Hi Steve, Thanks for writing and sharing your interests and insights (Sursound Digest Vol 56, Issue 2). It is always interesting to get input from people with different backgrounds, and it sounds as though you have an extensive background in the recording arts and music production.
I know what you mean about the “obligatory” NS10; in fact, one appears on the *Products* page of my personal site (cochlearconcepts.com) along with a 4000-series SSL console, and a classic combination of music production gear (e.g. tubed UA and Manly compressors). [The ugly dude in photo is yours truly.] Like many audio enthusiasts, I got into hi-fi as a youngster. I was an avid speaker builder, and authored a couple of articles in The Audio Amateur and Glass Audio magazine. As a person with some loudspeaker design experience, I took note of your comment, “This would also slot nicely into the change of directional hearing mechanisms, while at the same time not having a crossover in the centre of the most important mid range. It would also reduce the interference caused by placing drivers close together.” It’s interesting that many loudspeaker designs (to include highly regarded powered monitors) have a crossover point right smack in the middle of the ear’s most sensitive frequency range. The trade-offs for higher or lower xover frequencies are 1) the larger-diameter mid-woofer becomes directional at higher frequencies (all relative to cone diameter); 2) typical dome tweeters can’t manage the power or long cone excursions needed to reproduce low frequencies; and 3) adding a mid-range driver adds to the complexity of the design as well as physical size of loudspeaker system. I’m not saying anything you don’t already know here. But what could be interesting is designing an Ambisonic-specific loudspeaker system to offset the crossover frequency. I’m personally biased towards at least one single-coned, full-range driver: The Lowther (ok, it has a whizzer cone, but still no crossover network). But these guys are expensive, and the one pair I had were mounted in massive, acoustic-labyrinth enclosures. But on a more realistic notion, there are many good speakers that have smooth on- and off-axis responses from roughly 40 Hz up to 700 Hz. And I’m confident there are more than a few single-coned 4- or 5-inch drivers that can accurately reproduce 700 Hz to well beyond the upper mids. To complete the high-end, a tweeter (or array of tweeters) could be added. An analog (passive or active) crossover at 700 Hz wouldn’t be needed, as the B-format signal could be split into specific bands (high and low) ahead of the decoding. [This, by the way, is where I intended to do offline processing.] Such an arrangement would require two Ambisonic decoders (upper band and lower band decoders with their own, unique speaker sends). Fortunately, this isn’t a big processing load. I’d prefer to do this than split the highs and lows after decoding with a single decoder. If the crossover frequency was chosen to be 700 Hz (or 400 Hz), then a greater number of place-specific speakers could be used for the highs (as you suggested) than for the lows. The mids and highs could easily be grouped together (for economy). The loudspeakers handling 400 Hz and above could be two-way, but with a higher-than-usual crossover frequency (meaning conventional crossover but at, say, 5 kHz). Such a system would have atypical crossover frequencies, but the advantage would be keeping the crossover point out of the ear’s sensitive range as well as the range where phase anomalies (introduced by active or passive filtering) could be most audible. The directional characteristics of the drivers are a function of baffling and cone diameter, so cone diameter and enclosure size would be purposely small for the speakers managing 700 Hz and up. If such a system provided advantages, I suppose it would be ill-suited for any of the popular surround formats. The workaround would be to stack the smaller (one- or two-way) speakers atop the bass/mid-bass speakers and bi-amp them. Time alignment and additional subs optional. Many thanks for taking time to read. Best, Eric C -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130302/e3bf91d3/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
