Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 412 - AVS Forum
Forum Jump: 
 245Likes
Reply
 
Thread Tools
post #12331 of 12334 Old Yesterday, 05:30 PM
Member
 
Ratamacue's Avatar
 
Join Date: Jun 2012
Location: MN
Posts: 69
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 10
Quote:
Originally Posted by AustinJerry View Post
As you can see, changing the window to 450ms presents an entirely different picture. On the left waterfall, there is quite a bit of ringing starting at 50Hz and below, with ~27Hz and ~45Hz showing the worst problems. The right has similar issues, with something happening in the 80-90Hz range as well. Is either 27Hz or 45Hz a primary mode in your room? Did you publish room dimensions?
Thanks again for the follow up.

Yes the two measurements have some significant differences and is where I'm a bit confused. In the attached figure, It shows my two measurement from the earlier post => one is at 80db and the other is approaching 90 (very close to clipping during the measurement and I had to adjust). The latter shows a lot going on from 20-50hz v.s. not much ringing in the other one.

So the louder you perform the sweeps at, the more you excite the room and thus more ringing? If so, then what determines a proper sweep volume since the first graph "looks" better then the last one. IOW, you stated to perform another measurement at 90db since the previous measurement was too low, what does one look for that shows too low of a level?

Yep the room dims are 11x24x7. Shooting down the long wall. Mains are 8ft from front wall, 44" in between - from inside edge. MLP is about 70" from center line of the 44". Toed in so as to converge about 1ft behind MLP. I have tried a lot positions and this is, so far, the best. This configuration is also in the spot least likely to excite room modes.

Quote:
Originally Posted by AustinJerry View Post
IIUC, your mains are set to Large, i.e. full range? Have you considered setting them to small, and allowing the subs to carry the full load below the crossover? This might alter the bass response characteristics of the listening room. Depending on your satisfaction level with the sound, there are all sorts of opportunities for trying different configurations and speaker placements. The value of REW is that you can immediately assess the effect of every change you make.
I can change the xover point (not necessarily to small or large) on the mains and sub, but so far have preferred to play the mains full range with the subs in a support role crossed at 50hz (subs are 2 PSA XS15's).

The bass/lower frequencies are very important to me, my preference for sure. I'm pretty pleased with how much (for the better) I have improved the room with the treatments I have in place. Sounding very good right now. However, I would like to, if need be, to make proper trapping tuned to what REW indicates the problems are. e.g. Helmholtz, tuned traps etc.. Whatever it takes!! At least to experiment with. Although I wouldn't want it to get too dead etc,,
Attached Thumbnails
Click image for larger version

Name:	L+R+Sub 80db vs 90db.jpg
Views:	15
Size:	123.5 KB
ID:	390426  
Ratamacue is offline  
Sponsored Links
Advertisement
 
post #12332 of 12334 Old Yesterday, 06:04 PM
AVS Special Member
 
LastButNotLeast's Avatar
 
Join Date: Feb 2007
Location: 08077
Posts: 4,777
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 265 Post(s)
Liked: 285
Quote:
Originally Posted by AustinJerry View Post
I add passengers to deaden the sound.
As long as they don't need to be dead passengers.

Downloadable FREE demo discs:
http://www.avsforum.com/t/1475769/de...ently-authored 

Did you really need to quote that entire post in your reply?
LastButNotLeast is offline  
post #12333 of 12334 Old Yesterday, 06:18 PM
AVS Special Member
 
AustinJerry's Avatar
 
Join Date: Jan 2003
Location: Austin, Texas
Posts: 7,845
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 984 Post(s)
Liked: 884
Quote:
Originally Posted by Ratamacue View Post
Thanks again for the follow up.

Yes the two measurements have some significant differences and is where I'm a bit confused. In the attached figure, It shows my two measurement from the earlier post => one is at 80db and the other is approaching 90 (very close to clipping during the measurement and I had to adjust). The latter shows a lot going on from 20-50hz v.s. not much ringing in the other one.

So the louder you perform the sweeps at, the more you excite the room and thus more ringing? If so, then what determines a proper sweep volume since the first graph "looks" better then the last one. IOW, you stated to perform another measurement at 90db since the previous measurement was too low, what does one look for that shows too low of a level?

