When you re on a good thing, S-520 LOUDSPEAKERS

Transcription

1 ON TEST Usher Audio S-520 LOUDSPEAKERS When you re on a good thing, stick to it! It s a slogan that s been used by advertisers for decades; here in Australia it s most popularly associated with Reckitt Benckiser and its Mortein brand of fly-spray. I don t know how popular the slogan might be in Taiwan, where Usher Audio Technology, or Usher Audio, but generally known as just Usher, is that country s biggest and most famous loudspeaker manufacturer, but the company s founder and chief designer Tsai Lien-Shui has certainly embraced the philosophy of the slogan when it comes to Usher s diminutive S-520 loudspeakers. According to all reports, the S-520 s are not only by far and away Usher s best-selling model but also the model that has attracted the most reviews right around the world and continues to attract them, as this one attests so Tsai Lien-Shui has been keeping them in his range for a good many years. In fact I m not exactly sure how many years they ve actually been around, but you can follow the tracks the little S-520s have made across the Internet back more than seven years, so I would not at all be surprised if they have been around since the turn of the century. Usher itself was founded way back in THE EQUIPMENT Usher is fairly unusual amongst loudspeaker manufacturers in that it actually makes all the drivers it uses in its speakers in the same factory (now a brand-new factory in Taichung) as the speakers themselves. So in the S-520, which is a two-way design, both the 127mm bass/midrange driver (KSW2-29B) and the 25mm silk dome tweeter (UA025-10) are made by Usher itself. Usher also sells drivers to other manufacturers, but neither of these models is listed in its OEM driver catalogue, so presumably Usher is very sensibly making sure that no-one has access to the drivers it uses in its own finished loudspeaker models, which seems like good business to me. Although it s listed as a 127mm model (though Usher seems to work in the old imperial system, so it actually puts the diameter at 5-inches ) this dimension is actually the overall diameter of the soft parts rather than that of the chassis itself. One look at the chassis reveals one reason Usher might have chosen this option: the driver chassis is not circular, but has squared off sides. In fact the driver chassis measures 147mm corner to corner and 132mm across the flats. You don t get too many speaker manufacturers understating the size of their drivers, so chalk one up for Usher! But the really important measurement to make on a bass driver is of its Thiele/Small diameter, and on the S-520 s driver, this comes in at 104mm, which gives an effective cone area (Sd) of cm². Like many modern drivers, the cone is made 20 Australian HFJuly12_020 Test Usher.indd 20 26/06/2012 9:43:22 AM

2 Usher S-520 Loudspeakers ON TEST from polypropylene but unlike most, it s not coloured, but is instead almost perfectly transparent, so you can see right through it. Not many manufacturers are game enough to do this, because it means you can see directly inside the speaker cabinet and look at the quality of the driver chassis, the length and placement of the lead-out wires (tinsels) not to mention the cleanliness of the interior of the cabinet and the arrangement of the internal fill. None of this worries Usher, because the inside of the cabinet is spotlessly clean, the driver chassis is an impressively solid and beautifully finished casting and the tinsels are very high-quality and well-dressed. The large magnet on the driver is not shielded. The 25mm silk dome tweeter is all but invisible on the front panel, as it s protected by a dome of metal mesh that presumably also serves some acoustic purpose. The crossover network in the S-520 is constructed on a standard PCB that is elastomerically attached to the inside wall of the cabinet, immediately above the rear terminal plate. It has two air-cored machine-wound inductors that are not cross-mounted, four 15W wirewound cermet resistors and two Rapport metallised polypropylene film (MPF) capacitors. It appears that Usher has changed the components (and possibly the values of them) that it has used in the S-520 s crossover over the years, having in the past used plastic bobbins as coil formers (not present on our review sample) and bipolar electrolytics (also not present on our review sample). Unusually for a budget design, Usher provides the S-520s in mirror-imaged pairs, something I normally expect to find only in high-end, hand-made speaker designs, due to the added cost of manufacturing mirrorimaged pairs. So chalk up yet another one for Usher! Each cabinet measures 1mm wide, 2mm deep and 300mm high and is made from 19mm thick soft MDF. The bases of each cabinet are not threaded for spikes, as I might have expected. Instead, Usher provides small clear plastic stick-on dome-like feet as a do-it-yourself solution. The weight of the cabinets (6.3kg) gives an idea of the quality of the components used inside them, as well as the thickness of the cabinet walls. I estimated the S-520 s internal volume at around 7.5 litres. The pair local distributor Westan Australia loaned me for this review were finished in piano black, but the speakers are also available in snow white and violin wood veneer. (The S-520s were once available in other high-gloss painted finishes, including fire-engine red and Ferrari yellow but to my disappointment, Westan told me these finishes are no longer available.) The wood-veneered version of the Usher S-520 sells for $435 per pair. The Piano Black/ White versions sell for $4 per