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Any thoughts on my first measurements. The first graph is sub only (custom built Rythmik set at 20Hz mid dampening), the second is sub+mains, and the third is a waterfall of the sub+mains. Any thoughts on how this looks?

One question that I have as an amateur... why is 10hz to 40Hz so much louder than 40Hz to 200Hz? Is this how it's supposed to be?
 

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Discussion Starter #3
Thanks for the reply Wayne. I do have some other placement options. I'm mostly trying to confirm that I am using REW correctly.

Is it true that I can put the sub in the primary seating position and then take readings at various spots in the room to see what it would like like if I placed the sub in that location? If so, does it matter which direction I point the sub when I put it in the primary listening position (I have a front-firing sub).

Also, my primary use is for music listenting, with home theater a close second. As a result, I suspect I would prefer to focus more on that 30hz to 80hz region?

Oh, one other question for now... when I originally created my soundcard calibration file, I was connected to my pre-pro via the soundcard's analog outs. I have since switched to the soundcard's SPDIF output. Do I need to create a new soundcard calibration?

Thanks!
 

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I have since switched to the soundcard's SPDIF output. Do I need to create a new soundcard calibration?
How do you propose to do that?

I suspect I would prefer to focus more on that 30hz to 80hz region?
Your bottom end is a bit heavy for music.

Is it true that I can put the sub in the primary seating position and then take readings at various spots in the room
Yes, read this.

does it matter which direction I point the sub when I put it in the primary listening position
Not really. Put it on the floor in front of the couch and point it at your system. Once you find a good spot with the RTA, move the sub there and fine tune the position.

brucek
 

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elee,

brucek pretty much covered it. I'll just add:

Also, my primary use is for music listenting, with home theater a close second. As a result, I suspect I would prefer to focus more on that 30hz to 80hz region?
Yup. Lots going on in that region with bass instruments, and your response there is pretty rough (as you can see).

Regards,
Wayne
 
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Discussion Starter #6
brucek, Wayne,

Thank you for the replies!

To the soundcard calibration question... I guess I hadn't quite thought it through all the way. I guess I MUST use the analog outs on the soundcard to do the calibration. :doh:

Any thoughts besides placement as the reason for the lesser performance in the mid-bass region? I've done a fairly thorough job of treating room corners with superchunk bass traps.

Thanks!
 

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Any thoughts besides placement as the reason for the lesser performance in the mid-bass region?
Nope. You'll probably have to consult with the knowledgeable folks at our DIY Subwoofer Forum for that.

I've done a fairly thorough job of treating room corners with superchunk bass traps.
Although traps can reduce the distance between the worst peaks and valleys, their main function is to reduce low frequency ringing. Your waterfall chart shows yours are doing that quite nicely. :T

Regards,
Wayne
 

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Make sure you have the crossover adjusted all the way up on the sub itself and adjusted accordingly on the receiver. Seeing your response on the low end try the 28hz mode as well.
 
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Discussion Starter #10
Thanks for the suggestion. The readings above do have the crossover turned all the way up. I'm hoping to make some adjustments this weekend and will try the 28Hz setting.
 
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Discussion Starter #11
Can someone confirm that I am using the RTA feature correctly to position my sub? Here's what I think...

Spectrum Tab
Mode: RTA 1/24 Octave
FFT Length: 65536
Averages: 2
Window: Rectangular
Y Axis: dB

Generator:
Pink Noise
Sub Cal
Set RMS Level to 75dB

Put sub in main listener location
Press play button on Generator
Press record button in Spectrum window
Move SPL meter around the room and look for flattest response
 

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Pretty close, but you will get much more stable readings in the low frequency end by using Pink PN (Periodic Noise) rather than Pink Noise, you can get good results with Pink PN even without any averaging. You can also use a shorter FFT length for faster updates of the RTA display, 32768 is a good compromise between update speed and frequency resolution.
 
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Discussion Starter #13
I posted a quick reading of my sub+mains with the sub moved from the front to the back of the room. This looking like some improvement?

Thanks.
 

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Discussion Starter #14
I finally found some time today to play around a bit more. I tried to get my seating as close as possible to 38% from the back wall.

The first graph below shows some readings in the locations that I have available... blue = back corner, brown = front left corner, green = front middle, and red = along side wall right next to seating (kind of like an end table). Unless I am misunderstanding, the side placement (red graph line) looks to be about the smoothest.

The next graph shows the sub gain turned down a bit and the sub tuned to 28Hz Low Dampening. This seemed about as flat as I could get. Any thoughts on how this looks? I can't seem to do anything about that drop between 90 and 100. Is this something that I should worry about?

Thanks!!
 

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The next graph shows the sub gain turned down a bit and the sub tuned to 28Hz Low Dampening. This seemed about as flat as I could get. Any thoughts on how this looks? I can't seem to do anything about that drop between 90 and 100. Is this something that I should worry about?
Looking good. I would do a plot with the mains on and see if the dip goes away. Also, with the side placement, just make sure the bass is not localized when listening to anything. Other than that, that is a good looking graph.
 
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Discussion Starter #16
Thanks for the feedback! Unfortunately, it seems you're one step ahead of me... the bass is definitely localized now. I haven't made any adjustments to phase/distance settings. Maybe this will help? If not, are there other options for dealing with localization?

Thanks!
 

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Thanks for the feedback! Unfortunately, it seems you're one step ahead of me... the bass is definitely localized now. I haven't made any adjustments to phase/distance settings. Maybe this will help? If not, are there other options for dealing with localization?
Usually localization can some what be addressed by crossover points, but usually it is mostly based on location of the sub. What xo setting are you using? Looks like 80Hz. Try something lower like 60Hz. and see if you notice a difference. Can your mains go down to 60Hz.? It may be a good idea to do a graph of just your mains. Try them at different xo points and see what they can do. Since your Rythmik is doing a good job going so low and if your mains can handle it, you can try a xo as low as 40Hz. possibly.

Also try the "blue" location. You may still get "localization" of the bass when the sub is in the rear, but try it any way.
 
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Discussion Starter #18
Thanks. I'll experiment different crossover frequencies and see what I come up with. Can you tell me... when getting a graph of my mains, do I test with both of them connected or just one of them?

Thanks.
 

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Thanks. I'll experiment different crossover frequencies and see what I come up with. Can you tell me... when getting a graph of my mains, do I test with both of them connected or just one of them?

Thanks.
For what you are looking for, you can do both at the same time.
 
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Discussion Starter #20
I took a few more readings today...

The first is a graph of my mains. The red line is with my pre-pro crossed over at 80Hz and the blue is crossed over at 60Hz. There doesn't appear to be a much difference. However, I am surprised at how all over the place this reading is. Is this normal? (BTW, these are Salk SongTowers)

The next one is my sub + mains with my pre-pro crossed over at 60Hz. Looks like the dip around 100Hz from my earlier readings is pretty much gone. However, still a major dip around 167Hz.

Any advice?
 

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