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Discussion Starter · #1 ·
Hi. I stupidly went with reviews on a cheap logitech z-680 5.1 system. Mostly I am satisfied but the bass is ridiculously loud. Basically I have to put the bass level on the system to just above 0 to have it listenable and anything above that is silly.


I just moved into a new house and have one end of a 13 x 35 foot basement as my home theatre area. The theater is positioned perpendicular to the 35 foot run.


I can not control bass at the source (a dish/expressvu 922).


What would you do to decrease the bass output of this thing? Will muffling the bass do anything? Is plugging the air hole an effective muffling method? Can I aim the speaker at the floor?


Any help and positioning guidelines are appreciated. Thanks.


Brad Sears
 

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Plugging the port (aka air hole) would only probably lower the subs output at the lower frequences, but do close to nothing at anything else, and would probably risk damaging the driver itself as there may be times where it'd want to shoot past its excursion limits (bottoming out).


I doubt aiming it at the floor might help, but it's worth a try I guess.


Is it located into a corner? If so, try pulling it out more into the room.
 

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Discussion Starter · #3 ·
It is near a corner. I'll try some different placements and see if anything improves before I plug the port.
 

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Aha, that explains a lot. Let us know.
 

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I have the logitec 5100s with SB Audigy 2. I too had the same problem. I took the bass all the way down on the remote, and took the bass down on the console in the windows software... Works like a charm. The system sounds great!
 

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Discussion Starter · #6 ·
I can reduce the bass on my HTPC but not very well. I use the asus onboard sound via toslink at the moment and although it works for normal applications the dsp/equalizer is terrible.


I'm considering an Audigy. Can the Audigy process an external toslink feed like that coming out of my hd pvr? I'd like to be able to output both the HTPC and the pvr to the speakers. I have a toslink switch to change inputs.


Thanks for the help.
 

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Plugging the port is never dangerous to it. It WILL bring the volume down, but it will also bring the extention down (won't go as deep). It's getting closer to a sealed box like that. More like an aperiodic vent, but if you plug it well enough, sealed is a close enough approximation.


And yes, moving it out of the corner will bring the volume down as well.
 

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Quote:
Originally Posted by DonoMan
Plugging the port is never dangerous to it. It WILL bring the volume down, but it will also bring the extention down (won't go as deep). It's getting closer to a sealed box like that. More like an aperiodic vent, but if you plug it well enough, sealed is a close enough approximation.
Just curious as to how it isn't dangerous plugging the port.


According Unibox, when I plug my 5.5 cu.ft. sub, at 20hz, I'm about 6mm past xmax. I take it, in due time, this might really take a toll on the driver and eventually launch it to death. Take the plugs out, and I'm safe within xmax all the way.
 

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Sealed subs do NOT get more excursion than ported. That's just BS.
 

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Oh? Yet even the DIY sub experts at the PE boards think so.

As frequency approaches that at which the box is tuned, system output from the vent increases and is driven to full acoustic output by an ever-reducing excursion of the woofer itself. At this frequency, output comes almost exclusively from the vent and woofer excursion is at a minimum. This is quite different from a sealed system, where cone excursion increases four times for every octave of reduction in frequency. - http://www.termpro.com/articles/subwoof.html
 

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I believe that a sealed enclosure will require more power to produce the same level of output as a ported enclosure. With this in mind sealing the port in the enclosure in question should reduce the output using the same amount of input, which is the goal in this situation.
 

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Stuff a ferret family in it.





Seriously.
 

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Quote:
Originally Posted by Thomas Willard
I believe that a sealed enclosure will require more power to produce the same level of output as a ported enclosure. With this in mind sealing the port in the enclosure in question should reduce the output using the same amount of input, which is the goal in this situation.
Yup, but assuming the power supplied to the sub is enough to drive the cone past xmax, only then is danger involved.


I think if he plugs the port and doesn't hear any bottoming, he'll be fine, assuming reasonable listening levels.
 

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Quote:
Originally Posted by DonoMan
Sealed subs do NOT get more excursion than ported. That's just BS.
Mabey you should try covering the port & seeing for yourself on a ported system. You might just be suprised at how much more the driver will start moving.
 

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Quote:
Originally Posted by sonytheater
Mabey you should try covering the port & seeing for yourself on a ported system. You might just be suprised at how much more the driver will start moving.
Disclaimer: if you hear any clacking, it's not our fault. ;)
 

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Discussion Starter · #18 ·
With only a few minutes available last night I experimented by covering the port with good old duct tape. The volume did decrease thankfully.


The taped up port travells ~a centimeter with the bass tones. I'm much more in the range of listenable bass now and I'll experiment with placement options soon.


Thanks for all the comments.
 

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Move it out of the corner.
 

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Quote:
Originally Posted by bradsears
It is near a corner. I'll try some different placements and see if anything improves before I plug the port.
Move it out of the corner. You're picking up 6-12dB from the corner.
 
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