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Review by LEO SIMPSON Denon DCD-700AE compact disk player Now that DVD players are being made in the squillions and are very cheap, there are few hifi manufacturers actually making CD players. Denon is one of the few makers and their products are highly prized. The Denon DCD-700AE CD player is a high quality machine which provides the bonus of pitch control and being able to play MP3 disks. O UR FEATURE STORY on the hum problems introduced into hifi systems by DVD players with switchmode supplies and double-insulation (SILICON CHIP, October 2007) prompted the question: are CD players likely to produce the same signal-to-noise degradation in high-fidelity amplifiers? After all, what is the point in paying top dollar for premium hifi components which you expect to be utterly quiet, only to have them produce low level hum and buzz? The answer is that, unless the CD player in question has a conventional transformer driven supply, the hum and buzz problems will be exactly the same as for DVD players. There are two ways around this problem. The first is to use the digital optical output of your DVD or CD 10  Silicon Chip player in conjunction with the optical decoder in your home theatre receiver. If you take that approach, you would want to be sure that the digital decoder in your home-theatre receiver is at least as good as the decoder in the player. If not, the sound quality will not be as good as it potentially should be. In our experience, unless the home-theatre receiver is a top-end unit, with a price to match, its decoder and general performance are likely to be fairly ordinary. The second approach is to purchase a high-quality CD player with a conventional linear power supplier, such as this Denon CD player. Which is how we came to be reviewing this particular machine. Considering how compact most DVD players are, this Denon player is a fairly bulky machine, with dimensions of 434mm wide, 107mm high and 279mm deep, including rubber feet and front and rear projecting parts. It is also fairly heavy at 4.2kg, no doubt partly due to the internal mains transformer and partly due to the fact that the case is strongly built and has an extruded aluminium front panel. This is a refreshing change from the often flimsy construction of cheaper DVD players. The styling of the DCD-700AE is relatively simple and austere, in keeping with other audio products in the Denon range. The front panel is finished in brushed aluminium and is dominated by the dark plastic display window and the disk drawer. On the lefthand side are the pushbutton Power switch, 6.5mm headphone socket siliconchip.com.au and the associated volume control. On the righthand side is an array of nine pushbuttons which control the Play functions. 2-channel stereo disks.................. music CD, CD-R (audio), CD-RW (audio) Pitch control Frequency response................................................................... 2Hz - 20kHz Two small buttons are provided for pitch control, giving a range of ±12% in steps of 0.1%. Just as an aside, pitch control is very useful if you are a musician or a keen dancer. If you are musician, you may want to adjust the pitch of the music on the disk to match the instrument you are playing or to make it easier to use as an accompaniment to singing. If you are dancer, you may want to adjust the timing of the music (ie, beats per minute) to suit the dance, eg, Viennese waltz, quickstep, samba, etc. By the way, the pitch control on the Denon does not alter pitch independently of timing – the two are inversely locked together so that if you increase the pitch, the timing of the music will be proportionally reduced. Either way, pitch control can be very useful and is seldom found on CD players. By the way, if you are using pitch control, you cannot use the optical digital output. By definition, the pitch control is a function of the digital decoder and Denon have decided that if you are using the pitch control, you need the internal decoder and therefore no digital data will be delivered via the optical link. Dynamic range.....................................................................................100dB Remote control As is the case with DVD players, virtually all playback functions are accessed via the infrared remote control. The Denon’s control is quite a long slimline unit with the buttons laid out siliconchip.com.au Specifications S/N ratio............................................................... -110dB with respect to 2V Total harmonic distortion.................................................................0.0025%, 1kHz channel separation................................................................... -105dB Line output level.....................................................................2V (10kW load) D/A converters ......... advanced-segment 24-bit type 8-times over-sampling Power supply................................................................ 230V AC, 50Hz, 13W Dimensions..................................................434 (W) x 107 (H) x 279mm (D) Weight.................................................................................................. 4.2 kg in a logical array. Surprisingly though, it does not provide remote control of volume, which may be a drawback if your amplifier does not have remote control of volume. In other respects, the remote control is fine although it will not let you directly access tracks above 19. So if you have a 30-track disk (say) and you want to directly access track 25, you can go direct to track 19 and then repeatedly hit the “next track” button. Inside the chassis is also quite different from typical DVD players which often apparently have very little in the way of circuitry. Usually DVD players just have a small multi-layer main PC board which is densely packed with surface-mount devices (SMDs), together with another board which provides the switchmode power supply. In the case of the Denon, the main board is also a multi-layer board with lots of SMDs and there is an equally large single-sided PC board which appears to carry the audio output filtering and the digital optical output. An even larger single-sided PC board is devoted to the power supply which is fully linear. It uses a conventional laminated steel power transformer – not a switchmode component in sight. Denon have evidently made the judgment that if you want a CD player that is utterly quiet, then the way to do it is to use a conventional linear power supply. Denon have also evidently gone to some trouble with the orientation and mounting of the mains transformer, to ensure minimum hum induction. To further ensure a minimum of any digital artefacts, most of the control microprocessor’s functions are shut down during playback and the display itself can also be turned off. Another feature of the Denon DCD700AE is its use of 24-bit processing January 2008  11 The Denon DCD-700AE CD player is well made and uses a conventional linear power supply. The PC board at rear right carries the audio output filter which completely eliminates sampling