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Try to EQ Sub plus L/R powered mains?

4108 Views 29 Replies 5 Participants Last post by  weverb
Funny, I've read a bunch over here but I guess this is my first post.

I've played with REW and BFD for a while, and am not having much success getting my room EQ to settle down. I think I know why, but don't know how to attack the problem. I did a few searches here and found that it's not a good idea to try to EQ differing subs. Also multiple subs in general are hard in weird-shaped room. I have all three.

I have the "powered bass stands" (PBS, discontinued from AV123), with their ELT-1 bookshelf speakers (also discontinued.) The PBS are essentially 8" sealed, powered subs, in tall boxes that double as stands for the L/R speakers. I knew I had a poor room response (very heavy around 40 Hz) from previous sweeps I'd done with REW. Never tried to EQ it, because the subs would need separate EQ, and right now they get a speaker-level signal. [The PBS get a full-range signal from the receiver--set as "large"--and I use the PBS' crossovers to send the upper range to the ELT-1's. There is an option to send the PBS a separate line-level signal, and there is a line-level out for daisy-chaining.]

I can supply a link to AV123's Retired Products archive with the PBS, if you need...not sure I can do that with 0 posts.

Anyway, this week, I added a sub from the Outlaw sale (LFM-1 Compact). This sub gets me the low end (mid-20's) which was missing with the PBS. I like hearing these, especially when playing low-volume jazz--I can hear the bass line now :) BUT I hear definite resonances in the room at a number of frequencies. REW has confirmed this.

I've been trying various phase and level settings on all three "subs" (counting the PBS as subs), trying to tame the response, but this is just a confusing mess. I worked out some filters on the BFD and got nowhere near the predicted response, even with the PBS turned off.

So...I need to attack this problem in pieces, I think, and maybe just give up on the PBS(?) I would appreciate your comments on these ideas & questions. I need to step back and develop a plan...

1) Don't try to EQ everything at once (sub plus main/PBS). For now, maybe disconnect the PBS and use just the Outlaw by itself or with the L/R ELT-1 bookshelves. Set the receiver crossover to 80Hz.

-- Should I turn off the L/R speakers for this test, too?
-- Should I use the sub cal signal or the speaker cal signal?

2) If I keep the PBS in the test with the mains, maybe set the fronts to "small" to prevent the PBS from contributing much? This might be like not using the PBS at all.

3) Give up on the PBS/ELT-1 combo and go buy non-powered, near-full-range speakers for L/R. I feel like I need a near-full-range because this is used for 2-ch music as well as HT, and the bookshelves plus sub are a bit lacking in the midrange for 2ch.

I don't know. I'm a bit at a loss here. Not even sure I've outlined the problem clearly. :help:

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You might want to consult your manual or do some further testing. We’ve had people here who had this problem and eventually discovered that their receiver’s bass management only worked for digital sources and signals.
That would be me! :hissyfit:

Dave - have you tried your sub in the opposite corner up by the right speaker? Also, do you have enough slake in the wire to the right main to try moving it closer to the listening position? Maybe you can measure and find the better location, and when not in use, move it back against the wall like in your layout.
I've not tried the sub in the right front corner. When I originally selected the left rear corner, I had placed the sub on the couch, and then used my meter to check levels at several possible sub locations. The right front corner was very low level--pretty much like no corner at all.
You should try getting a REW graph in that location just for a comparison.

The room is hard to work with. The right front speaker really can't come closer into the room. Yes, there's slack in the wire, but pulling it forward puts it into the main walking path from the kitchen area to the stairs going up. The kids are bound to hit it.
I meant to just place the speaker there during listening times and move it back against the wall when not in use.
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