60 as the new 40? Given I'm model year 1962, I'd fancy this math in general. Today's we're simply on about hertz not years. Having ordered the fixed filter in my icOn4Pro SE at 40Hz, coming in low had been my first MO. It simply left me curious whether anything higher might not be preferable at least in certain cases. With Mark's three cards, I now satisfied my curiosity. Downstairs 60Hz was the favorite. These speakers are -3dB/33Hz on their own so make 25Hz at a bit better than ten decibels down. Bolting on useful bandwidth for music not movies is mostly a miss. Useful means noticeable. You'd have to strategically pick tracks with significant output at 25 cycles to hear improved extension. That still leaves the potential for superior quality if quantity is off the books. Here French designer Alain Pratali's 4th-order bandpass bass is unusual for high-end hifi—it's very common in automotive—by really doing the biz without incurring usual room punishment. A hidden 8-inch carbon-fiber woofer inside each speaker aces textural continuity with the vintage-inspired paper-cone dipole widebander. Improving quality across the reach it covers thus wasn't really in the picture either. That left raw output. Here this room with the door behind my seat left often to avoid pressure build-up plays it just a bit shy. Bolting on truly top subs with advanced motional feedback meant independent control over their gain. That rectified the room's minor shyness with one twirl on the K231's bass attenuator. Very basic, very effective!

At 40Hz I didn't get enough extra. At 60Hz the difference played across a wider selection of music whilst on matters of subjective linearity, 80Hz wasn't quite as good. Downstairs then, 60 really was the new 40. As it turns out, flexibility in these matters is king.

Upstairs meanwhile, I already knew that 80Hz hit my monitor setup straight on the head.

There I'd started with another fixed external Pál Nagy filter box. Now Mark's confirmed it. Given the sound|kaos monitors' smaller woofers, exploiting the Dutch 10-inchers more fully into the 2nd octave produced benefits of intelligibility and clarity. Running them sideways woofers out made for the very best timing. With stereo subs, could I move the transition even higher? I'd have to order extra filter cards to find out. Being perfectly happy with the 80Hz results, I'm just not properly motivated to try. Once that laziness gets boring, I might follow up.

For now, this is just a short I-exist note for SublimeAcoustic's affordable filter box. With it more listeners into sub-for-music setups can get into proper integration without spending big on a box from the posher competition. For more on the subject, go here.