SVS PC12-Plus and PC12-NSD Subwoofer Review

If there is a single subwoofer that revolutionized both the price/performance ratio and the way we buy subwoofers, the SVS Powered Cylinder is it. It was a simple equation. Custom engineered drivers, with ample power, wrapped up in a large efficient volume that was cheap to build and sold direct to the public, thus cutting out the middle man. The result was monstrous outputs, at very low frequencies for prices that made the eyes of a traditional manufacturer water.

This also made it cheap to make different variants, by simply altering the length of the cylinder, but in the current range this has been rationalized somewhat. The shortest cylinder (31in) is reserved for the base model PC12/NSD, the middle cylinder (39in) for the PC12/Plus and the tallest (46in) is now occupied by the PC13/Ultra. All are 39cm in diametre, which is a very small footprint, for such a large enclosed volume.

The subjects of this review are the PC12/NSD and the PC12/Plus, which beyond the apparent similarities, offer quite distinct feature sets.

The basis for both the PC12Plus and PC12NSD is, often unfairly, referred to as a hairy toilet roll. Unfair maybe, but it is a thick spiral wound cardboard tube and is as simple as it is effective. Being cylindrical, it is inherently resistant to expansion or contraction from the pressures within, in a way that a box just can’t manage, even with extensive internal bracing. This makes it very light too as the thickness of the tube is less than would be required in an MDF box. In fact, it is worth pointing out that contrary to appearances, the SVS cylinders are very stable, topple resistant subwoofers. All of the mass is in the driver and amplifier and they are all carried very low down. It’s certainly a lot more stable than the vast majority of floor standing speakers, with quite alarming lean angles possible.

Each end of the tube is plugged and capped with a sandwich of MDF which, because there is so little of it, is extremely stiff. The bottom baffle carries the driver, whilst the top carries the reflex port, or ports. This is the most visual clue as to the different tunes afforded to each of these PC subs. In the case of the shorter NSD, there is a single, central 75mm port, nominally tuned to about 25Hz, whereas the Plus, carries three. Working in concert with settings in the DSP brains of the plate amp, you can, using the supplied foam bungs and plug ports to achieve 20Hz, 16Hz and sealed ‘tunes’, each one sacrificing a bit of headroom at the feet of extension. Topping this off, is a press fit, perforated steel mesh grill, that prevents the ingress of toy cars, small animals and determined children.

The base of the SVS PC subwoofers, is a flat plate of MDF (with inlaid rubber feet) that is spaced from the driver to allow ample breathing room. This is to stop your shag pile interfering with the travel of the driver and not, as some would suppose, to stop your carpet from absorbing bass. The wavelengths involved are far too long to care how deep your carpet is. The drivers themselves are both nominal 12” units, both sport cast baskets and double stacked ferrite magnets but share little else in common and indeed are quite distinct from their sealed cousins. A ported subwoofer is a different environment from a sealed sub, with different demands. The NSD unit is an alloy cone with dust cap and has a 50mm diameter voice coil, whilst the Plus unit utilizes a composite laminate cone, a larger 75mm voice coil and has extra attention within the motor structure, to reduce voice coil inductance and distortion. SVS subs of yore, tended to deliver epic bottom end performance but were slightly less than complete in the upper bass, if they reached it at all. The modern motors employed in all of their current subs measure flat out to the frequencies demanded by modern micro satellites and they get there cleanly too.

Turning to the rear and we see further examples of the ‘Sledge’ plate amplifiers, now favoured, over what were found to be the less reliable BASH amps. The amplifiers featured here are basically identical units to those featured in the SB12-NSD and SB13-Plus subwoofers previously reviewed within these hallowed portals. There are subtle internal differences to the DSP applied within each SVS sub, as the performance envelope of each is quite distinct and is thus tuned to protect each driver and box combination.

The PC12-NSD's amp, the STA-400D has a basic set of controls – gain, continuously sweepable phase and crossover frequency which defeats at the top of its range. There are no high, or speaker, level inputs, but the stereo RCA phono input is matched by a couple of stereo RCA phono outputs. The first is a simple pass-through, that simply allows you to either daisy-chain more subwoofers, or pass the stereo signal through from your pre-amp to your power amp. The other is a 'High Pass' output that basically passes the signal through in much the same way, but minus the sub bass frequencies which are rolled off below 80Hz with a 12dB/octave slope. This latter connection, when it is available, is offered with stereo only listeners in mind, as stereo pre-amps often only have one pair of pre-outs.

