Can I down hz by largering ports?

nicasiox2

Member
2016-01-06 6:53 am
Hi, My sub brand said that I should build an enclosure which is 4.0 3f, and has (2) 4" round ports with a length of 15.75", doing that result in a box with a frequency of 28.5 hz.

Can I down some hz modifying the port length to for example 24", keeping same port diameter and of course, adjusting the total volume, because now larger ports are taking more volume, so I need to compensate that. Is that simple?

I want it to at least 24hz. :snoopy:
 

nicasiox2

Member
2016-01-06 6:53 am
Maybe.. depends if the driver can take it. Can you provide a link to the sub driver?

Sure, this is the subject :D.
BAMF-152 | PowerAcoustik

I am wondering how large can I make them without changing the diameter 4" and disrupting the quality sound, because if i modify that value, is expecting improving performance as much as possible. I am playing with Win ISD, seems I am going to need a tutorial, don't understand almost everything. Thanks.
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
You need woofer specifications Fs, Qts, Vas, etc... to see how lengthening a port will affect sound. It may actually just make slightly less bass above tuning.

If the ports tune to 28.5, they will tune to 24 by making them about 50% longer.

In a car, going sealed instead can actually get you bass down to 0Hz ;)
 
Hi nicasiox2.

I couldn't find the T/S parameters for this subwoofer so without them it's going to be a total guess as to what would work for that subwoofer. PowerAcoustik posts recommended box volumes but not a tuning frequency for the bassreflex. As for how low you can tune the enclosure it depends on the driver and the response your shooting for. When building bass reflex enclosures for car audio it's not necessary to tune very low and could sound very bad. If your wanting sound quality I would go sealed. If you want everyone to here you from blocks away go bass reflex. After having my vehicles broken into and the stereo equipment taken I don't want people to here me from blocks away any more.

Regards,
Matt
 

nicasiox2

Member
2016-01-06 6:53 am
Oh I see, I have the T/S parameters just right here:

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Hi nicasiox2.
After having my vehicles broken into and the stereo equipment taken I don't want people to here me from blocks away any more.

Regards,
Matt

Anyway I think that it's not a good idea driving while listening at very high power, I instead think that if you want to experience your music at very high levels, go to a place where's there's no people, go to a rural area, or anywheres not a problem listening at high power, you know, the police, etc. That's the only reason I would want a powerful equipment, you can always listening at low volume when driving.
 

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I made a couple quick calculations for a bassreflex. The BB4 alignment will give you a smaller enclosure with a Vb= 2.6cu.ft Fb=32.8 and an F3=28hz. Or a C4 alignment with a Vb= 5.35cu.ft Fb=23.6hz and F3=20.5. The F3 in the calculations are for free field measurements so in car responses will be much lower. There are many more alignments available, I just picked these as an example. Also if your interested a sealed box with 2.96cu.ft will give you a Qtc of .707.

Regards,
Matt
 

nicasiox2

Member
2016-01-06 6:53 am
I made a couple quick calculations for a bassreflex. The BB4 alignment will give you a smaller enclosure with a Vb= 2.6cu.ft Fb=32.8 and an F3=28hz. Or a C4 alignment with a Vb= 5.35cu.ft Fb=23.6hz and F3=20.5. The F3 in the calculations are for free field measurements so in car responses will be much lower. There are many more alignments available, I just picked these as an example. Also if your interested a sealed box with 2.96cu.ft will give you a Qtc of .707.

Regards,
Matt

Hey, thanks, now that you mentioned that I can get a Qtc of .707 by only increasing the sealed recommended size, I think I will go with that, don't want to go beyond than 4.0 3F, you know, the inconvenience of big things.

Now just wondering if is it true what this brand says, that this thing pushes 1900w RMS, 3800w peak power, even very cheap, in the $150 range.
 
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