# Need help - REW results contradicting Audyssey and SPL meter



## tarheel (May 1, 2010)

My REW graph contradicts my sub's level as set by Audyssey and my radio shack spl meter. Wondering which is correct of if I have something wrong in REW.

Here's the backstory - I bought some new speakers last week and decided to move my sub from front center to front corner placement while changing out the speakers. I reran Audyssey and validated levels with my spl meter (levels were consistent). I then ran REW to eq with my BFD.

The issue is when running a full range sweep, my sub's frequencies (crossover 70hz) were about 10db higher than my mains. I went into the AVR level settings and adjusted them down...here's a graph that I think was generated after reducing the AVR's sub level from -1 to -4; the sub frequencies are still 5-10db too high. I had to bring the AVR's sub level down about 10 in order to get a relatively flat response graphed from 20hz on up. 

Why do the REW results show my sub's dBs so much higher than what my meter/audyssey say? Could I have something set up wrong in REW? I didn't have this issue in the past though (prior to moving sub to corner).

Any advice appreciated.


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## JohnM (Apr 11, 2006)

REW setup looks OK. The SPL meter cal is included in the REW plots, but looks correct for your meter. 

When you check sub level with your SPL meter the test signal is concentrated in the range from 30 to 80Hz. The effect of the meter's C weighting is for the overall level to read a couple of dB lower than actual, so you tend to end up setting the sub a couple of dB higher if you try and match the reading to the mains, so that would account for some of the difference. 

Beyond that you are somewhat at the mercy of the test signal level generated by the processor when you check the levels. If, as a processor manufacturer, you wanted the sub to be set higher than flat then all you need to do is lower the test signal level by the amount of boost you want the sub to end up with, that might also be contributing. To investigate further you could set your speaker and sub trims to zero, connect the sub and then the speaker line level outputs to the soundcard input in place of the signal from your SPL meter and use the REW RTA to look at the actual test signal levels being generated by the processor.


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## tarheel (May 1, 2010)

JohnM said:


> REW setup looks OK. The SPL meter cal is included in the REW plots, but looks correct for your meter.
> 
> When you check sub level with your SPL meter the test signal is concentrated in the range from 30 to 80Hz. The effect of the meter's C weighting is for the overall level to read a couple of dB lower than actual, so you tend to end up setting the sub a couple of dB higher if you try and match the reading to the mains, so that would account for some of the difference.
> 
> Beyond that you are somewhat at the mercy of the test signal level generated by the processor when you check the levels. If, as a processor manufacturer, you wanted the sub to be set higher than flat then all you need to do is lower the test signal level by the amount of boost you want the sub to end up with, that might also be contributing. To investigate further you could set your speaker and sub trims to zero, connect the sub and then the speaker line level outputs to the soundcard input in place of the signal from your SPL meter and use the REW RTA to look at the actual test signal levels being generated by the processor.


Thanks for the suggestions...that makes sense. You've also got me thinking about something I hadn't considered....my AVR has Audyssey Dynamic Eq which I think can boost the lower freq's...I'm wondering if I have that activated now and didn't in the past. And now that I think about it more, I believe Audyssey enables it by default after calibrating so when I reran Audyssey after moving the speakers, it probably was enabled. I'll check this out this afternoon and rerun REW to see if that was it.


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## tarheel (May 1, 2010)

Just wanted to post a follow-up and confirm that my issue was due to having Audyssey's dynamic equalizer enabled. I disabled it and ran REW and then re-enabled it and ran REW to compare results. Here's a graph after eq'ing...

Pink is without dynamic equalizer. Blue is with it.


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## MikeBiker (Jan 3, 2010)

Good job on figuring out what was making the difference. With all that goes on inside AVRs, it's easy to overlook one of the many features that gets set without warning.


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