Author Topic: Help Fine Tuning The Room  (Read 13444 times)

Offline shadowlight

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Help Fine Tuning The Room
« on: August 02, 2011, 08:08:12 AM »
Hello Everyone,

The basement is finished and I had some folks over the weekend who help get it back together.  Need some more help in fine tuning the sound.  The room is 29' 9" (L) x 12' 6" (W) x 6' 11 or 7' (H).  The speakers are about 83" from the front wall and the seating position is around 135" from the back wall.  I ran some REW sweeps yesterday with the SPL meter set aroun 70db.  The "T" that you see in the picture is where the Cardas placement is suppose to be.

The blue line is for left speaker, the purple line is for right speaker and the red one is combined.  Not exactly sure how I can go about getting the right speaker to be bit more inline with the left.  The REW sweep is 1/6 octave smoothing applied.

I can potentially move the speakers forward another 4" or so, just in line with the hump in the 4th picture.  I am planning to add acoustically transparent projector screen right in front of the speakers once everything is in place speaker placement wise.

Thanks
« Last Edit: August 02, 2011, 08:20:46 AM by shadowlight »

djdube525

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Re: Help Fine Tuning The Room
« Reply #1 on: August 02, 2011, 09:08:41 AM »
Wow... the basement has really been transformed since the time I was there!

Nice job!  :thumb:

Offline shadowlight

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Re: Help Fine Tuning The Room
« Reply #2 on: August 02, 2011, 09:19:51 AM »
Wow... the basement has really been transformed since the time I was there!

Nice job!  :thumb:

Thanks Dave.  Are you going to join us in October?

Offline richidoo

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Re: Help Fine Tuning The Room
« Reply #3 on: August 02, 2011, 10:21:47 AM »
Deepak, the room likes nice!

Can you show the scans without any smoothing?

Offline shadowlight

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Re: Help Fine Tuning The Room
« Reply #4 on: August 02, 2011, 10:53:47 AM »
Deepak, the room likes nice!

Can you show the scans without any smoothing?


Thanks Rich.

As requested same color scheme.

djdube525

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Re: Help Fine Tuning The Room
« Reply #5 on: August 02, 2011, 11:38:28 AM »
Thanks Dave.  Are you going to join us in October?

Would be nice to meet up with the NY group again. I bet Princeton & surrounding scenery is beautiful in October.

I need to do some "checkin" to see if I can escape that weekend... and speaking of... which weekend is it again?

Edit: Nevermind - I found it (1st weekend in Oct)

Dave
« Last Edit: August 02, 2011, 11:40:55 AM by djdube525 »

Offline richidoo

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Re: Help Fine Tuning The Room
« Reply #6 on: August 02, 2011, 01:42:32 PM »
Pretty good FR there, deepak!

The dips at 44 and 72 are due to the dimensions of the room, see the attached picture of the modes and their interactions. The peak to the right might be the double mode at 133Hz, hard to tell without the scale at the bottom. The amplitude of the modes is not bad though, and evenly distributed. Is it concrete walls? Since there is a double peak at 133 It could be the echo from the opposite side wall, so damping there might kill that tall peak.  Look at the data and use the modecalc app to figure out the likely cause before you attack. Find the cause by trying to find a sound path from the speakers to the mic whose distance corresponds to the wavelength (or harmonic) of the frequency peak you want to kill. 

I would experiment with the placement of speakers first with few treatments in place, to minimize the dips, then experiment with the placement of those monster absorbers to see if you can further diminish the dips. The floor / wall joint corners near the speakers is a powerful place for bass correction because pressure is highest close to the speakers and you can catch a lot of energy before it pollutes the room.

The red speaker looks good, I would mark it's location so you can go back if your changes only make it worse. You can probably tame that 130Hz peak by moving that speaker slightly because I think it is a room width related mode. The peak is high enough freq that thick damping panels should be able to kill it if you can use enough, and find the right spots for them. 

