REW Frequency Response Measurements

[Jim W]

Greetings. I am new to this site and new to using REW and I hope someone can help me. I am in the process of subwoofer optimization and have been moving my 2 subs (JL Audio F113s) to various points in my room and measuring their responses at my 2 main listening positions. I have not even started attempting to phase match them but am just looking for the best locations first. I should also add that my listening room is less than optimal, as it has an opening and stairwell on one side in the front. Long story short, my room has some issues but what surprised me is that the frequency response for each listening seat hardly changes from subwoofer location to location. I would have expected a significant change from the subwoofer moving from the front center of the room to one of the rear corners but there was not one. Is this just because of my room or am I doing something wrong, which is entirely possible! If I increase the sub volume, the entire frequency response line moves up in sync. In my rudimentary understanding of accoustics this seems to imply that the large dips are not nulls and I wonder if I need to add additional subs to address the higher volumes I will need to fix the dips. I have attached my frequency responses for each sub location. I really appreciate any help. Thanks.

 

[John Mulcahy]

If the measurements are for different subwoofer positions in the room then what you are measuring must not be the subs, maybe the signal is coming from the main speakers? The output is being sent to L+R, if the main speakers are set as full range there wouldn't be any redirection to the subs.

 

[Sonnie]

F113s should be producing much higher output in the lower range, especially when in the corners.

I agree with John... perhaps you don't have your main L+R set to small with a crossover... and the signal repeated comes out of the mains.

Set the mains to small with an 80Hz crossover, and then start by measuring only the center primary listening position so that you can address the timing as well.

 

[Jim W]

If the measurements are for different subwoofer positions in the room then what you are measuring must not be the subs, maybe the signal is coming from the main speakers? The output is being sent to L+R, if the main speakers are set as full range there wouldn't be any redirection to the subs.

Thanks. In fact I did have the mains set to small with a very high (200 hz) crossover when I ran the sweep so it should have just been the subs. My main speaker are small 2-way Paradigm signatures so they don't go down very low. I also made sure all the eq was turned off on the JL 113s. Any other ideas? Could it be caused by my room? Thanks Again

 

[Jim W]

If the measurements are for different subwoofer positions in the room then what you are measuring must not be the subs, maybe the signal is coming from the main speakers? The output is being sent to L+R, if the main speakers are set as full range there wouldn't be any redirection to the subs.

I could have sworn I checked and re-checked the crossovers but I had failed to change the LR crossover (in spite of changing the others) so it was exactly what you thought! I feel very stupid now and am sorry to have wasted your time. Lesson learned is to check, re-check and re-check again all the basic settings.

 

[Jim W]

F113s should be producing much higher output in the lower range, especially when in the corners.

I agree with John... perhaps you don't have your main L+R set to small with a crossover... and the signal repeated comes out of the mains.

Set the mains to small with an 80Hz crossover, and then start by measuring only the center primary listening position so that you can address the timing as well.

Exactly what the problem was and as noted I didn't catch it and was certain that was not the issue. Not my best moment but I do appreciate your help too. Thanks.

 

[Sonnie]

Hmmm... looks like the subs have not moved in these measurements. It looks just like the response is coming from the mains.

 

[Jim W]

Hmmm... looks like the subs have not moved in these measurements. It looks just like the response is coming from the mains. View attachment 42069

Yes that is exactly what the problem was. Thanks again for your help. This is sometimes a vexing hobby!

 

[John Mulcahy]

Glad you worked it out