The remaining feature is a separate Auto ON/OFF toggle which simply switches the signal sensing to auto, on or off as there is a separate power on/off switch by the three pin IEC power socket. The Auto option is, as with all of the current generation of SVS plate amps, very effective and resists going to sleep if even so much as a whisper of a signal is present. Power is quoted as 400W continuous, with 800W available for transient peaks.

The STA-1000D in the PC12-Plus, which delivers a nominal 1000W (2300W peak) of power, is also a more powerful beast in terms of the setup options available. Stereo Balanced XLR and single ended RCA phono in and outputs are provided, but there is still no speaker level input. The inputs have a sensitivity toggle switch that allows users to compensate for the higher line voltages used in the 'Pro' environment. Aside from the On/Off switch and a separate Auto/Always On button, the Sledge Plate amp is devoid of all of the normal buttons and dials. All of these other functions are handled by a blue backlit LCD display and a single rotate/push to select dial, that as a whole is called the Integrated Function Controller (IFC). Accessing the parametres in the menu is a fairly simple push once to enter, turn to adjust, two push clicks to exit affair and it quickly becomes second nature.

As all of the usual controls are handled by the SB13's IFC, there are more features and options offered than the norm. For instance the Low pass filter (often called the crossover) allows you to select frequencies of 31/40/50/63/80/100/125Hz, but also whether you would like the filter slope to be 12dbB or 24dB octave or defeated altogether. However, there is also a high pass filter option that affects the stereo XLR and phono outputs mentioned above. If you were using the outputs to daisy-chain additional SB13s, you would leave the high pass filter set to 'defeat'. However, if you are using a stereo pre/power amp, you can high pass the signal returned to the power amplifier. The high pass frequencies and filter slopes are the same as for the inputs. The STA-1000D has a masterstroke of a feature - it can apply a delay to the signal returned to the stereo amp, to time align the sub with the speakers. Even in the bass managed world of AV receivers, the delay (or distance) applied to the sub is often woefully inaccurate as it's physical distance, as opposed to it effective distance, are two very different things. If you're in stereo land, there is no control at all. Get this delay/distance right and your soundstage just explodes in size. It's one of the few subwoofer controls that's quite easy to tune by ear.

As mentioned earlier, there is a setting to be used in concert with port bungs to 'tune' the PC12-Plus to either 20Hz, 16Hz or a quasi sealed mode with all ports bunged. The bungs do the actual tuning, the complimentary DSP setting applying a matching high pass filter below the port tune to protect the driver.

Further use of the inbuilt DSP, gives the user a single parametric equalization (PEQ) filters to tune out the worst room related response peak. PEQ filters are not only variable in the amount of cut or boost they offer, but also in the range of frequencies affected and at which frequencies the effect is centered. The frequencies are restricted to 31/35/40/46/50/56/63/70/80/90/100/112/125Hz. You will need an external method of measuring the in-room response in order to set the filter, but in conjunction with port tuning, it's possible to get some very good results, far in excess of simply dumping the sub in the room and indeed, better than some AV receiver auto setup routines I've sampled.

If the sheer height of an SVS cylinder poses some issues regarding placement, it's also one of the reasons they're relatively easy to set up. I'm not entirely sure why, but in all the rooms I've ever set one up in, they always seem to offer a relatively smooth response though the middle of their pass band, with only the lowest of room modes requiring the usual care and attention a subwoofer, that reaches this low, demands. I suspect it's got a lot to do with the relative separation of the the port and driver, distributing the their shared output over a larger spatial area, thus resulting in less localized room modes at any given listening position. You only really seem to tame the lowest of the room booms, that tend to predominate across most listening positions anyway. The nett effect is that you tend to end up with a bit less of a bass 'sweet spot'.

For the NSD I simply applied a few bands of EQ from my Behringer Feedback Destroyer, whilst for the Plus, setup was a bit more involved. Plugging one port to run in the 16Hz tune resulted in a bit more extension, with room gain compensating for the slightly earlier roll off. Two bands of on-board PEQ were enough to tame the remaining room related issues.

I've had a large variety of subwoofers through my room in recent months. From small ported boxes, to large sealed subs, occupying £300 to £4k. Nearly all have demonstrated how far the state of the art, in their respective niches, have come in recent years. The preponderance of cheap 'digital' power has allowed previously unheard of levels of performance to occupy surprisingly small and cheap subwoofers which can only be good news.

