REL Quake or ACI Force for semi small room

"That said when setting the sub up you would need to set the crossover slightly higher than the lower notes on the main speakers"

That has not been my experience at all. I have always had to set about 5 Hz lower than the stated -3dB point of my speakers.

Raul ... 2 subs MAY load a room better than one, but they also cost twice as much. Given a budget of $1000 I'd rather pick one $1000 sub than two $500 subs.

As for crossover ALWAYS being at 80Hz that would only apply if you are filtering the signal to the main speakers. If you are running the main speakers full range then the sub crossover frequency will depend on the specification of the main speaker. No one frequency will work.

yes, the guys at ACI recommend using a 60 or 80hz passive high pass filter on the mains. this just plugs inline to the interconnects b/t the pre-amp and amp.

i am curious if anyone has done this?

it certainly makes sense to not drive the speakers as hard in the lower realms.

at the same time, the thought of putting a cheap capacitor into my system seems like an added complication. because i have an intergrated, i'd have an interconnect leaving the pre-amp outputs, looping out, through the crossover, and right back into the amp input = weird.

my local dealer says that the high pass addition is silly, that the speakers roll off naturally where they should. the sub should just augment this natural roll off.

hum?

Dear Sean: It is not only that two subs may load a room better than one, it is that two are necesary for the stereo effect remember that the music is not only " fundamental frecuencies " but harmonics too.

Btw, I'm not saying that the crossover be ALWAYS at 80Hz but this is a good point to start when you are filtering the signal to the main speakers. I agree with you that no one frecuency will work.

+++++ " That has not been my experience at all. I have always had to set about 5 Hz lower than the stated -3dB point of my speakers. " +++++

I respect your point of view but I'm not agree with it on this regards: we have to remember that we use subwoofers not only for a better quality/quantity low bass but for a better mid bass/mid range performance.

Regards and enjoy the music.
Raul.

Dear Mattehw: With all respect your dealer dos not know nothing about, sorry.

+++++ " it certainly makes sense to not drive the speakers as hard in the lower realms..." +++++

Certainly is. Please read carefully the link that I already give you ( the one that I post in this thread ). Read from SUDDENLY and below. It will be interesting for you.

Regards and enjoy the music.
Raul.

Raul
Rel subs do not filter main speaker outputs.They are not like other subs and you cant think of them as such.When you set them at say 35 this not a typical crossover. The rel will rolloff below AND ABOVE this point.The proper setting depends upon the slope of the rolloff of both the speakers and the sub.For example: I dont recall exactly but I think the slope of rels rolloff(up) is 6db per octave which means a sub set at 20 will be -6db at @40hz (the octave is 20-40 at this frequency).This would integrate perfectly with speakers that were flat at 40 and -6db @20hz assuming the output is set properly.This is why rels are typically "crossed over"at such low frequencies. Obviously perfect integration is difficult to obtain but approaching it requires knowledge of the slopes of both speaker and sub frequency rolloffs(up). You could just "trust your ears" but this assumes you are used to flat response and not the more common midbase bump most are.
Jim