Do Cheap Ported Subs Have High Pass Filters? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 5 Unread Yesterday, 04:49 PM - Thread Starter
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Do Cheap Ported Subs Have High Pass Filters?

The setup I'm currently working on is somewhat unique in that I live in an apartment, but I have a general idea of how low frequency sound travels and how to tune things to avoid pissing people off. I'll be running everything from a htpc/gaming pc and should have access to some decent software for eq/filtering. With that In mind I figure the best route is a near field subwoofer setup, with an additional low pass filter applied in software, to really focus the energy into nailing flat to ~25 hz while keeping the volume low. I can then use some bass shakers for tactile feel.

This is by no means going to be a "reference level" setup, I'll probably have to apply some compression in software as well to ensure lower db details aren't lost in games/movies. Considering that I want to hear the bass frequencies from the sub, not so much feel them, any basic 10-12" cheap sub should have enough driver excursion to make 25hz audible at well below reference spl. The only problem is that most cheap subs are ported, and port tuned well above 25hz, so as to avoid blowing them up at levels that most people buying cheap subs are accustomed to.

In a well designed ported sub, there is generally a high pass filter involved to avoid over excursion below the port tuning point, can anyone name a few cheap sub brands that don't bother with the high pass filter? There is little point in eq to flatten out the range if a built in filter is going to thwart my efforts. I can block the port easily enough, but I imagine removing a hpf may be a little more involved...

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post #2 of 5 Unread Yesterday, 11:24 PM
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Originally Posted by AVMB View Post
Considering that I want to hear the bass frequencies from the sub, not so much feel them, any basic 10-12" cheap sub should have enough driver excursion to make 25hz audible at well below reference spl. The only problem is that most cheap subs are ported, and port tuned well above 25hz, so as to avoid blowing them up at levels that most people buying cheap subs are accustomed to.

In a well designed ported sub, there is generally a high pass filter involved to avoid over excursion below the port tuning point, can anyone name a few cheap sub brands that don't bother with the high pass filter? There is little point in eq to flatten out the range if a built in filter is going to thwart my efforts. I can block the port easily enough, but I imagine removing a hpf may be a little more involved...
Last I recall, the budget BIC PL-200 or F12 hit into the mid to low 20s, both can be found around $200-300, but you didn't mention a price point. Not sure about their HPF or tuning points though

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post #3 of 5 Unread Today, 12:45 AM - Thread Starter
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Originally Posted by Sekosche View Post
Last I recall, the budget BIC PL-200 or F12 hit into the mid to low 20s, both can be found around $200-300, but you didn't mention a price point. Not sure about their HPF or tuning points though
Hmm, sounds suspicious, would that be at +-3db? If it's close enough a little eq should close the gap, but I really don't want a boombox. I'm considering anything 500$ or less Canadian, but the less I have to spend to achieve the goal, the better.

Update:
Yeah, the Bic PL200 is -14db at 25 hz, I don't think room gain is going to help there, unless I build a home theater in a closet http://www.data-bass.com/data?page=system&id=47&mset=45
I seem to recall a frequency response mapping program for windows...I wonder if it can reverse engineer Thiele/Small parameters from a frequency response curve and enclosure capacity, would be useful in seeing the ported to sealed conversion outcome.

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post #4 of 5 Unread Today, 06:54 AM
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Short answer: No. That's one of the reasons why they're cheap.

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post #5 of 5 Unread Today, 08:30 PM
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Quote:
Originally Posted by AVMB View Post
Hmm, sounds suspicious, would that be at +-3db? If it's close enough a little eq should close the gap, but I really don't want a boombox. I'm considering anything 500$ or less Canadian, but the less I have to spend to achieve the goal, the better.

Update:
Yeah, the Bic PL200 is -14db at 25 hz, I don't think room gain is going to help there, unless I build a home theater in a closet http://www.data-bass.com/data?page=system&id=47&mset=45
I seem to recall a frequency response mapping program for windows...I wonder if it can reverse engineer Thiele/Small parameters from a frequency response curve and enclosure capacity, would be useful in seeing the ported to sealed conversion outcome.
You can use https://sourceforge.net/p/equalizera...ation-tutorial with REW to EQ. Not sure how something like the BIC PL200 would sound EQed flatter. I honestly didn't think it sounded too bad for music. At lower listening levels like you mention I think it could work. Depends on how picky you are and the pickier you are the more money that costs

Something like the Ultra12x would definitely hit 25hz with ease and has much SQ but is also over twice the price of the BIC. I have both subs and to me, the BIC sounds fine in a small room for music. I use it for my small desktop PC setup in a spare bedroom and it hits hard and sounds good to me. Sure it is not on the level of a Submersive but there is a slight price difference.

Anyway, I have used the Equalizer APO and it works pretty good. I haven't used it with the REW EQ feature that you can transfer the REW eq settings over to APO but I see that it can be done. I run my main living room, projector system thru my HTPC and mess around with APO and I like it but I usually leave it off and just use Audyssey LR bypass so no EQ on my mains and just EQ on the subs.

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