pair. If you re already thinking that the S-520s would be perfect for use in a home theatre system, Usher is ahead of you, because there s also a centre-channel version of the S-520, called the S-525. Also available is an Usher SW-520 passive superwoofer that essentially turns the S-520 into a floor-standing three-way speaker system and doubles as a speaker stand for the S-520. Sold in pairs, the S-520 superwoofers retail for $929 per pair. IN USE AND LISTENING SESSIONS Initially, when I applied the small clear plastic dome stick-on feet, I was worried that the feet would stick too firmly and would peel off the painted surface when I removed them to ship the review speakers back to Westan. In practise, the opposite was the case! The glue on the feet is so weak that the feet were continually either coming off or sliding whenever I repositioned the speakers. USHER AUDIO S-520 LOUDSPEAKERS Brand: Usher Audio Technology Model: S-520 Category: Bookshelf Loudspeakers RRP: $ Warranty: Five Years Distributor: Westan Australia Pty Ltd Address: 13 Bastow Place Mulgrave VIC 31 (03) (03) salesvic@westan.com.au LAB REPORT Very small Inexpensive High performance Relatively insensitive Low bass Stick-on feet Readers interested in a full technical appraisal of the performance of the Usher Audio Technology S-520 Loudspeakers should continue on and read the LABORATORY REPORT published on page. Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specifi c sample tested. Lab Report on page avhub.com.au 21 HFJuly12_020 Test Usher.indd 21 26/06/2012 9:43:22 AM

3 ON TEST Obviously, in a reviewing environment, the speakers being reviewed are moved far more often than they ll ever be moved in real life, but it means that if you are wanting to toe these speakers in, don t twist them while they re still sitting on a surface: first lift them clear of whatever surface they re sitting on, twist them in the air, and then place them back down. When wiring up the speakers I found that the speaker terminals were so close together that it was a little difficult for me to tighten them properly, so it might be better to use banana connectors instead of bare wire. When looking into this further, I realised that the banana plugs were close together because they re on standard dual banana 19mm centres. So, if you buy a Pomona dual banana plug, wiring the speakers will be really easy. The fact that the speakers are supplied as mirror-image pairs gives you additional flexibility when positioning the speakers, so that if you have them fairly close together and you re not getting quite the level of imaging you d like, you can swap the left and right speakers around so that the tweeter on each is on the outside, and thus further apart. Conversely, if you have your speakers too far apart, you can have the tweeters on the insides and thus closer together to improve imaging at this spacing distance. As with all small stand-mount/bookshelf speakers, where you place the speakers in your room will have an enormous effect on their performance. If you place them on stands and put them out into the room well away from walls, you ll maximise the stereo image and the depth of the sound stage, but at the expense of the low bass. If you put them close to a wall (still on their stands) or on a bookshelf or other flat surface close to a wall, you ll maximise their bass output but at the expense of the depth of the sound stage and, possibly, some small degree of imaging. I used the S-520s in all three positions and am pleased to be able to report that they sounded excellent in all three room positions or, for that matter, pretty much anywhere else I placed them in my room. I even used them for a while as the speakers for my computer, propping them up either side of the screen. (In fact they looked pretty good either side of my computer screen, because their black piano finish perfectly matched the black gloss bezel of my monitor, and they were also exactly the same height as it, so they almost looked as if they were built into the screen.) On stands in my listening room, with the tweeters at seated ear level, the S-520s sounded very impressive right from the outset and continued to improve as I put more and more hours on the speakers. My initial impression of a linear, precise and very accurate midrange sound was confirmed as the days wore on, but as the bass/mid driver s suspensions settled in I fancied a slight warmth tinging the sound as well, so there was none of the steeliness that can characterise the sound from, say, a specialist studio monitor. Bass extension was as I d expect from such a small driver/cabinet combination, but it rolled off smoothly and there was none of that boomy false bass that some manufacturers build in to make their small speakers sound impressive in a showroom. I d likely add a subwoofer in any room to ensure low-frequency extension right down to 20Hz, but if you re in a small room, you may be well-satisfied with the bass from the S-520s, even when they re mounted on stands, where the bass won t get any help from a near-by wall. Push the Usher S-520s back against a wall and not only will the level of the low bass pick up, but you ll get a better impression of how tight and dynamic the bass they deliver really is: Excellent performance. And if I was expecting imaging to suffer when I moved the speakers back against the wall, well I was wrong and boy can these speakers image! Wow! The sense of there being a stage in front of you is incredibly realistic, and I could pick where performers are located quickly, easily, and with pin-point precision. And although stage depth and image height are