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Velodyne SC-IW In-Wall Subwoofer

Part III

August, 2007

Ross Jones

 

The Sound

With all the disclaimers and limitations about in-wall subs in mind, I prepared myself for an experience that would be heard rather than felt. Wrong. I immediately starting pulling out discs with 32 Hz bass/organ pedals (the SC-IW's are rated to 22 Hz).

"Cans and Brahms" from Yes-Fragile (DVD-A), "Dance On a Volcano" from Genesis-Trick of a Tail (SACD) and Virgil Fox's direct-to-disc recording of "Bach's Tocatta and Fugue in B minor". With the SC-1250 amp providing 1250 watts of power, and the SMS-1 smoothing out room modes, it was an impressive display.

I spun up "The Chain" from Fleetwood Mac's superb DVD-A Rumours. Mick Fleetwood's quarter-note kick drums belted me in the chest, without any hint of bloat or muddiness (how's that for technical terms?!) John MacVie's ending bass vamp, rooted in A minor with plenty of open E notes (lots of energy between 41 and 55 Hz), came through loud and clear.

Switching to movies, I cranked up the usual scenes familiar to aficionados of on-line subwoofer forums (including Darla tapping on the aquarium glass from Finding Nemo and the pod race tunnel scene from The Phantom Menace). While the in-walls could not match the same visceral punch of having two free-standing subwoofers corner- loaded in my room, the Velodynes were certainly up to the task of conveying the physical impact of the soundtrack. In other words, I still get my kids running from all corners of the house to sit in the sweet spot and feel the shaking.

The bottom line (sorry, couldn't help myself) is that the Velodyne SC in-walls sound great. I didn't feel like I had to compromise on quality sound and robust SPLs in order to gain the benefit of in-wall speakers. Plus, my wife (who watched horrified while holes were cut in our drywall and dust clouds billowed everywhere) loves them, and of course that's what it's all about. Right?

On the Bench

The SC series in-walls are designed so that two of them can be driven by a single Velodyne SC-1250 amp, which is stable down to 4 ohms. Thus, the SC-IW's are rated at a nominal impedance of 8 ohms each.

The calibrated microphone was placed 1 meter from one of the driver openings in the wall for measurements. The other driver was disconnected for these measurements.

At 20 Hz, THD+N was 13.7%. The maximum SPL setting was 95 dB. With two drivers, you will be able to get 3 dB additional.

At 31.5 Hz and 100 dB, distortion decreased to 2.25%.

At 40 Hz, THD+N was less than 1%.

And at 50 Hz, 0.66%. Overall, very good for a driver that is in the wall with limited enclosure volume.

Below is the room response with and without the SMS-1 correction added.

Pink noise frequency sweeps were conducted at 1 meter, with the SMS-1 equalization off (red), and engaged (yellow). The uncorrected response graph demonstrates that the SC-IW's frequency response is basically flat (the hump resulting from room modes) before dropping off at 22 Hz, as advertised. The yellow graph (SMS-1 engaged) means that it is equalizing for flat response at the prime seating position 12 feet away, but since the room response measurement was taken one meter from the subwoofer, EQ corrections are magnified in the closed-mic response.

Between 20 Hz and 100 Hz, except for the tuning frequency, the impedance is 8 ohms. Electrical phase stays within 500.

Conclusions

Velodyne took a pretty big risk putting its name on an in-wall subwoofer, and it paid off. Employing a radical design, the SC-IW's put out big-time sound, making it a no-brainer proposition for those wanting to free up their living space. If you're looking for a subwoofer (or two) to match the clean lines of that shiny new flat screen display or dedicated theater, but don't want to settle for less than high-quality sound, the Velodyne SC-IW subwoofers are the way to go.
 

- Ross Jones -

Copyright 2007 Secrets of Home Theater & High Fidelity

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