Velodyne obviously intends its CHT-Q
Series subwoofers to be used in home theatre applications. This is not mere supposition on my part: it’s printed right there on the front of the Owners’ Manual: ‘Remote Controlled Home Theatre Subwoofers.’ However, proving that you can have your cake and eat it too, I found that I would be more than happy to use Velodyne’s CHT-12Q in an audiophile-quality home hi-fi system.
The Equipment
Upon opening the packaging, and placing this relatively small subwoofer (and I mean small—it’s only 457mm high, 381mm wide and 495mm deep) on the floor, the very first thing I did was remove the front grille, be- neath which I found something surprising. No, it wasn’t the input for a microphone—I quite expected that. What was unexpected was the slot at the bottom of the front panel. I had been labouring under the impression that all Velodyne’s subwoofers used infinite baffle enclosures, yet here was the CHT-12Q with a bass reflex enclosure… though I noted when reading the specifications that Velo- dyne obviously prefers to call it ‘slot-loaded bass reflex.’
I was actually quite pleased about the bass reflex port, because although infinite baffle (sealed) subwoofers have extraordinarily smooth and extended bass, bass reflex subwoofers are far more efficient (because they harness the energy from the rear of the cone that is completely lost in an infinite baffle design) and because I personally think the bass from a reflex enclosure has a little more bottom-end ‘punch’—especially on transients—which I particularly like, and therefore I am prepared to trade this against a slight loss of deep bass extension. However, when I did a quick check-up via the miracle of the Internet, it transpired that I was labouring under a mis-impression regarding Velodyne using only infinite baffle, because Velodyne actually has a very large number of subwoofers with bass reflex enclosures…
though it also has an equally large number with infinite baffle enclosures! Indeed this time around it was my turn to be surprised by the sheer number of models Velodyne has in its range—it’s quite incredible!
What is also incredible is that the CHT-12Q has Velodyne’s auto-equalisation circuitry, which automatically adapts the frequency response of the subwoofer for best results in your room. To use it, all you have to do is position Velodyne’s tiny microphone at your usual listening position, using the miniature microphone stand that’s also supplied, and plug the other end of the microphone lead into the mini socket on the front panel of the subwoofer that I mentioned earlier (which is so much more sensible than putting the socket on the rear, as was the case with earlier Velodyne subwoofers!). Then—after making sure the CHT-12Q is switched on, all you have to do is press the ‘EQ’ button on the remote. That’s it. In a few moments you’ll hear the first of a series of frequency sweeps and, after 40 seconds or so, the job is done and you simply disconnect the microphone, lead and microphone stand and pack them all away for if you ever need to use them again. I should note that you don’t have to use the auto-tuning if you don’t want to. If you just plug the CHT-12Q into mains power and connect the LFE output of your AV receiver to the LFE input on the rear panel of the CHT-12Q, you can be up-and-running with just a flick of the on/off switch and a push of the volume control. However, the simplicity of the calibration procedure is such that it will only take a few extra minutes, so why wouldn’t you?
Unfortunately, although the inbuilt calibration can match the CHT-12Q to your room, it can’t match its output to that of your main speakers or to your AV receiver. So you will still have to set the CHT-12Q’s high-pass control and volume control by ear—as you would with all other subwoofers. If your AV receiver is a recent model and has its own inbuilt calibration, you can use this
to aid set-up. However, note that you must always run the CHT-12Q calibration BEFORE you run your AV receiver’s calibration. (Also, since most AV receivers have only a limited calibration range, it’s still better to set up by ear first, and then run the two automated calibration routines.
When the Velodyne equalises itself, it does so for the flattest response, which it then makes available ‘au naturel’ in the Jazz/Classical preset position. This ensures tight, clean, extended—and perhaps most importantly— accurate bass response, but when you’re playing video games, or watching an action movie, you don’t necessarily want accurate bass, you want ‘oomph’ and excitement! This is where the other three presets come in: ‘Movies’, ‘R&B/Rock’ and ‘Games’. The titles are self-explanatory, but of course you can use any setting you like, no matter what you’re doing. If you’re playing a video game and you think the game sounds the best when you’re using the ‘Movies’ preset, then use the ‘Movies’ preset! There are no rules.
The CHT-12Q’s driver has a cone of reinforced fibre that’s driven by a two-layer copper voice coil. I measured the cone as being 330mm in diameter overall, a little larger than claimed by Velodyne, but the Theile/Small diameter is 258mm, which gives a cone area (Sd) of 523cm². The bass reflex slot beneath measures 345×31mm. The amplifier plate on the rear has the usual rotary low-pass crossover filter, but it works ‘backwards’ to usual, so that the subwoofer operates at its maximum bandwidth (120Hz) when the control is fully counter-clockwise, and at its minimum (40Hz) when it’s fully clockwise. The crossover slope is 12dB/octave (24dB/octave ultimate). The volume control is far from conventional, being push-button(s) rather than rotary. (However the only time I can imagine you would use the push-buttons is if you have mislaid the remote or let the batteries run flat.) Below the volume control is a two-position slider switch marked ‘Stand- by’ and ‘Always On’ that self-evidently
equipment 