Top notch speakers with their own sub

Equalizing peaks and nulls becomes more practical with a distributed multisub system. Before equalization the peaks are less peaky, the nulls are less nully, and there is less spatial variation (meaning that the response doesn't change as much from one location within the room to another). That being said, I'd still be hesitant about putting a lot of boost into a null unless you had plenty of headroom available - which apparently was the case in Marty's situation.

Hey Duke (or anyone else who cares to comment) - Is a flat response always necessarily an ideal target? I can understand addressing major dropouts at the sweet spot, certainly. When we go attend a concert the folks on the mixing board aren't getting a flat response from the room, are they? So if we're just talking about bringing the intent of the sound engineer / producer's work into our listening room with the least coloration/distortion, I expect that would lean towards the flat response, but could that also, for any reason, tend to sound any more or less engaging than a response that is more typical of most rooms (ie peaky)? Just curious what your take on that might be. Certainly if the Planetarium system speaks to this end it is a very convincing voice for that approach. I just wondered if that was the ultimate goal, or is that only a shade of something broader in what you are trying to achieve? What occurred to me as extraordinary about what you've achieved, at least in the room I heard, was a very natural and seamless integration of the low-end that did not call attention to itself as such, it was simply there at one end of the spectrum, yet was unmistakable as such. What I've objected to in some other approaches is that you become very aware of the low end to where it becomes distracting. I don't know whether this is due to overemphasis, room nodes, or some other imbalance. So is a flat response always the goal? Or?

Discussion on sub equalization and placement going on today is precisely the reason I hesitate straying from the mainstream speaker establishment. Now I have more plausible theory as to why major speaker manufacturers don't want to package non-integrated subs with their main speakers for music listening just yet. The technology is not sufficiently developed. Secondly, the idea of having 4 sub is quite intrusive, one way to get into major fight with your wife. Oh well, back to square one for me! But then the Prelude MTS is not bad at all really.

Jax2, in my opinion fairly flat in-room response is the goal in the bass region, and above the bass region, I prefer a gently downward-sloping curve. If I have to choose between too much and too little bass energy, I'll choose too little because that's less likely to be distracting.

Which brings up something else that most rooms do at low frequencies: Boundary reinforcement, sometimes called "room gain". Breifly, as we go down in frequency and the wavelengths become progressively longer relative to the distance to room boundaries, the first reflections become more in-phase rather than random-phase, so the net result is a roughly 3 dB per octave rise in bass energy as we go down below 100 Hz. This of course varies from room to room and with speaker positioning within a room, but since subs are usually placed close to the intersection of at least two room boundaries (on the floor and up against a wall) it's worth taking into account.

Without going off on a long semi-technical tangent, I'll just say that in my opinion a worthy "target curve" for a subwoofer system would be the approximate inverse of this 3-dB-per-octave typical room gain. If the subs are "flat" all by themselves, by the time room gain is factored in they will be bass-heavy. But if we have to err, imho best to err on the side of too much bass rolloff rather than not enough, so I'd rather have 6 dB per octave of rolloff (before room gain) below 100 Hz instead of none at all.

Duke

Jax,

Killing the nodes bewteen 50hz and 150hz makes a HUGE difference IME. Getting flat in-room response in this range is really worth some effort and -IME- it will take some effort. I use bassbusters for the octave above 80hz - which works very well - and active PEQ below. In addition to much improved impact, weight, and "punch", the midrange sounds cleaner. Really flat response in this region also allows a more seamless integration of mains and subs - if you're crossing this high. My rule of thumb, cross where it's flat. The bass will seem to be a natural part of a seamless whole - it won't "stick out" at all. At least, not to me.

Below app 50hz, the whole excersize becomes a lot more subjective - IMHO. Again, weight is impacted as is, to my surprise, soundstaging. I'd heard people make this claim before, but I was doubtful - it wasn't intuitive. As it turns out, getting it right down low allows deep bass notes to "bloom" and expand in a way that feels natural and seems to define a larger space. To my ear, there's a decently broad band around truly "flat" response that achieves this result. I chose to extend flat in-room response to 25hz because it measured well and sounded great. Other folk's MMV.

Marty

BTW I currently use a pair of 12" Rythmik subs which require much less EQ than the 8" Velodynes.