SVS AS-EQ1 SubEQ Review

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AVForums takes a look at the SVS subwoofer EQ system...

by AVForums Jul 18, 2009 at 12:00 AM

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    SVS AS-EQ1 SubEQ Review
    SRP: £699.00


    Subwoofer Eq'ing used to be simple. There were only two subwoofer EQ devices available to the consumer market; one was a refugee from the live music arena, looked like something off the shelves of Dixon’s circa 1984, was more than a bit tricky to use, but worked very well and was staggeringly cheap. The other cost five times the price, actually looked like something you wanted to see in your rack and whilst arguably not quite as effective, made up for this in spades with it’s flexibility and relative user friendliness.

    The key phrase there was “relative user friendliness”, because neither were exactly plug ’n’ play and it was perfectly possible to actually make your in room frequency response worse than before you started. Worse still, if the bug of ‘EQing’ bit, you could easily spend hours listening to strange droning test tones that upset household pets and partners, whilst posting frequency response graphs on-line with a view to endlessly discussing every intricate wiggle on a fundamentally straight line. What real people in the real world craved was a reliably automated device that would allow them to spend more time using their systems than tuning them and allow them to rejoin their families in normal pursuits. Well blow me if after what feels like a lifetime of waiting, I’m not staring at the second ‘automatic’ device in as many months and rumour has it, there are more on the way!

    The subject of this review is the SVS AS-EQ1 (hereafter, EQ1) which is aimed toward the top end of the consumer market. It is the result of a collaboration between well known on-line-only subwoofer retailer SVS from the US of A and room equalisation gurus Audyssey Laboratories Inc.

    Nuts & Bolts

    Opening the solid double carton reveals the EQ1, wall-mart power supply, a printed quick start guide, CD containing the full manual, a microphone pass-through cable, some 19” rack mount ears, a USB cable and finally, the custom measurement microphone. The USB cable is because you will need a computer running Windows XP or Vista in order to do the number crunching for the EQ1, to which you then upload the results. This is not a stand alone device.

    The EQ1 itself is of average, but very tidy build being pressed steel for the most part and is thankfully a full sized component. Fixed to the front by magnets is a removable face plate machined from billet aluminium. This sizeable chunk of metal does wonders for perceived build and the unit’s look as it covers up the plethora of front mounted socketry not required in day to day use. It’s the rear of the unit that gives the first sign of what you’re paying for as not only does it have two subwoofer RCA outputs (no balanced XLRs here), it has two RCA subwoofer inputs too. This is the first unit that can accept not only a stereo input, but also deliver a stereo output and equalise two subwoofers separately.

    Up to now equalising two subwoofers has been possible, but they were essentially treated as a single mono sub as they were fed from the same mono output, even if the input signal was originally stereo. This gives enormous flexibility and future proofing as, via various options in the set-up menu, you can cope with anything from two subs from two inputs down to one sub from one input and any variation in between. Looking forward, the possible requirements of future 7.2 surround sound amplifiers made possible by the new HD sound formats are therefore catered for. It’s good to see that you won’t be replacing yet another component in under two years due to technological churn.

    To complete the picture of the rear is an On/Off switch (what is wrong with the front panel?) and an additional RCA output used for sending a test tone to one of the front speakers. It doesn’t EQ the front speakers, but it gives a relative level against which the EQ1 balances it’s output.

    Removing the front panel reveals the socketry most frequently used. There is a single microphone input for the supplied mic, but there is also another microphone in plus output for those with Audyssey EQ equipped receivers to loop through their existing mic. As there is no point in getting the amp to EQ the subwoofer where an EQ1 is in the chain, the pass through feature allows the EQ1 to send a perfect response back to the amp as if there were a perfect sub in play and thus the amp does nothing to EQ the response.

    From the domestic point of view, it is certainly a very comprehensively featured unit, but Pro Installers may bemoan the lack of XLR in/outputs and a 12v On/Off trigger. The fit and forget nature of the EQ1 plays right into the custom installers hands and the processors they install will have 12v triggers, so that is a trick missed by SVS as far as I can see.

