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| ARCAM FMJ CD33 COMPACT DISC PLAYER | ||
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Arcam produced one of the first UK made CD players back in 1986. We have been Britain's leading manufacturer of quality CD players for more than the last ten years. The FMJ CD33 player is the second CD player design to grace the exclusive FMJ range. It follows nearly four years on from the launch of its predecessor the CD23. The CD23 has established a reputation for superior performance from critical listeners around the world. We always knew the CD23 would be a hard act to follow, but the challenge was one that our talented design team met with commitment and enthusiasm. The results show that we have achieved a new benchmark in CD replay. Representing the pinnacle of CD reproduction at a real world price, the CD33's sound quality outperforms players many times more expensive in terms of sound quality. The CD33 incorporates the latest thinking in state of the art analogue and digital audio design. Key performance areas include upsampling the 44.1kHz digital data stream to 192kHz which allows us to use a very high frequency analogue output filter for improved phase and frequency response. The DAC circuit board uses a total of four 2-channel Wolfson 8740 DACs. These multi-bit sigma delta devices are in our opinion one of the best performing DAC chips available today. Using several in parallel further reduces noise, distortion and improves linearity. The DC coupled output stage comes with sophisticated servo control for optimum control of low frequency output. The precision required to reproduce music to a level that is truly astonishing is hard to comprehend. The attention to detail required in the design and development of the CD33 is reflected by the ultra high level of performance that this player delivers. The definition in the sound stage produced from the best CDs is proof that our obsession with design accuracy measured in parts per million is justified. The goal of the FMJ team was to improve on this already superb player. To achieve this the CD33 has a new four-layer circuit board and a totally new power supply configuration. We have added a high quality toroidal transformer to supply the sensitive audio circuitry in the upsampling multi DAC board. The improvement in definition in the lowest frequency range is palpable. Further improvements centre on the use of a new material for the player's chassis that is made using a special vibration damping laminated construction. Although it is four times more expensive than our standard chassis, it is worth every penny! The extra rigidity provided by the precision-machined 8mm thick aluminium alloy front panel also contributes to a performance that is so assured you will find new life in even your oldest CDs. The long years of painstaking development will only take you a few minutes to appreciate. A demonstration from one of Arcam's appointed specialists will confirm the FMJ CD33 as a modern classic that will bring added enjoyment from all your CDs for many years to come. Design Details Background The Ring DAC employed a novel multi bit sigma delta architecture, originally developed for military radar systems. It was based on a number of unitary weighted parallel current sources, driven in such a way that any errors in the individual sources were averaged over time and converted to innocuous low levels of white noise rather than unpleasant distortion. The resultant audio output was exceptionally clean and transparent. The technology was used by dCS itself in discrete form in a number of studio and later high-end audio applications - the lower cost IC version was developed exclusively for Arcam. The IC version of the Ring DAC was subsequently incorporated into two further Arcam CD players, the DiVA series CD92 and the FMJ series CD23. All three players have received considerable critical acclaim and well over ten thousand are in use worldwide. Nevertheless, five years later, technology and the world have moved on. Several regular IC manufacturers have now adopted similar multi bit sigma delta architecture, with varying degrees of success, and the technique of upsampling, once again initially pioneered by dCS, has further improved the performance of DACs when decoding conventional audio CDs. With these new factors in mind, Arcam's engineers set out to produce new CD players that would surpass the performance of its Ring DAC designs. Arcam's new solution - the Upsampling MultiDAC The Wolfson WM 8740 is a sound choice for a number of reasons - it is a state of the art multi bit sigma delta design, using dynamic element matching to negate any matching errors in its 64 internal current sources. It uses a low order modulator to minimise ultrasonic noise. It handles 24 bit word lengths and sample rates up to 192 kS/sec, with a high quality in built digital filter with a choice of roll off rates and it is possible to run it in both differential and parallel modes to further improve dynamic range. The illustration below shows a block diagram of the Arcam Upsampling MultiDAC module.
In the Arcam MultiDAC design, four WM8740s are used - i.e. eight DACs altogether or four individual DACs per channel, comprising two pairs in parallel driven in differential mono mode. This arrangement drives residual noise down to around -120dB (A weighted) with distortion levels measured in parts per million and text book low level linearity. The system architecture also allows the left and right channels to be fully isolated. Note the proprietary left/right datablockers which isolate the left channel's digital data from the right channel's DACs and vice versa. This lowers the levels of digital noise on the actual DAC dies, with a consequent small but useful improvement in sound quality. An Analog Devices AD1896 second generation asynchronous sample rate converter is used to upsample the incoming16bit, 44.1kS/sec CD data stream to a 24 bit signal at a rate of 192 kS/sec, which is then fed to the left and right DACs. Whilst no new information beyond that already present on the CD can be generated, this technique allows the digital filters in the DACs to have a relatively gentle slope starting well beyond the audio pass band, minimising any pre and post echoes on transients. This is thought to be one of the factors that make a properly decoded upsampled digital signal sound better than its normal native rate counterpart. The higher sampling rate also means the turnover frequency of the analogue high pass filters can be raised. This reduces high frequency audio phase shift, resulting in a more natural spatial presentation. Of course a successful design is not only dependent on using the proper ICs; it also requires great attention to detail to every part of the circuit and its physical layout. Some examples of the attention to detail applied to the MultiDAC can be seen in the picture below and include:
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