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to t a h W hen do w e got you’v oney no m 12  Silicon Chip Hifi on a Budget Don’t settle for an all-in-one sound system if you have only $600 to spend on hifi gear. You can get much better sound by buying genuine hifi gear secondhand. By OWEN DAVIES & JULIAN EDGAR F OR MANY YEARS now, mainstream budget audio gear has been more show than go. Manufacturers have concentrated on attracting buyers not through good sound quality but by offering more flash­ing lights than an aircraft cockpit. And although they offer a convenient mix of tape, radio and CD facilities, the now popular budget-priced three-inone systems inevitably impose severe compromises in sound quality. For starters, the amplifiers of these systems generally have mediocre output power and distortion figures. The loudspeak­ers will also be quite mediocre. To cut costs, the speaker boxes in budget systems will be manufactured from thin particle board, will house low-cost paper-cone drivers and will lack the proper crossover networks necessary for good hifi sound reproduction. Instead of spending $500-$600 on a new all-in-one system, we suggest that you barter your hard-earned cash for a series of separate secondhand components. The secondhand gear ABOVE: This Philips 260 stereo preamplifier was bought for just $75. It was teamed with the Philips 360 50W RMS/channel power amplifier shown at right (also $75), the two providing an excellent combina­tion. Note that the amplifier features peak power meters on its front panel. It’s obvious that it’s not a budget amplifier as its standard of construction is very high. FACING PAGE: This box is a good prospect for new drivers. Its surface finish is in good condition, so it still looks the part. September 1997  13 A CD player is by far the best budget sound source. This Teac PD-200 player cost just $80. Avoid choosing very old CD players if possible, as many would have worn drive mechanisms. might lack the bells and whistles of the all-in-one stuff (eg, infrared remote control) but if it’s good sound quality that really interests you, the secondhand path is the way to go. Put simply, carefully selected separate components will give better sound quality than a combined unit and will be better built into the bargain. They might lack the integrated look of a combined unit but they can more than compensate for that in how they sound. And isn’t the quality of the sound the reason that you buy a hifi? Separate components also come into their own if one compon­ent needs repairing. The reason for this is that you can continue to use the rest of your gear unless, of course, it’s the amplifi­er that’s at fault. What to buy We recommend that the system be made up of a separate amplifier, CD player, speakers and a tuner if you desire. Avoid cassette decks at all costs unless you have a specific reason for Build It Yourself? Why buy an old amplifier when you can build a new one with better specifications for the same money? While there are plenty of good-quality amplifier kits about, we don’t recommend that you build one unless you’re already an experienced kit builder. A $300 amplifier kit is, after all, just a pile of components and unless you build it 100% correctly, it won’t work. Of course, if you do have previous kit building experience, a kit amplifier is well worth considering. There are also smaller kits like subwoofer adaptors and loudspeaker protectors on the market. The outlay of money for these is comparatively small and they are simpler to make than a kit amplifier. You also end up with a product that’s not readily available, especially on the secondhand market. Incidentally, be very wary of buying an already-constructed kit amplifier. Who made it – a beginner or an experienced elec­tronics technician? You just don’t know, so stay clear unless you have the skills to judge the standard or workmanship or you know the person who built it. 14  Silicon Chip wanting a tape player! Compact discs (CDs) offer far better sound quality than tapes – it’s as simple as that. Cheap, good quality components can be sourced from second­ hand dealers and pawnbrokers, or through private sale. Major chains such as Cash Converters usually have a wide selection of compon­ents at the one site, allowing various units to be compared for price and features. Good deals can be had if you are prepared to bargain with the retailer and you can sometimes get 10% or more off the marked price. But how do you know which components to select? Let’s take a look at what’s available and what to go for. Amplifiers Many amplifiers from the late 1970s and through the 1980s were of unusually high quality. Their front panels and control knobs were made of thick, anodised aluminium, they had ample power outputs and their power supplies were generally more than adequate. Remember, we’re not comparing the very best of today’s amplifiers with the midrange amplifiers of 10 years ago. Instead, we’re looking at what you can now buy new for $200 versus what you can get for that same $200 if you go back a few years. When selecting a secondhand amplifier, brandnames are everything. Sony, Pioneer, Sansui, Onkyo, Philips, Kenwood, Denon, Technics, Rotel and Marantz all produced attractive, good-sounding amplifiers during this era and these are the names worth looking for. When shopping for an amplifier, several physical factors can give clues as to its performance. Check how heavy the unit is – if it appears light for its size, the power supply (mainly the transformer) is probably small and not up to the job of providing the high current demanded by the amplifier modules. Conversely, big transformers and filter capacitors indicate that the power supply can provide a constant high