Roksan Oxygene integrated amplifier

Integrated amplifiers
Roksan Ltd. Oxygene

Unfortunately, Apple does not support AptX on its iOS system at the time of writing, but it is supported on Motorola, HTC and Samsung Galaxy phones, as well as Galaxy tablets. Strangely, it is also supported on Apple OS X for its computers, so it’s possible AptX compatibility will become available on later iterations of Apple’s iDevices, or operating system. 

The only other connections on the rear panel are subwoofer outputs and multi-way loudspeaker terminals, and a strange connection that looks something like a Neutrik Speakon. This is intended for a forthcoming power supply upgrade.

The amplifier design itself is fascinating. It is a Class D design, using Hypex UCD 400 Class D modules to deliver 75 watts into an eight ohm load and 150 watts into a four ohm loudspeaker load. Class D amplifiers do not tend to react well to lower speaker impedances than this, so avoid using the Oxygene with ‘difficult’ speaker loads. Although every manufacturer of Class D modules makes a claim to delivering good sound, Hypex is commonly considered to be the best of breed in sound quality. 

Why fascinating? Roksan has also taken the rare step of coupling these fast Pulse Width Modulation amplifier modules with a linear power supply. Normally, designers use Class D modules with switch-mode power supplies in order to keep the size and weight of the amplifier down. There is no strict demand for switch-mode power from the Class D modules however, and instead Roksan uses a linear PSU with a pair of big toroidal transformers inside the amplifier’s case. Roksan is not the only company to approach Class D in this manner, but the trade-off (or maybe the hidden benefit) is the size of the chassis means the Hypex modules (capable of up to about 400W) are limited to 75W into eight ohms, because it places a ceiling on the size of the transformer. 

Design-led? Bluetooth? Class D? Subwoofer outputs? I can’t think of anything less appealing to the rank and file hi-fi enthusiast. And that says more about just how out of touch those rank and file hi-fi enthusiasts are with the way non-audiophiles live today.  I can see this amplifier sitting under the TV screen in many living rooms, the two loudspeakers making sound for both audio and video entertainment, with the listener porting music from his or her tablet wirelessly. I can see this happening because that’s exactly how the Oxygene ended up being used, with the display dimmed or off to keep from acting as TV distraction.

The first day of use, I must admit was disappointing. Out of the box, the Oxygene lives down to all those bad-news stories enthusiasts like to lay at the door of Class D; it was flabby in the bass and thin and brash sounding in the treble. If it carried on in the same vein, I’d have sent it back unreviewed and unloved. In truth, I lost the next two days, because I had friends staying for the weekend, but this sentence hides an interesting story. Quite without prompting, One Direction started blaring out of the Oxygene mid-Saturday, and it kept happening. This was the result of the teenage daughter of my friend discovering the word ‘Roksan’ on her phone, guessing (correctly) that ‘0000’ was the code and essentially ‘hacking’ the hi-fi. While deeply annoying – hearing ‘Little Things’ for the eleventy-third time in a row can drive you round the bend – it also showed just how easy the Oxygene is to use, and how it will be used. Unfortunately if you turn off the Oxygene, when said teenager powers it up again, it retains the input but resets the volume level to a moderately loud ‘20’. 

Maybe it was a few days of running in, or maybe it was exposure to Harry Styles, but by the end of the weekend, those initial misgivings about the Oxygene had vanished completely. I couldn’t put this down to familiarisation with the product sound, because it was filtered through the system being dominated by use as either TV sound or the audio plaything of a teenager. All I know is the sound of the music I played on the Sunday night bore little relation to the sound of the music I heard two days previously. Things got better on the subsequent midweek listening session, but I couldn’t perceive any notable improvements after a few days of running in. 

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