz, 0dBW) –13.8dB to –1.2dB/–11.9dB
Digital jitter (CD) 900psec
A-wtd S/N ratio (CD/Amp) 81.1dB (0dBFs)/83.1dB (0dBW)
Distortion (CD, 0dBFs/Amp, 0dBW) 0.14-0.90% / 33-0.028%
Power consumption (Idle/2x6W output) 9W / 28W
Dimensions (WHD) / Weight 458x258x222mm / 9.1kg