I am a firm believer in room treatments...I just don't like the way most of them look. I don't want to have my living room looking like a quasi-anechoic chamber or recording studio. Low frequency correction is particularly challenging because large bass wavelengths require large structures to treat them.
Spatial Computer's Black Hole Anti-Wave Generator reduces the effects of room resonances in the bass region by analyzing the sound picked up by a calibrated microphone and then generating an out of phase cancellation signal. Its designer is Spatial Computer's president, Clayton Shaw. Clayton is also the designer of the Emerald Physics loudspeaker line.
My listening room/living room presented some challenges due to its size (21 x 17 with 10 foot ceiling) and due to large openings into other rooms (adjoining 11 x 11 dining room with 12 foot ceiling and adjoining great room/kitchen area). I also had some concern about whether the bass output from my larger than average loudspeakers (64" H x 22" W x 13" D) would overwhelm the smallish Black Hole (17" H x 17" W x 16" D). The optimum placement in my room was near the large archway leading into the great room area. This location was also directly in front of the left speaker and 17 feet away. This was not the most satisfying aesthetically, but it was workable.
Figure 1. Two channel system listening room.
Black Hole Specifications:
Type: Active acoustical resonance damping device with on board signal processing.
Operating Range: 22 Hz - 220 Hz.
Power Output: 240 Watts RMS.
Transducer: 12 inch long-throw.
Weight: 50 pounds.
Dimensions: 17" H x 17" W x 16" D.
Price: $1295 Internet direct (www.spatialcomputer.com)
Trial Period: 30 day with full refund of purchase price (minus two-way shipping).
I did not hear or measure any improvement with the first unit I received. Clayton responded to my email within a few hours and he suggested talking me through some diagnostic procedures. We determined that the processor was not working and may have been damaged in shipping. A return shipping label was emailed for the defective unit and a second unit was promptly shipped. The second unit worked as specified.
Figure 2. The Black hole provided an elegant solution to some of my room resonance issues.
Figure 3. The Black Hole uses a Dayton Audio NS310-44 long-throw 12" transducer.
The grille frame is held in place by small magnets.
Figure 4. The plate amp is a Dayton Audio SA240 which delivers 240 watts RMS.
Figure 5. Accessories: Dayton Audio EMM-6 calibrated microphone, microphone 90-degree adapter and 18
AWG power cord.
Figure 6. EMM-6 microphone mounted.
Figure 7. The location of the IEC jack does not lend itself to aftermarket power cords with large connectors.
Figure 8. I switched the stock 18 AWG power cord with a 10 AWG Signal Cable MagicPower cord. There was
no audible or measurable difference in performance with either the MagicPower or stock power cord. The
AudioQuest 90 degree adapter was required to provide enough space for the MagicPower cord's connector to
clear the heat sink fins.
I ended up using a Volex 14 AWG power cord with 90 degree connectors on both ends so that the cord would lay flat against the wall and lay flat against the rear of the Black Hole. I still needed to use the AudioQuest adapter with the Volex cord.
Figure 9. Double-boxed packaging with thick Styrofoam sheets between boxes.
Figure 10. Inside the inner box was thick foam, bubble wrap and kraft paper.
Figure 11. The Black Hole's piano black finish was wrapped in kraft paper, then with a layer of bubble wrap.
Pulp paper is mildly abrasive, so I'm not sure I would have chosen it as a wrapping material for a glossy
furniture grade finish.
Setup consists of attaching the microphone, placing the unit in a corner of the room's rear wall and plugging it in. No calibration is required, but some experimentation with placement and settings for gain and center frequency must be done. The manual discusses other placement options if rear corners are not available. The best sounding location in my room was determined through a combination of listening and measurement with Dayton Audio's OmniMic Acoustic Measurement system.
My listening room has a response peak of 14.6 dB at 41 Hz. Room gain, within reasonable limits, is actually desirable because human hearing has less sensitivity to bass frequencies. Therefore, room gain, within reasonable limits, contributes to perceived flatter, more natural response.
The human ear is most sensitive to frequencies in the range of 2 kHz to 5 kHz. This range corresponds to the range of harmonic (overtones) of human voices, which have a fundamental frequency range of 85 Hz to 225 Hz for adult males and 165 Hz to 225 Hz for adult females. The differentiating aspects of individual voices which have similar fundamental frequency range is due to differences in harmonic content. The heightened sensitivity in the 2-5 kHz range provides babies with the ability to quickly memorize the harmonic signature of their mother's voices and it provides small children with the ability to quickly identify their mother's voices in noisy environments if required. Likewise, adults are able to memorize and identify the harmonic signatures of their children's voices and are able to consciously or sub-consciously identify the mood and other verbal communication cues of people they talk to. For example, the harmonic structure of most people's voices changes considerably when they lie.
One good thing about room resonances is that they are not audibly apparent unless something excites them. The larger the room, the lower the room resonance frequency and the smaller the chance that it will be excited and that such excitation will be distractingly obvious. In my case, I listen to a moderate amount of music with electric bass content (that low E1 note at 43.6535 Hz!) and bass synthesizer content (that low F1 note at 41.2642 Hz).
The Black Hole was only able to provide 3 dB of correction in my room, but that was enough for significantly audible results. On musical selections with heavy bass content, the bass was faster, more natural sounding, more articulate and much more detailed. George Howard's "Diane's Blues" ("Attitude Adjustment" CD, track 4 or "Very Best of George Howard" CD track 5) has a low F1 synthesizer bass note at 00:10 into the track. That two-second note effectively drowned out the other percussion instruments and also obscured some mid range sounds because of the attention called to the heavy bass. Switching on the Black Hole cleaned things up considerably. The bass became tonally balanced with the mid and high range sounds.
I gained a greater appreciation for the richly detailed snare drum solo on Dave Brubeck's Take Five ("Time Out" CD, track 3). I appreciated it even more from the higher resolution SACD. I appreciated it much more on the much higher resolution 180 gram vinyl. The vinyl offered more tactile sensation, more skin and stick sound, more sharply defined and clearer reverberant echos from the center and right center of the sound stage and more stereophonic realism.
There was also greater clarity at the sides of the sound stage where percussion instrument sounds were frequently located. Some users have reported increased sound stage width with the Black Hole. This may have been actual lateral expansion or it may have been perceived lateral expansion due to greater image clarity and detail at the sides of the sound stage.
Aside from the greater clarity and detail from bass, percussion and drum instruments, I was also impressed by the increased weight and clarity of low notes from acoustic and electric pianos.
There were no apparent sonic anomalies, artifacts or aberrations introduced by the Black Hole. I assure you that I was quite diligent in listening for them.