AudioQuest DragonFly Cobalt USB DAC/Headphone Amp Lab Report

Lab Report

While the Cobalt represents the most significant update on AQ's DragonFly series, this is not for the 'headline' reasons you'll probably read about elsewhere. Yes, the Cobalt uses an ES9038 DAC in place of the Red's ES9010 [HFN Oct '16] and with the slow roll-off mode of the minimum phase digital filter selected. So the Red has a flatter response of +0.1dB/20kHz (44.1kHz/48kHz media) and –0.85dB/45kHz (96kHz media) while the Cobalt rolls-off to –2.0dB/20kHz and –8.45dB/45kHz, respectively. Stopband rejection is poorer too at just 40dB but ringing and phase distortion are much reduced. Thus AQ's Cobalt may offer a slightly different tonal colour even though harmonic distortion is unchanged over the Red – 0.02-0.05% at the same 2.18V maximum voltage output, falling to a minimum of 0.0025% over the top 30dB of its dynamic range [black trace, Graph 1 below].

This, the usefully low sub-0.5ohm output impedance and 53mW/25ohm power output are unchanged because the Cobalt uses the same ESS 9601 headphone amp as the Red. Jitter is still very low at <20pec (unloaded) thanks largely to the excellent rejection of the ESS DACs and 'StreamLength' USB transfer protocol. But the real headline is tucked away in the small print: 'Improved PSU filtering increases immunity to WiFi, Bluetooth, and cellular noise'. In practice AQ's new 5V line conditioning is so successful that the S/N, when driven via a 'clean' USB hub like the Melco N10 [HFN Jun '19] or a noisy PC, is unaffected at a massive 110dB (A-wtd). The Red varies between 94dB to 106dB depending on the quality of the USB hub [red trace, Graph 2]. So not only will the Cobalt offer a truly consistent performance but you also save the cost of an AQ JitterBug [HFN Oct 15]! PM


THD vs. digital signal level at 1kHz (black, 600ohm; red, 25ohm; 0dBFs = 53mW and –35dBFs = 1mW) and 20kHz (cyan, 600ohm; blue, 25ohm)


High resolution 48kHz/24-bit jitter spectrum – DragonFly Red [red] versus DragonFly Cobalt [black]

Maximum output (re. 0dBFs into 47kohm) 2.18V
Max. power output (re. 0dBFs into 25ohm) 53mW @ <1% THD
Output Impedance (20Hz-20kHz) <500mohm
A-wtd S/N ratio (0dBFs; 25ohm/47kohm) 106.5dB / 110.0dB
Distortion (20Hz-20kHz, re. 10mW) 0.016–0.011%
Frequency response (20Hz-20kHz/45kHz) +0.0 to –2.0dB/–8.45dB
Digital jitter (into 25ohm / 600ohm) 450psec / 15psec
Power consumption 5V USB hub-powered
Dimensions (WHD) / Weight 19x12x67mm / 40g
Price £270
Supplied by: AudioQuest UK
01249 848 873