    Whilst I’m moaning, I’ll get another one out of the way; Status LEDs. Whilst it is nice to have a green LED lit to confirm the unit is on and another to confirm Audyssey is engaged, I have no need for them to double as ground level emergency escape lighting. With the room lights on it’s not too bad, but plunge the room into pitch black for the sake of a projector and it is extremely distracting. Okay, sitting off axis makes matters a lot better and a bit of opaque tape can take the sting out of the searing brightness too, but this is a top end unit so why should I have to?

    Whilst I’m on a roll, I'll complete the hat-trick. This is another gripe that doesn't detract in any way shape or form from the EQ1’s performance. It's the “Calibration Certificate” that you can print via your PC, once you’ve finished running the equalisation routine. The waterfall plots I've posted below show what Audyssey is doing in both the frequency, amplitude and time dimensions. They are the absolute minimum for seeing what Audyssey has achieved in your room and even then, each graph is only representative of the single position it was measured at. If you want to know what's going on in the seat next door, then you need to move the mic and measure again to produce a separate waterfall. The Calibration Certificate comprises an overtly smoothed before and after graph in only frequency and amplitude dimensions and is thus, practically useless. To the uninitiated, the certificate also implies that the plot shown is actually available in any seat and that, I feel, stretching the truth somewhat. It is a very smoothed average of the responses for every position you measured, but there is no one seat you can sit in and experience that response. I had problems printing my Calibration Certificate and only discovered after the EQ1 went back that Vista PCs need to be told they're American before it will work, so the example shown above is a borrowed from SVS. As annoying features go, just add it to the LEDs and it certainly isn't a deal breaker.

    Gripes over and as I say, nothing that detracts from the performance.

    Set Up

    Once you’ve loaded the supplied software onto a PC, it’s a simple matter of plugging the PC into The EQ1 with the supplied USB cable and plugging the measurement mic into it’s jack socket. Guided by the PC’s on screen instructions, you are first asked to place the microphone at ear height in the listening position (the back of the sofa won’t do, so get a mic stand or find a tripod) and with the software’s help, you set the SPL levels of the chosen speaker and the subwoofer to match. Audyssey will also determine the distance you should set for the subwoofer in your amplifier’s menus. This distance will account for not only the physical distance, but also any additional delays due to signal processing – in the case of the EQ1, that’s 8.5ms which is roughly like saying the subwoofer is 2.8m further away than it actually is. Audyssey consistently gave a total distance setting of 6.2m in my room so it’s not hit and miss like some automated routines. However, the EQ1 does not suggest a distance setting for the one speaker that has been included in the measurements. The ultimate effect of setting the subs distance this accurately is therefore rendered slightly moot if you lack the ability to do the same for the speakers and as anybody with an Audyssey equipped amp or processor will tell you, the effective distance of your speakers can be quite different from their actual distances. I would have preferred it the unit had offered up a distance to add on to that of the measured speaker or even an absolute measurement for that speaker as well as the sub.

    SVS  AS-EQ1 SubEQ Set Up

    Next is the process of actually EQing the room and it is impossible to talk about an Audyssey EQ equipped device without a word about what they claim makes their EQ different, so I’ll try and give a potted version in the way my limited intellect understands it.

    All of the common bass EQ devices take an analogue music signal and convert it into the digital domain for processing. Everything that happens to the signal before it gets reconverted back to analogue and sent on it’s way to the subwoofer is a very complex mathematical process. The fundamental difference between most devices is simply the mathematics employed and Audyssey claim to use a different style of maths to everyone else. The nub of it is that when you apply a DSP filter to a signal, that signal gains an echo (continues to ring) after the original signal has passed. Audyssey employs Finite Impulse Response (FIR) filters that, as the name suggests, limit this ringing compared to the more common Infinite Impulse Response filters employed by every one else. It is this property, plus the sheer number of filters this method enables that gives Audyssey one of it’s main claimed strengths – the resolution to tame even the minor imperfections in a response. There are of course advantages claimed for IIR filters too, but that's one for the forums and the chaps clever enough to actually programme this stuff.

