Thinking about going from Sealed Sub to Ported to gain about 5db - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 28 Old 11-02-2012, 07:41 AM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I currently have the following components in my Passat

12" Kenwood W3013PS 4ohm (400RMS) in Atrend E12S B Box Series Sealed Box (about .8 Cubic Feet) pushed by Kenwood Kac-7205 (500RMS @4ohm).

I was going thru the manual and noticed that bigger ported Box can gain me good 5db (which I assume is pretty significant). See below:



My set up sounds great currently (AMP does overpower the sub and its set to about 60-70 gain /no bass boost crap), but I wouldn't mind more deeper/powerful bass. Also I wouldn't mind building a new Box (already have MDF board and it would be a cool project for me and my boys.

I guess the question is, would it be worth it to go from Sealed box to Ported and from .8 cubic feet to 2+ cubic feet as per below.


Based on my speaker manual it seems like I''m current;y on the low end of the cubic feet for Tight bass. Guessing going to a much bigger box and switching to Ported box can gain me significant difference.

Any thoughts?

TIA
passaturbo is offline  
Sponsored Links
Advertisement
 
post #2 of 28 Old 11-02-2012, 01:13 PM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
i've got some thoughts..

first of all,
a subwoofer CAN sound tight in a ported box.
if it doesnt, well then the subwoofer isnt liking the ported part and you need a better quality woofer.

there's two ways to build a ported box tune.
one is to match up the tune with the highest impedence on the impedance curve .. and that means a subwoofer that gives you that information.
the other way is to see if the subwoofer will play the notes you need a boost at in the car, and then tune the box for what is hard to gain inside the vehicle.


it really isnt easy to find the frequency that needs boosted without knowing the cubic feet of the interior .. and not everybody knows the math equation for that number (including myself)
if you had an equalizer..
i would say use a swept sine sweep to get the sweep sounding as flat as possible in the box you already own.. that probably means turning up some frequencies really high and turning the other ones down all the way.
it doesnt need to be really loud, just loud enough that you can hear where the big dip in loudness inside the car.
you are probably guessing for a number between 20hz - 30hz .. but maybe it is lower than 20hz (im just saying dont be totally suprised if it is).


i can say the normal prebuilt port tunes are 30hz or 32hz and they arent low enough to satisfy the full extension that can be had from a subwoofer system.
and i cant say just tune it to 20hz - 25hz because i dont know what the rolloff of the subwoofer is.

it is responsible for me to tell you..
if the subwoofer rolls off a good amount at 25hz and you tuned the box for 20hz .. then there is going to be a dip at 25hz and also 20hz wont be as loud as it could be.
it could prove to be wasteful to over-shoot the low tune .. especially if you can simply tell the 20hz tune exists but it isnt keeping up with the rest of the frequency response by a large decibel number of 6dB or more.

i just dont want to see you tune the box and then be stuck with a low tune that is quite a few decibels lower than the rest of it.
because then it is like you've got this soft rattle coming from the trunk that isnt very loud compared to the subwoofer playing music, but the rattle is the subwoofer system trying to itch and scratch at the tuned frequency.
then you would be asking yourself 'where is the boost from my horn?'

i think the real trick is to get the rolloff extended as far as possible without any large dips.
people stick to that advice because most people dont use an equalizer with their subwoofer.. so it has to sound good the first time.
but chances are, the box tune wont be as low as it could be.. because if the box builder went even lower, then there would be a dip somewhere that needs a boost from the equalizer.. but the lowest extension would probably increase too.


because the impedance rise for subwoofers is usually between 20hz and 30hz .. it means the speaker cone will not see much movement there because there is lots of resistance there compared to the rest of the frequency response.
yes..
you can port the box at a specific number, and then the box looses pressure after that frequency as it goes lower .. but you can use that to your benefit to give the subwoofer some extra opportunity to flap the cone in and out.
it is like saying you are giving yourself an equalizer boost from the cone movement being much extra without any extra boost from the amplifier or equalizer.
its a valid trick to get some extra extension.

