Ok, I understand that a powered sub can have both line and power inputs, but my question was about using the B power output of the amp to feed an unpowered sub
It is that boom from the Elac's or any other speaker for that matter that causes the problem with integration, and hence the need for a high pass filter. The lower end of its frequency band is most times an issue of builders trying to eek out low end extension. This in turn leads to several issues, but what is heard is an unnatural bass hump where the sub and speaker are replicating the same frequencies at different amplitudes. In two way designs this chase for low end extension also also impacts the clarity and volume of midrange frequencies(compression). By cutting off the lowest frequencies the midrange driver is freed up producing a better sound. One of the best sounding systems I have heard recently was centered around some 801's crossed at 80hz. You wouldn't think a speaker that big would realize a benefit, but it sure did.
I would like to hear more about your experience. I did notice you use REL; how is that employed? Where are you crossing? Being a D’Appolito might also come into play.
Perhaps still on topic... I have multiple systems throughout my home, with all of them being supported by at least one subwoofer. Choosing but one of them to focus on the most recent of this thread's posts... In my family room I have a Pioneer AVR. I use its stereo Zone output as the source for another system in my living room (56' of 12AWG speaker cable away.) Only a pair of speakers (Totem Sttaf) and a subwoofer (Velodyne Chrysalis Photon-10) sit in the living room (very high WAF!) Because neither the AVR's Zone outputs (stereo L/R RCA), nor the subwoofer, can do proper bass management (ie. have a HPF), I use an external crossover (Rolls SX45) for that task. So the signal flow is: Pioneer AVR Zone stereo RCA out > Rolls SX45 (HIGH OUT) > (above ~75 Hz) NAD 2155 power amp > Totem Sttaf (MONO LOW OUT) > (below ~75 Hz) Velo subwoofer On their own, the Totem Sttaf are a surprisingly capable pair of speakers - even in the bass region - however whenever they are pushed to moderate levels and beyond, they begin to get seriously overloaded by the bass, compressed, and the midrange goes to crap. They are the perfect speaker to illustrate the need for proper bass management! They can't be left to their own devices (ie. let them roll off "naturally" in the deep bass). Take away their low frequency duties and there is a tremendous improvement in how the system sounds. Plus there's at least a full octave of solid bass added to the bottom end of the system - for music that demands it. Jeff
In my experience a properly integrated sub always enhances the midrange of good speakers running full range. My speakers run full range, the Rel is dialed in (using high level, speaker connection from the amp) where it sounds best. One click up or down on the crossover, one click up or down on the gain (both on the Rel) and the magic is gone/back. Taking away the low freqs of my speakers (using the 'classic way' of hooking up a sub, via a subout) sounded like krap and took away all that magic. If your speakers can't handle big volume and sound muddy or whatever in low bass, I understand you would want to use that method, but mine sound perfect allright with big volume.
Pretty sure you'd need a separate amp to push the passive Sub, but dont quote me. This is why I mentioned the powered Sub and my B speakers output.
You wouldn't believe how many non-audiophile/hometheater guys (whose 'feature rich by default' rigs i've audited) have better sound with little effort than the audiophiles with their feature starved high dollar gear.
I won't/can't say too much, but it is now a widely understood issue. The "how" while saving face is part of a delicate melding of several issues outside of the obvious. But yes, you are correct in that the low feature offerings, as it is right now, aren't providing the optimal experience that other lesser gear does. It will get there. I don't just belive you, I have seen it with my own ears. It doesn't just impact the electronics end, it's the speakers that is the hurdle. "Hey, ...uhhh... everything we have been telling and selling you is wrong. Oops."
IF-and it's a big IF with smaller speakers-you can crank them up to them moon and they don't distort, then you don't need a highpass filter. If as is more usual, the speakers distort due to the woofers moving like crazy, then you MUST have a highpass filter.* Which most 2-channel units stupidly do not have, even ones with a "subwoofer" output. - Sorry, you just have to really check the manual. If it does not mention anything about highpass or filter, there isn't one, too bad so sad "Thank u NEXT") - Nor do they have room correction, which is almost a must to more easily integrate a subwoofer and definitely to achieve flatter bass.** Some subwoofers have limited correction functions. - Hence even for stereo you may well be better off with an AVR. Don't assume stereo units automatically sound better because they are somehow more "pure" or whatever, it's not that simple. As for Well, an inexpensive one like Monoprice I bought my brother, or Dayton or Klipsch or Polk will be definitely be better up to medium loud volume levels, so long as you get a big cone (i.e. 12"+). Some cheap plastic bandpass piece of turd with an 8" driver, NO. *Adding a sub will add more bass but won't reduce the mains' distortion. **see the curves at, for instance Audyssey MultEQ-X Room EQ Software Review Test Bench JL Audio Fathom f110v2 powered subwoofer Measurements
