# help with frequency response in listening position



## theshade (Oct 21, 2007)

I measured the following using a radioshack sound level meter using the six octave files from 16 to 160 hz and entered them into the worksheet compensation charts for the 4050 radioshack. All measurements were started at 16 hz 80 db. The subs are an adire tempest 15 inch in a sealed enclosure and a kicker solobaric 10 inch in a ported 22 hz tuned enclosure. One measurement is for the adire only, another the kicker only and another for both. I have the following questions:

1. Are the frequency responses normal? I remember not having that much deviation when I measured the adire in another room. 
2. If used singly what measurement would you guys prefer? 
3. Is the green response which is for both subs better than the subs measured alone? 
4. Can you guys recommend what to do with the measurements? I will be using a Behringer BFD.

Thanks.


----------



## fusseli (May 1, 2007)

In what environment did you take the measurements and where was your meter in relation to the subs? Do you have a computer that you could use to take some measurements with REW?


----------



## theshade (Oct 21, 2007)

The measurements were done in room. One sub placed about 2 inches from a side wall and three feet from the corner. This sub is beside the listening position. The other sub is at the opposite end of the listening position flush in a corner. The sound level meter is placed at the listening position. I have a computer but don't have a sound card as recommended by the rew threads. I just used the excel file for the 4050 radioshack.


----------



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

> 1. Are the frequency responses normal? I remember not having that much deviation when I measured the adire in another room.
> 2. If used singly what measurement would you guys prefer?
> 3. Is the green response which is for both subs better than the subs measured alone?
> 4. Can you guys recommend what to do with the measurements? I will be using a Behringer BFD.


Yes, the response is perfectly normal. If the response was perfect, that would not be normal.  You’re going to get different response in every room, so it’s also normal that you got a better measurement with the Adire in another room.

The green (both) measurement looks better than either singular measurement. Dealing with the 31-60Hz depression with a BFD would definitely make an audible difference. :T

Regards, 
Wayne


----------



## theshade (Oct 21, 2007)

Thanks for the response. I just measured again summed responses last night. I changed crossovers and phase and came up with new responses. The red one and the blue one. The green one is the measurement before. 

 

I also tested them all watching clips of War of the Worlds and Underworld Awakening. I did not see the graph of the measurements until a few minutes ago when I inputed them into the excel file. I just wrote down the readings of the SPL meter last night. 

Based on my tests of the clips, I liked the blue one most. When I watched a full movie though(Rise of the Planet of the Apes), the bass seemed a tad too powerful and had to put -4b from the sub response in the receiver. It seemed perfect. Now looking at the graph it seems that the low frequencies are way overblown even though I liked what I heard and felt. What do you guys think is the best measurement? Is the blue one a house curve? Do I still need to equalize it?


----------



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

I’d equalize it. Whatever you did to get the blue trace, that’s the one you want. If you flatten out that bit hump at 28 Hz, you’ll have some awesome response. :T

Regards, 
Wayne


----------



## theshade (Oct 21, 2007)

Thanks for the reply. Ill also try to measure again this weekend while repositioning a bit and maybe I can get a better response with equalization. Ill also try to measure 70 db reference 16hz on SPL meter. I used 80 db and realized now from browsing the forum that 70db is being used. Please also correct me if I'm wrong. I set the levels of the fronts surround and sub to about the same db using the receiver when I do measurements. 

On movies, I am happy with the blue one but on music no. I get dif pressure from right ear and left ear. Pressure on right ear seems to be stronger. I tested using Spanish Harlem by Stacy Kent and So Nice by Stacy Kent and Jim Tomlinson. Maybe I just need to attenuate that peak like you suggested. I thought it could already act as a house curve. 

Based on the blue measurement however, I will study how to do the BFD again. The last time I used it was ages ago. And I forgot how to do it. Preliminary questions though. 1 filter 28 hz? Attenuate by 10 db? Wide bandwidth? Forgot about the bandwidth fine etc though. Anyway, I'll try to study them. 

Thanks a lot for helping.


----------



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

theshade said:


> Preliminary questions though. 1 filter 28 hz? Attenuate by 10 db? Wide bandwidth?


That’s basically it. :T The peak is asymmetrical, though (meaning it’s steeper on one side than the other), so it’ll probably take an additional filter somewhere around 22 Hz to finish things off.

Regards, 
Wayne


----------



## theshade (Oct 21, 2007)

I drastically changed the positions inside my room. I removed the room divider. Inverted the placement of the tv and front speakers. Listening position is now in the middle of the room. Measured the responses of the subs when placed in different positions. It took a lot of patience measuring, listening to music and movies for each change in position. I am happy now though.

Final positions of the subs are middle of front wall and 1/3 of back wall. -10 db for the sub in the receiver.

Measurements below are without using the BFD. The red trace is for the summed response. Does this still need equalization? I don't know if the measurement is perfect but finally I am happy with the sound for both music and movies. Thanks.


----------



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

Hey rock,

Your summed response curve is one of the best I’ve seen without equalization. :T EQ could clean up things further, but the audible results would be much more subtle than the improvement you got between your first and last graphs.

Regards, 
Wayne


----------