    The second part of the Audyssey equation and this will sound familiar to anybody who has read the DSpeaker Anti-mode 8033 review, is that the EQ-1 and Audyssey in general balances the need for a flat frequency response against the need for swift decay of the actual sound being reproduced in the room. Removing the overhang caused by the resonances of room modes is as important as a flat response, because the human ear is poor at discriminating the difference between the two; the response needs to be short to sound rather than look flat.

    SVS  AS-EQ1 SubEQ Set Up

    The final and possibly most important part of the Audyssey jigsaw, is the ability to compensate for a wide area of listening positions. In fact the EQ-1 being a derivative of the full Audyssey MultEQ XT can utilise readings spread across 32 individual measurement positions. Clearly you don’t have 32 seating positions, but spreading the measurement points around and in between the seats you do have, allows Audyssey to build up a fuller picture of the room and then figure out a ‘best fit’ response curve that suits all positions simultaneously. What is not possible is an individually tuned response for each listening position. After all, a subwoofer cannot output a frequency at different levels to suit different positions at the same time, so there can only be one EQ curve. The crucial bit is that the end response curve that Audyssey generates is not a simple average of all the measured positions, but a far more selective look at the common factors across the positions. Thus, if only one position out of the possible thirty two suffers a peak at a certain frequency, there is little point in Audyssey tuning it out as every other position will suffer a dip instead. Equally, all positions may suffer the same peak in response as a result of the floor to ceiling dimension related mode and thus that peak will be attacked quite aggressively.

    SVS  AS-EQ1 SubEQ Set Up

    So, you measure as many other positions as needed although you must measure at least three. I tried numerous variations from SVS's suggested 60cm spacing to saturating the area around the main listening couch in a grid of 30cm squares. The latter proved the most satisfactory in my room as long as you avoided measuring within at least 30cm and preferably 60cm of a wall; Too many measurements in the heavily boundary reinforced area near a wall tended to bias results into rolling off the bottom end a bit early. I found that the greatest benefit was derived by letting Audyssey build up a picture of the room where we actually sit, rather than as whole and ignore the poor individual who, on those rare full house nights, will find themselves sitting 90cm from my front right speaker.

    In that seat, uneven bass is the last thing you’ll be worrying about if I've got the control of the volume, so why compromise all of the other positions trying to make it fit? Because I was EQing quite a restricted zone of seating, I found that after about 12 measurement positions Audyssey had a good enough grip of the matter to render extra measurements superfluous in adding to the effect.


    But what an effect! I can imagine that a fair few people might feel a bit under whelmed by a mercilessly flat response, but as someone who tends to chase accurate, rather than massive bass and never really bought into the 'house curve' idea, I find the EQ1 to be right up my audio street.

    Most satisfying to these ears are two particularly noticeable effects. The first is the way the sound stage (particularly in stereo) seems to swell in size beyond the confines of the speakers. It's not a small difference and switching the EQ1 in and out from the PC whilst listening to music was akin to having a large scale/small scale switch only due to the lack of equalisation, it was the small scale rendition that suffered odious amounts of disproportionate waffling bass. EQ is never a substitute for effort and even the EQ-1 can't make poorly set-up speakers image well, but it will add an extra dimension to a system where care has already been taken. Imaging maintains it’s coherence well off axis too. Sitting at either end of the sofa just resulted in a slight shift of image toward the direction you had moved in, but the spacing within the sound stage was maintained very well. I can normally only achieve such an effect about a foot or two either side of the central hot seat, so having measured to just out wide of and around the sofa really has helped expand the critical listening area, exactly as advertised.

