Chord Electronics Mojo 2

Half the size of a pack of cigarettes, the Chord Electronics Mojo 2 houses a DA converter and headphone amplifier that should meet high demands. The device replaces the successful and visually almost identical previous model that has been on the market for seven years. The matt black box is made of robust CNC-milled aluminium and can be used either mobile or stationary. The four embedded semi-transparent hemispherical buttons that light up in different colours and indicate operating states are very eye-catching. This is extraordinarily decorative.

Targeting

The quality of headphone amplifiers and converters available as consumer solutions, especially with smartphones and laptops, is more about providing a complete set of features than satisfying upmarket sonic demands. It is obvious that in such devices, the transducer section is subordinate to requirements such as space-saving and power consumption, and for reasons of cost alone is unlikely to be of any significance. In addition, some smartphones now do without analogue outputs altogether and rely solely on Bluetooth wireless links. An external wired solution with audiophile standards is just what is needed. It takes care of sound reproduction. For this purpose, it converts the digital data stream from the player back to an analogue level and amplifies the signal for use with headphones.

What’s inside?

The technical basis of this UK-made device is an FPGA (Field Programmable Gate Array) that has been optimised precisely for the requirements of audiophile sound reproduction. Accordingly, the product does not use converters from AKM, ESS or other manufacturers but technology developed in-house, for which Chord-Electronics company founder John Franks was able to engage the specialist Rob Watts, who follows his own audiophile path and has contributed significantly to the manufacturer’s excellent reputation.

Compared to the previous model, the processing power has increased and approaches the more expensive Hugo 2. According to the manufacturer, the increased processing power is used for an even more optimised and tonally neutral conversion with more precise digital filter stages and improved noise shaping – i.e. for the newly added functions “crossfeed” and “equaliser”.

Interfaces

Audio signals find their way into the Chord Electronics Mojo 2 via coaxial (3.5 mm jack) and optical S/PDIF interfaces, Micro-USB and finally also via USB-C. The Mojo 2 is also equipped with a USB port. Sampling frequencies of 44.1 to 768 kHz (up to 32 bits) and DSD are supported, provided that the player stores, plays back and transmits the corresponding source formats. On the output side, two jointly adjustable 3.5 mm headphone outputs are provided. However, there are no RCA outputs for operation with an amplifier like on the Hugo 2 or balanced interfaces for headphones. Neither is there a Lightning connector, but it can be adapted.

Battery

Chord Electronics claims that the Mojo 2 offers significantly more efficient battery management with reduced losses, faster charging times and less heat generation. The capacity of the permanently installed battery has been slightly increased, but the playing time is still around eight hours, indicated by a multi-coloured LED. Not a marathon performance, but in practice, it is quite sufficient, as the Mojo 2 will probably be used stationary (see Sound). The automatic shutdown after ten minutes of silence is a nice practical feature. The ability to recognise a constant power connection and adjust the charging management accordingly is just as clever – as it increases the product’s life span. The only flaw is that charging still requires the use of the dedicated micro-USB socket, which is now less common.

Streaming with Poly

The Chord Electronics Mojo 2 can also be used as a HiRes-capable streamer via the Poly model (firmware 3.0 or higher), although this was not available to us for testing. This additional module acts as a DAP with a microSD card slot and supports wireless transmission methods via WiFi and AirPlay with DLNA compatibility as well as the somewhat outdated Bluetooth protocol 4.1. As with its predecessor, Poly is connected to the Mojo 2 as a plug-in module via four sockets. This explains why these sockets had to remain in exactly the same place, just like the micro-USB charging socket.

In practice

The four variably illuminated buttons on the Chord Electronics Mojo 2 are used for function control and status indication, such as sampling frequency. One button is for switching on and off, while the middle two larger “balls” can initially adjust the output level and trigger a mute function. The fourth key is for menu control. Here you have access to further functions via colour coding, which is adjusted via the volume keys: Display brightness, the rather discreet three-step crossfeed function, which influences the perception of the stereo centre, and a key lock to prevent the Mojo 2 from being adjusted accidentally. In addition, there is the aforementioned tone control in the form of four fixed frequencies, each of which can be lowered/raised by up to ±9 dB.