current. A big, heavy amplifier will usually be a powerful amplifier. You should also take a look at the heatsinks. Large, cast aluminium heatsinks indicate high output power and efficient heat dissipation. In fact, high power output is vital. That’s because a 20W RMS amplifier is more likely to distort than one rated at 100W RMS because it can be driven into clipping (overload) more easily. And an amplifier that’s been driven into clipping not only sounds awful but is also likely to damage your loudspeakers if left in this condition. If the amplifier is bought privately, the seller will often have the original owner’s manual. This will usually include a specifications panel which lists power output and distortion levels. In some cases, a sticker on the rear panel will list this information. Amplifiers with power outputs in the range from 40-100W RMS per channel (or more) are the ones to look for. If possible, ask the seller to fire up the amplifier with a signal source and loudspeakers connected. This will allow you to verify that the unit is working correctly. In par­ticular, check that the amplifier is not plagued by excessive hum. You can do this by disconnecting the signal source and winding up the volume control. You should only hear a faint hum and just a little hiss from the loudspeakers when the volume control is fully advanced. While you’re at it, check for scratching noises and pops from the loudspeakers when the volume, balance, bass and treble controls are adjusted. These noises indicate worn or dirty tracks in the control pots. Don’t automatically reject an amplifier if this occurs, though – a spray of electronic contact cleaner will often Portable CD players such as this Sony D-50 can be picked up for about $70. cure the problem. Alternatively, it may be possible to have the pots re­ placed, particularly if you can do the job yourself. Separate units Although harder to find, separate preamplifier and power amplifier units can theoretically provide cleaner sound than an equivalent integrated amplifier. In practice, you’d probably be hard put to tell the difference but if you do come across sepa­rate pre-amplifier and power amplifier units, they’re well worth considering. They can also be used in conjunction with electronic crossovers (available in kit form) to run separate subwoofer and satellite loudspeaker systems. Prices for a good used amplifier generally range from about $80 to $200, depending on the brand and This Kenwood KA-7300 integrated amplifier boasts a power output of 80W RMS per channel and features splittable preamplifier and power amplifier stages. It cost just $150, the price forced downwards by the missing side panel! September 1997  15 can indicate laser tracking problems or excessive wear in the gear drive mechanism. If you or a friend has a CD which is scratched and difficult to play, test it in the unit under consideration and compare the results with a known good machine. A good performance indicates that the error correction circuitry is up to scratch. We can’t stress enough how much better a CD-based system will sound in comparison to magnetic tape. All the problems that plague tape – head wear, hiss, narrow dynamic range and wow and flutter – are nonexistent with the digital technology of compact disc players. And CD players are cheap. Loudspeakers Avoid speaker boxes like this one. Repairing the surface finish – whether it’s plastic, paint or natural wood – is time-consuming and difficult unless you have special skills. As already mentioned, the loudspeaker systems associated with all-in-one units have only mediocre performance. Many of them lack bass response and have a tendency to sound “tinny” and overbright. Some power output. CD players Since its introduction in the early eighties, the compact disc has become a popular and affordable playback medium. It offers fast track access and, most importantly, delivers excellent sound reproduction courtesy of its digital recording format. As such, it’s hard to beat when it comes to buying sound quality. Try to avoid older, first-generation CD players because their mechanisms are likely to be worn and they’re more likely to suffer from mechanical failure. The laser pickup can also fail in older machines. CD players featuring 1-bit D/A (digital-to-anal­ og) serial conversion are generally regarded as sounding better than those with 16bit D/A conversion but it takes a keen ear to pick the difference. Basically, if you find a player in good order and at the right price, you can ignore the conversion technique used. Most of the brands mentioned above apply to CD players as well. These units can be picked up for $80-150. A cheaper alternative can be a portable CD player. Sony and Technics with their Discman and MASH portables, respectively, produce very good miniaturised units. Older models of these units can be purchased for as little as $70 but the sound quality will 16  Silicon Chip This box has easily removed (and replaced) front and rear pan­els. It also uses gussets to strengthen the mitred corner joins. It’s a perfect recipient for new speakers, particularly as its original drivers were nothing to write home about! not be as good as that from a full-sized CD player. Make sure that, in addition to a headphone socket, the unit also has a line level output for connection to an amplifier (a headphone socket may not provide sufficient output to drive an amplifier). Be critical when searching for a CD player. Ensure that all segments of the LCD or LED display light up correctly and be sure to check track access times. Long track access times feature only a single wide-range driver which struggles to cope with the entire frequency range. Others go too far the other way and use three or even four