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Looks pretty good, but if you still have the localization problem then you might be better off moving the sub. Did you try the rear corner (blue response in previous graph) again?

Also, I am surprised there was no difference between 60 and 80Hz. Maybe brucek can shed more light on this.

The dip at 167 Hz. can probably be fixed with room treatments.
 

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Discussion Starter #22
Thanks weverb. After a brief listen, the localization seems less, but not gone, at 60Hz crossover. I have not tried the rear corner again, but I do plan to.

brucek, any light to shed?

Would I use a 2" or 4" absorption panel or some other type of treatment to address the dip at 167Hz? How would I go about determining the position for the treatment?

FYI, I do currently have many of the room corners treated with superchunk bass traps.

Thanks!
 

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I think the sub + mains looks fairly good.

At 60Hz, I can't imagine localizing a sub.

To determine if the 167Hz mains dip is a result of cancellation between the two speakers or between one speaker and the room, try measuring each one separately. A small movement of one might make a lot of difference.

brucek
 

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Discussion Starter #25
I took a few more readings. Any help understanding them would be most appreciated!

As suggested earlier, the first graph shows readings of each speaker. Red is the sub and mains together, green is the left front speaker, and gold is the right front speaker. Does this offer any insight into the dip around 169Hz? :dontknow:

The next graph shows my sub and mains with my pre-pro crossed over at 60Hz. The red line shows the crossover setting on my sub set at about one-o'clock (scale ranges from 40Hz to 160Hz). The gold line shows the crossover setting on the sub at about eleven-o'clock. The red line looks a bit flatter, but I wonder whether dialing up the crossover setting on the sub is contributing to my localization issue. I'm really confused by how the crossover setting on my sub works with the crossover setting of my pre-pro... and how do I go about finding the best setting for each?? :scratch:

The next graph shows my mains without the sub. Green is pre-pro set to large with no sub, black is 60Hz pre-pro crossover, and blue is 80Hz crossover. Not posting this one for any reason in particular, though it does seem an odd looking graph to me? ...actually, I just realized something, this contradicts my earlier posting showing no difference between 60Hz and 80Hz crossover setting. Guess I must have screwed up something the first time. Why do my mains dip like that between 30Hz and 80Hz?

Finally, I posted my first attempt at an ETC reading. To be honest, I have no idea how to read it. :huh:
 

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As suggested earlier, the first graph shows readings of each speaker. Red is the sub and mains together, green is the left front speaker, and gold is the right front speaker. Does this offer any insight into the dip around 169Hz? :dontknow:
Ok, I am going to take a stab at answering this but hopefully Wayne or brucek will give us better information. It looks like both of your mains may be causing the dip. I think you can address this by trying to move them around. If not, I still think it can be handled by a treatment panel. By the way, that is a good looking graph even with the 167Hz dip!

The next graph shows my sub and mains with my pre-pro crossed over at 60Hz. The red line shows the crossover setting on my sub set at about one-o'clock (scale ranges from 40Hz to 160Hz). The gold line shows the crossover setting on the sub at about eleven-o'clock. The red line looks a bit flatter, but I wonder whether dialing up the crossover setting on the sub is contributing to my localization issue. I'm really confused by how the crossover setting on my sub works with the crossover setting of my pre-pro... and how do I go about finding the best setting for each?? :scratch:
I would put the sub xo back to the red line setting. I would think you would want to bypass the sub xo and only use the pre-pro crossover.