maximised when the speakers are standmounted, there are still plenty of positioning cues even in close-to-wall and bookshelfmount positions. One thing that concerned me was that I thought the upper treble of the Usher S-520s was a little laid-back, when every review I d ever read of them over the years pointed to it being a little on the bright side. Maybe Tsai Lien-Shui had taken notice of his critics and padded down the tweeter a little on more recently-produced models? I decided to remove the grilles from the speakers and found that the upper treble picked up to a point where it was, to my mind, perfectly balanced certainly there was no way it was bright so I suspect this 2012 version of the long-running S-520 design sounds different to earlier versions because it is, in fact, different to earlier versions, despite having the same model number! The sense of there being a stage in front of you is incredibly realistic The S-520s were certainly power-hungry. Where I normally listen with my pre-amp s volume control at the 9 o clock position, I found that with the S-520s I had to raise the volume control to over the 10 o clock position to get my preferred playback levels. The S-520s sounded excellent at the listening level I found most comfortable in my room, but if I turned up the volume beyond this level, the speakers did not respond linearly, so if you have a very large room and you intend to listen at very loud levels, you ll likely have to look elsewhere, or look to adding a subwoofer to relieve the speakers of the onerous task of trying to reproduce very low bass. CONCLUSION These speakers sound very, very good, there s absolutely no doubt about that, and I am sure that this is the major reason they ve been so successful in the past and will continue to be successful for Usher into the future. However, I think there are other very important reasons for their popularity. The first of these is undoubtedly the very reasonable (a.k.a. low!) retail price, one that on a sound-quality for your dollar basis, puts the Usher S-520s right up there in the upper echelons of desirability. The second is the absolutely superb build quality, which is rare to find in any loudspeaker at this price-point. Finally there s their size or rather the lack of it. These speakers are small. Tiny. Which means that your other half will be delighted to have a pair (or several pairs, if you want to use them in several rooms, or all in the same room in a home theatre set-up!) in your home. Heartily recommended! greg borrowman 22 Australian LAB REPORT ON PAGE HFJuly12_020 Test Usher.indd 22 26/06/2012 9:43:24 AM

4 LAB REPORT CONTINUED FROM PAGE 20 TEST RESULTS measured the frequency response of the Usher S-520 loudspeakers as extending from around Hz to 20kHz ±3.5dB, which is an excellent result particularly in the low frequencies for such a small loudspeaker. This response is shown graphically in Graph 1, but the trace shown is actually a composite, as you can see from the caption below it. The section of the trace below 1kHz was acquired using pink noise as a test stimulus, and was the result of averaging nine different sweeps, using nine different microphone positions in front of the speaker. The trace above 1kHz (spliced to the lower section via post-processing) is the result of a single measurement using a gated measurement technique, with the microphone acquiring the measurement three metres in front of the baffle, directly on-axis with the tweeter. An expanded view of this highfrequency measurement is shown in Graph 2. As you can see, it s very smooth, with only a minor but fairly broadband suck-out between 2kHz and 6kHz. There s a small glitch in the response just above 16kHz, but it s so narrowband that it would not be audible, especially at this frequency, which is above most people s ability to hear. The same is true for the larger suck-out above 20kHz. What is interesting and apparent on this graph is that the speaker grille has a significant effect on the linearity of the frequency response across the region between 6.5kHz and 9kHz. As you can see, there are two traces on the graph with the black one showing the response without the grille in place, and the red trace showing the response with the grille fitted. You can see how the two traces diverge. Despite the 5dB difference between them, I really don t think the difference between grille on and grille off would be audible. Or, if it was, it would only be so under carefully controlled listening conditions, using material specifically selected to have musical information 20 Hz K 2K 5K 10K 20K 40K Graph 1. Frequency response. Trace below 1kHz is the averaged result of nine individual frequency sweeps measured at three metres, with the central grid point on-axis with the tweeter using pink noise test stimulus with capture unsmoothed. This has been manually spliced (at 1kHz) to the gated high-frequency response, an expanded view of which is shown in Graph 2. 0 Hz 1K 2K 5K 10K 20K 30K Graph 2. High-frequency response, expanded view. Test stimulus gated sine. Microphone placed at three metres on-axis with dome tweeter. Lower measurement limit 0Hz. Black trace measured without grille in place. Red trace shows response with grille fitted. [Usher S-520] Ohm 40 wpor Deg 1 rt Test Labs Hz K 2K 3K Graph 3. Low frequency response of front-firing bass reflex port (red trace) and woofer. arfield acquisition. Port/woofer levels not compensated for differences in radiating areas. [Usher S-520] Hz K 2K 5K 10K 20K 40K Graph 4. Impedance modulus of left (red trace) and right (yellow trace) speakers plus phase (blue trace). Blue trace shows l.f. section only, pink trace shows h.f. section only. Black trace under is reference 6-ohm precision calibration resistor. [Usher S-520 Loudspeaker] 20 Hz K 2K 5K 10K Graph 5. Averaged frequency response using pink noise test stimulus with capture unsmoothed (red trace) and smoothed to one-third octave (blue trace). Both traces are the averaged results of nine individual frequency sweeps measured at three metres. [Usher S-520 Loudspeaker] 20 Hz K 2K 5K 10K 20K 40K Graph 6. Composite response plot. Red trace is output of bass reflex port. Dark blue trace is anechoic response of bass driver. Pink trace is gated (simulated anechoic) response above 400Hz. Black trace is averaged in-room pink noise response limited to 20kHz. [Usher S-520] Australian HFJuly12_020 Test Usher.indd 26/06/2012 9:54:25 AM

