Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 496 - AVS | Home Theater Discussions And Reviews
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post #14851 of 14861 Old Today, 01:50 PM
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Quote:
Originally Posted by gh32 View Post
I have this issue also, but with the UMM-6 USB mic. My AC, refrigerator, and dvr all off. My noise floor seems to be around 60-62db. Interested to see what your issue might be.
With my UMIK-1 my noise floor was reading in the low 60s which surprised me. Then I noticed my AC was running. Once I shut that off it was in the mid 40s give or take. And that is with the relatively loud set top box.

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Originally Posted by AustinJerry View Post

The frequency response seems to drop off the shelf above 8Khz. What is going on with your high frequencies? Are you applying EQ up there? The average level of the signal above 100Hz is 65-70dB. The curve rises to 90dB at 20Hz. I have heard of house curves, but this seems to be quite heavy in the bass. Surprisingly, the waterfall shows pretty good control of the bass resonance--what bass treatments are you using? With the aggressive bass boost, I expected more ringing, but the absence of ringing suggests that the bass probably sounds pretty tight.
...
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Originally Posted by JohnPM View Post
Measurement file indicates it was made with an RS meter, should ignore everything above a few kHz. Also seems to be clipping somewhere in the measurement chain causing very high odd order harmonic distortion (meter range set too low, perhaps).
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Originally Posted by markus767 View Post
^
I would suggest to wait for your UMIK-1 to arrive. There's just too much room for error with the Radio Shack SPL meter.
Thanks guys. My UMIK-1 came last night. I was glad to see that the high frequencies did not roll off at all like what was measured when I used the RS meter. So while the RS meter did a decent job reading the high end from near field, it was way low when reading it from 16 ft. across the room at the MLP. Good call to ignore it and wait for the UMIK-1.

As Jerry pointed out, I have an issue with the sub running way to hot. I'm not sure when this happened. Its been years since I last calibrated with REW and my BFD. And I know when I finished with that it was all dialed in nicely. Now it is obvious that something changed. The gain knob on the sub is in a place where it would be really hard for someone to have turned it or bumped into it, so not sure how it got this way.

Anyway this weekend I'm going to redo the EQ. I'll use YPAO to start with and let it do its thing. Then I'll EQ the sub. Hopefully REW will do all the heavy lifting as far as its recommended filters. I'll post an updated set of measures once completed.
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post #14852 of 14861 Old Today, 02:19 PM
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I'd do the sub first, then YPAO. It works better for me that way with MCACC, which also doesn't eq subs, but will set the level and distance.

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post #14853 of 14861 Old Today, 02:36 PM
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I'd do the sub first, then YPAO. It works better for me that way with MCACC, which also doesn't eq subs, but will set the level and distance.
Thanks. I have the Yamaha RX-V1800. From what I recall, it does make some changes that could affect the subwoofer response. I can't quite remember, but it may EQ down as low as 100 Hz? My thought is that I'd rather have it EQ the whole system as much as it can, then I can come and fix the bass with REW and BFD. At least that way when I finish I know what the result is. If I was to do the sub EQ first and then YPAO, it could (I suppose?) make a chance that then messes up my BFD eq (I EQ to sub + L/R, so if YPAO changes even L+R it could throw off the overall FR). What do you think? Have you experimented with doing it both ways (one first, then the other)? How confident are you that YPAO after the fact will not mess up the sub? Thanks!
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post #14854 of 14861 Old Today, 02:48 PM
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I'm confident that, if MCACC "messes up" my subs, I can correct it. I've never used YPAO, so I defer to your experience.
I do the subs without mains, so I know where I'm starting from. Then adjust/correct/fiddle afterwards.
Have fun.

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What is a good general rule of thumb for determining where to set the subwoofer gain control (on the sub itself)? The REW User Guide talks about using -30 dB and setting the volume control on the AVR (or within REW) so that the SPL is around 75 dB. However, depending on where my gain control is on the sub, I can reach 75 dB with the sub with the AVR master volume set pretty low or pretty high. Basically I'm wondering what a good neutral starting point is.

I like a house curve of +8 at 20 dB to +0 at 80 dB. I know how to load this into REW. But do I then need to set my starting SPL dB so that the sub is producing 75+8 = 83 dB, and then the BFD will use filters to bring the house curve slope down into play?

Thanks.
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post #14856 of 14861 Old Today, 04:32 PM
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Quote:
Originally Posted by lovingdvd View Post
What is a good general rule of thumb for determining where to set the subwoofer gain control (on the sub itself)? The REW User Guide talks about using -30 dB and setting the volume control on the AVR (or within REW) so that the SPL is around 75 dB. However, depending on where my gain control is on the sub, I can reach 75 dB with the sub with the AVR master volume set pretty low or pretty high. Basically I'm wondering what a good neutral starting point is.

