Sub bottoming out

[alexwakelin]

My HT system is pretty modest, Sony STR-DG510, 5x JBL venues and a Dayton 8" sub. This system is pretty much exclusively used for watching movies. As you've gathered from the title I have a problem with the sub bottoming out on bass heavy scenes in movies. When I originally purchased the sub I knew I would eventually replace it and it would become my computer sub. I don't listen at extemely loud volumes, I don't think my receiver has ever been turned up past 50%, and I turn the sub up just enough to feel the bass. I'm probably just expecting too much from a small 8" sub.

So, my question is how much sub do I need to fix my problem? I know this is a very subjective question. My room size is 13x17. If I step up to the dayton 12", just how much "more sub" would I be getting? Dayton claims 35hz for the 8" and 25hz for the 12". Do subs bottom out because of the driver size/too much power or because they are trying to go lower than the rated frequency? I know I can set the crossover frequency in the sub, but is there a way to set it up so it doesn't go lower than the rated 35hz? Sorry for having so many questions, I'm still a bit of an audio noob.

 

[TLS Guy]

My HT system is pretty modest, Sony STR-DG510, 5x JBL venues and a Dayton 8" sub. This system is pretty much exclusively used for watching movies. As you've gathered from the title I have a problem with the sub bottoming out on bass heavy scenes in movies. When I originally purchased the sub I knew I would eventually replace it and it would become my computer sub. I don't listen at extemely loud volumes, I don't think my receiver has ever been turned up past 50%, and I turn the sub up just enough to feel the bass. I'm probably just expecting too much from a small 8" sub.

So, my question is how much sub do I need to fix my problem? I know this is a very subjective question. My room size is 13x17. If I step up to the dayton 12", just how much "more sub" would I be getting? Dayton claims 35hz for the 8" and 25hz for the 12". Do subs bottom out because of the driver size/too much power or because they are trying to go lower than the rated frequency? I know I can set the crossover frequency in the sub, but is there a way to set it up so it doesn't go lower than the rated 35hz? Sorry for having so many questions, I'm still a bit of an audio noob.

If your receiver has an infrasonic filter use it. I assume this sub is ported. In any ported enclosure, the driver will off load below F3, and the cone excursion will rapidly increase below that. If the excursion exceeds the drivers mechanical limits then you will have bottoming, which damages the driver.

Take a look at these graphs, and pay particular attention to the cone displacement graph, of this 12" vented sub.

Now look at this same driver in sealed alignment.

A sealed sub does not suddenly offload, but the drivers limits can still be exceeded.

 

[Exit]

I have an 8" driver subwoofer that bottoms out too on low bass. Does anyone know of an inexpensive solution to cut off the low frequencies at some point such as 50Hz, for example, to make the subwoofer more usefull?

 

[TLS Guy]

I have an 8" driver subwoofer that bottoms out too on low bass. Does anyone know of an inexpensive solution to cut off the low frequencies at some point such as 50Hz, for example, to make the subwoofer more usefull?

If you place a filter starting to roll off at 50 Hz, you won't have a sub any more. That point is about an octave above prime sub territory.

 

[j_garcia]

What you really want to filter out is probably about 20Hz and below with a sub that is -3dB at 35Hz. It is the subsonics that could be causing your problem, but I do think you are expecting a bit much from that sub.