Originally Posted by wylist2
Nevermind on that last question. I lucked out and found a random image that had the same units and they look like they are "JL Audio FATHOM SAv2 Subwoofer Amplifier".
A new question is, if the Lab.gruppen Lake LM 26 DSP crossover was used for LCR mains and subs, was the extra functionality of those JL Audio subwoofer amps superfluous? Could 8 regular power amps be used without adjustable knobs for "LP Filter" and "LP Freq"?
No, not superfluous, as the amps are designed to linearize the SHOC24 subwoofers' free-field
response, i.e. if you put the SHOC24 sub in a suitably large anechoic test chamber (or outdoors) it will give you a textbook flat response when partnered with this particular amp. (If you used the amp on a subwoofer with, say, a different driver and/or enclosure dimensions, the response would have a different (non-flat) shape.) Because the companion amps are designed and programmed by JL exclusively for KYD's unique driver & enclosure combination, the system's electrical, physical, thermal etc. limits are known and incorporated in the amp's circuitry to keep driver and amp within their clean, safe operating areas. This helps us get the output, extension and low distortion we're looking for in an enclosure that's only 6 inches deep.
The Lake LM DSPs, on the other hand, are used to shape the subwoofer system's global response in Rob's room
. We spec'd Lakes because the math engine behind their filter construction allows my calibration team and me to drill down as far as we'd like in our tweaking without having to worry that we're simultaneously creating a batch of new, unintended issues (incl. adjacent filter interactions) -- problems that bedeviled audio engineers for decades ... until Lake came along. (If you're mathematically inclined, google "root raised cosine filters" and look up David McGrath's and Justin Baird's "Raised Cosine Equalization Utilizing Log Scale Filter Synthesis," delivered at AES Convention 117 (October 2004). It's paper number 6257.
Hope that helps.