The next graph shows my mains without the sub. Green is pre-pro set to large with no sub, black is 60Hz pre-pro crossover, and blue is 80Hz crossover. Not posting this one for any reason in particular, though it does seem an odd looking graph to me? ...actually, I just realized something, this contradicts my earlier posting showing no difference between 60Hz and 80Hz crossover setting. Guess I must have screwed up something the first time. Why do my mains dip like that between 30Hz and 80Hz?
That's what we should see. I think this is correct. :scratchhead:

Finally, I posted my first attempt at an ETC reading. To be honest, I have no idea how to read it. :huh:
You want to zoom in and only look at the first 10-20 milliseconds, not out to 2 seconds. You want to find all the major peaks in that time span and figure out the distances. Combinations of that distance will help you narrow down what surfaces need more absorption put on them. Here is an example of mine:



That second peak right after the initial one is either my back wall (couch is against my back wall) or the couch its self. The peak that I measured out to be 6 feet tells me something within 6 feet of the mains or mic needs to be addressed. I believe it is the ceiling. Then you can see the much smaller peaks that will then need to be address. This graph also helps when you trial place a panel to be sure you have it located correctly.

How did I do brucek/Wayne? :sweat:
 

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elee532, you have to switch the ETC plot from DBFS to %FS as weverbs plot shows.

The peaks will show the extra distance the signal had to travel to reach the mic. So a back wall at 3 feet from the mic will show up at 6 feet in the ETC.

brucek
 

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So my comments were correct? :rubeyes:
 

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So my comments were correct? :rubeyes:
Seemed reasonable to me :)

The sub's own crossover should be set as high as it goes (or defeated if that is an option) so that the pre-pro is handling the crossover.

One thing the ETC highlights is fairly high distortion - those smaller peaks that happen before the main peak are distortion harmonics. Suggests your sub may be working fairly hard even though the measurement levels don't look especially high.
 

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Discussion Starter #30
The sub's own crossover should be set as high as it goes (or defeated if that is an option) so that the pre-pro is handling the crossover.
This is still confusing me. :dizzy: My pre-pro is set for 60Hz crossover. As the two measurements below show (red line shows the crossover setting on my sub set at about one-o'clock (120Hz?) - the dial on my sub ranges from 40Hz to 160Hz - and the gold line shows the crossover setting on the sub at about eleven-o'clock (80Hz?).)

This higher crossover setting on the sub shows a flatter response line. Doesn't this reflect that the sub is now producing output all the way up to 120Hz? Wouldn't this be contributing to my localization issue? If my pre-pro is set to 60hz crossover, shouldn't the sub only be getting signal at 60hz and below? :dizzy:

One thing the ETC highlights is fairly high distortion - those smaller peaks that happen before the main peak are distortion harmonics. Suggests your sub may be working fairly hard even though the measurement levels don't look especially high.
This is really vexing as well. The gain on my sub is at about 50%. Moreover, the bass extension frequency switch on the sub is set to 28Hz and Damping is set to Low. I would think these settings would reflect about the easiest load possible on the sub?

Thanks for any additional info!

 

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This is still confusing me. :dizzy: My pre-pro is set for 60Hz crossover. As the two measurements below show (red line shows the crossover setting on my sub set at about one-o'clock (120Hz?) - the dial on my sub ranges from 40Hz to 160Hz - and the gold line shows the crossover setting on the sub at about eleven-o'clock (80Hz?).)

This higher crossover setting on the sub shows a flatter response line. Doesn't this reflect that the sub is now producing output all the way up to 120Hz? Wouldn't this be contributing to my localization issue? If my pre-pro is set to 60hz crossover, shouldn't the sub only be getting signal at 60hz and below? :dizzy:
Crossovers provide a smooth transition, not a sharp cutoff. If you play with the target settings in REW you can see (in the target curve) what the crossover response looks like for various crossover frequencies for a subwoofer or non-full range speaker. For a 60Hz crossover the sub's output is down 6dB at 60Hz and down 25dB at 120Hz. By bringing the sub's own crossover into play as well you speed up the rolloff of the sub's output but create a dip in the transition between sub and mains.

