Q ACOUSTICS CONCEPT 500 LOUDSPEAKERS
How good does a design have to be to win a ‘Loudspeaker of the Year’ award? Here’s where you find out….
Iwas quite taken by several of the statements in the Owners’ Manual provided with the Concept 500 speakers. One of them was: ‘ Speaker positioning in a room is not an exact science. Even experts will find it necessary to experiment.’ Another was: ‘ Try to achieve the best balance between bass quantity versus quality and vocal quality versus intelligibility.’ These are the best two bits of advice I have ever read in an Owners’ Manual, and I am guessing that the man behind these words is none other than Karl-Heinz Fink, founder and owner of Fink Consulting, the company which is primarily responsible for designing loudspeakers bearing the Q Acoustics brand name.
Unlike many loudspeaker manufacturers, which do not mention Fink Consulting’s involvement in their designs (I’m thinking about Mission’s LX range and its high-end Pilastro, Tannoy’s Mercury and Revolution ranges, and Mordaunt-Short, to name just three) Q Acoustics is quite happy to advertise its relationship with Fink. And why not? According to Ketan Bharadia, of What Hi-Fi magazine, Fink Consulting is: ‘ the most important speaker company you’ve never heard of.’
The equipmenT
They say beauty is in the eye of the beholder, and to my eyes, the Concept 500s are truly beautiful loudspeakers. The very first thing that caught my eye was the circular (well, almost circular!) chrome-coated cast aluminium bases that support the speakers. I’ve never seen such a design used on a speaker, and I just love the way it looks. I love it so much that I wish Q Acoustics had been a bit braver and made the base a complete circle, so it protruded from the front and rear of each speaker as well as from the sides. (As designed, the base is ‘flattened’ where it passes underneath the front baffle and the rear panel. As well as looking great, the base also gives excellent side-to-side stability, so despite their not-inconsiderable height (1175mm) the Concept 500s are very stable.
But if you lift your eyes from the aluminium bases, you’re set for even more gorgeousness, apparently the brain-child of Fink Consulting designer Keiron Dunk. First, there aren’t any sharp edges in sight… all edges are beautifully rounded. Then there’s the colour scheme, which on my sample was a front baffle of such deep high-gloss blackness that you could be looking into a shiny black hole. This superb black finish extends along the sides and top of the cabinet for three-quarters of the way, after which it transitions to a rosewood wood-grain finish that then entirely covers the rear baffle. So when you’re looking at the speakers from the rear, it appears that they have a high-gloss rosewood finish, whereas when you look from the front, it appears that the speakers are finished in gloss black. It’s only when you view the speakers from the sides (or from the three-quarter views) that you realise you’re getting a bit of both. Q Acoustics also makes the Concept 500 available in a gloss white/pale oak combo, which I think looks even better again, but obviously that’s always going to be a personal call! I can say this with some authority, because although I loved the look of these speakers, I did receive a few comments that the design was ‘too modern’… so some traditionalists might not approve of it.
That the Concept 500s are so stable is good, because not only are they not small, they’re not light either, with each speaker tipping the scales at 42kg. This size and weight is mostly due to the fact that the Concept 500 uses Q Acoustics’ ‘gel-core’ cabinet construction, which is mostly comprised of three layers of MDF, with non-setting ‘gel’ sandwiched between the layers. Q Acoustics claims that its gelcore construction technique reduces cabinet resonances by an average of more than 6dB over the midrange and more than 10dB at high and low frequencies. The idea is that vibrations in one layer of MDF are not transmitted to the next layer, because the gel material (which also acts as an adhesive, to bond the panels together) absorbs any vibrations, or—as Q Acoustics’ product brochure puts it—‘ allows the kinetic energy generated by the drive units within the cabinet to be dispersed as heat, preventing them colouring and degrading the speaker’s musical output.’
The gel-core construction explains the weight of the cabinet, but the size is necessary because the internal volume of the cabinet is a critical factor in determining the low-frequency response of the Concept 500 (or any loudspeaker, for that matter), which Q Acoustics specifies at 41Hz. Because the cabinet walls are so thick, the designers have had to make the outside dimensions of the cabinet much larger in order to deliver the required internal volume. The size is also because of the internal volume used up by the amount of internal bracing that’s been used in the Concept 500—bracing that Q Acoustics has trade-marked as ‘P2P’ (‘Point to Point’) bracing. But there’s yet another reason for the size of the cabinets.
