Ported and enclosed

[P057]

Yeah you might have come in here when reading the title thinking wtf?

This is a dumb question since i know it CAN be done, but i'm wondering if its going to sound ....WORTH the trouble...

Can you mix Ported with enclosed subs? just wondering..

i already have ported and i love the loud clear bass but sometimes i hate the low responsiveness.. I would like enclosed subs to play back only a certain frequency, usually the frequency has a nice quick punch to it that the ported is a little laggy in.

....Wondering if it'd work....

[Notladstyle]

Yeah you might have come in here when reading the title thinking wtf?

This is a dumb question since i know it CAN be done, but i'm wondering if its going to sound ....WORTH the trouble...

Can you mix Ported with enclosed subs? just wondering..

i already have ported and i love the loud clear bass but sometimes i hate the low responsiveness.. I would like enclosed subs to play back only a certain frequency, usually the frequency has a nice quick punch to it that the ported is a little laggy in.

....Wondering if it'd work....

Yeah its called a bandpass box -

you put a ported box on one side and a sealed box on the other side of the sub - they are actually more innacurate than a vented or sealed box but they have somewehre around a +10db gain when properly tuned at the tuning freq but a much more bumpy slope in response on either end of their response range.

For SQ and clean response you cant beat a sealed box.


**EDIT**

Now that I think about your Q, are you saying put one ported and one non ported?

If so then having them both running the same signal will be really dirty bass as the response will be totally different for both speakers but if you were to say set one sub to 30-60hz and the other to 60-120hz it would probably give you improved performance and also take advantage of each box's traits.

Rather than a port & sealed I would use two ported boxes - one for really LOW like ported to 25hz and the other ported to like 40hz with crossovers complimenting their port freqs.

[P057]

Now that I think about your Q, are you saying put one ported and one non ported?

If so then having them both running the same signal will be really dirty bass as the response will be totally different for both speakers but if you were to say set one sub to 30-60hz and the other to 60-120hz it would probably give you improved performance and also take advantage of each box's traits.

Rather than a port & sealed I would use two ported boxes - one for really LOW like ported to 25hz and the other ported to like 40hz with crossovers complimenting their port freqs.

yeah thats what i meant, but i was leaning towards the second part of your idea in the first paragraph. Right now my ported dual 12's are both running from 35hz to i THINK (from last time i looked) 80 hz I'm thinking of turning it down since its picking up a lot of junk i dont really want... too bad the stupid MP3 recordings are junk and drop out a lot of random bass frequencies =/ it sounds really weird when one freq is REALLY emphasized and sounds great and the song decides to change the freq and the mp3 encoding drops it out and then it changes freq again (its increasing a bit) and then my subs pick the sound up again =\.

I cant get this music anywhere else so i have to deal with it unfortunately =[.

[Notladstyle]

yeah thats what i meant, but i was leaning towards the second part of your idea in the first paragraph. Right now my ported dual 12's are both running from 35hz to i THINK (from last time i looked) 80 hz I'm thinking of turning it down since its picking up a lot of junk i dont really want... too bad the stupid MP3 recordings are junk and drop out a lot of random bass frequencies =/ it sounds really weird when one freq is REALLY emphasized and sounds great and the song decides to change the freq and the mp3 encoding drops it out and then it changes freq again (its increasing a bit) and then my subs pick the sound up again =\.

I cant get this music anywhere else so i have to deal with it unfortunately =[.

even 128kb/s (so called CD quality) drops freqs below 30hz and compresses everything from 30-120hz so badly its impossible to get a good clean bass signal from it.

I used to download music from kazaa n stuff but now that I have excellons all the way around I can hear the distortion so I started using bittorrent to download whols CDs in ISO format. 100% pure audio - just takes a little longer and you have to download 400mbs...

[TBSpyder]

One sub playing at a different frequency than the other you mean? Don't do it. Your box may just be tuned improperly. Otherwise, you could get some 3 ways for up front...and build small enclosures in your doors for the mid woofers to give you more of that tight kick.

