# What does "Good" look like ?



## jstefano (Jan 2, 2008)

Can somebody point me to what a "Good" graph looks like for a Sub and Mains ? or where can I find info on interpreting my measurement's.
Thank you


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## brucek (Apr 11, 2006)

In a perfect world, a mains plus sub response looks like a flat line.

The pic below shows a perfect sub, and a perfect set of mains using a 80Hz crossover.

The resultant signal when they combine in the perfect room is a flat line.












brucek


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## LHD (Oct 10, 2008)

Bruce,

Why would you want a dip of 6db at the crossover point instead of overlapping flat and falling off on the other side?


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## brucek (Apr 11, 2006)

The graph shows the response of the sub and the response of the mains on the same plot (in blue). 
When signals leave the speakers they add, resulting in a flat response (as shown by the red line).

brucek


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## Sabby (Nov 10, 2008)

I am also using REW for the first time. Very powerful seeing the impact of the sub on the room and how movement and EQ changes the picture. My plot is similar to the one posted here. I am using an ART 351 for EQ. Where there are peaks can I cut them with the EQ and try to lower the overall level to the area of the nulls. I have lower output in the 60 to 85 hz range and have tried raising them with 6db on the ART with some improvement. Can I cut 40 and below to create a level output or is it better to leave the higher output for "movie impact" 

Similar to the plot posted in the range where I have lower output the lower output is there with mains only, sub only or both on. My crossover is at 90 - testing 60hz or 120 hz made little difference on the lower output in the 60hz to 85 hz range


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## brucek (Apr 11, 2006)

Sabby, Welcome, but I would prefer if you started your own thread and not hi-jack this one. 

Please include a jpg of your graph in your thread so it's easier to analyze your response.

If you need to add posts to clear the initial forum posting restrictions, go to the post padding thread and insert some pads.....

brucek


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## ludwignew (Nov 14, 2008)

About the subwoofer response, it has to be flat too or has to be like a "u" inverse form?

It depends on how do you want your sub to sound? If you want more impact or definition?


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## brucek (Apr 11, 2006)

Don't understand the question............


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## SteveCallas (Apr 29, 2006)

Here is an example of good....and extremely lucky. I had this response with no EQ in an apartment in St. Louis with vaulted ceilings and odd angled walls - there were no parallel walls in that place. Sub sat in the front left corner.


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## ludwignew (Nov 14, 2008)

Sorry, my english is not as good as yours.

What would be the best frecuency response for a subwoofer? It has to be flat?

Does it matter if you want more impact, or more sound definition?


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## ludwignew (Nov 14, 2008)

Thanks Steve.

Just a question. That graphic is with all your speakers or just fronts and sub?


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## thewire (Jun 28, 2007)

Impact and sound definition? Are you asking about the waterfall plots? Probobly not words I myself would use to describe a frequency response. If it is a house curve, or your running your subwoofer hot, this might fall more along the lines of human hearing. Human hearing is based on things such as amplitude, distortion, resonances. The difference for example with HD audio and other codecs is minor by comparrison. The fact is, there was once a time when all we looked at was a frequency response, but at this day and age we also look at decay. Here is a good example of a waterfall plot and an example of what good decay looks like.


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## SteveCallas (Apr 29, 2006)

ludwignew said:


> Just a question. That graphic is with all your speakers or just fronts and sub?


That was the sub and the mains only in stereo mode on my receiver. I wouldn't dare even think of trying to ensure my surround and rear speakers yielded a flat FR at my listening position - not because I don't think there would be merit in it or anything like that, but rather because it would probably drive me insane and take up way too much time :R


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