They say beauty is in the eye of the beholder, and to my eyes, the Concept 500s are truly beautiful loudspeakers
They also contain ‘pressure equalisers’, which are columns filled with absorptive material that have been ‘tuned’ to damp resonances inside the cabinet… or, if you like, equalise internal air-pressure variations. The pressure equalisers could be necessary because of the height of the speakers, and/or the location of the bass/midrange drivers and/or the size of the bass reflex port (about which more later).
In the Concept 500 design, as in other of its ‘gel-core’ designs, Q Acoustics has also mechanically decoupled the 28mm soft dome tweeter from the gel-core cabinet by means of a flexible mounting ring. I am a great fan of isolating tweeters in this fashion, because the performance of a tweeter can be dramatically altered by cabinet vibrations. By way of example, consider this extreme example: To deliver an audio signal at 10kHz, a tweeter dome has to move back and forward ten thousand times every second, and this forward/backward movement amounts to only a few microns of travel. So if a loudspeaker cabinet is also vibrating at 10kHz (sympathetic vibration caused by the tweeter itself), and it goes ‘backwards’ at the same moment the tweeter’s dome goes ‘forwards’, the dome’s net movement would be zero, so you wouldn’t hear anything at all. It’s for this reason that Q Acoustics is far from being the first to isolate a tweeter from a front baffle… but it must be said that the practise of isolating tweeters from baffles is not yet common, (though increasingly so in recent years) because of the increased costs involved and the additional difficulties it creates during the manufacturing process.
Despite the size of the cabinets, the Concept 500 is a three driver, two-way bass reflex design, using quite small-diameter bass/ midrange drivers. When I say ‘quite small’, Q Acoustics lists their diameter at 165mm. I’m not sure how it arrived at this figure, because I measured the overall diameter—as measured on the front baffle—at just 154mm. The total moving diameter is 142mm and the Thiele/ Small diameter is 130mm, which gives a surface area (Sd) of 133cm². This means that if the bass were being delivered by a single driver, rather than two, it would have an Sd of 266cm², which would translate to an overall driver diameter of around 204mm.
The cones of the bass/midrange drivers are made from coated paper rather than from thermoplastic, which will please the traditionalists, as it’s rather standard. What is not so standard—and also not obvious—is that they have 35mm diameter voice coils, which are rather larger than the usual 25mm diameter voice-coil one would normally expect to find on a driver of this size. The larger diameter means more turns on the former, giving increased conductor in the gap for better drive, and also means better power-handling capacity. The increased area of the coil surface also means better cooling, so less chance of any compression effects. The wire itself is copper clad aluminium and the former glass-fibre. The roll surround is rubber, rather than the popular (but prone to disintegration) foam that is often used as a cost-saver by some manufacturers.
The two midrange drivers and the tweeter are arrayed in ‘MTM’ fashion (with the tweeter midway between the two bass/midrange drivers). The small fabric cloth grille is stretched over a plastic frame and secured in place on the front baffle by small hidden magnets (hidden on both the grille frame itself and the front baffle).
The bass reflex port, located low down on the rear panel, is very large, with a diameter of 100mm and a tube length of 170mm. The port is made from pre-formed thermoplastic and is rounded at both ends to reduce turbulence. As with many manufacturers, Q Acoustics provides a foam bung that can be used to fully or partially block the port, but unlike many manufacturers, Q Acoustics provides some very sensible advice about how and when to use the bungs. The Owner’s Manual first advises that the Concept 500 speakers are designed to work best when they’re between two and four metres apart, at least one metre from side walls, and between 600mm and one metre from rear walls. It then says: ‘ The closer the speakers are to the rear wall the more the bass frequencies will be reinforced until they overwhelm the overall sound. In this instance closing the rear port with the foam bung will tend to reduce bass, which is useful when domestic circumstances demand that the Concept 500 is
The bass reflex port, located low down on the rear panel, is very large, with a diameter of 100mm...
used closer to a rear wall. Ensure that the bungs are fitted snugly into the port, but avoid inserting them too far. You will find the overall level of bass is reduced but bass extension and definition will be increased. The optimal position of the speakers will only be found through experimentation and by making small adjustments during the first few listening sessions. The foam bungs come in two parts, so that they can be used to fully or partly close the rear port. Again, the optimum configuration of the port can only be found by experimentation.’ So more good—and superbly comprehensive—advice from Q Acoustics then!