[TJElite]

One sub playing at a different frequency than the other you mean? Don't do it. Your box may just be tuned improperly. Otherwise, you could get some 3 ways for up front...and build small enclosures in your doors for the mid woofers to give you more of that tight kick.

I have to agree here. Just changing the port tuning frequency of the box won't do what you are looking for. The response curve of a ported enclosure is dependent on the TS parameters of the speaker...not just the tuning frequency. Unless you have a pretty good modeling program, you'll probably never get it right.

I think you're also backwards in your thinking. From your first post, you seem to not like the low bass coming from your ported subs, so you want to add some sealed. In a car, a sealed box will reproduce lower frequencies than a ported box, in almost all instances. A ported box has very little output below the tuning frequency, usually between 30-45 hz. So, adding a sealed subwoofer will only increase the bass output below this region.

What I think you are hearing is the increased output around the port frequency. I would guess that if we modeled your box, we'd see a pretty big hump in the response. This is one of the pros (and one of the cons) of a ported box...you can get significantly more output at certain frequencies. Depending on the size and shape of this hump, it can be a good thing, or a very bad thing.

So, here is what I suggest, in order:

1. Switch to a sealed box. As NotLADstyle said, you can't beat them for all around sound quality and simplicity. Just about every kind of music will sound good on a properly designed sealed system.

2. Add some serious midbass, preferably up front. In my opinion, this is one of the most overlooked areas in car audio. This could actually be step one, as it is a good idea in any case, but I think switching to a sealed box is more important for you. Most people don't have enough midbass, and if they do, its usually in the rear of the car. I'd suggest at least 6 1/2s in the doors. TBSpyders idea of a small enclosure is excellent. I also like the 3-way suggestion. Let the 6 1/2 be a midbass. It should have a LPF, ideally down around 500 hz. You can get by with a good 2 way system, but it still needs a LPF, even though it will probably be up around 3khz. Most Coax's are out, here, but any midbass up front is better than nothing.

3. Get your existing box modeled, and see what it looks like. We use Bassbox for this, and its very enlightening. Ideally, you'd also get the acoustics of your car mapped with an RTA. After you know all of this, you're might find you need a new box. Remember, there are always trade-off's...tuning that makes your system sound truly huge on some music (or even just some songs) can make it sound really bad in other places. If all you listen to is rap, this can be mediated (there are still gives and takes, though). If you like to listen to lots of different music, you'll need to give up more output, in trade for smoother freq. response. In the end, your speaker selection and your car acoustics will play big roles in this. You might find that you have trouble getting a ported design that you like. Refer to suggestion 1.


Step one is pretty easy for any doityourselfer. Step 2 is not much more difficult, but you might want to get some help on speaker selection. Step 3 will probably require you to find a shop, or other professional.

Toby

[Notladstyle]

Its like a research paper except with no numbers/formulas. I challange everything you wrote above not because I read it but because I didnt see any numbers while I skimmed through it.

[TJElite]

Its like a research paper except with no numbers/formulas. I challange everything you wrote above not because I read it but because I didnt see any numbers while I skimmed through it.

I did use some numbers, so your skimming skills need improvement. :D

What sort of numbers would you like? Since he didn't give me any speaker or box parameters, all I could talk in was generalizations.

If I had TS and box parameters, not only could I give you numbers, I could paste scientific looking little graphs in here, as well.

Would that make you warm and fuzzy inside?


Toby

[Notladstyle]

I did use some numbers, so your skimming skills need improvement. :D

What sort of numbers would you like? Since he didn't give me any speaker or box parameters, all I could talk in was generalizations.

If I had TS and box parameters, not only could I give you numbers, I could paste scientific looking little graphs in here, as well.

Would that make you warm and fuzzy inside?


Toby

freq. response for two identical subs one ported and one sealed at 27hz.

[TJElite]

freq. response for two identical subs one ported and one sealed at 27hz.

OK, what are the specs of the ported box? what size sealed box? Any particular woofer?

I'll take a couple of liberties in the meantime. Here is a Crossfire BMF1028, 10" woofer in a sealed 1 cu ft box vs. a 1 cu. ft box tuned to 35 hz. The orange is the ported response, the red is sealed.

