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Luxman A-371 amplifier & D-351 CD player Luxman is a hifi brand which will be wellknown to many older enthusiasts but perhaps not so well known to younger read­ers. Produced by one of the smaller Japanese hifi companies, Luxman has a reputation for high quality equipment with no unne­cessary frills or gimmicks. We recently had the chance to review two models from Lux­man’s recently released range, the A-371 stereo amplifier and the D-351 compact disc player. Now while these units have a wealth of features, their front panels are certainly clean and well laid out and not at all daunting to the user. In addition, they have one other feature which will be most attractive to many users – front panels in champagne finish. These are a welcome alternative to black finished front panels. Talking about the A-371 amplifier first, this is an attrac­tive unit which at the same time is quite subdued in its styling. It measures 437mm wide, 125mm high and 363mm deep, including knobs and rear projections. It weighs 9.5kg. 30  Silicon Chip The control layout is fairly simple with a large volume control knob on the right hand side and then three small knobs for bass, treble and balance controls. There are eight large pushbuttons, for power and source selection: VCR, LD (laser disc player), AV (audio visual source), phono, tuner, tape, DAT and CD. As well, there are three smaller pushbuttons for selection of two pairs of loudspeakers, mono mode and two modes called “CD synchro” and “CD straight”. We’ll talk about these a little later. All source selection and control of the volume level can be done via the infrared remote control, a feature which is becoming standard with a lot of hifi equipment these days. On the rear panel, there is the usual plethora of RCA phono sockets, including those for video input and output signals. There are eight shrouded binding post terminals for connection of loudspeakers and a pair of jack sockets marked “bus line” which enables other Luxman equipment to be controlled via the ampli­fier’s remote control handpiece. Inside, the amplifier is packed with a surprising amount of circuitry. Apart from that which you would expect in a normal amplifier in the way of preamp, tone control and power amplifier boards, there are boards associated with the pushbutton source selection and the infrared remote control, all of which is overseen by a custom microprocessor. There are two power transformers, one small and one quite large. We assume that the small one is energised all the time so that the amplifier’s remote control circuitry can respond to the remote handpiece or front panel power button and “wake up” the main power supply when required. The amplifier is double insulated and comes with a twin-core mains flex. The internal wiring does appear to conform to double insulation standards but we do regard it as dangerous in one aspect. If the cover of the amplifier (or the matching CD player) is removed, the 240VAC wiring connections are completely unshrouded and it would be easy to touch them inadvertently. Granted, the rear of the chassis has a warning notice saying “Caution: risk of electric shock. Do not open” but we would like to see those 240VAC connections made much safer for the person who will inevitably open the case at some stage in its life. To provide the remote volume control facility, the volume control is powered by a small DC motor via a clutch which lets the user adjust the control manually if desired. For the purists, the A-371 has its “CD straight” feature. By pushing this button, most of the switching, tone control and other ancillary circuitry is bypassed by the input signals from the CD player and they go straight from the volume control to the power amplifier circuitry. D-351 CD player The other piece of equipment in this review is the Luxman D-351 CD player which has an overall width and styling to match the A-371 amplifier. Note however that it could be unwise to stack equipment on top of the A-371 amplifier as this would possibly cause problems with ventilation in FACING PAGE: the A-371 integrated stereo amplifier comes complete with IR remote control & delivers 70W RMS per channel. Below is the D-351 CD player which also features IR remote control. The interior of the A-371 stereo amplifier has quite a few PC boards, with additional boards being required for the front-panel pushbutton controls & the video switching inputs & outputs on the rear panel. Note the generously proportioned power transformer which is fitted with a copper strap. the amplifier and it might also cause hum induction into the CD player. If the equip­ment is to be stacked, the amplifier should at the top, for best ventilation. Dimensions of the Luxman D-351 CD player are 438mm wide, 90mm high and 346mm deep. It is a conventional front-drawer loading machine