Around the back of the Q Acoustics Concept 500 is a plate with a two pairs of large, bi-wireable terminals, shorted by buss-bars for those audiophiles using only a single set of speaker cables. If you’re using multiple cables to bi-wire the speakers, or you’re bi-amping, you should remove the buss-bars.
Up high on the rear of the cabinet is a very large plate which, if you removed it, would reveal that the PCB-mounted crossover network is attached to the rear of it. On the plate are three small holes. These are provided so you can adjust the level of the high-frequencies to suit your room by inserting a link between the middle and the right-hand hole, or between the middle and the left-hand hole. For example, if you link the central hole with the right hole, using the ‘jumper’ bar provided by Q Acoustics, you will increase the level of the high-frequencies delivered by the tweeter, which you might do in order to compensate for a room that’s very acoustically absorptive due to the presence of thick carpets and/or soft furnishings.
Conversely, if you have a bright-sounding room because of the presence of lots of glass or other hard acoustically-reflective surfaces, you can reduce the level of the highs by not linking any of the holes. If you have a room that’s neither absorptive nor reflective, you’d insert the ‘jumper’ bar into the central and left-most holes (about which more in a moment).
It is very important to note that although the construction suggests that the ‘jumper’ might be an encapsulated resistor (as used by some high-end manufacturers), it isn’t. It’s just a section of bent steel, with 0 resistance, around which is a ‘grip’ to make it easier to insert and remove. So don’t go trying to use resistors instead of the supplied ‘jumper’ bars!
IN USE AND LISTENING SESSIONS
Before telling of my listening experiences with the Concept 500 speakers, I have a confession to make, which is that when auditioning speakers, I rarely read the Owner’s Manual. The reason I am making this confession is that when I first fired up the Concept 500s, my immediate impression was that the high frequencies were a little light-on. ‘ Maybe the speakers need a bit more running-in time,’ I thought to myself. A week later, the bass and midrange had definitely benefited from the additional running-in time, but I thought that the treble was still a tad diminished.
Now as it happens—and as mentioned previously—the level of the Concept 500s high frequencies can be adjusted by means of inserting shorting links on the rear panel. The speakers are supplied without the links in place, and I had naively assumed that this was the normal ‘default’ setting for the tweeter. I was wrong. It turned out that this is the ‘less treble’ setting, so I was hearing exactly what the designers had intended: less treble. Needless to say, when I inserted the links (one in each speaker) to connect the middle terminal to the one to the left of it, the level of treble was then delivered at a level that I found not only completely satisfactory, but also beautifully balanced with that of the bass/midrange drivers.
One of the first tracks I played in order to evaluate the bass performance of the Concept 500s was Fellow Creatures from bassist Jasper Høiby’s album of the same name (though I use the word ‘album’ loosely, since you can download hi-res tracks individually if you like). Why Høiby? Well if you can’t trust a composer whose primary instrument is double-bass to give himself some great bass lines and music that explores the outer limits of what a double-bass can do, who could you trust? Høiby delivers in spades of course, using his mighty instrument’s full frequency range and full dynamic range, and all the playing techniques at his disposal. I could easily hear that the Concept 500s are digging deep far into the bass, and despite the extremely low pitches being reproduced, the sound was still tuneful and melodic and there was no unwanted doubling. That beautiful ‘stringy’ bass sound you hear in live performance is clearly audible.
The clarity of Høiby’s double bass is even more audible on the intro to Collective Spaces, a track that’s also highlights Mark Lockart’s saxophones and Laura Jurd’s trumpet. Corrie Dick’s work on drums is a standout on this track, and you can hear the bounce of his pedal on the kick drum and the sizzle of the sound of his tapped cymbals. You can also hear the acoustic around the cymbals, which kinds of gives away how they were recorded, but also shows how revealing the Concept 500s are of recording technique.
The Q Acoustics Concept 500s projection with vocals was impeccable. Listening to Matilda, from Pete Cullen’s ‘Saltwater Cowboy’, Cullen’s distinctive quintessential Australian drawl leaps from the speakers as if he were cradling his mandolin in your living room.