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Discussion Starter · #1 ·
I picked up an SPL meter from Aperion. I calibrated all my speakers first with the AVR test tones to level match them. I bumped the subs up a few db from the others. Then I decided to graph a room response from my primary listening position. Here is what I came up with. I know I know, get REW!! I dont have a laptop, and Ill be damned if I have to take my huge tower downstairs. This is all assuming I did everything right. The subs are Xover @ 80hz. What is with that huge spike of 20db from 45-50hz? My room is a dedicated room, and is treated. Is there much I can do about the spike if moving the subs is not an option?


EDIT: Here is an updated graph using the corrections. Also I must have measured something wrong the first time from 45-50Hz, but there is still a big drop off within 10Hz(36-25).
 

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Are these raw measurements (uncorrected)? Where'd you get your tones? How did you play them back, exactly? What setting did you use in the AVR? Is that both front speakers and the sub? What speakers and what sub? Is your sub's low-pass turned up as high as possible (or bypassed, if you have that option)?
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by sivadselim /forum/post/18155720


Are these raw measurements (uncorrected)? Where'd you get your tones? How did you play them back, exactly? What setting did you use in the AVR? Is that both front speakers and the sub? What speakers and what sub? Is your sub's low-pass turned up as high as possible (or bypassed, if you have that option)?

Here ya go.


1. Raw I haven't looked into corrected measurements for this meter, if there are any. (could the corrected measurements make up 20db?)

2. Real Traps Test Tone CD

3. I played them back using my ps3 one at a time.

4,5. Set to stereo mode with the fronts unplugged. So just the sub.

6. 2 MFW-15's

7. You lost me. I only have one cable going into the LFE on each sub. Not hooked up with the stereo(red/white) connections. If that helps.


Also, SPL meter is set to C-weighted, and SLOW.
 

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Did you put the meter on a tripod at the listening position on the couch, and stand back to do the readings? Are you changing the scale/range on the meter when the SPL is higher/lower?


And are you sure you added the correct values in to compensate for the meter, because it looks like you're getting very little output from your dual MFWs under 30Hz.


It's very possible that the location you have your subs in is sucking out the bass below 30Hz to basically nothing.
 

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It's not bad except for the roll-off under 40Hz...
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by cyberbri /forum/post/18156647


Did you put the meter on a tripod at the listening position on the couch, and stand back to do the readings? Are you changing the scale/range on the meter when the SPL is higher/lower?


And are you sure you added the correct values in to compensate for the meter, because it looks like you're getting very little output from your dual MFWs under 30Hz.


It's very possible that the location you have your subs in is sucking out the bass below 30Hz to basically nothing.


I did have it on a tripod at one point. But then placed it on the back of the couch so the mic end was a few inches off the couch. The meter didn't change from me moving around it. Yes Im changing the range as per the instructions.


Lilgator: This was post audyssey. But I may run it again and check the levels just to be safe.


Eric-t: Thats the problem with having a dedicated space setup like a movie theater. I don't have room anywhere else to put the subs except up front.


cyberbri: But thats where a lot of the good rumbling bass is
.
 

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Quote:
Originally Posted by skid_68 /forum/post/18156873


I did have it on a tripod at one point. But then placed it on the back of the couch so the mic end was a few inches off the couch. The meter didn't change from me moving around it. Yes Im changing the range as per the instructions.


Lilgator: This was post audyssey. But I may run it again and check the levels just to be safe.

Eric-t: Thats the problem with having a dedicated space setup like a movie theater. I don't have room anywhere else to put the subs except up front.

cyberbri: But thats where a lot of the good rumbling bass is
.

Do you have a pic of the room? Also when using an SPL meter it needs to be pointed at a 45 degree angle toward the ceiling and not pointed directly at the front speakers.
 

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Quote:
Originally Posted by skid_68 /forum/post/18156873


cyberbri: But thats where a lot of the good rumbling bass is
.

That's the problem, huh! Audyssey does pretty good up top keeping things flat, but you have no deep bass. Try turning off Audyssey and re-measure to see what happens.


If you can't move the sub, can you move the couch forward/backward say 1 foot?


If it's the room that's sucking out the low bass, you could get a $3K subwoofer and put it there and you'd have the same low bass problem as you do now. You have to move the sub and/or seating to get that bass back.
 

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Quote:
Originally Posted by eric-t /forum/post/18156905


Do you have a pic of the room? Also when using an SPL meter it needs to be pointed at a 45 degree angle toward the ceiling and not pointed directly at the front speakers.

That doesn't matter much if you're only measuring the sub/bass.
 

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Quote:
Originally Posted by tesseract67 /forum/post/18156897


Most SPL meters and microphones are inaccurate at frequency extremes. Holding the meter by hand will give poor results.

http://www.avsforum.com/avs-vb/showthread.php?t=505236

But they are usually inaccurate in consistent ways from meter to meter, so by adding specific compensation values you can arrive at something quite close to the actual SPL. cmryan already posted a link to find those compensation values for his meter, and he already factored those in.


I agree that holding by hand isn't good for taking multiple readings over time.
 

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Quote:
Originally Posted by skid_68 /forum/post/18155566


I picked up an SPL meter from Aperion. I calibrated all my speakers first with the AVR test tones to level match them. I bumped the subs up a few db from the others. Then I decided to graph a room response from my primary listening position. Here is what I came up with. I know I know, get REW!! I dont have a laptop, and Ill be damned if I have to take my huge tower downstairs. This is all assuming I did everything right. The subs are Xover @ 80hz. What is with that huge spike of 20db from 45-50hz? My room is a dedicated room, and is treated. Is there much I can do about the spike if moving the subs is not an option?


EDIT: Here is an updated graph using the corrections. Also I must have measured something wrong the first time from 45-50Hz, but there is still a big drop off within 10Hz(36-25).

If you really want to get upset-play a tone and then move your meter around the room and see what you get. Note where the highest and lowest points were.


Now play a different tone and move it around some more.


Don't forget to move it up and down a bit also.


Don't get mad and throw your meter against the wall
-welcome to the world of measurement.
 

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Quote:
Originally Posted by Ivan Beaver /forum/post/18157084


elcome to the world of measurement.

Err, welcome to the world of acoustics.
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by jpmst3 /forum/post/18157614


Are you using any EQ?


You might be able to tame the peak out enough that everything else is flatter overall.

Just Audyssey. Ive seen lots of people say they didn't like how audyssey setup their subs, and would run it without the sub hooked up. Maybe Ill try that.
 
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