with the usual range of playing facilities, includ­ing random play and programmed play. If used with Luxman’s system bus, it can also provide “CD synchro” recording to a cassette deck, as mentioned above. In addition, the D-351 has “Edit Play”, a playback feature not found on most machines. You can use “Edit Play” when program­ming the machine for recording on to tapes. For example, you can set a play time of 45 minutes and then program in tracks to be recorded. This avoids the common problem when taping CDs to cassettes and finding that the tape ends mid-way through a track. It also has infrared remote control via its own RD-351 handpiece or via the comprehensive RA-371 remote control supplied with the amplifier. Funnily enough, as with most CD players having remote control, you can January 1994  31 The interior of the D-351 CD player has an uncluttered layout. Note the optical fibre socket & system bus sockets on the rear panel. The rear panel also carries a level switch which sets the maximum output signal to 2V or 1V RMS. even open or close the drawer remotely although you still have to load the disc in or take it out, by hand. You might think there is not much use in being able to open or close the drawer remotely and in the case of this player, even to turn on the power, but it does make sense to do so. Why? Because it stops you from putting your fingers on the front panel and thus preserves the finish as long as possible. If you don’t think that is relevant, take a look at the most used buttons on your present gear or home appliances. After a few years, the wear and tear can become quite obvious. Interestingly, if you are using the D-351 together with the A-371 amplifier and have them interconnected via the system bus, you get an extra level of playing convenience. Not only do you not have to turn each piece of equipment on or off separately, but if you select CD as the source, it will immediately start playing a disc or, if no disc is present, it will open the drawer ready to receive one. The D-351 CD player has its own stereo headphone socket and volume control, a worthwhile feature, particularly if you want to use the CD player on its own. And if you want to use the CD player with a DAT recorder, you can link the two together via the D-351’s optical fibre output. A large easy-to-read digital display is a feature of the front panel and you can program it to play up to 24 tracks. 32  Silicon Chip Natu­rally, you can do all this from the remote control for the A-371 amplifier so you don’t need more than one remote handpiece. Two small switches on the rear panel of the D-351 provide facilities not found on other players. One switch allows the maximum output signal voltage to be reduced from 2V to 1V. This is useful because it is a closer match to the output signals from other program (line) sources such as tuners and tape decks. Thus there will be less change in volume level when switching between sources. The second switch allows for timer operation. With the switch in the ON position, playback operation starts automatical­ly when power is applied, if a disc is inside the machine. Taken as a pair, the Luxman A-371 amplifier and D-351 CD player work very well together, as you would expect. They are quiet at all times and subjectively, they produce very good quality sound. And the measurements back up that impression. Test results Rated power for the A-371 stereo amplifier is 70 watts per channel for a total harmonic distortion of .01% over the frequen­cy range of 20Hz to 20kHz into 8Ω loads. Our tests showed that the amplifier met this specification easily and with plenty to spare, as far as power output was concerned. We measured maximum power at 85 watts per channel at 1kHz with both channels driven and 96 watts with one channel driven, into an 8Ω load. Power into 4Ω loads was somewhat higher, at just over 130 watts, and this also confirmed the Luxman specification. The signal-to-noise ratio was 82dB A-weighted with respect to 5mV and 1kHz for the phono inputs which was exactly as specified, while the S/N ratio for the line inputs (CD etc) was slightly over 101dB, a little better than the spec. Maximum boost and cut for the bass and treble controls was a little over ±8dB. This is somewhat less than is typical for mainstream stereo amplifiers and receivers but we think that this is probably good practice. After all, on most hifi systems the tone controls are rarely, if ever, used and if you are routinely using your system with lots of bass boost, there is something wrong with it (or, dare we say it, something wrong with you!). For its part, the D-351 CD player performed very well too, as you would expect from a system that claims dual D-A convert­ers, 8-times oversampling and 18-bit digital filters. Its fre­quency response was within ±0.6dB from 20Hz to 20kHz and its signal to noise ratio for the same