Question for RH
T_Bop -- Sat, 07/02/2011 - 08:58
Mr. Harley,
Please allow me to beg your assistance in answering a question that has puzzled me for a long time.
Many modern speakers, certainly since the 80's, are designed with a "time aligned" baffle that is either sloped or stepped back. I confess that I don't totally understand it's purpose but I'm not arguing with the results.
However, the real puzzle starts with large speakers like the Infinity IRS, the Coltrane Supremes, the Nola Grands, etc. Whenever those speakers are positioned for listening, the woofer panels are often several feet behind the midrange/tweeter panels.
I'm assuming time alignment involves the laws of physics - however, this is an assumption that I'm totally willing to be wrong about. But if that is the case, how is it that these larger speakers seem to violate these inviolate law of physics? And while we're at it, most stand-alone subwoofers often suggest corner placement well away from the main speakers.
Your assistance in this matter is appreciated.
T_Bop
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Stepped or slanted baffles attempt to time align the acoustic centers(usually the point at which the voice coil meets the diaphragm/cone) of the drivers concerned. There is much more involved, for proper time alignment, as x-over networks will create phase shifts, lobing is an issue, etc. More to the point of your question though- You are correct in assuming that woofer placement, not aligned with the rest of the system, will cause time/phase anomalies. TacT, Lyngdorf and some others have provided us with digital correction(for home audio) for just that problem. I've been actively bi-amping my speaker systems since 1981, and always aligned the woofer systems(transmission lines) with the mains(mostly planars), prior to the purchase of a TacT RCS 2.2X(now quite modded). Placing the woofers behind the plane of the mid/high sections of multi-cabinet systems is probably an attempt to avoid the interferences/reflections that having objects between your mains can cause. A trade-off between wonderful imaging and proper time/phase coherence. I've found that to be not so great an issue, with planar speakers, as they are much more directional than coned systems. Placing a subwoofer/woofer system in the corner(s) of the room, reinforces the bass produced, so the woofer doesn't have to work as hard to load the room(something the TacT/Lyngdorf systems allow, without penalty). Happy listening!