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Audioquest Dragonfly Cobalt

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Audioquest Dragonfly Cobalt DAC and Headphone Amplifier

By Alex Colburn

 

Introduction:

            Four weeks into the COVID-19 lockdown I’m working from home and spending a lot of time sat in front of a computer screen in the study. Distractions are only too frequent; noises and voices filter through from inside and outside disturbing concentration and leading to long periods of gazing out of the window. Why is there so much activity, there’s supposed to be a lockdown in progress? I decided to try and lock out (no pun intended) the disturbances and donned a pair of headphones plugging them into the audio out socket on the computer. It seemed to be working, distractions eliminated and I get to listen to a great selection of music. Though I had plugged in the odd set of ear buds or cheap headphones in the past, this was the first time I had seriously considered trying some headphones of decent quality.  Listening to music I am very familiar with on my Oppo PM-1 headphones it became painfully obvious the quality of the audio output on the computer was sadly lacking in many respects so I began to wonder what options were out there to improve the situation.

            A little bit of Internet research revealed a multitude of potential solutions ranging in price from a few tens of pounds (the usual multitude of Chinese offerings) to thousands. To narrow down the choice, I decided it had to be small and simple to implement, have USB connectivity, did not need external power or batteries and flexible enough to be used with other devices like mobile phones. I didn’t want to spend a lot either as hopefully the lockdown will not last forever. Reviews of the various options pointed me in the direction of Audioquest’s Dragonfly series of USB powered integrated DAC and headphone amplifiers. I eventually settled on their Cobalt model and in due course placed an online order with one of their numerous stockists. Interestingly, while speaking to the dealer on the phone, I learned that business was very good in the HiFi trade and generally bucking the retail trends during the pandemic.

 

Description:

            Audioquest who are probably better known as a cable manufacturer, expanded their product range to include DAC’s a few years ago. The Dragonfly series of DAC/headphone amplifiers bear a marked resemblance to a USB pen drive, a long narrow body with gold plated USB A plug at one end and 3.5mm stereo jack at the other. Three versions are available with the colour of the casing uniquely identifying each model, Black, Red and Cobalt. Black is the entry-level model with price and performance increasing through the red to the top of the range Cobalt. The Cobalt model is a vivid blue colour and since cobalt is a hard shiny metal it clearly refers to the cobalt oxide that makes up the cobalt blue pigment well known to artists. The body construction appears to be a robust powder coated die cast aluminium with a colour coordinated plastic push-on cap to protect the USB connector when not in use. A translucent dragonfly logo emblazoned on the body is illuminated by multi-coloured LED’s inside the body to indicate its various operating modes.

The Dragonfly was delivered in classy glossy packaging with instruction manual, free trial offers for the Roon control point software and Qobuz subscription, a protective leather storage pouch and Audioquest Carbon-level Dragontail USB A to USB C cable for connection to android mobile phones. Users of Apple iPhone/iPad devices with their proprietary “Lightning” connector will require an additional USB A to Lightning adapter cable. Audioquest recommend the Apple USB to Lightning camera adapter, which they say is more robust, sounds better and has the bonus of allowing simultaneous charging. Operating systems supported include: Apple OS X 10.6.8 (Snow Leopard) or later, Windows 7-10, Apple iOS 5 or later and Android mobile devices. Standard control point software such as Roon can be used to operate the Cobalt but Audioquest have worked with Qobuz and Tidal to integrate Dragonfly DACs with their apps over a broad range of platforms.

 

Technical discussion:

            The casing of the Cobalt model has a deeper semi-cylindrical appearance than the other models in the range presumably because of the extra electronics packed inside. Based on the USB 1.0 standard, the interface runs on Gordon Rankin’s “StreamLength” asynchronous transfer firmware and does not require the installation of software drivers. Inside the DAC is the flagship ESS Sabre ES9038Q2M in mobile version, which generates an ultra low jitter clock signal to control the conversion process and a Microchip PIC32MX274 microcontroller. The “Monoclock” single clock architecture allows the Dragonfly to provide greater resolution and clarity compared to other DAC architectures with multiple clocks. Audioquest claim that the minimum-phase slow roll-off filter in the ES9038Q2M “results in naturally expressive sound that is always emotionally engaging and never fatiguing”