The operating concept is coherent but requires a period of familiarisation. Even then, the Mojo 2’s colour language is rarely self-explanatory. It looks good but is rather compromised by the reduced format and design. Nevertheless: I found this compromise quite feasible because, as a rule, you won’t constantly be turning the advanced parameters for crossfeed or the equaliser. A display would definitely have altered the visual concept.

The level reserves of this headphone amplifier are well proportioned even for low-power models. Presumably, Chord Electronics has dispensed with a dedicated line-level mode. This was not a real problem because the maximum level of the headphone outputs was sufficient for this application, but unfortunately also carried the risk of overdriving a conventional input.

Application: A mobile converter and/or headphone amplifier always requires additional space in your pocket and comes with supplementary charging logistics. Today’s smartphones usually deliver their sound wirelessly via Bluetooth to the in-ears. In the case of the Mojo 2, sounds go digitally from a smartphone to the converter and from there to your headphones via cable. This is more complicated, but the signal reaches you in uncompressed audiophile quality, provided the appropriate sources are available. For me, the advantage of such solutions is chiefly found in quiet listening environments, such as in a hotel room.

Sound

The previous model received good reviews for its sound quality. From a purely technical point of view, it delivered not only a flawless frequency response but also a high-resolution, dynamic, noise-free sound image that was precisely reproduced in terms of time, spatial and panoramic resolution.

The Mojo 2 also provides an output power that drives even sensitive, quiet headphones with sufficient level – and this was even true for a double pack. Our listening tests were with the Sennheiser IE 600, the 64 Audio U6t and the Sennheiser HD 800 S. The Chord Electronics Mojo 2 drove all our test headphones confidently, with really powerful levels when needed, in the spirit of a high-quality power amp.

For a substantial sound assessment, additional explanations are needed. First of all, today the level of modern converters is quite high. As a result, the comparison to a smartphone’s built-in transducers can initially be surprisingly low for untrained listeners. In addition, you hear the sound source and the headphones themselves first and foremost.

With a little patience, however, the differences become apparent. With the Chord Electronics Mojo 2, you have the mobile counterpart of a high-quality converter/amplifier combination that might be found in your living room and thus get an extra five to ten per cent sound quality out of your signal chain.

The differences are quite subtle, but they do add up. The better the overall chain from the sound source to the headphones, the more noticeable the added value.

The Chord Electronics Mojo 2 ultimately delivers a more coherent, three-dimensional sound image with even finer details. The room and the stage are better constructed and illuminated. At the same time, the details become more audible over the entire frequency response. This can manifest itself as increased speech intelligibility, as a selective flashing of sub-bass or as a suddenly audible interplay of two instruments where one had previously perceived only one sound source. I also think that a more complete transmission of the stored sound information leads to a more emotional, relaxed overall experience. It should be clear that these improvements are most noticeable in quiet listening environments.

And so then, depending on the environment, source device and headphones, the increase in sound can be remarkable. With a good signal chain, one dives deeper into the sound image and discovers the subtleties associated with the instruments, the mix, the room and the dynamics. This may sound like a matter-of-fact analysis, but that is exactly what this transducer does not allow itself to be tempted into. It manages to package the gain in information coherently, effortlessly and musically. However, uncompressed source material is required.

Tone control

The four-band equaliser is a masterstroke. Unless you judge equalisation to be undesirable in advance, you can use this function to compensate for general weaknesses in certain headphones or for tuning to suit your taste.

The outer bands start at 20 Hz and 20 kHz, very low and high respectively, and can be adjusted in 19 steps, which are indicated via colour combinations. In doing this, you actually get a considerable amount of low-frequency boost and air without it sounding overdriven, muddy or bilious. With high-quality headphones, you can “heat up” the sound around the bottom or, conversely, protect less level-stable headphones from overload in the bass range. For example, the bass in Whitney Houston’s “Exhale” could be boosted very impressively. The band at 120 Hz provides an overall bass emphasis, but one should be careful not to make it sound unbalanced. The same applies to the 3 kHz band, which also significantly influences the sound. Here, too, one should not overdo it when manipulating the equaliser.