# My First Graph with a null at crossover



## RingoHung (Jan 13, 2014)

I have generated my first frequency response curve for my subwoofer. Unfortunately, I have found a null at around 80Hz which is indeed my crossover point with the main speakers. As my Nuforce AVP-18 allows only 3 EQ settings for subwoofer, I have to manually increase the gain by 8db at 81.92 Hz in order to have a smoother curve at the crossover. 

Is it a good idea to pump up the gain like this? Or I could have a work around? 

Besides, should I also address the null at 57.2Hz?

Please help! Thank you in advance!


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## Phillips (Aug 12, 2011)

RingoHung said:


> I have generated my first frequency response curve for my subwoofer. Unfortunately, I have found a null at around 80Hz which is indeed my crossover point with the main speakers. As my Nuforce AVP-18 allows only 3 EQ settings for subwoofer, I have to manually increase the gain by 8db at 81.92 Hz in order to have a smoother curve at the crossover.
> 
> Is it a good idea to pump up the gain like this? Or I could have a work around?
> 
> ...


Best to find the best position first with REW RTA. The null (notch) might decrease or go away.

Then try the phase then the distance setting in your AVR receiver.


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## RingoHung (Jan 13, 2014)

Thanks for the suggestion. Although the location is pretty much fixed, I would try adjusting the phase and distance!


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## Wayne A. Pflughaupt (Apr 13, 2006)

RingoHung said:


> I have found a null at around 80Hz... I have to manually increase the gain by 8db at 81.92 Hz in order to have a smoother curve at the crossover.
> 
> Is it a good idea to pump up the gain like this? Or I could have a work around?
> 
> Besides, should I also address the null at 57.2Hz?


Unfortunately it’s impossible to equalize a null - see here for more info. As Phillips said, your only option is phase adjustments and/or relocation of the sub.

Regards, 
Wayne


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## RingoHung (Jan 13, 2014)

Thank you very much for your advice!


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