# Surround Measurement - Check My Results?



## Lonely Raven (Aug 27, 2008)

Greets all. 

I'm getting ready to build and deploy some room treatment. I have two portable (155lbs so portable is relitive) bass traps ready to be dropped into the corners. I have 18 Panels of JM814 2" semi-ridged I'm going to cut up for a Super-Chunk, and I have 10 panels of 1.5" Thermafiber left over from the portable bass traps. I'm also working on building some poly diffusors for the back wall, and very likely some more JM814 panels for first reflection points. 

Before I move forward, I want to make sure this looks right. 










Yamaha Dolby Digital Surround setup with my favorite DSP setting, Elemental Designs Under-Screen 6T6 Mains with 5T5 rears, Wicked One Sub (36"X36"X14") with a pair of JL Audio 10W7 Dual Voice coil drivers powered by an EP2500. 

Measurement taken through an ECM8000 through Mackie mixer (set flat) through my HTPC. Mic Cal loaded, Soundcard Cal done. And the chart is 15-20k with 105db top which I'm reading is our standard format around here. 

I hope I did all that correctly. I'm still winging this, and I just want to make sure my base measurement looks right before I start rolling in sound treatment. Otherwise I won't really have a solid handle on how much change I'm doing.

I'm also not sure how to do the RT60 or any of that...which I'm understanding is also important. Though with all the carpet and huge blackout curtains I have, is probably not too bad except for the front to back flutter echo I can clearly hear while clapping (or talking for that matter).

Please, chime in any suggestions. I'm going to go cut up some insulation and make me a supa-dupa-chunk!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, Raven!



> Yamaha Dolby Digital Surround setup with my favorite DSP setting,


Bypass all digital processing, as it can impart frequency response changes as part of the soundfield. You want your measurements to be in two-channel, with all onboard EQ from the receiver bypassed. I prefer to take separate readings for the left and right speakers.

Since you’ll be adding bass traps, you’ll want to look at “before and after” waterfalls.

Did you use our ecmnew calibration file for the mic?

Regards,
Wayne


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## Lonely Raven (Aug 27, 2008)

I've not generated waterfalls for this measurement. Though I looked at some from when I was putzing around with REW trying to figure my way through it. I can generate and post a waterfall if I can get some help in reading it?

So I should be doing this only in two channel? 

I figured since the center channel imparts such a sonic footprint, that it would be included in the measurements. Or am I not understanding a key point?

I'll rerun this really quickly with FX off and only run Mains + Sub and post my results. 

Thanks for the start! 

~Eric~




Wayne A. Pflughaupt said:


> Welcome to the Forum, Raven!
> 
> Bypass all digital processing, as it can impart frequency response changes as part of the soundfield. You want your measurements to be in two-channel, with all onboard EQ from the receiver bypassed. I prefer to take separate readings for the left and right speakers.
> 
> ...


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## Lonely Raven (Aug 27, 2008)

Side note: I have about 8' of 34" face triangles cut out. I'm considering making a wood cage to hold them in 4' sections so I can easily move and measure and compare to my hard-shell portable diffusers. I'm going to eat dinner while I ponder this and see what I come up with.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Lonely Raven said:


> I've not generated waterfalls for this measurement. Though I looked at some from when I was putzing around with REW trying to figure my way through it. I can generate and post a waterfall if I can get some help in reading it?


We can help. 



> So I should be doing this only in two channel?
> 
> I figured since the center channel imparts such a sonic footprint, that it would be included in the measurements. Or am I not understanding a key point?


Sure, the center is important, but how can you tell anything about it with all the other speakers running at the same time? It’s easy enough to move the center speaker cable to the left or right channel and get a specific measurement of it.

Regards,
Wayne


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## Lonely Raven (Aug 27, 2008)

OK, here's Sub and Mains, no Surround, no Room Treatment. I had to dial the sub down to almost nothing at it was pinging 105db at the same setting I get 75db in surround mode. And I still have a low freq hump. I wish that hump was at 15Hz!


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## Lonely Raven (Aug 27, 2008)

Wayne A. Pflughaupt said:


> We can help.
> 
> Sure, the center is important, but how can you tell anything about it with all the other speakers running at the same time? It’s easy enough to move the center speaker cable to the left or right channel and get a specific measurement of it.
> 
> ...


I see your point. 

Similarly my thoughts were that since I'm listening in Surround mode 98% of the time, that I should be doing my measurements in Surround mode and trying to dial in the room in Surround mode. 

But I will defer to your experience till I get a better grasp of all this.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Okay - getting back to your original post: 


Lonely Raven said:


> Before I move forward, I want to make sure this looks right.
> 
> I just want to make sure my base measurement looks right before I start rolling in sound treatment.


Looks good – I think you’re good to go. :T Be sure and save your readings, for later comparison.

Regards,
Wayne


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## Lonely Raven (Aug 27, 2008)

Waterfall of Sub with Mains.


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## Lonely Raven (Aug 27, 2008)

Wayne A. Pflughaupt said:


> Okay - getting back to your original post:
> 
> Looks good – I think you’re good to go. :T Be sure and save your readings, for later comparison.
> 
> ...


Great! Thanks!

Um, yeah, I forgot to save once and shut off the computer...so I'm being extra careful this time to make sure I"m on the right track.


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## JohnM (Apr 11, 2006)

For your waterfalls set the axes to 45..105dB and 15..200Hz (use the button second from the right in the toolbar) and change the frequency axis from linear to logarithmic by clicking the button third from right in the toolbar.


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## Lonely Raven (Aug 27, 2008)

JohnM said:


> For your waterfalls set the axes to 45..105dB and 15..200Hz (use the button second from the right in the toolbar) and change the frequency axis from linear to logarithmic by clicking the button third from right in the toolbar.


Thanks, John. I'll take care of that tonight when I get home from work, and post the correct waterfall.


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## brucek (Apr 11, 2006)

> my thoughts were that since I'm listening in Surround mode 98% of the time, that I should be doing my measurements in Surround mode


REW is a mono signal and will not be compatible with the surround modes, since they rely on phasing for their steering....

brucek


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