I like a house curve of +8 at 20 dB to +0 at 80 dB. I know how to load this into REW. But do I then need to set my starting SPL dB so that the sub is producing 75+8 = 83 dB, and then the BFD will use filters to bring the house curve slope down into play?

Thanks.
Let's start from the final objective. After running room correction, all speakers should measure 75dB at the MLP. (This is before you turn up the sub trim/gain as per your preference).

Not being familiar with MCACC, I think that it does nothing for the sub channel. So I would start out with setting the sub gain so that it measures 75dB at the MLP. Run the room correction and then check all levels to ensure that they are the same. The final step would be to increase the sub level to establish your house curve.
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post #14857 of 14861 Old Today, 04:37 PM
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Quote:
Originally Posted by AustinJerry View Post
Quote:
Originally Posted by lovingdvd View Post
What is a good general rule of thumb for determining where to set the subwoofer gain control (on the sub itself)? The REW User Guide talks about using -30 dB and setting the volume control on the AVR (or within REW) so that the SPL is around 75 dB. However, depending on where my gain control is on the sub, I can reach 75 dB with the sub with the AVR master volume set pretty low or pretty high. Basically I'm wondering what a good neutral starting point is.

I like a house curve of +8 at 20 dB to +0 at 80 dB. I know how to load this into REW. But do I then need to set my starting SPL dB so that the sub is producing 75+8 = 83 dB, and then the BFD will use filters to bring the house curve slope down into play?

Thanks.
Let's start from the final objective. After running room correction, all speakers should measure 75dB at the MLP. (This is before you turn up the sub trim/gain as per your preference).

Not being familiar with MCACC, I think that it does nothing for the sub channel. So I would start out with setting the sub gain so that it measures 75dB at the MLP. Run the room correction and then check all levels to ensure that they are the same. The final step would be to increase the sub level to establish your house curve.
Thanks. However doesn't REW need to take the house curve into account when creating filters and EQ work? The house curve is a slope. So I can't just turn up the gain afterward to achieve the house curve...?
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post #14858 of 14861 Old Today, 05:07 PM
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Originally Posted by lovingdvd View Post
Thanks. However doesn't REW need to take the house curve into account when creating filters and EQ work? The house curve is a slope. So I can't just turn up the gain afterward to achieve the house curve...?
When you measure with REW, the curve reflects response anomalies caused by the room. The output level of the sub doesn't affect the shape of the response curve, it simply raises the curve up or down. When you use the REW EQ tool, a very important step is to set the level. So what I am saying is that the overall sub level should have no impact on the REW EQ filters.
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post #14859 of 14861 Old Today, 05:22 PM
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Originally Posted by AustinJerry View Post
When you measure with REW, the curve reflects response anomalies caused by the room. The output level of the sub doesn't affect the shape of the response curve, it simply raises the curve up or down. When you use the REW EQ tool, a very important step is to set the level. So what I am saying is that the overall sub level should have no impact on the REW EQ filters.
Yes I agree. I think we may be saying two different things. I'm imagining a perfectly flat FR from 20 Hz - 20 kHz (we can dream right? ). Now with a house curve of +8 dB at 20, fading to +0 dB at 80 Hz, think about what 20-80 Hz now looks like on that curve. If we tell REW to use that house curve, it needs to take that into account as it cuts frequencies to make that slope in the FR to match the house curve, yes? Or am I just totally off base here?
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post #14860 of 14861 Unread Today, 05:54 PM
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Has anyone compared the 90 degree calibration for the UMIK-1 that comes from the MiniDSP website (when you enter your serial number) to the 90 degree calibration files that you get from Cross-Spectrum Labs? How does the calibration done by MiniDSP compare to the way CSL does it?

I asked because I noticed the values in the two calibration files are quite different.

Here's two quick examples:

For 95.5 Hz:

95.51000000000001 0.64 0 (from the CSL calibration file)
95.552 -0.3178 (from the MiniDSP calibration file)


For 19.78 kHz:

19782.16 -8.16 0 (from the CSL calibration file)
19770.697 -6.1828 (from the MiniDSP calibration file)

Am I correct to assume that of the two the one from CSL should be more accurate (and if so, just how much more accurate)? The only obvious difference I see is that the MiniDSP file stops at 20 kHz and the CSL one goes to 25 kHz. But I'm assuming for REW and our calibration purposes there is little point in worrying about anything over 20 kHz. Certainly I know I can't hear of 15 kHz. I think most teenagers can't hear past 20 kHz.

Thanks!
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post #14861 of 14861 Unread Today, 06:11 PM
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Originally Posted by lovingdvd View Post
Now with a house curve of +8 dB at 20, fading to +0 dB at 80 Hz, think about what 20-80 Hz now looks like on that curve. If we tell REW to use that house curve, it needs to take that into account as it cuts frequencies to make that slope in the FR to match the house curve, yes? Or am I just totally off base here?
I do this, and it usually works (just change the slope to get what you want).
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