Ditch the internal xover and use the sub....

Was helping my son with his system last night. He has a Sony HT receiver and uses the pre-outs to drive Parasound amps into a pair of Mackie studio monitors as mains. Also uses a Velodyne FSR-12 sub.

No matter how we diddled the settings, the sub was boomy and nasty. Finally, I ran the pre-out directly to the sub and sent the high-pass line out from the sub to the Parasound amp. Designated the Mackies as "large" so the LFE went there instead of to the now-unused sub out. HUGE improvement. Hard to believe the Sony internal Xover was that bad or that the Velodyne was that much better (I'm not a fan of either brand). Any thoughts?
Interested approach! I have wondered this as well. I am using a Velodyne HGS-18 (currently using the crossover on the Velodyne) and my preamp is the Proceed PAV/PDSD. My right and left speakers consist of B&W 801's.

I guess I have always run a 5 channel system, not 5.1 channel. I never liked how the sub integrated with the movie soundtrack, and came to the conclusion after trial and error, that it was not the sub (REL Q100E). Adjusting room accoustics was not an option.

The REL also has high-pass connections that run the sub off the signal from the speaker terminals. This is usually how you run the sub for 2 channel audio. I set the HT receiver to "no subwoofer" which sends the entire signal to the speakers so they run full range. I then set the sub in high-pass mode below the speakers so they just fill in the bottom the same as for 2 channel. In our family room this works much better. The bass was too localized for my taste when the sub did most of the work in 5.1 mode running through the subwoofer pre-out.

The lines between what one uses as a woofer and as a subwoofer are very blurred. Subwoofers are primarily designed to be used as "SUBwoofers" i.e. "below the normal range of a woofer". As such, you have to cross them over at a very low frequency and keep the upper and mid-bass out of them. Otherwise, you'll run into the two woofers ( mains and subs ) overlapping within a small frequency range and producing a noticeable hump in the response. This is especially true of a ported design, as the upper bass / lower midrange walks right our the vent from the rear of the cone. This can contribute to the "muddy" or "overpowering" effect that many folks tend to run into. Front loaded subwoofer designs will also tend to suffer from this, as you can hear the harmonic overtones coming from the woofers and this adds to your ability to "localize" the sound. Sean
A friend uses two subs. The first comes out of the sub output from his denon home theatre receiver (avr 3801); this is a McIntosh HT-2 passive sub (dual 12" woofers) powered by two channels of a Parasound hca 1206 (bridged for 350 watts). This provides the bass for home theatre duty.

The second sub is a fairly old Mirage PS180 (180watt, 12") and gets its signal from the speaker wires for the pair of Linn Tukan front stereo speakers. When listening to stereo only the McIntosh sub is not used; when listening to DVD material then both subs are used.

The results are quite spectacular; and that is when listening from the porch. The new neighbours are not impressed favourably.