    SVS  AS-EQ1 SubEQ Listening

    The second impressive effect was the way the subwoofer just disappeared. With music the integration between sub and speakers is inaudible and I did go looking with all of my time worn favourites. I feel fully justified in trotting out some hackneyed expression about subterranean bass depth appearing to emanate from small speaker cabinets, because in this instance it's fully justified. Shorn of all excesses in SPL or decay, bass is effortlessly nimble and tuneful and the closer your music is to acoustic, the more you'll notice the improvement; The EQ1 is particularly beneficial in helping to describe the space in which a performance is taking place. If the room is a tight, low ceiling basement jazz club or the stage of a purpose built venue, you know which is which even before the music starts.

    Of course, all of this would be for nought if the musical enjoyment were to the detriment of movie fun, but more than a bit of the buzz the EQ1 is generating is precisely because it doesn't. If anything, the disappearing act it performs on the sub makes the arrival of a real movie LFE moment all the more startling. Without the chesty voices or overly resonant background noises to let you know there's a sub at work, when an impact does arrive, it's contrasting impact and depth is greatly increased. Without the traffic noise being overtly bass heavy, the explosive opening scene of Children of Men is still delivered with all of the visceral impact you could hope for, but because the impact is delivered from a darker background of bass, the dynamic attack of the explosion gains a new concussive ferocity.

    Further more, against this darker background small bass effects gain greater presence within the mix. In Master & Commander the sounds of footfalls on the wooden decks above sounded more like hard heeled footsteps on wood than small bass explosions devoid of tonal colour, plus the location of effects within the surround sound field was far more precisely placed in direction and distance than I recall. Quite a beguiling quality and also distracting, because whilst I normally try and write a few notes as I watch things (having no real memory of my own to call upon), in the case of Kung-fu Panda I wrote nothing but the title despite having watched the entire film often enough to know it off by heart. The same thing happened with CDs too and it's a good sign; when ones attention wanders from the process of looking for faults and just enjoys the film or music, then things are being done right. There was even a whole week when I didn't re-EQ or adjust anything. I just listened to and watched stuff; Imagine that!


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    SVS AS-EQ1 SubEQ Review

    So is the EQ1 is a success? Without a doubt, but only as long as know how to use it, which means it slightly misses the mark of being a truly 'auto' EQ. You do need to experiment with microphone placement and you do still need a rudimentary understanding of the way bass works in a room in order to get the best from it because if you don't, it is possible to make aspects of your bass performance worse. That said, it is only getting you to do the legwork and it shoulders the really hard number crunching that would be well beyond even the most experienced EQ user, so it's not really asking a lot. Any easier than this and you'll find you're paying for a professional installer.

    Those with no intention of sitting anywhere other than the main listening seat, nor any intention of running a second sub, or with a particularly benign room may question the need to spend quite so much. My experience with the AS-EQ1 is that it can still justify it’s price in it’s ability to cope with both awkward rooms and also eek out the last percentages of performance in good rooms by bringing it’s extra resolution to bear on the problem; the last 5% of performance is always more expensive than the first 5% and the EQ-1 will hunt it out.

    There are issues that I've mentioned, some of which like overly bright LEDs are unforgiveable from a home cinema manufacturer – they of all people should understand dark rooms. Other niggles are perhaps me being picky, but whilst the power drawn from your wall socket at idle is perhaps milliamps, I'm going to start a one man crusade to see power buttons back where they belong, even if it's only for power standby! All that said, I know at least one user who wasn't even aware the LEDs changed colour, nevermind how bright they are because his kit is in a cupboard, and his amplification doubles up as a powerstation for a small local village so for some, these issues are non, if you follow.

    In every respect that actually matters SVS have an awesome bit of kit on their hands that delivers exactly what is promised; effective equalisation of bass over a wider than average area with a guided workflow that won’t leave a beginner baffled. It can interface with your current amp where necessary and is as future proof as anything out there and tops all of this off by keeping both the music and movies boys happy.

    Conclusion? Domestic subwoofer equalisation has a new reference.

    Suggested retail price when reviewed: £699.00

    The Rundown

    Build Quality




    Ease of Use


    Audio Quality


    Value for Money




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