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Discussion Starter #1 (Edited)
I have some basic experience with sound (home, car, pro) but am a noobie to REW and BFD.
My listening room is 9' x 15' x 8'H. Carpeted floor, window with drapes on one side, and a couch so it's really a fairly "dead" room, although small. I have an L shaped computer desk in one corner of the room, facing one of the "long" walls. This puts my "mains" (Wharfedale 8.1s) in a nearfiled position, rear of them is about a foot in from the wall, spread 4 feet between them, three feet from my head. No need to discuss the sub yet (the plot is with the sub turned off). This computer desk is pretty big so the speaker closest to the corner is about four feet from the side wall. I set my rig up putting my analog RS meter on a mic boom stand, placed near the sweet spot where my head would be. RS cal file loaded, and sound card calibration file loaded.

Studying my graph, the bad peak at 134 Hz and the response at low frequencies is the nature of the speakers, but the null at 80 Hz and the very non linear response at higher frequencies appears to be interaction of the room? Is it normal to have 12db worth of difference just due to constructive and destructive interaction of sound waves? While playing a sine wave, I can move around the room and hear areas with high levels, and other areas of nearly complete cancellation. Some of these areas are towards the center of the room. I was aware this happened with low bass, but this seems to be going on at higher frequencies as well.

I'm inclined to fix the 134 Hz peak, boost up the response from say, 80 hz to 110, another filter to roll off below 80 Hz, then work on integrating the sub from there.

You probably wouldn't know if from the graph, but overall these speakers sound nice (especially with a sub). I can hear the 134 Hz peak in music with a wandering bassline, though.
 

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Doesn't sound like you have a lot of wiggle room, but moving speakers (even a bit) sometimes makes a large difference.

Try one main at a time and see if it's a speaker versus room or a speaker versus speaker problem.

Because, as you admit, it isn't a very nice response.

brucek
 

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Studying my graph, the bad peak at 134 Hz and the response at low frequencies is the nature of the speakers, but the null at 80 Hz and the very non linear response at higher frequencies appears to be interaction of the room?
And the desk the speakers are sitting on... There is no null at 80 Hz. Nulls are narrow and deep, yours is very broad (more on this below).

Is it normal to have 12db worth of difference just due to constructive and destructive interaction of sound waves?
Did you look at any of those graphs I posted?

While playing a sine wave, I can move around the room and hear areas with high levels, and other areas of nearly complete cancellation. Some of these areas are towards the center of the room. I was aware this happened with low bass, but this seems to be going on at higher frequencies as well.
The only thing you need to worry about is the listening position.

I'm inclined to fix the 134 Hz peak, boost up the response from say, 80 hz to 110,
Probably shouldn’t boost anything below the peak – the steep roll out indicates that that’s the point where your speakers are “done.” I.e., that’s as low as they’re going to go in this room.

Regards,
Wayne
 

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Thanks for posting those graphs of others' rooms, Wayne. Gives me a bit of perspective.

Bruce, I ran two more trials, one with the right speaker only (green) and one with both (red). Looks like at least part of the problem, but not all, is speaker vs. speaker.

My computer desk is steel with a glass top. I'm wondering if it would help to put some type of sound absorbing mat in front of the speakers, on the desk. Treatments on the walls would help, but probably wouldn't pass the wife. Otherwise if it's speaker vs. speaker, i'm not sure what else to do other than slight relocation as suggested.

I'll do some playing with BFD, get the mains the best I can then add the sub. The sub is a Rythmik 15 and has a single band PEQ. The BFD will be running only the mains for now.

Wayne, normally I would agree not to try to boost but in this case due to my gain structure, I have quite a bit of headroom on the BFD, I'd like to try to get stong response from the mains down to 80 hz then let it drop down from there where the sub takes over. These Wharfedales are great sounding speakers but not much on bass. If you force them to play it with eq, they will play it quite cleanly (within reasonable limits) but their natural response is just weak down low. I wonder where the port is tuned? I've been considering a set of nice nearfield monitors with 8" woofers, like the JBLs or Mackies.

thanks,
-Scot
 

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My computer desk is steel with a glass top. I'm wondering if it would help to put some type of sound absorbing mat in front of the speakers, on the desk.
If the mat helps, it’ll only be for above 1 kHz or so. Below that point, the issue is the room and boundaries.

Looks like at least part of the problem, but not all, is speaker vs. speaker.
If the two speakers are showing differing response, the most likely culprit is asymmetrical placement – i.e, whatever is behind / beside / in front of etc. one speaker is different for the other.

The BFD will be running only the mains for now.
Okay for testing, but for a permanent fixture I’d recommend using something better.

Wayne, normally I would agree not to try to boost but in this case due to my gain structure, I have quite a bit of headroom on the BFD, I'd like to try to get stong response from the mains down to 80 hz then let it drop down from there where the sub takes over. These Wharfedales are great sounding speakers but not much on bass. If you force them to play it with eq, they will play it quite cleanly (within reasonable limits) but their natural response is just weak down low.
The issue isn’t the BFD’s headroom – it has plenty. The issue is the speakers. You can’t get crazy bass-boosting with 5 1/4” woofers. They just won’t take it. So be careful...

I wonder where the port is tuned?
You should be able to get some idea with REW. Just stick the mic dead in front of the port and take a reading. I would expect a “haystack” type reading.

Regards,
Wayne
 
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