Do you think you need a subwoofer?

Raul---What is your view of the method used in the Legacy Focus: Including separate subwoofer drivers in the same box as the tweeter, midrange and regular woofers, and bi-amping with a crossover.

In this way, (i) the stress of reproducing low bass sound is removed from the woofers, and (ii) separate amplification is provided for the subwoofers.

In this way, separation is achieved without the cost of an additional box.

Is there any downside to this approach?

Dear Jim: THis Legay is a very nice approach/design that address the IMD subject between other things.

Downside?, well nothing is perfect: if I was Legacy I will make those bass drivers self powered with a dedicate amplifier that match exactly the drivers needs and take care in deep about isolation between those bass drivers and the whole speaker.

I never have the opportunity to hear the speaker but seems very good and has very good reviews.

Regards and enjoy the music.
Raul.

Dear Jim: Other factor that could help to that Legacy speakers is to separate the subs from the main box.
Anyway it looks like a very good speaker.

regards and enjoy the music.
Raul.

Raul, from my earlier post, you know I agree with the benefits of subwoofer(s) to both extend low frequency response and reduce distortion on speakers and amps for the upper bass and midrange.

But I have a question for which I wonder if your experience may suggest an answer. At what frequency will these benefits diminish to the point where they may be of little value?

For example, I don't doubt adding subwoofer(s) while rolling off the bass on the main system will benefit a two-way speaker where the woofer is operating up to somewhere between 1,200 to 2,400 Hz before crossing over. Similarly it still benefits any three-way speaker where the woofer operates up to somewhere between 320 and 600 or so Hz. But what about a system where the woofer crossover is near the top of the accepted bass range, 160 Hz? If this is also a candidate for reduced distortion benefits to the upper bass and midrange, it would seem the subwoofer crossover would be quite low, say around 40 Hz. Is this correct?

Please share any experience that can answer these questions.

Dear Pryso: The range ( high/low )i the IMD depends mainly on the quality of the woofer driver and how low goes on the bass ( deep bass ).

Normally if the speaker croosover is set at 160hz to the mid-bass driver seems to me that that bass woofer could goes at least to the mid twenties.
The frequencies below 45-50Hz needs a biger woofer excursions that 50hz-up, these biger excursions are the main " culprit " ( not the only ) that the IMD goes high, so if you liberate this woofer from 50Hz down you will have improvement/benefits for lowering the IMD in the main speakers and a better main amplifier performance ( btw, we have to think that because a speaker does not have response, say, at 25Hz this does not means that the amplifier is not working in that frequency and below it. ) and obviously a better quality low bass performance through the dedicated subwoofers.
In this ( yours ) example the high-pass could be at 50-55HZ and the low-pass ( sub's ) at 80Hz, this depend if the filters are first, second or third order. So almost always we can have benefits through the sub's integration with passive main speakers.

As always the differences and improvements/benefits are system dependent and there are no precise " rules " on the subject other than " test and error ".

Regards and enjoy the music.
Raul.