DPS-10 Features and Measurements
The rear panel features a low-pass filter on the upper-left which is continuously variable from 40 to 120Hz at 12db/octave. When the knob is at the extreme counter-clockwise setting the filter is defeated. The 10" driver has a natural roll off starting around 200Hz, and this is the only slope the signal is subjected to in the "direct" setting.
Lower on the rear panel is the phase switch, providing an option of 0 or 180 degrees. This is a useful feature where you are limited to placement options in the room (this applies to most of us with spouses). A continuously variable range would be better, but this feature is not so easy to use properly. Here is how I setup this feature. First you complete setup of the location, output level and low-pass settings. Use a track with a single bass instrument, such as 'Bass Resonance test' (Chesky Jazz and more Audiophile tests Vol2, Chesky, JD68). Play the track several times under each setting and try to observe where the sound seems more "right". Things to look for are:
- Is the entire sound coming from one point in space?
- Are the notes whole with no lag between lower and higher fundamentals and do the frequencies around the crossover point not have a severe dip?
Of course, all of these issues could also be driven by your room resonances and main speaker response, making this an admittedly difficult task to discern without the proper measurement tools. A choice of two settings is enough to drive one batty, and is more than the functionality I would expect to see at this price-point.
Under the phase switch is a pair of RCA jacks for line-level input. The left jack doubles as the input for a LFE signal from a receiver or processor. Below that are a set of spring-clip type speaker level inputs and outputs. Running the length of the center is the heatsink for the amp and on the other side is the "captive" power-cord and a rocker-type power switch.
DPS stands for 'Digital Power Slot'. Other than that being a trademarked name and referring to the digital-processing and slot-shaped port there is nothing of significance to discuss. The signal path in this unit takes an analog signal and converts it to digital, allowing all functions on the front panel to be done in that domain. The signal is then converted back to analog for the remaining processes. A purist approach would eschew the A-D and D-A conversion, but again I digress from the scope of this product.
A control panel is located on the front of the top side. This panel features presets for "Movies", "R & B/Rock", "Jazz/Classical" and "Games" - each of these yielding a different response curve (see measurements below). These presets were an early indication that this product may be geared to a novice audience, who would be impressed by such subterfuge. I would strongly suggest sticking with the "Jazz/Classical" preset, which yields the relatively flattest curve (see graph).
Also, on this panel are two buttons for increasing and decreasing the output levels. This is probably the worst design for level-control in a subwoofer. The actual level is not indicated, so you cannot really tell what setting you are at. The imbedded blue LEDs blink at an increasing or decreasing rate as you change the volume setting, but I found that of no practical help. Also, the control is placed in easy reach where children can (and mine did) change the settings. Finally, a single press of the button changes the output several decibels at a time, which does not exactly allow for fine tuning and system integration. The level-setting feature in most surround receivers will easily do a better job and we recommend you use that control to fine tune your volume. There also is a "Night" setting which limits the maximum level.
Audio Measurements
The following measurements were done outdoors, approximately 60ft from any structures (my neighbors think I am nuts), using a radio shack SPL meter. Tones were generated by the ACI test disk and the readings were normalized for the known errors of this meter, via a spreadsheet provided by ACI.
Graph1 Frequency Response Measurements at Various SPL Levels (Jazz EQ Mode Only)
Three curves were measured in an open space, you should expect about 6db of gain in an indoor setting. The first curve yielded a peak of 87db at a distance of 6 feet. Reducing that to a standard 1 meter distance would add 6db, as would placing the sub indoors. In other words, at this level you would have a peak of about 99db at one meter indoors, quite an output. You would be loco to listen to peaks much louder.
The other two curves, if measured indoors would have a peak at one meter of about 112db and 116db (now you would have to be muy loco ). However, you can see considerable compression kicks in. This is visually evidenced by a less flat curve at higher levels.
On the first curve the -6db point (from peak) is somewhere around the 35Hz mark, and -10 around 25Hz. This in effect would have the result of giving small and miniature speakers the low end extension of what would be considered "full-range" speakers. So your handful sized speakers with a high WAF rating, can now have respectable bass extension, for not a lot of money in a fairly small and attractive package, with no pretensions of aspiring to high-end performance. This really is what this subwoofer is intended for, and again, it is very important to understand this context.
Graph2 Frequency Response Measurements for Various EQ Settings
For kicks I measured the various presets, and it pretty much reflects the intended spikes in response. The "Jazz/Classical" mode yields the flattest curve, and I would recommend sticking with it for all applications.