5 LAB REPORT consistently in this frequency region, and even then only in a direct A B comparison. Because of this, I would recommend leaving the loudspeaker grilles in place at all times, to prevent damage to the drivers (although the tweeter is protected by a very sturdy metal mesh, so there s little chance it could ever be damaged). Graph 3 shows the near-field response of the bass/midrange driver and the front-firing bass reflex port. This near-field measuring technique doesn t work well at higher frequencies, hence the upper response of the bass/mid driver appears to roll off earlier than it would if the response was truly anechoic. However, you can see that in the low frequencies the small bass/midrange driver rolls off quite early (starting at around 130Hz) at a rate of around 12dB per octave, to a minima at 42Hz. The port is not tuned to exactly counterbalance this minima, but a little above it, so the output of the bass reflex port peaks at around 48Hz. The port does, however, usefully reinforce the bass right across the region Hz. The only issue with the port is that high-frequency peak in its output at around 1.3kHz, which obviously impacts on the bass/midrange driver s response, as you can see clearly by the bump in the trace above it at the corresponding frequency. If you look at Graph 4, which shows the impedance of the speaker, you can see that this point corresponds exactly with the electrical crossover point between the bass/midrange driver and the tweeter, and also puts a glitch in the combined impedance trace. If you look at Graph 6, you can see that there s an effect on the overall far-field response too, albeit only a very small one. I d say it s the result of one of the inevitable trade-offs that speaker designers make to ensure maximum performance at minimum cost. Speaking of impedance, impedance runs (shown in Graph 4) show a fairly typical bass reflex alignment for this design, with the two low-frequency resonances at 30Hz and 81Hz and the minima at 48Hz, as you d expect from the frequency at which the bass reflex port s output is at its maximum. The overall impedance is mostly above 8Ω, dipping in the audio band only between 1 400Hz and between 3.2 7kHz. The design s minimum impedance is 6.5Ω, which occurs at 233Hz, which means that under the rules of the International Electrotechnical Commission, the Usher easily qualifies as an the frequency response extends from around Hz to 20kHz ±3.5dB, which is an excellent result! 8Ω loudspeaker. Designer Tsai Lien-Shui has made his design even more amplifier-friendly by ensuring that the impedance of the design increases with increasing frequency, as you can see on the graph by the rise in response from 5kHz up to the graphing limit at 40kHz. Usher s factory also obviously has very good quality control procedures in place, because the matching between the left and right speakers is excellent, with the impedances almost overlaying each other, and only diverging very slightly below 30Hz. The phase angles are also kept under control, staying mostly within 30 except for a slightly larger swing at Hz. There is absolutely no evidence on the traces of any panel resonances, but this is hardly surprising given that the cabinet is so small. Graph 5 shows the averaged frequency response of the Usher Audio S-520 both unsmoothed (red trace) and smoothed via post-processing to one-third octave (black trace). The upper graphing limit for this trace is 10kHz, but you can see that between 140Hz and 10kHz the response is essentially within a 2.5dB envelope, or 140Hz to 10kHz ±1.25dB. Most of the 2.5dB difference is due to the upper midrange being pushed upwards a little, so there s a gentle lift from 0Hz to 1.3kHz, followed by a gentle fall to reference level at 3kHz. measured the output of the Usher Audio S-520 at exactly 83.8 at a distance of one metre, using a 2.83Veq input signal and its standard, stringent test procedure. This test protocol almost always results in significantly lower figures than those claimed by manufacturers, but in the case of the S-520 it fell short by quite a bit, as Usher claims 86. The lab s result indicates that the Usher is a very low-efficiency design and as such, it will most definitely benefit from being connected to higher-powered amplifiers: I d suggest an absolute minimum of -watts per channel. I was not surprised at the low efficiency, and neither should you be: ALL small loudspeakers are relatively inefficient it s an inescapable law of physics. I was very impressed with the measured performance of the Usher Audio S-520 in every respect. It has a very flat, extended response, a controlled impedance and the pair matching is almost perfect. Overall, it s an excellent example of good speaker design. Steve Holding avhub.com.au 91 HFJuly12_020 Test Usher.indd 91 26/06/2012 9:44:31 AM