artefacts. and 8-times over-sampling. Denon is rather vague about what this means apart from stating that it delivers superior quality in the DCD-700AE’s audio playback performance. Hmm. Yep, that would be right. The player transport is centrally mounted and is a fast and quiet unit. It appears to be reasonably immune to external shock, as when you might inadvertently bump the case while it is playing. disk in the drawer, load it and almost immediately it displays the number of tracks and the total duration. Press play and it does so immediately – no dithering about! And when you select another track, it goes to it almost immediately, within less than a second. Nor is there is any suggestion of high frequency “frizzle” or any other extraneous noises that are sometimes evident with the cheaper DVD players. All of which is as it should be, of course, but it bears stating because by comparison, DVD players are often so hopeless at playing compact disks. As noted above, the Denon deck will also play disks recorded in MP3 or WMA format and it has comprehensive features to display track titles, folders and so on. That is a convenient feature but we think that anyone who is truly committed to sound quality will not be doing most of their listen- ing to MP3 or WMA files, whether they are recorded at the maximum sampling rate or not. Issues Getting Dog-Eared? REAL VALUE AT Using it When you start using the Denon, you rapidly become aware of the differences between it and typical DVD players. For a start, it does not wait for what seems like an interminable period before it determines that you have, in fact, loaded an audio disk and then take a further time to display the tracks. With the Denon, you put the Performance As with most CD and DVD players, the specified performance levels are fairly brief and it is not really possible to judge potential sound quality by reference to them. For example, the Denon lists frequency response as being between 2Hz and 20kHz but with no decibel limits. Ideally, it should be within ±0.3dB or better. After all, such performance limits were being routinely achieved with CD players being produced 20 years ago. Similarly, total harmonic distortion is quoted at .0025% at 1kHz which again is not very demanding. How about distortion at 10kHz and at low levels, at say -40dB below the maximum (ie, at a level of 20mV instead Keep your copies safe with these handy binders. $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. 12  Silicon Chip siliconchip.com.au of 2V)? This is never stated but really, if the manufacturer wanted to give a real indication of quality, that is what they would do. They would also give an indication of the efficacy of error correction which would tell you how good the player was at coping with badly scratched disks. OK, so we put the player through a battery of tests, starting with test disks by Philips and Technics. Test results Frequency response was the first parameter to be tested and we achieved a response from 20Hz to 20kHz within +0.04dB and -0.02dB or you could just state it as flat within ±0.03dB. Just read that again: ±.03dB! This is truly “ruler-straight”. So why is Denon so coy about its frequency response? Separation between channels came in at -106dB between 100Hz and 10kHz, compared with the claimed figure of -105dB at 1kHz. At 20kHz, separation was -103dB. Signal-to-noise ratio also came in at -106dB with respect to 2V and with a noise bandwidth from 10Hz to 22kHz. These figures are not just very good; they are truly excellent because what they don’t indicate is what we didn’t measure. Er, what? In the past, whenever we have measured a CD player, we have always had to go to special lengths to remove the over-sampling artefacts at 44kHz, 88kHz (2-times oversampling), 352.8kHz (8-times over-sampling) or whatever. In fact, that is the sole reason we have a “brick-wall” passive 20Hz to 20kHz filter to match our Audio Precision test gear – to remove the digital sampling artefacts! But the Denon DCD-700AE has no measurable artefacts or any digital noise whatsoever, regardless of the noise bandwidth used to make the measurement. The only noise is very low-level hiss. And while the player can have its display turned off, to remove any noise due to that source, we measured the same result whether the display was on or off. Linearity tests always separate the ordinary CD players from the good ones and here the Denon excelled. The test involves reducing a 1kHz sine­ wave by precise 10dB steps (from a test disk) and reading off the results. This is a measurement of the linearity of the Digital-to-Analog converter. Most siliconchip.com.au players are OK down to -70B but below that they are in trouble. At -80dB, the Denon was -80.2dB. At -90dB (as far down as we can go), the result was -90.11dB. Excellent. Finally, we did a range of harmonic distortion tests, starting at the maximum level of 2V (or 1.95V in the case of the Denon). Over the frequency range up to 5kHz, we got readings of .008%, increasing to .029% at 20kHz. This is very good. Then we went further and took more measurements at reduced levels, including the suggested test above at -40dB. Under these conditions you always expect increased distortion because the overall signal range for the sampling process is much reduced. Even so, the Denon came in with good performance, giving a measurement of 0.13% at 1kHz and -40dB (2mV) level. We could go on but you should have the overall picture by now: this is the best CD player we have ever measured, although to be frank it is quite a few years since we last put a good quality CD player through its paces. Suffice to say, Denon could trumpet their very good performance figures but for reasons known only to themselves, they don’t. Ultimately, sound quality is every bit as good as you would expect. Interestingly, I think that this player has more definition of low level bass signals than I have heard with my existing CD players. That could be a direct result of the very good low level linearity of this player. The Denon DCD-700AE CD player is also utterly quiet and does not inject any hum and buzz into the companion amplifier. So if you have the very best amplifier in your system, you can expect the Denon not to add any noise apart from a teeny amount of hiss which you might hear if you put your ear right up to the tweeter. Finally, as you might expect with a product from a specialised audio manufacturer, the Denon DCD-700AE is not cheap and is certainly vastly more expensive than run-of-the-mill DVD players which are made in huge quantities. On the other hand, used in a high-quality system, it will sound a lot better. The DCD-700AE is priced at $699 including GST. For further information on Denon products and availability, contact 1300 134 400 04 or log on to www.audioproducts.com.au SC       CNC Packages We now have Hi Performance Stepper motor Driver packages to get you started on your CNC project, whether it is a mill, foam cutter or laser cutter. We also sell the drives, motors and controllers individually. 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