Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 530 - AVS Forum | Home Theater Discussions And Reviews
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post #15871 of 15892 Unread 08-26-2015, 05:38 PM
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Quote:
Originally Posted by AustinJerry View Post
you didn't follow my recommendation for changing the time window from 300 to 450ms on the waterfall.
I followed the recommendation but buggered up editing the pictures apparently. Re-posting here. Hopefully these are more compliant.

Quote:
Originally Posted by Audionut11 View Post
The waterfall looks (more than) reasonable IMO. 35-40dB down within 300ms @ 20hz and at 60hz it's around 55dB down. Can you post the mdat? Dropbox or some other file host.
Linked (hopefully)

Subs only. 80hz low pass. No EQ. No phase adjustment.
Suggestions to improve? What to tackle first?

Maximum output distortion


Maximum output waterfall


Maximum -25db waterfall


Max output
https://www.dropbox.com/s/3fkue4gbdk...2025.mdat?dl=0

Max output -25db
https://www.dropbox.com/s/21epqwp3q5...2025.mdat?dl=0
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post #15872 of 15892 Unread Yesterday, 05:08 AM
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Quote:
Originally Posted by markus767 View Post
No, that's not really what I'm saying. Posting graphs isn't pointless (the REW default is actually quite useful for spotting modal problems) but you need to understand what exactly they are showing.
I much prefer, as a newbie, that graphs be posted (albeit incorrectly) than that an mdat get posted.

In the latter case, as a student, I see an mdat get posted, some gurus go off and do various incantations over it, and a recommendation pops out ("your coffee table is in the wrong place").

In the former case, a graph gets posted, there's a back and forth about the proper way to present it to show the issues, then the graph is the basis of discussion for the ultimate recommendations.

It's the reading of the graph I want to learn how to do. I think I know well enough how to post files on the Internets. :-)
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post #15873 of 15892 Unread Yesterday, 05:13 AM
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Originally Posted by DavidK442 View Post
Maximum output distortion
Even though it's at maximum, that 10% distortion is very audible IME. It fuzzes up the bass. If you can either not play so loud or get more sub power somehow that would pay off.

Your maximum waterfall looks not as desired but the one at normal level is pretty good. Little ringing until it gets down into the frequencies where you can't deal with it effectively anyway.
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post #15874 of 15892 Unread Yesterday, 05:33 AM
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Originally Posted by DavidK442 View Post
Subs only. 80hz low pass. No EQ. No phase adjustment.
is this the output from 4 ported 1260w subs that are listed in your build thread?

if so, it seems a little strange that you don't have a sharper rolloff. I think it's fair to say you're on the verge of driving them to distress and probably have already got there at <20Hz. I would say that a safe maximum level is probably ~2-3dB lower than this. What is your usual maximum listening level? Do you run with any sort of lift into the bass region or go with a measured flat curve?
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post #15875 of 15892 Unread Yesterday, 07:20 AM
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Originally Posted by 3ll3d00d View Post
is this the output from 4 ported 1260w subs that are listed in your build thread?

if so, it seems a little strange that you don't have a sharper rolloff. I think it's fair to say you're on the verge of driving them to distress and probably have already got there at <20Hz. I would say that a safe maximum level is probably ~2-3dB lower than this. What is your usual maximum listening level? Do you run with any sort of lift into the bass region or go with a measured flat curve?
Yes, one ported 1260W in each corner of my room. I have a 12db/octave high pass set at 18hz. Would like to have a steeper cut-off. I imagine that room gain is working to bolster frequencies below tuning.
I do not typically listen at the maximum output but at moments, during bass heavy scenes in movies, I have measured 110db. I agree, clean output is likely a couple db lower than what I have posted as a maximum. At Max -5db distortion drops considerably.

I have no ability to EQ the bass at this time, but am considering an equipment upgrade to give me the capability. How detrimental are the peaks and valley's in my low end frequency response?
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post #15876 of 15892 Unread Yesterday, 07:28 AM
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It is fairly flat tbh though i would think the peaks and overall shape would accentuate the punchiness over the low end. You may like this of course so that is not necessarily a bad thing. EQ would help you smooth the peaks out to give a v flat response and also let you play with tilting the signal shape. It would also let you apply a steeper hpf to protect them under tune.

I would get some DSP in there if I were you
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post #15877 of 15892 Unread Yesterday, 07:33 AM
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Originally Posted by DavidK442 View Post
Yes, one ported 1260W in each corner of my room. I have a 12db/octave high pass set at 18hz. Would like to have a steeper cut-off. I imagine that room gain is working to bolster frequencies below tuning.
I do not typically listen at the maximum output but at moments, during bass heavy scenes in movies, I have measured 110db. I agree, clean output is likely a couple db lower than what I have posted as a maximum. At Max -5db distortion drops considerably.