drivers, when just two correctly match­ed drivers would do a better job. Like the equipment that powers them, these speakers are a compromise between performance and price. One inexpensive way around this problem is to source old speaker enclosures and “re-speaker” them. The enclosures must be rigid and constructed from a dense material like chipboard or, ideally, MDF (medium density fibreboard). Secondhand dealers, garage sales and auctions provide the best sources for old, well-made speaker boxes. When tapped, the box shouldn’t vibrate – instead, it should have a low natural resonance so that the resultant sound is not coloured. If the box does resonate unduly, extra internal bracing in the form of timber offcuts (about 30 x 30mm in cross section) can be placed between parallel panels to provide extra stiffness. Make sure that the surface finish of the box is in good condition. If the box is covered in plastic imitation wood­grain, check to ensure that this isn’t peeling anywhere. Repairing the surface finish – whether it’s plastic, paint or natural wood – is time-consuming and difficult unless you have special skills. The best boxes to find are often those where a fascinated young child has deliberately stuck sharp objects through the speaker cones! These boxes can often be picked up for as little as $20 a pair and all you have to do is replace the drivers. The woofers in older enclosures are often useless, as their foam or rubber surrounds perish after about 10 years. A replace­ ment 10-inch “polycone” woofer of reasonable quality can be had for about $70, while an equivalent 8-inch woofer costs about $55. The volume of the box can be determined by measuring the internal dimensions. For example, a box measuring 50 x 25 x 20cm has a volume of 25,000cc (cubic centimetres) or 25 litres. This volume measurement can then be used to select a suitable driver. As a general rule, the larger the enclosure and the woofer, the lower the bass response. Enclosures with vents or ports are known as bass reflex designs. The other type of enclosure is the fully sealed (or infinite baffle) design. A bass reflex design will have better low frequency response but requires a vent (or port) to properly tune the enclosure. This usually consists of a small-dia­meter tube fitted to the baffle. Electronics stores like Jaycar and Dick Smith Electronics list recommended enclosure volumes for each of their woofers. Jaycar also give the recommended cabinet dimensions for Putting The Words Into Practice By now, you’ve probably read the main text and are saying to yourself “Yeah, fine; it all sounds good in theory but I bet these guys have never really gone out and bought stuff at the prices they’re talking about”. Well, read on! Here’s a list of the equipment recently purchased by co-author Owen Davies for a home stereo system and the prices that he paid. Teac PD-200 CD player ...............................................$80 Philips 260 stereo preamplifier.....................................$75 Philips 360 stereo power amplifier ..............................$75 Kenwood KA-7300 integrated amplifier .......................$150 Jaycar active crossover kit ...........................................$70 Satellite speakers: Jaycar 6-inch polycone woofer ....................................$22 x 2 Philips 25mm dome tweeter ........................................$17 x 2 Jaycar crossover .........................................................$15 x 2 Subwoofer ...................................................................$70 TOTAL: $418 Owen built his own speaker boxes and bought stands for the satellite speakers. But even if these cost $100 (they didn’t!), that still adds up to less than $520 for the complete system. both sealed and vented designs and even list the vent details. Old paper cone tweeters can be replaced with more modern dome substitutes that retail for around $25. These feature im­ proved transient response and sound much more realistic. The only modification required will involve increasing the cutout size in the baffle. Crossover networks Installing proper crossover networks can yield vast im­provements in sound quality. A crossover network splits up the signal so that the correct band of frequencies is fed to each driver. This is particularly important for midrange drivers and for tweeters, to ensure that they do not receive bass frequencies which could produce damaging cone excursions. Both 2-way and 3-way crossover networks are available from the major electronics retailers. Lacking from most cheaper and older speaker enclosures is some form of damping material. This material, commonly called “Innerbond”, can be placed inside the box to make it more acous­tically “dead”. It does this by reducing internal reflections which can interfere with the speaker cone and produce unwanted resonances. Even cheaper than Innerbond is quilt wadding, avail­able from most dressmaking supply shops. Using separate satellite and sub­ woofer systems can also produce very good results. These can either be powered actively (ie, by using separate amplifiers for the satellites and sub­woofer) or via a passive type cross–over network. The advantage of this type of setup is that the satellite speakers can be quite small, as their response only needs to go down to about 100Hz, where it will overlap with the upper end of the subwoofer’s response. Conclusion Good hifi sound is available on a budget if you choose good-quality secondhand components and are willing to upgrade old speaker boxes. Although your system mightn’t have the chic ap­pearance that’s apparently all too important these days, it will more than compensate for this in sound quality. And that’s really what it’s all about. SC September 1997  17