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I do not recall REW having ever done this before to me but basically regardless of what I do for adjustments, at the apex of the house curve target the response below that freq (for example 30 hz being the apex) zero adjustment is applied for correction. I believe I have investigated every angle and just can't figure out why. I have attached an example photo as reference. As seen, the measurement below 30Hz is exactly as it was measured and made no correction to match the target curve even though it was within a couple Db.

I have tried multiple measurements in different rooms and systems and the result is the same so I must be doing something wrong. Preferences are match range 15 to 80Hz, max adj 16, 2db flatness target and max boost. When I select match target to response it just ignores everything roughly 35hz and below in this particular example.
 

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Discussion Starter #2
Re: Can't figure out why EQ will not correct entire measurement

Here is the same graph showing where the filters are being applied. Clearly ignoring the lower range and don't know why.
 

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Try moving your target level down.
I think REW stops adjusting below the Frequency where the SPL level falls significantly below the target.
 

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- I think you may have run into ( an unintended consequence of ) this feature ;

Online Help File said:
Note that REW will not apply filters below the frequency at which the measurement first exceeds the target to prevent trying to boost a response below its natural roll-off, if you wish to lift the low end response this can be done with manually applied filters but beware of exceeding the excursion limits or headroom of the woofer.
- Seems to me ( as the text suggests ) that in your case , all lower-range Auto-EQing action will stop at 38hz because that peak is above the Target Curve .
- Though I :dontknow: this to actually be the case .

:sn:
 

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Thanks for that catch. I think you may be on to something there. I don't recall reading that before but when I lower the target level I do get it to make some adjustments as jtalden suggested. That seems counter-intuitive to me since when you apply a house curve you usually have a need to increase the lower end. In my case my measurement is so close to the target I thought it should just tweak that lower end up a couple db and problem solved. Hmmm....I guess I don't understand why it would work this way. What's the purpose of a house curve then? Also, my subs are more than capable of producing 20hz quite well it is more a positioning issue so another reason I would like REW to help out. Of course I can do it manually and have done so but maybe we should have the option to disable that "feature"

Also, I don't really understand what is happening to my overall actual response when I lower the larget level. IE is this creating some negative effect of some sort or are we cheating to get REW to play nice with that target curve. Great program (couldn't live without it) I just don't fully understand how it works yet. I can interpret well enough just the logistics of the program throw me sometimes.

Thanks for the insights.
 

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<<<<<snip>>>>>
Of course I can do it manually and have done so but maybe we should have the option to disable that "feature"
I imagine there are at least a couple of work-arounds ( that circumvent this feature ) . Here's one I would try ;

- Manually EQ that peak until it's no longer above the Target Line . Any filter ( set to manual ) won't be engaged/used by the next Auto-EQ session ( which you then run ) .

:sn:
 

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Thanks for that catch. I think you may be on to something there. I don't recall reading that before but when I lower the target level I do get it to make some adjustments as jtalden suggested. That seems counter-intuitive to me since when you apply a house curve you usually have a need to increase the lower end. In my case my measurement is so close to the target I thought it should just tweak that lower end up a couple db and problem solved. Hmmm....I guess I don't understand why it would work this way. What's the purpose of a house curve then? Also, my subs are more than capable of producing 20hz quite well it is more a positioning issue so another reason I would like REW to help out. Of course I can do it manually and have done so but maybe we should have the option to disable that "feature"

Also, I don't really understand what is happening to my overall actual response when I lower the larget level. IE is this creating some negative effect of some sort or are we cheating to get REW to play nice with that target curve. Great program (couldn't live without it) I just don't fully understand how it works yet. I can interpret well enough just the logistics of the program throw me sometimes.

Thanks for the insights.
> For a SW with limited capacity it is a bit risky to apply much boost below the freq where a speaker starts to drop off its SPL in a free field environment. That point is nearing its design limitations. Determining this freq in a room can be tricky as the room response can mask the true speaker response. It is better to look at the manufacturer’s data.

> In practice it is very common and relatively safe to boost the low end just below the rolloff as much as 6 dB with a Q = 2 filter to extend/flatten the low end response. Many people go much beyond that and most SWs are designed such that they tolerate very significant overload without damage. Overload will increase distortion rapidly however.

> As SW capacity is increased (more or bigger SWs) or listening volumes are lowered greater EQ boost is no longer any real issue. The best way to determine how much SPL at each frequency a SW can produce is to calculate its capacity using its TS parameters, listening distance, and room size.

> As a matter of safety REW stops boosting below where the SPL drops below the target level, but is up to the user to decide what that safe frequency/boost is for the SW and to adjust the target level accordingly. The only impact on the overall setup is that the output level of the SW is changed for a given volume setting. So if the target is reduced 2 dB and the REW selected EQs are applied then the SW level in the AVR will need to be set 2 dB higher to match the speaker levels.
 

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Discussion Starter #8
>
> As a matter of safety REW stops boosting below where the SPL drops below the target level, but is up to the user to decide what that safe frequency/boost is for the SW and to adjust the target level accordingly. The only impact on the overall setup is that the output level of the SW is changed for a given volume setting. So if the target is reduced 2 dB and the REW selected EQs are applied then the SW level in the AVR will need to be set 2 dB higher to match the speaker levels.

Thank you all. Everything that was shared is now better understood by myself but specifically this helps me understand what is going on and how to work around it.
 
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