At 27hz, the sealed box is approx. 0.5 db louder than the ported. You can also see how the ported box rolls off at approx. 12db per octave from 50 hz, while the sealed rolls off at a shallower 6 db per octave.

Since these are arbitrary designs for an arbtrary woofer, I don't know how this pertains to the original question. But you asked for it.

Toby

[Notladstyle]

OK, what are the specs of the ported box? what size sealed box? Any particular woofer?

I'll take a couple of liberties in the meantime. Here is a Crossfire BMF1028, 10" woofer in a sealed 1 cu ft box vs. a 1 cu. ft box tuned to 35 hz. The orange is the ported response, the red is sealed.

At 27hz, the sealed box is approx. 0.5 db louder than the ported. You can also see how the ported box rolls off at approx. 12db per octave from 50 hz, while the sealed rolls off at a shallower 6 db per octave.

Since these are arbitrary designs for an arbtrary woofer, I don't know how this pertains to the original question. But you asked for it.

Toby

hmm looks like not only does the sealed box hit cleaner, it hits lower.

[TJElite]

hmm looks like not only does the sealed box hit cleaner, it hits lower.

Ding, ding, ding, ding, ding...

Johnny, tell him what he's won...

Toby

[P057]

Yeah i was just curious, im not spending any money till i buy my Z32 =P

[Notladstyle]

Ding, ding, ding, ding, ding...

Johnny, tell him what he's won...

Toby

another subwoofer to go into my horribly oversized enclosure?

[P057]

Yeah i was just curious, im not spending any money till i buy my Z32 =P

I'm ok with my dual 12" ported polk and my infinitys. Thats perfect for now. I'll think about sealed for the Z32 =/ especially since it has a bit more confined space than my altima trunk.

But yeah cool info guys, thanks for the heads up and bring down on my ported

notladstyle really answered a lot, i knew mp3's fked up my stuff but i didnt think to that extent, too bad i dont have the originals of the music i have, its hard to find so im kinda stuck with it. i guess good thing is the more recent the release the better the bass.

I wish i knew some good music to really get the bumpin going.

[TBSpyder]

I wish i knew some good music to really get the bumpin going.


http://www.tamparacing.com/forums/audio-hq/286974-all-time-best-songs-jam.html

[TJElite]

notladstyle really answered a lot, i knew mp3's fked up my stuff but i didnt think to that extent, too bad i dont have the originals of the music i have, its hard to find so im kinda stuck with it. i guess good thing is the more recent the release the better the bass.

I wish i knew some good music to really get the bumpin going.

A lot depends on how the MP3's are encoded. The secret is in the bit rate. Higher bit rate = better sound. Problem is that higher bit rate also takes up lots more room. The answer is variable bit rate.

I use two programs, both free. The first is called exact audio copy. This program makes a copy of any CD. The neat part is that it uses error checking to make perfect copies, even from banged up CD's. It won't work with seriously trashed CD's, but most scratches, etc. seem to be fine.

The second program is called LAME. Its an MP3 VBR creation algorythm created by some guys at MIT (I think). Its built in to EAC. It basically goes through and assigns bit rates based on musical content. The higher the complexity, the more bit rate it gets. This gives high sound quality, in small spaces. I've got an IPOD full of VBR tunes done this way, that I'll be happy to let you all listen to on Saturday. Some of it is pretty complex music, and I can't tell any difference from the original CD.

One more thing to note, this applies to MP3's only. The Itunes stuff is actually AAC, which is the audio Codec of MP4's (movies). A 128kb/s AAC is significantly better than a 128kb/s MP3. For MP3's, you need to be in the 300+ Kb/s to sound good. LAME encodes up to 600 something. That's the problem with most peer to peer song shares...big bit rate = big size = long transfer time...so most rips are of very low bit rate.

Toby

[P057]

yeh, i know all of that, i just didnt know it knocked off so much out of the bass section. Makes sense since most people would listen to their mp3s on their headphones or something which produce (GENERALLY) not too much heavy bass.

I like VBR, problem is when i download junk off BT, usually people put it in 128kbps...

but w/e