The localisation issue may be a result of the distortion. The ETC shows significant harmonics from 2nd right up to 6th (so for a 50Hz input that means distortion products at 100, 150, 200, 250 and 300Hz), and these are at the output of the sub, they are not reduced by changing the crossover setting. It does seem odd, as high distortion would typically be seen in a sub being driven past its capabilities but from the extension you have your sub seems very capable - unless that extension is being achieved by boosting the sub's low end and that boosting is contributing to the distortion.
 

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Discussion Starter #32
OK, as if I'm not confused enough already... :gah:

It seems I am getting completely different results depending on the Start and End Frequency that I use for my sweep. The blue line is when I use 0 to 200Hz for my sweep. The purple line is when I use 0 to 15,000Hz for me sweep.

The results are obviously dramatically different up to about 20Hz. Any insight as to what's going on?

Thanks!
 

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That is very odd. You don't have a procesor that applies any sort of dynamic EQ or dynamic loudness do you?
 

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Discussion Starter #34
No dynamic EQ or loudness on my pre-pro (Emotiva LMC-1). When I take my readings, pre-pro reads "bypass mode, PCM48k." Sounds Effects are checked as disabled on the Enhancements tab for the playback devise in Windows. Here's another graph using various sweep settings.

Red = 0 to 200Hz
Gold - 0 to 500Hz
Green = 0 to 1,000hz
Aqua = - to 5,000Hz
Black = 0 to 15,000Hz

I have no idea what to make of this?? :gah:
 

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The difference in the various sweeps is how long the signal spends at the lowest frequencies. If the sub is very non-linear below 20Hz changing the time spent there would affect the level of distortion products. You may get a sense of that from watching the driver as the sweep progresses. You might get more consistent results by changing the sweep start frequency to 10Hz or higher.
 

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Discussion Starter #36
JohnM, thank for the reply! I understand what you are saying re: the length of time at each frequency during the sweep might differ depending on the sweep range. However, I'm kind of lost after that (i.e. non-linear sub?). I'm pretty much an amateur at this stuff.

FYI, I did try starting my sweep at 10Hz instead of 0, but the results were the same as above.

What does all of this say about my sub? Which results, if any, results are accurate?

Thanks!!
 

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It almost looks like your amp is switching through the different damping options. It looks similar to the last three graphs on this page:

http://www.rythmikaudio.com/eq.html

:huh:

Is there a way to check the incoming signal response to the sub to eliminate it as the cause? This might help narrow down where the problem is coming from. You know, test something like:

1. Signal coming out of the computer before the pre-pro.
2. Signal coming out of the pre-pro before the sub.
etc.

brucek has mentioned similar tests to others. If I remember I did something like it to test if my pre-pro's xo was working properly.
 

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Is there a way to check the incoming signal response to the sub to eliminate it as the cause?
Test the receivers response out the LFE port by using REW.

Just as you would test a loopback cable from line-out to line-in to get a flat response, simply include the receiver in that loop and take a measure. You have to fuss with the levels a bit when doing the Check Levels routine, but it's easy enough.

Connect soundcard line-out to receiver AUX-in, and receiver Sub-out to soundcard line-in, and measure.

Be sure the meter cal file is cleared and the soundcard cal file is loaded.

The response should be just like one of the REW targets, except it will roll off down low. Measure from 0Hz.

brucek
 

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Discussion Starter #39
brucek,

I'm think I am misunderstanding your instructions. When I follow what I think are the connection instructions you provided above, the output meter reads about -15 but the left/right input meters read nothing. Is the SPL meter supposed to be connected in the mix somewhere?

Thanks and sorry for my ignorance here!
 

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Is the SPL meter supposed to be connected in the mix somewhere?
No, you're measuring the electronic frequency response of your receiver by itself, just as if it was a loopback cable. No meters, no speakers - you're measuring the electronics.

Connect soundcard line-out right channel to receiver AUX-in right channel, and receiver Sub-out to soundcard line-in right channel. Run the Check Levels and Calibrate routine and Measure.

but the left/right input meters
You'll only be looking at the right channel input meter. The left channel is not used.

brucek
 
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