In the last article I reviewed the Meridian, TacT and Lyngdorf room correction products against the set of functional criteria that were previously established. Today I’m going to look at room correction products specifically designed to be used with subwoofers only.

The functional criteria have been shortened to fit into the table. Here is the interpretive legend:

• Choose Freq --> Must not apply correction filters above the transition frequency OR must allow the user to switch off room correction above the transition frequency. Since all these devices are designed to be used on subwoofers only (which are typically used only below 80Hz-100Hz) they meet this criteria by default.
• Choose Target --> Must allow the user to choose a target frequency response
• No A/D or D/A --> Must not perform an un-needed analog to digital or digital to analog conversion. This requirement is not really appropriate for subwoofer correction devices designed to be used in a home theater environment, since no pre-processors that I know of provide a digital low frequency effects (LFE) output. The only exception to this would be devices that also incorporate crossover functionality (such as the Velodyne) and could end up finding service in a two channel system.
• Auto Measure --> Must provide automatic measurement and correction filter generation capabilities

If you didn't read the detailed and comprehensive introduction to room correction, see this article.

Notes:

(A) The SVS AS-EQ1 uses licensed Audyssey correction algorithms (FIR filters) and provides capability to set individual correction filters for two subwoofers. It has two sub inputs and two sub outputs. This is a pure equalizer, and does not provide any crossover functionality. It is therefore designed to be used primarily in a home theater type system where the pre-pro looks after the crossover.

(B) The Velodyne SMS-1 provides parametric EQ filters implemented in the digital domain. It provides multiple presets, useful if you want different set ups for home theater and stereo. Another very useful piece of functionality is the provision of an adjustable low pass crossover and high pass output. Although the Velodyne unit provides capability to attach up to three subs, it must be realized that the correction filter applies to all subs. There is a facility to pass through an unaltered signal to another SMS-1 box in case separate correction filters are needed for each sub.

(C) The DSPeaker box is a one input, one output automatic room correction device that can apply up to 24 bands of parametric EQ. It does not provide any crossover functionality.

(i) The AntiMode 8033 provides limited ability to boost the 25-35Hz or 15-25Hz frequencies.

(D) The Audyssey Sub EQ box provides two sub inputs and two sub outputs. No crossover facilities are provided.

(ii) The Audyssey ‘Installer Kit’ must be purchased in order to generate the correction filters for the Sub EQ. The kit includes a measurement microphone, the software and a microphone stand.

What do you think? Have I missed any subwoofer only room correction devices? Let me know, as always, via the comments!