Bob: you're right about the tape loop. I've seen it in demo setups in audio stores, but in actual use you'd have to fiddle with the subwoofer's volume control every time you changed the master volume at the preanmp.
As for your second comment, ultimately it *can* be true, but that depends on the lower reach and dynamic capability of the L-R speakers AND the user's demands for volume and dynamic range. Why spend the extra money for external crossover and high pass filter if the user's listening needs don't demand it?
When Carl Marchisotto was making Alon speakers (before he moved on to Nola), he had a monitor speaker for which he created a subwoofer. He designed it so the monitors continued to run full range even when adding the subwoofer. It *can* be done, but it also depends on room size, the dynamics and frequency range of the mains, and the demands of the listener.
For example, if the L-R speakers have a sensitivity of 89 dB and make real music down to 50 Hz, the need for a high pass filter isn't the same as for a mini with 4" woofers, 84 dB sensitivity, and a 70 Hz cutoff point. The first example could get by without a high pass in most situations; the second one pretty much needs one except for small rooms playing small ensemble acoustic music.
As for your second comment, ultimately it *can* be true, but that depends on the lower reach and dynamic capability of the L-R speakers AND the user's demands for volume and dynamic range. Why spend the extra money for external crossover and high pass filter if the user's listening needs don't demand it?
When Carl Marchisotto was making Alon speakers (before he moved on to Nola), he had a monitor speaker for which he created a subwoofer. He designed it so the monitors continued to run full range even when adding the subwoofer. It *can* be done, but it also depends on room size, the dynamics and frequency range of the mains, and the demands of the listener.
For example, if the L-R speakers have a sensitivity of 89 dB and make real music down to 50 Hz, the need for a high pass filter isn't the same as for a mini with 4" woofers, 84 dB sensitivity, and a 70 Hz cutoff point. The first example could get by without a high pass in most situations; the second one pretty much needs one except for small rooms playing small ensemble acoustic music.