The purple/green speaker is probably will improve with some position tweaks, start small first, like an inch at a time. You'll get a feel for what it will need. You can't make perfectly flat response with just position and treatments, but you should be able to get within +/- 10dB without breaking the bank, and it looks like you are not far off, except for those three spikes related to room dimensions.   The difference in overall level is probably due to the different distances of the absorbers to the speakers. Remove them from the room and scan it again, you should see more similar volume levels. Notice how the peaks ignore that, because mic is picking up room modes there which are no affected by the absorption in that location.

I believe that optimizing the speaker location is the first priority, then adding treatment to cure the leftover problems is the most efficient way to go about it. It's a big job.

If the speakers end up asymmetric to the room shape that is OK as long as your listening triangle is symmetrical and equal distance from tweeters to ears. You have some asymmetry to the room anyway, like the ceiling bumps, etc. The asymmetry makes data "roughness" that you can use to your advantage by moving speakers around til you find a sweet spot. Roughness makes more sweet spots. A friend is helpful to press the scan button after you move the speakers, so you don't have to get up and down so much. Mark the floor when you find good location candidates.

Offline shadowlight

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Re: Help Fine Tuning The Room
« Reply #7 on: August 02, 2011, 02:00:54 PM »
Thanks Rich.  The green and the purple is the response from the right speaker, while the blue one is the left one and the red is combined.  Which direction do I move the speakers is it front to back or side to side.  I can move it in to the center of the room but moving it to the right might be a issue.  Will remove the panels and run the sweep again.

Thanks

evan1

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Re: Help Fine Tuning The Room
« Reply #8 on: August 02, 2011, 02:04:33 PM »
Dee

You need to take better pics. I guess we all did a pretty good job to start. Keep at it

Offline richidoo

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Re: Help Fine Tuning The Room
« Reply #9 on: August 02, 2011, 02:36:22 PM »
Wow, the blue is seriously perfect. Weld that sucker down to the floor before anyone goes near it!  Just get a mono needle for your TT and forget about stereo!

The other isn't too bad either, just those peaks, no big wide toughs or peaks. Ignore the stuff below 40Hz, nothing you can do about that and no content down there anyway. Just focus on the mode peaks and you're golden.

You'll have to see how the peaks change when you try moving the one speaker. When you are close to a wall the effect of a small movement can be amplified over distance if there are other reflections involved in that FR peak.

So basically you just have to see what happens in each direction, or use the mode calc to help predict the cause of the modes. You have to make your own test method that goes with your own style and reasoning process. Intuition is helpful here.

Offline shadowlight

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Re: Help Fine Tuning The Room
« Reply #10 on: August 02, 2011, 02:47:03 PM »
Dee

You need to take better pics. I guess we all did a pretty good job to start. Keep at it

Yep, thanks for the help.  Sorry, lousy at taking pictures.  Let me know what additional detail you need and will snap some more.

evan1

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Re: Help Fine Tuning The Room
« Reply #11 on: August 02, 2011, 03:01:06 PM »
Dee

You need to take better pics. I guess we all did a pretty good job to start. Keep at it

Yep, thanks for the help.  Sorry, lousy at taking pictures.  Let me know what additional detail you need and will snap some more.


I don't need additional detail. I think you should be proud and show off that room.

Online etcarroll

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Re: Help Fine Tuning The Room
« Reply #12 on: August 02, 2011, 04:00:25 PM »
Wow... the basement has really been transformed since the time I was there!

Nice job!  :thumb:

It really is transformed from what it was.

I'm jealous.

"...if you want to enjoy your gear, don't listen to anything that might be better."

Offline tmazz

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Re: Help Fine Tuning The Room
« Reply #13 on: August 02, 2011, 06:36:40 PM »
I can't say I know what it was like before, but it sure looks good now. :thumb:
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lonewolfny42

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Re: Help Fine Tuning The Room
« Reply #14 on: August 02, 2011, 08:17:53 PM »
Wow... the basement has really been transformed since the time I was there!

Nice job!  :thumb:

It really is transformed from what it was.

I'm jealous.



WOW...Looking good D.....a really nice change !!!  :beer: