Testing the DSpeaker Anti-Mode 8033
The
DSpeaker Anti-Mode 8033 is an automatic subwoofer EQ device, it aims to simplify the process of equalising a subwoofer whilst employing advanced algorithms to generate precise filters to counter room modes. It is supplied complete with a measurement microphone. Given my long-standing interest in EQ I bought one to see how well it performs.
The device is very compact, just 126 mm x 80 mm x 28 mm. It has a separate “wall wart” power supply. The front panel has a 3.5mm connector for the measurement microphone; 2 buttons to activate the EQ process, bypass the device or select two bass boost profiles, “Lift 25” and “Lift 35”; and the on/off switch.
The rear panel has a power input, an RCA connector for the sub output from your AV procesor and two RCA connectors for the output to your subwoofer, one of which is inverted (equivalent to setting your sub's phase control to 180 degrees). Usually only one output would be used, though both could be used to drive a passive sub in a bridged configuration with a stereo amp.
The 8033 is for use with subwoofers only. It operates at a 4kHz sampling rate and has a frequency response that is -3dB at 3.3Hz and 100Hz. The response is only relevant when the device is in bypass mode, as it internally applies EQ to give a flat response when it is active. The graph below shows the bypass response.
The processing delay through the unit is 2.7ms, equivalent to 0.9m or 3 feet on a processor's distance setting. Note that the unit has 3dB of gain (the output level is about 1.5 times the input level) even in its bypass mode, remember to recalibrate your sub level after inserting it. THD when fed a 0.5Vrms 40Hz test tone was well below 0.1%.
Operating the unit is very simple. Just connect it up, plug in the microphone and place the mic in your listening position, then press and hold the 2 buttons for a few seconds to start the EQ process. The unit begins with a few seconds of adjusting the level for the mic then starts its sweeps. There are 4 sweeps in total, each lasting 1 minute. Once the sweeps have completed the job is done. It does allow multiple measurements to be taken in addition to the primary position, and according to the manual combine the measurements to deliver EQ that works over a wider area than from a single measurement, though I didn't test that.
I tried the unit out in my lounge, feeding an REL Stadium II sub in one corner of the room, which gets down to about 20Hz in-room. This was the first time I'd measured the sub in there since the room was extensively rearranged. I compared the results of the 8033 with those I got using a BFD (DSP1124P) applying manual EQ. The room itself is L-shaped, with patio doors right across one end.
Here are the results with no EQ (red), the 8033 (green) and then the BFD (blue). Graph axes are from 35dB to 95dB vertically and 15Hz to 200Hz horizontally.
The 8033 has nicely levelled out the two areas of major resonance.
Here are the spectral decay plots for each case, first no EQ, then the 8033, then the BFD.
Finally the waterfalls, no EQ (red), the 8033 (green) and then the BFD (blue).
The 8033 does a reasonable job overall, though I had hoped for a little better. In fairness, this is a very difficult room to deal with. The L shape combined with the effect of the patio doors in one wall and a large window on the wall opposite result in two clusters of closely spaced modes spanning about 23 – 31Hz and 52 – 65Hz. To get the results in the manually applied BFD EQ I spent about 3 hours tweaking, remeasuring and re-tweaking the settings, using all 12 filters and the benefit of many years investigating EQ for subwoofers. I applied no filters above 65Hz as there were none left in the channel I used, although another 12 can be had by looping through the other channel I'd kind of had enough by then
. To get the 8033 results I pushed two buttons and made a cup of tea. I would expect that in a more conventionally shaped room it would perform even better.
The 8033 worked well and is very easy to use. I would still strongly recommend that anyone wanting the best from their subwoofer spend some time measuring its performance in the room and seeing the effects of changing its position and/or where you sit, as devices like the 8033 or the BFD can only really help with countering the boost from resonances, they cannot correct the dips that all too often occur at certain positions. Having done that though, the 8033 offers an easy way to get the modal EQ aspects covered.
Advertisement 
