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Discussion Starter · #1 ·
I would like to use the SVS PB10-NSD response curve on SVS' website as the basis of my question. The sub starts to roll off at 20hz, but it still shows 80db of output at 15hz. If I watch a movie at a volume level of 80db or less, does that mean that I could see extension as low as 15hz?


I am trying to understand how to compare my own situation to what I see on these response curve charts. How does one compare what is in these charts to the type of performance that a person would get in their own room?


Thanks
 

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Typically the in-room response will be a little deeper than what's measured via the outdoor ground-plane technique. How much deeper it is will depend on the size of the room and whether the room is sealed or open to other rooms. Small sealed rooms give the most gain. Large open rooms show less gain. Different rooms can vary widely in how much room gain is seen. It is possible you may have some extension to 15hz, but it might not be strong enough to be noticeable. By that point the response is rolling off pretty rapidly.
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by mojomike /forum/post/15572826


Typically the in-room response will be a little deeper than what's measured via the outdoor ground-plane technique. How much deeper it is will depend on the size of the room and whether the room is sealed or open to other rooms. Small sealed rooms give the most gain. Large open rooms show less gain. Different rooms can vary widely in how much room gain is seen. It is possible you may have some extension to 15hz, but it might not be strong enough to be noticeable. By that point the response is rolling off pretty rapidly.

Thanks, and that is pretty much how I understood it. What I don't understad is the roll off. If I set the subwoofer to have an output similar to my mains, and I am watching some material at 80db, what will the frequency range be at that volume. Will the roll off be the same whether I am listening at 70db or 90db (about 13db from 15-20hz on the PB10-NSD), or will the frequency extend to 15hz at 70db because the response curve shows that it can provide that much output? I assume it is the former, and that I would need an EQ to make the sub flat from 15-80hz at 80db. Is that correct?
 

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The rolloff will remain the same until the sub begins to show signs of compression where the ratio of the output at deeper frequencies can no longer keep up with the volume you dial up. You may also reach a point where limiters kick in to protect the woofer from damage. Also as you increase the vaolume, the percentage of distortion can start to become significant.
 

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Quote:
Originally Posted by brianjb /forum/post/15573244


Thanks, and that is pretty much how I understood it. What I don't understad is the roll off. If I set the subwoofer to have an output similar to my mains, and I am watching some material at 80db, what will the frequency range be at that volume. Will the roll off be the same whether I am listening at 70db or 90db (about 13db from 15-20hz on the PB10-NSD), or will the frequency extend to 15hz at 70db because the response curve shows that it can provide that much output? I assume it is the former, and that I would need an EQ to make the sub flat from 15-80hz at 80db. Is that correct?

In addition to what mike said, you have to realize that very low tones have a higher threshold of audibility. The thereshold of audibility at 15 Hz is 90 db. The PB-10 simply will not put out 90 db at 15 Hz in your room.


Ported subs, like the PB-10 usually have a filter that rolls off response below the resonant frequency to protect the driver from damaging itself trying to reproduce loud sounds below its resonance frequency.


As the tone gets lower and closer to the resonance frequency the cone moves less and more and more of the output comes from the port.


Useful response of the PB-10 is 18 Hz. Once the output falls 3 db down, the sub is about done.


Adding EQ (to extend low frequencies) to a relatively small sub like the PB-10 generally doesn't work because the driver and amp are already at their limits.
 
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