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Discussion Starter · #1 ·
I was Curious how the ULF trim behaved on my HSU ULS-15 Dual drive.

I downloaded some tones from the web. I picked sub 20 hz tones to see the behavior of the ULF adjustment.


The FR I got surprised me. The system sounds good but the drop is SPL did not appear normal to me.


How should I interpret this? These are from the listening position which is 30" off the back wall. After considering it I thought I might have measured too close to the wall and was getting excess gain effect from the wall.

This is corrected with the ULF set to 16hz. Audyssey on Dynamic EQ on.


 

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Quote:
Originally Posted by t6902wf /forum/post/15506018


I was Curious how the ULF trim behaved on my HSU ULS-15 Dual drive.

I downloaded some tones from the web. I picked sub 20 hz tones to see the behavior of the ULF adjustment.


The FR I got surprised me. The system sounds good but the drop is SPL did not appear normal to me.


How should I interpret this? These are from the listening position which is 30" off the back wall. After considering it I thought I might have measured too close to the wall and was getting excess gain effect from the wall.

This is corrected with the ULF set to 16hz. Audyssey on Dynamic EQ on.




ULF Trim at 16 is to get flat response to 16 Hz OUTDOORS.


I think you are thinking about it the opposite way.


So, the more reinforcement you need, the lower you set the ULF Trim.


Try setting ULF trim to max, 50Hz, and rerun your graph.
 

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Somehow I doubt that graph is really a true response. Can you measure it using REW?
 

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Discussion Starter · #4 ·
I don't have REW.


ULF set to 16 does nothing it does not reinforce 16hx it just does not roll it off.


Here is the readings with it set to 50hz. You can see that it rolls off the low frequencies. This is how I have run the system with ULF set to 50.

 

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Discussion Starter · #5 ·
I doubted the graphs also so I got REW up and going and this is what I cam up with.


The graph is with ULF trim at 50Hz, no Audyssey.


 
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