Yep the room dims are 11x24x7. Shooting down the long wall. Mains are 8ft from front wall, 44" in between - from inside edge. MLP is about 70" from center line of the 44". Toed in so as to converge about 1ft behind MLP. I have tried a lot positions and this is, so far, the best. This configuration is also in the spot least likely to excite room modes.


I can change the xover point (not necessarily to small or large) on the mains and sub, but so far have preferred to play the mains full range with the subs in a support role crossed at 50hz (subs are 2 PSA XS15's).

The bass/lower frequencies are very important to me, my preference for sure. I'm pretty pleased with how much (for the better) I have improved the room with the treatments I have in place. Sounding very good right now. However, I would like to, if need be, to make proper trapping tuned to what REW indicates the problems are. e.g. Helmholtz, tuned traps etc.. Whatever it takes!! At least to experiment with. Although I wouldn't want it to get too dead etc,,
The difference in the two waterfalls is caused by the shorter 450ms window, not the level of the measurement. The guideline for levels is to have ~40dB above the room's noise floor. Did you measure the noise floor? Many of us are seeing a 50dB noise floor with USB mics.

The reason I ask about the speaker settings is once again to encourage you to experiment and measure. That's why we are in this thread--to throw our preconceived notions out the window and try different things. After all, you can always go back to what you had. Running capable tower speakers as full range is an emotional thing, I know.

Here are your room modes:



BTW, if I understand the speaker and MLP placement, you have approximately a 17.4 degrees angle with the MLP. Isn't this pretty close? If the speakers were 80" apart, you would have a 30 degree angle, which is closer to the "classic" angle recommended by many. Just curious.
AustinJerry is offline  
post #12334 of 12334 Old Yesterday, 09:42 PM
Member
 
Ratamacue's Avatar
 
Join Date: Jun 2012
Location: MN
Posts: 69
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 10
Quote:
Originally Posted by AustinJerry View Post
The difference in the two waterfalls is caused by the shorter 450ms window, not the level of the measurement. The guideline for levels is to have ~40dB above the room's noise floor. Did you measure the noise floor? Many of us are seeing a 50dB noise floor with USB mics.

No, I will go back and get the noise floor documented, sorry.

However, now I'm confused regarding your statement "The difference in the two waterfalls is caused by the shorter 450ms window, not the level of the measurement". In my 80db vs 90db waterfall pic, I went back and adjusted the 600ms (blue one at 80db) waterfall to 450ms and it doesn't show the ringing the 90db waterfall shows? Meaning the only difference between the two was the much higher level sweep (90db), which to me indicates the higher SPL sweep influenced what the waterfall is showing?


The reason I ask about the speaker settings is once again to encourage you to experiment and measure. That's why we are in this thread--to throw our preconceived notions out the window and try different things. After all, you can always go back to what you had. Running capable tower speakers as full range is an emotional thing, I know.

Here are your room modes:



BTW, if I understand the speaker and MLP placement, you have approximately a 17.4 degrees angle with the MLP. Isn't this pretty close? If the speakers were 80" apart, you would have a 30 degree angle, which is closer to the "classic" angle recommended by many. Just curious.
If I'm understanding your comment on the 17.4 angle at the MLP => it's based on 1/3 rule (24 / 3 = 8 and 11 / 3 = 44in) which is to get into the ballpark to avoid room modes etc.. Its close I suppose, but with only 11ft, there isn't a lot space width wise. By design, it leaves room behind and to the sides of the speaker. They aren't buried in the corner or next to a wall / boundaries. As you pointed out, there are many options for placement and I'll try some at the 30deg (closer to side walls) and see how things correlate.

Also, the subs in the current spot offer great integration so far (corner loading/reinforcement). I can't tell where they are. If I move them closer to the back of the mains (say 1ft behind), they seem to be in a null and don't produce much low end at all.

Attached is my layout, thanks again for your time.
Attached Thumbnails
Click image for larger version

Name:	room layout.png
Views:	8
Size:	569.8 KB
ID:	390673  
Ratamacue is offline  
Reply Audio Theory, Setup, and Chat

Tags
Dayton , Dayton Audio , Room Equilizer Wizard Rew

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off