How can a subwoofer expand the soundstage?


I have recently added a Rel Storm III to my two channel system (Essence Sapphire amp, modded Essence Reference Super Gems, Arcam FMJ 23T CD, SOTA Sapphire TT, Benz Glider, Audible Illusions Preamp). I immediately noticed an improvement in imaging and depth of the sound stage at all frequencies. The REL manual specifically mentions these benefits. Can someone please explain how adding a driver that's designed to play at lower frequencies can have this kind of impact? I will NEVER take the REL out of my system.
rockyboy
Rockyboy… I experienced the same phenomenon you describe when I switched my Theta Casablanca to run a sub in 2 channel Stereo mode with my Usher Be 718’s. Prior to that I was only running the sub for 5.1 home theater. Considering the fact that I already was crossing the loss pass signal to a phantom sub, I really wasn’t expecting image and sound stage to improve. The best way to describe the change is to say it was like setting the Usher’s free.
Stanwall, I am vey surprised to hear the subwoofer manufacturer recommends running the main speaker.
My understanding is there are tremendous benefits to be had by crossing over somewhere around or under 100Hz to a powered sub, even on quite good fairly 'full range' speaker.
Perhaps others can comment.
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
Well said Horacio. Being passive of course REL must advise running the main speakers full range. I'd withdraw my previous post if I could, it's not relevant here.