            Audio file formats supported by the DAC include MP3, PCM up to 24bit 96kHz and MQA with the Dragonfly logo illuminating in different colours to reflect the mode the DAC is operating in. The relevant colour codes are, red: standby, green: 44.1kHz, blue: 48kHz, Yellow: 88.2kHz, light blue: 96kHz and purple: MQA. When I first used the Dragonfly, I found myself looking for tracks to check all the colour codes were working only to find that indeed they were! The ES9038Q2M incorporates a 64 bit bit-perfect digital volume control that is directly controlled by the host system’s volume, pause and skip controls. Recent research by Audioquest has resulted in the development of enhanced power supply filtering techniques to reduce the increasingly pervasive noise from WiFi, Bluetooth and mobile phone signals. Audioquest sell a Dragonfly accessory called the “Jitterbug”, a USB data and power noise filter which I suspect is the same noise filter technology used in the Cobalt but now available separately for the black and red models. Output from the DAC is passed to an ESS Sabre 9601 headphone amplifier, which has a 2.1Vrms output capacity that is capable of driving low impedance headphones. All of the Dragonfly series of DAC’s are firmware upgradeable for any future software enhancements.

 

Audition:

Due to special offers, I currently have subscriptions to both Qobuz Studio and Tidal HiFi so this was the ideal cross-platform method of auditioning the Dragonfly Cobalt. I used my Oppo PM-1 planar magnetic headphones in all listening tests. Both Qobuz and Tidal apps have the ability to completely bypass the computer audio system and control the Dragonfly directly leaving the audio stream blissfully clear of system alerts and interrupts. The computer audio system still works in parallel for system alerts so you may want to mute or turn the volume down for those.

Initial impressions were good; the contrast with the computer audio I had become accustomed to was quite dramatic, what I was hearing sounded like HiFi rather than something more akin to lift music. Audioquest recommend leaving the Dragonfly permanently plugged in to a live USB socket so it’s warmed up ready to go straight from the off. I did notice over a period of about ten minutes or so the music began to be delivered with more authority so a short warm up seems essential. Even after many hours of use, the body remained just mildly warm to the touch, I couldn’t find any power consumption specs but it seems to be power efficient. The volume control has more than ample resolution and operated cleanly and smoothly without any apparent steps.

Low-level fine detail was there, absolutely essential in creating a believable soundstage presentation. Instruments were definitively placed with good separation, stable positioning and no smearing. There was also the illusion of some level of image depth in as much as you can expect from a pair of headphones. Bass depth was available in spade loads with good attack and no timing issues, overhang or bloating. Oppo say the PM-1’s go down to 10Hz, not that you would be able to hear that low but Audioquest do not seem to quote a frequency response spec for the Cobalt. Mid range voice reproduction was clear and natural, Cara Dillon’s voice on “Live at the Grand Opera House” was as good as it sounds on the main system. High frequencies were crisp and clear, percussion on Evelyn Glennie’s “Ecstatic Drumbeat” was hard and fast with natural decays.

One of my pet hates when listening with headphones is hearing noise during quiet passages but the Cobalt passed this test with flying colours. Though I often found myself using the volume control close to its maximum level, we all tend to listen at higher levels when using headphones, the Cobalt still delivered ample volume into the 35 Ohm Oppo headphones. The illuminated logo was useful in confirming the data rate of the music I was streaming, both Qobuz and Tidal apps have settings to limit the stream bandwidth presumably so as to limit consumption of mobile data allowances.

Audio performance on mobile devices was to all intents and purposes indistinguishable to that on a laptop or desktop. There was a noticeable increase in battery usage on an iPhone but it should still give many hours of listening from one charge. The main negative aspect to operation using a mobile phone was having a clunky adapter and the Dragonfly hanging off the bottom of it, if I was out on the move the combo would be tiresomely inconvenient.

 

Conclusions:

For many, and I include myself here, the biggest attraction of the Dragonfly is its size, simplicity of use and broad compatibility. The fact that it has all these properties and also turns in a great performance is a bonus. Having now spent several hours a day over many days listening to the Dragonfly Cobalt which is much more than I would normally spend listening to the main system I feel confident in saying it would give many expensive stand-alone DAC/headphone amplifier combos a good run for their money. Considering the price-performance ratio of the Dragonfly Cobalt it is good value for money and I’m certainly glad I invested in one.

 

Technical specifications:

Input: USB 1.0

Output: 3.5mm jack socket, 2.1Vrms, 16 Ohms minimum headphone impedance

Files formats supported: MP3, PCM up to 24bit 96kHz and MQA

Microcontroller: PIC32MX274

DAC: ESS Sabre ES9038Q2M

Headphone amplifier: ESS Sabre 9601

Volume control: 64 bit bit-perfect digital

Dimensions: 12mm H, 19mm W, 57mm L

Price: £215

 

Associated review equipment:

Oppo PM-1 planar magnetic headphones

Apple iMac computer

Apple Macbook Pro computer

Apple iPhone 8

Apple USB to Lightning camera adapter

 

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