# Weird Waterfall charts



## buzztiger (Oct 16, 2006)

I have measured frequency response of my subwoofer sucessfully with room eq. However when trying to get the waterfall charts there seems to be a problem. Below is the kind of plot i obtain. Is this Right ? even when i measure other speakers in another room the decay is so long.


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## brucek (Apr 11, 2006)

> Is this Right ?


Sure, just use a reasonable scale.

Set vertical Graph Limits scale to 45dB-105dB.

Set horizontal Graph Limits scale to 15Hz-200Hz.

Click Log graph.

brucek


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## JohnM (Apr 11, 2006)

Even with more usual scale settings I doubt that is a valid measurement. You need to go back and make sure you can make a valid loopback measurement of your soundcard then check you are getting proper measurements of your system.


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## Blaser (Aug 28, 2006)

yes, otherwise that sounds like there is no decay at all...


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

buzztiger said:


> I have measured frequency response of my subwoofer sucessfully with room eq. However when trying to get the waterfall charts there seems to be a problem. Below is the kind of plot i obtain. Is this Right ? even when i measure other speakers in another room the decay is so long.


 
Wow, it feels like I’m looking into a fish tank... 

Regards,
Wayne


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## buzztiger (Oct 16, 2006)

After reading the post on hard knee house curve played around with BFD. Then i got the following graphs. Waterfalls look so horrible. I dunno how to solve this problem. I thought eq could help. Looks like it didn't.


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

It’s not as bad as you might think. For one, your level is really high. If it were down at the 80 dB range, as is more typical, it would look more like what you’re used to seeing on other threads. Also, switch the window to a longer duration, like 500 or 600.

Regards,
Wayne


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## brucek (Apr 11, 2006)

> Waterfalls look so horrible


Switch to LOG from LIN so it matches the Response graph. 

(I kinda feel 300msec time scale is best to use so you don't fool yourself into thinking all is well)

Lower the target so you have a more reasonable view of what's happening.

Either way, you can see how the signal at ~40Hz only drops about 8dB in 300msec. Even after 300msec, that signal will be quite present in the room. It starts to muddy the sound a bit. 

brucek


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## JohnM (Apr 11, 2006)

What EQ settings did you try? What effect did they have?


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## Blaser (Aug 28, 2006)

brucek said:


> Either way, you can see how the signal at ~40Hz only drops about 8dB in 300msec. Even after 300msec, that signal will be quite present in the room. It starts to muddy the sound a bit.


Supposing the measurments are correct, he need a BFD fast.


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## buzztiger (Oct 16, 2006)

blaser said:


> Supposing the measurments are correct, he need a BFD fast.


I am already using BFD.


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## buzztiger (Oct 16, 2006)

I have redone all the eqing from start after reading the hard knee house curve. Thankz alot for such a fantastic information Mr Wayne. Now the low bass sounds powerful. I have used house curve values given by Ayreonaut. These house curve values sounds the best for my room. Below are the new freq response and waterfall chart. Still got 40hz ringing. Any idea how to solve this ?


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## brucek (Apr 11, 2006)

> Still got 40hz ringing. Any idea how to solve this ?


Be sure it's a result of your signal and not simply noise in the room at that frequency.

Do a no signal spectrum to take a look. See here. Note the furnace noise in my spectrum.......

brucek


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

> Still got 40hz ringing. Any idea how to solve this ?


For one, don’t bet the farm on a single waterfall reading. Take several measurements and waterfall all of them – you’ll see that some will look better than others.

For another, your first graph showed ringing in the same place as the second one – only the signal level changed. A 600 ms window will show you what’s happening “long term,” whether the ringing eventually plays out or not.

Regards,
Wayne


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