How can a subwoofer expand the soundstage?

Psacanli,

What Stanwal said is correct (I believe) and what you say is also correct (I believe). REL does recommend running their subs in paralel to the full range speaker and the speaker be ran full range. This is done without any additional crossovers. REL subs usually don't perform too well above 50 or 60 Hz, but are outstanding in the lower frequencies.

On the other hand, to get the benefits you mention you need an external crossover before the amp to let it only reproduce higher frequencies and the speaker do the same. Doing this you prevent the speaker go into low freqs where many speakers increase distortion a lot. So you get more headroom on the amp + less bass-related distortion from the speaker, and then let the sub handle all the low freqs. However, to do this you need a different kind of sub that you can crossover at 80 to 100 Hz...like a JL (I hear).

I hope this helps. Please note much of the above is not first hand experience but rather learnings from reading this forum!

Regards,
Horacio

Dbphd,

Thanks for your feedback. This is valuable info for me, as I ponder over the value of adding an external crossover before the amp. Would appreciate your thoughts on this.

I run B&W 804s, which are said to have a frequency response down to 38Hz -3dB and while B&W doesn't publish distortion figures I believe they probably increase distortion quite a bit at the lower frequencies...maybe under 50 Hz?. I also have a REL Storm III, which as noted doesn't like being crossed over much higher than 50 Hz...therefore I wonder if getting an external crossover, like a Bryston 10B, to let the B&Ws reproduce only freuqencies above say 50Hz is worth it. Unfortunately I live in a place where buying used and giving it a try is not easy...Any thoughts?

Sorry I'm way off topic!