# Audyssey and bass Null's



## f0zz (Dec 1, 2011)

I have a reciever with Audyssey XT32. I haven't used it yet as my HT is still under construction. I know I have a null in my bass response at the seating position. Can Audyssey help fix this? If it can, how is it doing it? It must be more than just EQ adjustments? Just trying to understand how Audyssey works (or doesn't).


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## Kal Rubinson (Aug 3, 2006)

f0zz said:


> I have a reciever with Audyssey XT32. I haven't used it yet as my HT is still under construction. I know I have a null in my bass response at the seating position. Can Audyssey help fix this? If it can, how is it doing it? It must be more than just EQ adjustments? Just trying to understand how Audyssey works (or doesn't).


It cannot fill a null nor can any EQ, afaik. You have to fix the underlying problem by repositioning sources and/or listening position or modify the acoustics of the room.


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## f0zz (Dec 1, 2011)

Thanks, that's what I figured.


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

f0zz said:


> I have a reciever with Audyssey XT32. I haven't used it yet as my HT is still under construction. I know I have a null in my bass response at the seating position. Can Audyssey help fix this?


Depends on what you’re talking about when you say “null.” Some people confuse a “trough” with a null. And some people assume that a bass “dead zone,” like you often have in the dead center of a square or rectangular room, is a null.

A true null is typically narrow and deep, as the picture below shows. Nulls can’t be corrected with equalization.









*Nulls before equalization*








*Nulls after equalization*​

A trough is usually a rather broad depression in response and can typically be corrected with equalization, as the graphs below show.









*Trough before equalization*








*Trough after equalization*​

A dead zone is problematic if your listening position happens to be in the middle of one, but not impossible to deal with. It only requires more gain from the sub, or perhaps additional subs to generate more output.

With that background, addressing your question as to what Audyssey can or will do with your null: Obviously it will depend on what your “null” actually is. Audyssey can compensate for a trough and a “dead zone” with appropriate equalization and / or boosting the sub level (if it does that – don’t have Audyssey personally). However, Audyssey will not be able to do anything with a true null.

Regards,
Wayne


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## Kal Rubinson (Aug 3, 2006)

Wayne A. Pflughaupt said:


> A dead zone is problematic if your listening position happens to be in the middle of one, but not impossible to deal with. It only requires more gain from the sub, or perhaps additional subs to generate more output.
> 
> With that background, addressing your question as to what Audyssey can or will do with your null: Obviously it will depend on what your “null” actually is. Audyssey can compensate for a trough and a “dead zone” with appropriate equalization and / or boosting the sub level (if it does that – don’t have Audyssey personally). However, Audyssey will not be able to do anything with a true null.


Agreed. I was taking him at his word that there was a real null to deal with and, as you say, Audyssey will not be able to do anything for that. It is, in fact, limited to about 9dB of boost, iirc, and, for a true null, that is like pouring a pint of water into a gallon bucket with a hole in it.

OTOH, Audyssey will help with troughs and peaks and, generally, will improve overall response as well as subjective enjoyment.


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## zheka (Jun 11, 2010)

Wayne A. Pflughaupt said:


> A true null is typically narrow and deep, as the picture below shows. Nulls can’t be corrected with equalization.
> 
> 
> View attachment 35214
> ...


Hi Wayne,

I noticed that, in my room, changing distance settings for subwoofers in AVR affects nulls, or what looks very much like the picture of null you posted. Does it mean it is not a true null then?


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

Hard to say for certain it’s a null in that case without trying to EQ. However, with the proper time alignment the problem should disappear.

Regards, 
Wayne


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