B&W ASW700 / PV1 and Velodyne SMS1 Subwoofers

Double Subs

The B&W ASW700 and PV1

Despite costing roughly the same, these two designs could hardly be more different. The 700 is relatively conventional in sub-woofer terms, consisting of a10” high power, long throw woofer in a traditional compact enclosure, driven by 500 Watts of class D amplification. The line level input has a switched low pass filter adjustable from 40 to 140 Hz, level and phase controls, and a fixed third order high pass output at 80Hz.

The PV1 is very different. A classic case of form following function; small, beautifully formed and extremely solid, the die cast sphere construction naturally creates an extremely low resonance enclosure while the two highly developed 8” units work in opposition to cancel out internal vibration. Amplification comes in the form of 500 Watts of ICE power – a variation on class D topology – that must be pretty compact as there’ll be precious little room after the drive units have taken up most of the internal space. The PV1 can operate from either the loudspeaker terminals via a small telecoms jack (and supplied cable) with an adjustable high pass filter from 40 to 140 Hz, or line level where the input is fixed at 150 Hz. Uh, why? I guess its fine if you are using an AV receiver with a filtered LFE output, but otherwise the lack of adjustment severely compromises the flexibility of the PV1 in other systems. I probably don’t need to add that I find the high-level loudspeaker connection inelegant, and one that doesn’t really make sense to me, but it did force me down a rather radical path that I might otherwise not have explored, as I will explain later. Despite being wildly different in their design and dimensions; the quoted bass roll off is remarkably similar, the ASW700 having a -6dB point at 17 Hz as opposed to the PV1 at 18. Of course, that doesn’t take into consideration the attainable level at that point.

The ASW700 packed plenty of punch when it came down to it, reminding me a little of the REL from the last session. Despite the (relatively small) 10” woofer, there was plenty of power to be had, and the ‘dry’ crisp presentation blended in well with both the 805’s and the AE22’s. Where the 700 seemed to have an edge over others that I have recently listened to was with the speed and precision it exhibited with kick drum, showing little tendency to wallow or drag behind. But it was less good at opening up the soundstage and conveying a sense of space in the way that the Eclipse managed so well. But as with the Velodyne, pressing two into play yielded results that were far greater than the sum of the parts, even with the doubling of price. At this stage I tried the rest of the system through the high-pass filter of the ASW’s, reset the levels and had a good listen. Despite the degradation of having to run long interconnects to and from each sub, and the quality of the circuitry within, the results went a long way to providing the kind of benefits I was really looking for; the equivalent of a good, full range system. Freed from the constraints of having to reproduce low bass, the 805’s were able to play that much louder without trouble, and there was suddenly that slam and impact that one often hears with a good active set up, which was kind of the direction the system was heading in. Re-positioning the subs for the higher crossover point proved to be a bit of a challenge, and I actually ended up with the subs on 12” stands; slightly against the grain, as subs tend to rely on the 6dB boost gained by sitting on the floor, but with more than enough bass capability on tap that was not a problem. Integration seemed to be far better, and I spent a considerable amount of time listening to loud music freed from the constraints of level limitations in the main speakers. This of course set me thinking about the PV1’s, and that problem with the fixed 150 Hz input…

The PV1: Can something this compact create any worthwhile bass? In a side-by-side comparison, the PV1 is just not capable of generating similar levels of deep bass to the ASW, or any of the other subs for that matter. But deep, seismic bass at high levels; as I suggested at the beginning of this article, that’s not really what I’m looking for. When it comes to music, the PV1 has a real advantage over many others, as it is incredibly fast. The ASW was pretty good in this respect, but the PV1 had a real snap and bite that served to enhance timing rather than drag it down. In terms of bass weight, it became clear that in my relatively large room one was not enough, adding extra impetus to the double-sub argument. (Incidentally, if you have a bad back, the PV1 is a real bonus when it comes to fiddling around with positioning; just remove the plugs and roll it around the carpet.) My biggest problem was that I didn’t like the sound I was getting feeding them from the main loudspeaker terminals, so I ended up using the Velodyne SMS 1 as a low pass filter, which of course meant that I had the benefit of the digital EQ if I so desired. Which I didn’t really, but I did end up using the measurement facility to construct a simple passive filter to sit between the ARC SP10 pre-amp and Naim power amp to roll the main speakers off at 150 Hz.