Day 2:
Day 2 was spent finishing the tuning process for the Main arrays (to the 1/2 point) Now that we have done all 4 arrays we will copy the the settings over to the other side and then verify the symmetry of the other speakers. We are setting that part aside, moving on instead with tuning other systems and leaving all of the symmetry verification for later.
This tuning is a multi-part affair, for a very multi-purpose, multi-channel system. While the Main system and subwoofers will be used in a fairly traditional manner, the surrounds will be used as spatial image movement, surround envelopment and also as reverberation enhancement: the Constellation system. I will be staying here after the SIM tuning, to help with the Constellation calibration. In total I will have 8 nights on site.
Pierre Germain and Steve Ellison of MSLI will be joining me for the Constellation (Pierre on day 3 and Steve on Day 4). Acoustically the room is quite dry – a bit surprising considering we have a 5,000,000 gallon swimming here – OK I COULD NOT RESIST. – There are 10,000 absorption panels, each about 2×2 meters, 4 inch thick (at least). The reverb time is under 1 second in the high end, quite amazing for a room of this volume. We will be extending the reverberation with the Constellation system, recirculating the sound through hanging mics and back through the extensive speakers around the room.
Our mission today wwas to make progress on the mains and also to get a 25% slice of the room’s surround/constellation speakers so that Pierre could be kept busy upon his arrival tomorrow. Most of this was accomplished.
The secondary Main system is the Sound-Beam 2 (SB-2) . This is what it sounds like – a parabolic dish speaker system with 20 degree coverage over almost its entire operating range. There are 8 units and they cross their beams in the center of the room, giving secondary coverage to the opposite side of the room. So each seat is covered ABOVE at a 66ms distance by the Melodie array and also by the 2x distant SB-2. The controlled pattern of the SB-2 allows it to be used selectively across the pool with minimal self-interference – (readers of my book will note that this is the ultimate Point-Destination array – but since it maintains its control over its full range, it comes out the other side of center able to achieve isolated coverage on the far side. If there are set pieces in the middle, then things will get interesting for sure, but this secondary source alloows for vertical image movement (the SB-2s appear much LOWER to the listener than the Melodies – which are nearly overhead to the front rows.
So Day 2 was spent CAREFULLY aiming the SB-2s. I MEAN CAREFULLY. One of the interesting aspects of the SB-2 is its pattern is the ultimate in symmetry – a circle. We overlapped them slightly (-4 dB to -4 dB) along the center line in order to make sure they met above and below – visualize a binocular pattern – two circles, slightly overlapped at the center.
After finishing the beams we proceeded on to three of the 4 levels of perimiter surrounds/delays/ constellation speakers. We equalized and level set the individuals. The combination would have to wait for Day 3……….
I strongly vote for getting that much absorption in every room where loud speakers are about to be placed.
Agreed, Harald,
It is great when you can start with a neutralized room, especially when the venue will have a big variety of sound experiences. The show here will vary from a very up close – dry – experience to bathing in reverberation from all directions. This is where Constellation pays off – able to move between those experiences on a cue.
How are you EQing the SBs? Are you reducing the LF because it’s less directional and will spill onto the unintended side, or are you going for flat? Where are the subs?
Regarding room acoustics, it seems that very wet rooms are the trend in Nashville these days 😉
Daniel,
Each individual SB-2 was EQ’d in its range of coverage. Then they were combined and we looked for LF buildup. The LF is only a small amount wider than the HF so there was not much adjustment required.