# REW waterfall graph



## Ashmanuk (Sep 14, 2007)

Hi al,

What does a good waterfall graph look like ? I will be measuring from say 10Hz to 100Hz they are two dual oppossed DIY subs I have built and would like to see what affect Audyssey XT32 has on and off through REW.

I have only ever used the plot graph with 1/3 smoothing, but reading on the web people seem to be using 1/12 smoothing ? If you could give me some tips that would be great as well.

Thank you


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## SAC (Dec 3, 2009)

An ideal waterfall shows a smooth frequency response (gain) with a smooth roll off without ridges (resonances).

I would suggest testing each sub's response individually and also another test with both driven. Make sure the mic remains in the same position for ALL tests. If you want to compare them with other sweeps later, you will want to establish a plumb bob or other method that will allow you to replace the mic capsule in the exact same spot.

With Audyssey turned off, use a full range sweep starting at, say, 5 Hz (instead of 0 Hz so that you do not get a warning) and let it run to about 20,000 Hz.

No smoothing.

If you like, after generate the sweeps, post the REW .mdat data file and we can help you window it, etc..


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## Ashmanuk (Sep 14, 2007)

SAC thank you for your help much appreciated. 

I think I have done a very stupid thing and got one of the inukes speaker cables around the wrong way and was out of phase  silly me

The bass response is even now across all my seats and needless to say much deeper 

Once again thank you.


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

Ashmanuk said:


> What does a good waterfall graph look like ? I will be measuring from say 10Hz to 100Hz


As you may know, waterfalls are only relevant for the bass region, about 200 Hz and below. A “good” waterfall will show full decay of about 300 ms or less, down to the room’s noise floor, from about 50 dB above the noise floor. Typically that’s unrealistic in most rooms that don’t have low-frequency treatments, though.




Ashmanuk said:


> I have only ever used the plot graph with 1/3 smoothing, but reading on the web people seem to be using 1/12 smoothing ? If you could give me some tips that would be great as well.


Typically no smoothing for a sub-only graph, and 1/3 or 1/6-octave smoothing for full-range graphs showing the upper frequencies. This eliminates the comb filtering most rooms display due to reflections, and lets you see the underlying frequency response.

It would be great to see some graphs – see here:

Posting A Graph
Getting Graphs Ready to Post


Regards,
Wayne


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## Ashmanuk (Sep 14, 2007)

Wayne A. Pflughaupt said:


> As you may know, waterfalls are only relevant for the bass region, about 200 Hz and below. A “good” waterfall will show full decay of about 300 ms or less, down to the room’s noise floor, from about 50 dB above the noise floor. Typically that’s unrealistic in most rooms that don’t have low-frequency treatments, though.
> 
> Typically no smoothing for a sub-only graph, and 1/3 or 1/6-octave smoothing for full-range graphs showing the upper frequencies. This eliminates the comb filtering most rooms display due to reflections, and lets you see the underlying frequency response.
> 
> ...


Hi Wayne  

Thank you I will follow those links, now I have both subs in phase it sounds so much more focused


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