Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 775 - AVS Forum | Home Theater Discussions And Reviews
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post #23221 of 23230 Old Today, 07:03 AM
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Originally Posted by tjcinnamon View Post
I read the REW guide and I'm curious what a "bad" (audible) distortion level would be?

The guide says: There are differing opinions regarding “acceptable” levels of distortion.

What is the general range and what is a universally agreed upon range. For example 10% is universally agreed upon (although likely facetious response)

Also, is there anyway to test with "all speakers driven"? With 9 channels running that's when I'm likely to get a severe power dip in my fronts.
Acceptable levels of distortion also depend on frequency. A 10% distortion at 1000Hz would probably be more noticeable than 10% at 20Hz.

Why would you want to measure all speakers driven? This would not happen often listening to real-world content.
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post #23222 of 23230 Old Today, 07:16 AM
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Quote:
Originally Posted by AustinJerry View Post
Acceptable levels of distortion also depend on frequency. A 10% distortion at 1000Hz would probably be more noticeable than 10% at 20Hz.

Why would you want to measure all speakers driven? This would not happen often listening to real-world content.
Good point. Perhaps most driven. It's likely the front 3 will be driven simultaneously then ATMOS upmixed generally adds a touch to those tracks. If the surrounds are running there's at least 2 more. So I think 7 of 9 (star trek voyager reference) could reasonably be running. I think enough to cut the wattage running to my front 3.

https://www.soundandvision.com/conte...iew-test-bench

I can't think functionally how to test something like this. I would need to run all of the speakers and then test in a different room

-------------

I'll look to see what levels of distortion debates I can find.

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post #23223 of 23230 Old Today, 04:43 PM
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Ok took my first shot at this =) Pretty sure I probably screwed some things up haha. Following the Faq when setting up the volume I went up a little over 90db since my noise floor was a little over 50db. I am a little confused the faq says pick center channel then it says use the sub cal, which uses the sub, so why choose center channel?? I tried both sub cal and speaker cal and got 93db speaker / 95db sub based on my volume with Audyssey off and 92/92 with it on. I think I may have run out of headroom when measuring the sub , the number turned red and read 5db. Looking at my results there is a large dip between around 110db on my rear speakers, they are di/bipoles though, not sure if that has something to do with it. If anyone wouldnt mind taking a look at my results and giving me some pointers on where to go from here I would appreciate it!

I ran two runs , one without Audyssey on and one with it on reference which is what I usually use.
https://www.dropbox.com/s/bjucn31mnc...sults.zip?dl=0

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post #23224 of 23230 Old Today, 05:05 PM
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Originally Posted by grendelrt View Post
Ok took my first shot at this =) Pretty sure I probably screwed some things up haha. Following the Faq when setting up the volume I went up a little over 90db since my noise floor was a little over 50db. I am a little confused the faq says pick center channel then it says use the sub cal, which uses the sub, so why choose center channel?? I tried both sub cal and speaker cal and got 93db speaker / 95db sub based on my volume with Audyssey off and 92/92 with it on. I think I may have run out of headroom when measuring the sub , the number turned red and read 5db. Looking at my results there is a large dip between around 110db on my rear speakers, they are di/bipoles though, not sure if that has something to do with it. If anyone wouldnt mind taking a look at my results and giving me some pointers on where to go from here I would appreciate it!

I ran two runs , one without Audyssey on and one with it on reference which is what I usually use.
https://www.dropbox.com/s/bjucn31mnc...sults.zip?dl=0
The only thing I notice is that bass response seems to fall off rapidly below 40Hz, assuming that the left and right speaker measurements include the sub(s) as well. Otherwise, I don't see major issues with frequency response.

The impulse response shows quite a few early reflections. The waterfall shows a ringing issue at 50Hz in the left channel.
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post #23225 of 23230 Old Today, 05:11 PM
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Quote:
Originally Posted by AustinJerry View Post
The only thing I notice is that bass response seems to fall off rapidly below 40Hz, assuming that the left and right speaker measurements include the sub(s) as well. Otherwise, I don't see major issues with frequency response.

The impulse response shows quite a few early reflections. The waterfall shows a ringing issue at 50Hz in the left channel.
Thanks Jerry. I would assume the sub was used based on the cross over settings on the receiver. I am running two SVS SB12-NSD in a 18x15 room, I thought it was overkill so that kinda sucks to hear haha. Can you explain the ringing issue? Would I be able to correct something like that with the audyssey app?
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I am a little confused the faq says pick center channel then it says use the sub cal, which uses the sub, so why choose center channel??

I'd like to hear this answered??????
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post #23227 of 23230 Old Today, 05:37 PM
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I am a little confused the faq says pick center channel then it says use the sub cal, which uses the sub, so why choose center channel??

I'd like to hear this answered??????
The difference between the sub cal and the speaker cal is the range of frequencies used in the sweep. If you choose the center channel, the sub is included by virtue of bass management. You want the measurement to include frequencies that would be reproduced by the sub channel as well, thus the sub cal is used. Make sense?
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post #23228 of 23230 Old Today, 05:40 PM
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Originally Posted by grendelrt View Post
Thanks Jerry. I would assume the sub was used based on the cross over settings on the receiver. I am running two SVS SB12-NSD in a 18x15 room, I thought it was overkill so that kinda sucks to hear haha. Can you explain the ringing issue? Would I be able to correct something like that with the audyssey app?
Bass ringing is normally addressed by room treatments, so I doubt that the Audyssey app would make much of a difference. If you generate the waterfall graph for the left channel, you will see a ridge in the graph that is centered around 50Hz that extends from the bottom of the graph to almost the top. That is the evidence of ringing.
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post #23229 of 23230 Old Today, 05:49 PM
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Quote:
Originally Posted by AustinJerry View Post
Bass ringing is normally addressed by room treatments, so I doubt that the Audyssey app would make much of a difference. If you generate the waterfall graph for the left channel, you will see a ridge in the graph that is centered around 50Hz that extends from the bottom of the graph to almost the top. That is the evidence of ringing.
Thanks again, I do have treatments in the room, just havent done bass traps yet, guess this gives me a good reason to!
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post #23230 of 23230 Old Today, 06:00 PM
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Thanks again, I do have treatments in the room, just havent done bass traps yet, guess this gives me a good reason to!
You should also asssess the effectiveness/positioning of the existing treatments, based on the reflections shown in the ETC measurements.
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