Am I on the right track here?

Recently I decided it was time add a sub to my system. Fortunately I stumbled on REW at about the same time. I ordered a Hsu VTF-3 MK2, and while I was waiting for it to arrive I took the time to learn REW. Once I figured it out it works wonderfully on my notebook with my M-Audio Firewire Audiophile. I measured the Mains, then cringed at the graph for a while, but such is life. I did learn that where I have my main speakers located the frequency response dropped off rapidly below 80hz, so a sub=good idea. I also took my computer sub (Klipsch SWS) and tried it in various places to find some possible locations for the VTF3.

Now I will take a minute to explain my room here… It is very large. 5000+ cubic feet thanks to the lovely open floor plan of the house. It is (relative to the location of system) 16’ long, 26 wide, and with the ceiling starting at 12’ at the front and sloping down to 8’ in the back. This is open to the kitchen area, and the front entrance.

When the new sub arrived, I decided to try it in a back corner first. Way too easily localized. 80hz is the lowest crossover setting I get on my Panny xr 55. It’s great otherwise but it has a severe lack of bass management. For me to not be able to localize the sub, it has to be directly behind me, which works quite well practically.

It sounded great with the exception that to even be able to perceive any lower bass, below 40hz, I have to set the volume much higher than balanced. The graphs from REW (which I don’t have otherwise I’d post… I guess ‘Ill have to make some more and save these) show that it get a fairly jumpy but at least in the same general area as the target response down to a huge peak at around 50hz. After this however it drops about 10 to 12 db and stays very flat down to about 15hz or so. The graph resembles a staircase.

I’m wondering what the best solution to this would be. 2 parametric filters would bring the mid bass down to level of the rest, and I could turn up the subs volume. I would just buy a BFD, but thankfully I discovered before I did that my receiver doesn’t have a distance setting for the sub, so I can’t compensate for its delay. I’m looking at the Rane PE 17 since its all analog with no delay. Its expensive, but I’m certainly not getting my moneys worth out of the sub as it is.

That’s my current plan. Anything I’m missing or overlooking here?
Again, I’m very impressed with REW, as it has made most of this possible or at least much easier.

[brucek]

Anything I’m missing or overlooking here?

I can't imagine that you would perceive the one foot delay that the BFD introduces.

The RANE is a nice unit though with good specs and a range down to 10Hz. The analog dials will make it a bit more of an iterative setup with REW, but no big deal.

It would be useful to see some graphs, but you may as well wait until you get the parametric.

brucek

I'll agree the Rane PE17 is a good unit, its alot cleaner than my PE15. I beleive it was a 2v per se since the PE15 was kinda noisy. All though I could get it upgraded.

Good luck.

T

I can't imagine that you would perceive the one foot delay that the BFD introduces.

Hmmmm, I guess thats where I'm not really sure what to expect. I have no experience with delays. The sub is 2 feet away from the listening position while the mains are 10 feet away. If I could get away with a digital unit that would be nice, especially something like the ULTRACURVE PRO DEQ2496. While it'd be overkill for just the sub I could find some other uses for it (secondary system where I'm much less picky about the signal). And its optical connection is interesting... though I doubt I'd want it in the main signal chain, but then I haven't tried it.

[JohnM]

sarvus wrote:

The sub is 2 feet away from the listening position while the mains are 10 feet away.

In that case adding some delay to the sub path would help with time alignment, though the very small delay through the BFD (or similar units) is pretty much inconsequential. At such low frequencies the ear can't pick up on arrival time cues, the effect of delay compensation in the sub path is on response through the crossover region as in effect it shifts the sub's phase. The sub's phase controls, if offered, provide the same ability to adjust relative phase to the mains through the crossover region.

Thanks to all for the advice.

I've got a DEQ2496 on the way. When I get it set up I'll make some graphs.