I have no ability to EQ the bass at this time, but am considering an equipment upgrade to give me the capability. How detrimental are the peaks and valley's in my low end frequency response?
In addition to considering adding DSP, have you experimented with various sub placements, using REW measurements to help? Corner placement is not known to produce the smoothest bass response, and tends to exacerbate resonance.
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post #15878 of 15892 Unread Yesterday, 09:21 AM
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so whats the recommended way to rew 2 subs together? I cant figure it out. It doesnt make sense to me to record 1 sub at a time cause they play together when I listen to music or movies. 1 sub at a time would give me false data if I have 2 no?

Power: Marantz sr7008, NAD C 275Bee x 2, Video: Oppo 103, Samsung 75un6300
Speakers: Focal aria 948, Focal cc800v, Klipsch synergy KSF 10.5 Subs: Velodyne HGS 12, VA 1512
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post #15879 of 15892 Unread Yesterday, 09:22 AM
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Quote:
Originally Posted by AustinJerry View Post
In addition to considering adding DSP, have you experimented with various sub placements, using REW measurements to help? Corner placement is not known to produce the smoothest bass response, and tends to exacerbate resonance.

Small room, big cabinets so limited possibilities. The fronts are pretty much locked in place but I can flip the rear subs around to fire at each other rather than at the walls. That will position the drivers at roughly 1/4 wall length. Will give it a try. Thanks.


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post #15880 of 15892 Unread Yesterday, 09:46 AM
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Originally Posted by torii View Post
so whats the recommended way to rew 2 subs together? I cant figure it out. It doesnt make sense to me to record 1 sub at a time cause they play together when I listen to music or movies. 1 sub at a time would give me false data if I have 2 no?
When you play the REW test tone to either the left, right, both the left and right channels, or the center channel, and the speakers are all set to "small", the bass frequencies below the crossover are sent to both subs. So you don't need to do anything special, the measurements include the subs by default. If you want to measure the subs by themselves, turn off the main speakers. And no, you would normally not measure one sub at a time, unless the purpose of the measurement was to assist in the proper placement of the sub.
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post #15881 of 15892 Unread Yesterday, 09:51 AM
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Quote:
Originally Posted by AustinJerry View Post
When you play the REW test tone to either the left, right, both the left and right channels, or the center channel, and the speakers are all set to "small", the bass frequencies below the crossover are sent to both subs. So you don't need to do anything special, the measurements include the subs by default. If you want to measure the subs by themselves, turn off the main speakers. And no, you would normally not measure one sub at a time, unless the purpose of the measurement was to assist in the proper placement of the sub.
thank you, this helps alot
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Power: Marantz sr7008, NAD C 275Bee x 2, Video: Oppo 103, Samsung 75un6300
Speakers: Focal aria 948, Focal cc800v, Klipsch synergy KSF 10.5 Subs: Velodyne HGS 12, VA 1512
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post #15882 of 15892 Unread Yesterday, 10:15 AM
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I know Jerry‘s guide says the lower limit to all measures should be 15Hz, but given my sub distorts greatly around there would it be easier on my sub if I set the lower limit for measures at 20Hz or even 25Hz? My sub is rated down to 25Hz and actual measures confirm this.

"Frequency THD H3 (%)
16.000 104.2 20.8
16.469 78.3 27.2
16.951 36.9 21.0
17.448 39.2 27.6
17.959 39.0 24.6
18.486 27.4 13.5
19.027 14.9 5.97
19.585 12.1 6.78
20.159 12.3 8.91
20.749 12.8 6.75
21.357 12.5 4.81
21.983 6.46 2.71
22.627 5.85 2.31
23.290 5.53 2.54
23.973 3.98 1.47
24.675 2.41 0.879
25.398 2.20 1.22

26.143 2.17 0.740
26.909 1.88 1.03
27.697 1.57 0.943
28.509 1.36 0.734
29.344 1.45 0.524
30.204 1.63 0.623
31.089 0.940 0.617"

As you can see THD is quite high below 20Hz and even 25Hz for that matter.
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UN46EH6030 Calibration/Settings
Display: Samsung UN46EH6030 LED-LCD TV; Audio: Yamaha HTR-3066 AVR/AMP, Sony Core Bookshelves (Sony SS-CS5) and Center (Sony SS-CS8) as fronts, Cambridge Audio S20 Bookshelves (CA S20-N) as surrounds, Dayton Audio SUB-1200 as subwoofer; Sources: PS4 (doubles as primary BD player), Xbox One, PS3, Xbox 360, Motorola RNG150N (Cable Box)

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post #15883 of 15892 Unread Yesterday, 10:28 AM
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Quote:
Originally Posted by PlasmaPZ80U View Post
I know Jerry‘s guide says the lower limit to all measures should be 15Hz, but given my sub distorts greatly around there would it be easier on my sub if I set the lower limit for measures at 20Hz or even 25Hz? My sub is rated down to 25Hz and actual measures confirm this.



