Arcam hi-fi separates have always been aimed at the mass market, but have often ended up being just a little quirkier than most. Always well engineered, the company frequently takes brave engineering approaches, sometimes with great success – and this high end CD player launched at the turn of the century is a case in point. Using unique technology licensed from dCS, the FMJ CD23 was an evolution of the Alpha 9, famous for being the first affordable implementation of the Ring DAC.
Multibit converters work well when correctly adjusted, but are critically dependent both on the tolerances of their resistor networks and on glitch-free electronic switching. Unfortunately, time and temperature drift play havoc with them, causing high distortion and poor noise modulation performance. Bitstream overcomes this but gives a poor signal-to-noise ratio which is only overcome by heavy oversampling and noise shaping. Problems here cause unpleasant in-band idle tones and sound degrading timing errors.
The Ring DAC avoided such pitfalls by using technology developed by dCS (Data Conversion Systems) based on advanced military research on aircraft radar, seen in later versions of the Harrier jump jet. Combining multibit and Delta Sigma technology, it works by continuously varying the number and positions of the selected current sources from sample to sample, as though around a circle. This ensures the inevitable slight variations in the values of the current sources are randomly distributed throughout the quantising range, effectively turning tolerance errors into random white noise rather than distortion. The result is high linearity plus very low noise and distortion.
The CD23 was a deluxe version of the Alpha 9 – to go with the Pacific Microsonics HDCD digital filter, low jitter Sony CDM14 transport and high precision analogue stages, a new motherboard, extra vibration damping, modified power supply and the exquisitely finished metal casing and front panel were added. Even the control buttons and packaging were upgraded, giving the look of a seriously high end bit of kit. The result was a classy looking product which looked and felt a league above the plasticky Alpha 9.
It was a delightfully easy player to use, ergonomically satisfying and totally fuss-free. Aside from the usual programming functions, it offered just a ‘scan’ facility (which played the first ten seconds of every track in sequence) and ‘space’ which added a four second between every track (for the benefit of cassette deck music search systems). Along with a useful display dimmer and coaxial and optical digital outs round the back, that was your lot!
The sound was remarkably sophisticated yet musically engaging by the standards of its day, conveying sparkling harmonics in all their glory. Midband was tight, bass supple and tuneful, and hi-hats sweet and sonorous. Most impressive though was the way the Arcam constructed a cathedral-esque acoustic around the speakers, with amazing depth perspective and brilliantly focused stereo images. It offered most of multibit’s glory with none of the fizz. It had a beautifully even-handed tonality with a hint of warmth, a super-fluid bass that bounced along like a new rubber ball, and sweet, spacious treble.
Ask dCS what they thought of the CD23’s Ring DAC implementation, and off-the-record you understand, they called it “a bit noisy”, but that’s from a company used to selling DACs at twenty times the price. In truth, Arcam said its FMJ CD23 was one of the best one-box players around at the time, and it wasn’t that far wrong. £1,100 new in 2000, it’s now a few hundred pounds in good used condition, and very fine value for audiophiles on a budget.