bandwidth was 92.5dB and 104dB with A-weighting. We measured harmonic distortion at around .0035% for low frequencies but found that the figures rose quite considerably as the frequency was increased due to the presence of supersonic sampling artefacts at 44.1kHz. We were a little surprised by this in view of the fact that the D-351 is claimed to be an 8-times over­ sampling machine. Normally, 8-times over­sampling means that the residual sampling artefacts are at 352kHz (44.1kHz x 8) and at a very low level. Where the D-351 really does shine is with its linearity performance. This is measured with a compact disc with 1kHz signal levels that are progressively reduced, to an ultimate level of -90dB. By the time the level is reduced to -80dB most CD players have an error of around +2dB or so while at -90dB, the error can be as much as +5dB; ie, the actual measured signal level drops to -85dB instead of -90dB. At -80dB, the D-351 had an error of just +0.4dB while at -90dB the error was +2dB. This is very good. The separation between channels continued on page 92 Philips slashes DCC prices In a dramatic move to get DCC players and recorders moving in the marketplace, Philips has announced big price cuts. The fullhouse DCC900 recorder, previously priced at $1799, is now $999 while the DCC600, previously $1499, is multiple remote loads with separate on/off coding and receiving `loop back’ acknowledgement of switching function. All systems have a 2km range from a radio licence exempt HF transmitter with excellent long wavelength diffraction performance around obstacles in the propagation path. The transmissions are digitally encoded and the the dry batteries give 6-12 months’ service. For further information, contact McLean Automation, PO Box 70, Freemans Reach, NSW 2756. Phone (045) 796 365. now $799. And the recently released DC130, pictured here being used by Australian aerobics champion Sue Stanley, is now $699. Customers who have already purchased a DCC player or recorder at the old prices need only call Philips at (008) 80 3312 to receive a complimentary set of 25 pre-recorded DCCs. High-power subwoofer for cars Kenwood Electronics has announced a subwoofer and dedicated subwoofer amplifier guaranteed to rattle the windows. Called the Letterbox, it measures only 251mm wide, 266mm high and 400mm deep and can be mounted behind the seat, on the van floor or in the boot. The Letterbox is a bass reflex design employing what Kenwood call a spherical flow duct. This is a tapered port to enhance low frequency response down Luxman amplifier & CD player: continued from p.32 check­ed out at -93dB at 1kHz which is not quite as good as the claimed -100dB but the dif­ ference is largely academic since anything over -70dB is more than adequate. Measurements aside, we can state that both the A-371 stereo amplifier and D-351 compact disc player are very fine products. They work well and produce excellent sound quality and, as the final icing on the cake, 92  Silicon Chip they come with a 5-year full parts and labour warranty. Pricing is $1399 for the A-371 amplifier and $799 for the D-351 compact disc player. Luxman equipment is available from selected hifi retailers. For the name of your nearest dealer, contact the Australian distributor for Luxman, International Dynamics Pty Ltd, 78-80 Herald St, Cheltenham, Vic 3192. Phone (03) 585 0522. (L.D.S.) delow 40Hz. Combined with reasonably high efficiency (90dB), can deliver lots of bass. Designed to be used as a single unit or in a multi-subwoofer set up, the Letterbox can handle bass program material up to 200 watts. To drive the subwoofer, Kenwood market the KAC-714 mono power amplifier, rated at 100 watts but capable of delivering around 200 watts on peaks. Measuring only 280mm wide, 50mm high and 170mm deep the KAC-714 can fit snugly into most boots. A built-in crossover offers variable cut off from below 30Hz to 200Hz and an input gain control match the sound levels to other speakers. The Letterbox subwoofer is priced at $399 while the KAC-714 mono power amp is $349. Both units are covered by a twelve month parts and labour warranty. For further information on Kenwood car audio products and your nearest Kenwood car audio dealer, phone (008) 066 190. Digital DC power supplies The new Leader Digital Series regulated DC power supplies consist of five models: two 18V, two 36V and one 70V model. Intended for R & D, automated and educational applications, the series features optional GPIB for computer control. The power supplies can also be remotely controlled using the standard remote control connector. For stable output, voltage drops caused by test leads resistance and contact resistance at the output terminal are compensated for by using the sensor plug provided. For further information, contact AWA Distribution, 112-118 Talavera Road, North Ryde, NSW 2113. Phone (02) 888 9000. SC