Firing up the PC12-NSD was a sanguine reminder of how much output is lost in squeezing the air in a small box and how much 'free' output is available from a big, deep tune port. You simply cannot plumb anything like the depths, with such authority at high SPL for so little money any other way. Even as a music first boy, it's quite cathartic to hunt out the bass test disks and movie clips, just to measure satisfaction in sofa displacement. That's not to suggest there is no subtlety to this delivery, as deep bass without texture, is just waffle. It is a historical signature of SVS that their bottom end is as firm and yet supple as any you will find. From deep organ, to alien super weapons, it's the taut description of the longest of bass wavelengths that delivers the reality, or illusion of it.

But and you can't get away from this, it's the sheer output the little (okay, it's relative) NSD manages to achieve, whilst apparently failing to break sweat. It has limits, after all it is only packing 400W. Clever limiting in the DSP, ensures you don't hear untoward noises that herald the onset of an an actual, physical driver limit, or an amp running out of steam. The NSD goes as loud as it can and simply doesn't go any louder. It delivers thunderously low bass that shakes your room, but stops just short of delving deep into infrasonic territory. That's where the room pulses, despite a lack of apparently audible bass. This requires a bigger, more powerful subwoofer running a lower tune. Lest we forget, once you get below the port tune of a ported sub, the protection provided the low end high pass filter stops play fairly quickly, curtailing bottom end extension.

And that's where we step up to the PC12-Plus which ticks all of those boxes. On a lot of movie effects, the increase in performance is quite subtle, mainly because the extra control affected by the more powerful amp and refinement of the better driver is actually delivering a bit less. There's a bit less overhang, a bit less distortion, which initially sounds a little calmer, a little more measured and less in yer face. Bur when a big 'moment' arrives, a Skadoosh, a warp jump, etc, it is immediately apparent, in no uncertain terms, what that little bit of everything extra delivers. With near double the power on tap supporting a lower tune, big impacts not only sound more brutal, they feel more brutal. They're quicker to hit, hit harder and let go that bit quicker, increasing the sense of texture, As a result and although I hate to use the word in the world of sub bass, the Plus paints bass with more colour and better contrast between the subtle shadings. It gives an extra fibre to the tone of more delicate sounds like that of a Cello, with a bit less bloom letting the natural wooden warmth of the instrument become more apparent.

Which is interesting, because if you could level a criticism at the SVS cylinders (and boxes) of yore, it was that the thuggish enthusiasm for life at the bottom end, wasn't quite matched by upper bass finesse. They were far from bad, it's just that the backdrop of their bottom end proficiency exposed this area. The upper bass just sounded slightly more obvious, slightly less comfortable and this translated into merely an okay music performance, if your principle measure of music performance wasn't enhanced by simply turning it up. Evolution has paid much attention to the motor structures of SVS drivers and the response has been extended at both ends of the operating range. Whereas it used to be true that the big SVS subs were happiest with large speakers capable of meeting them on their own terms at an 80Hz crossover, the modern incarnations are happier bedfellows with a wider range of partners. Now, a four foot tall, sixteen inch diametre, fluffy subwoofer may not be an obvious match for eight inch high micro satellites, nor even a likely one, I agree. But there are more reasons to use different crossover points, than the size of your speakers alone.

Clean upper bass is less aurally locatable, allowing a higher crossover, which in turn allows the subwoofer to handle more of the onerous bass duties. This not only increases your speakers headroom and lowers their distortion; it allows you to EQ more of the bass response on the one channel that it is cheap and easy to do it on. This increased proficiency in the upper bass increases the impact and speed of musical transients, regardless of crossover point and it gives the current SVS subwoofers more rhythmic drive and pace. They simply sound more engaging with music, rather than the slightly disinterested, slightly detached presentation of years gone by, that seemed at odds with their gusto elsewhere.

Which brings me back to the bottom end and why you really WANT the bigger tube, even if your head and pocket tell you the NSD has it covered 95% of the time. If the NSD wobbles the room in a pleasant way, the Plus flexes it. It's savage in the way it threatens the fabric of your home, with doors and windows visibly bending under the most insane movie effects. The Autobot somersault in the first of the current Transformer movies has long been a demo favourite of mine, as the sustained drop into infrasonic naughtiness is protracted. It makes it easy to hear where the actual in-room response of a subwoofer effectively stops, as opposed to measures. The PC12-Plus tracked the effect all the way to the end, the sineusoidal motion of the settee being so slow as to almost allow you to count the cycles. Okay, that's not quite true unless you can count nought to sixteen in one second, but it's a bit like riding a Harley with the revs measured by thumps per lampost passed. It FEELS that low. Brilliant.

SVS PC12-Plus and PC12-NSD Subwoofer Review