I think you pretty much answered your own question. Doesn't make a lot sense to measure outside the limits of your equipment and in fact could lead to other issues.
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post #15884 of 15892 Unread Yesterday, 10:30 AM
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I think you pretty much answered your own question. Doesn't make a lot sense to measure outside the limits of your equipment and in fact could lead to other issues.
So, 25Hz seems best then.
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post #15885 of 15892 Unread Yesterday, 05:38 PM
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Quote:
Originally Posted by jkasanic View Post
Quote:
Originally Posted by PlasmaPZ80U View Post
I know Jerry?s guide says the lower limit to all measures should be 15Hz, but given my sub distorts greatly around there would it be easier on my sub if I set the lower limit for measures at 20Hz or even 25Hz? My sub is rated down to 25Hz and actual measures confirm this.



I think you pretty much answered your own question. Doesn't make a lot sense to measure outside the limits of your equipment and in fact could lead to other issues.
Following the same logic, do I want to measure LFE only up to 200Hz instead of up to 300Hz? I don't have distortion figures above 150Hz to look at, but there is no output above 200Hz and not much above 120Hz.
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post #15886 of 15892 Unread Yesterday, 08:02 PM
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Originally Posted by PlasmaPZ80U View Post
Following the same logic, do I want to measure LFE only up to 200Hz instead of up to 300Hz? I don't have distortion figures above 150Hz to look at, but there is no output above 200Hz and not much above 120Hz.
300Hz is in reference to the modal region with your sub(s) and mains playing together. Very few subs will extend to 300Hz on their own.
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Quote:
Originally Posted by PlasmaPZ80U View Post
I know Jerry‘s guide says the lower limit to all measures should be 15Hz, but given my sub distorts greatly around there would it be easier on my sub if I set the lower limit for measures at 20Hz or even 25Hz?
For better comparability all measurements posted here should use the recommended range. For personal use set it to whatever is useful to you.

Markus

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post #15888 of 15892 Unread Today, 06:52 AM
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300Hz is in reference to the modal region with your sub(s) and mains playing together. Very few subs will extend to 300Hz on their own.
I think the guide said 15Hz-300Hz for sub only too.

UN46EH6030 Calibration/Settings
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For better comparability all measurements posted here should use the recommended range. For personal use set it to whatever is useful to you.
Well, now that I'm aware my sub is straining below 25Hz to produce any output, I don't see myself ever measuring below 25Hz with this sub again. No point in harming the sub just to show 10Hz lower.

UN46EH6030 Calibration/Settings
Display: Samsung UN46EH6030 LED-LCD TV; Audio: Yamaha HTR-3066 AVR/AMP, Sony Core Bookshelves (Sony SS-CS5) and Center (Sony SS-CS8) as fronts, Cambridge Audio S20 Bookshelves (CA S20-N) as surrounds, Dayton Audio SUB-1200 as subwoofer; Sources: PS4 (doubles as primary BD player), Xbox One, PS3, Xbox 360, Motorola RNG150N (Cable Box)
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post #15890 of 15892 Unread Today, 07:41 AM
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Originally Posted by PlasmaPZ80U View Post
Well, now that I'm aware my sub is straining below 25Hz to produce any output, I don't see myself ever measuring below 25Hz with this sub again. No point in harming the sub just to show 10Hz lower.
I would get new sub(s) instead
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post #15891 of 15892 Unread Today, 09:18 AM
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Quote:
Originally Posted by markus767 View Post
Quote:
Originally Posted by PlasmaPZ80U View Post
Well, now that I'm aware my sub is straining below 25Hz to produce any output, I don't see myself ever measuring below 25Hz with this sub again. No point in harming the sub just to show 10Hz lower.
I would get new sub(s) instead
If I could afford the kind of sub that goes 1-2 octaves lower without major distortion and with sufficient output, I would have bought one to begin with.

No sense in upgrading something I bought in March of this year. Besides I'm saving up for an AVR with solid eq capability.

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post #15892 of 15892 Unread Today, 09:23 AM
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If I could afford the kind of sub that goes 1-2 octaves lower without major distortion and with sufficient output, I would have bought one to begin with.

No sense in upgrading something I bought in March of this year. Besides I'm saving up for an AVR with solid eq capability.
Build them yourself. No special magic involved building a capable sub. You should easily find suitable drivers in the DIY space.

Markus

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