for example..
i've got two twelves in my room with a box tune of about 28hz
but my soundcard lets me do a 10hz boost anywhere from 1dB up to 12dB .. and because the box loses pressure at 28hz .. i can get the cone moving at 10hz easier because it is loose.
and that means i can turn on the 10hz boost and actually get some output from it even though the box it tuned higher at 28hz.
i dont get output from the port at 10hz, the boost comes from the speaker cone itself.

i would of went lower with my tune, but i had sealed boxes and looked to see how much port was needed to convert it to a ported tune.
it isnt a perfect 28hz because of the port taking up some of the space.
but i put in some polyfil to slow down the soundwaves a little bit and make the soundwaves move around inside of there as if the box was a little bit bigger.

my system can get down to the 20hz area .. and i can tell you simply what it sounds like.
it sounds like i didnt go to some store like bestbuy or walmart and get ripped off bringing a toy home to play with.

and it should hold as true for everybody because they have been saying it again and again since the 1990's ... the frequency response needed for cd's is 20hz - 20,000hz
going without the 20hz has a big impact.
it's the difference between a childs toy and an adults tool.

the frequency response listed for that subwoofer is 34hz - 300hz
i have no idea if it will play below 34hz
but i know you dont want any sub to stop playing at 34hz because that is just too high.

i couldnt find any information about the measured frequency response or the measured impedance curve.
i cant really be of any more help with that subwoofer.
anwaypasible is offline  
post #3 of 28 Old 11-02-2012, 02:11 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks for the response.

You didn't really answer my main questions though.

Will bigger/proper size box for my woofer make it sound better.

And will going ported and increasing Cubic Feet x3 produce louder/deeper base.

Based on the graphs from Kenwood's manual it seems like it would by 5db....is that worth it? is it a significant difference?
passaturbo is offline  
post #4 of 28 Old 11-02-2012, 02:53 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

Thanks for the response.
You didn't really answer my main questions though.
Will bigger/proper size box for my woofer make it sound better.
And will going ported and increasing Cubic Feet x3 produce louder/deeper base.
Based on the graphs from Kenwood's manual it seems like it would by 5db....is that worth it? is it a significant difference?

yeah he pretty much just rambles on with whatever topic he is feeling at the time, and unfortunately it never helps.

Yes you will gain loudness and deepness when going ported....if the driver can handle and the amplifier can control the woofer with subsonic filter.

There are a gazillion online discussions about sealed vs ported...i suggest you do some reading on the plusses and minuses.

Tim
tundrSQ is offline  
post #5 of 28 Old 11-02-2012, 02:59 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tundrSQ View Post

Yes you will gain loudness and deepness when going ported....if the driver can handle and the amplifier can control the woofer with subsonic filter.
There are a gazillion online discussions about sealed vs ported...i suggest you do some reading on the plusses and minuses.

I've been searching around and most people do say Ported is louder and deeper.

But it seems like based on my set up the difference will be even more significant as I'm currently running way too small of a sealed box for my speaker.

5db is a pretty significant difference correct?
passaturbo is offline  
post #6 of 28 Old 11-02-2012, 04:14 PM
AVS Special Member
 
cubdenno's Avatar
 
Join Date: Dec 2008
Location: Cham-Bana Illinois
Posts: 1,486
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Liked: 62
Tight bass is actually a function of the mid bass speaker. Has nothing to do with the sub.

That said, we really need to understand what happens in a car to help you understand what is going to happen when/if you change the enclosure.

Your vehicle whether its a small cab two seater or a suburban, it is an enclosure. Leaky, but an enclosure none the less. This vehicle will have an acoustic response because its an enclosure called cabin gain or transfer function. It is a boost in frequencies under around 60 hertz at about 12 db per octave. This is why sealed enclosures and even why small woofers can produce amazing amounts of bass as compared to out of a vehicle. This cabin gain couples very nicely with the 12 db per octave roll off that a sealed enclosure has. If I was not on this iPad at McDonald's I would post some graphs. To show what I am explaining.

So if you like the acoustic properties of your sub set up in your car but want a low end bump, be warned that the boost of a ported enclosure will really see a huge boost in output because of that same cabin gain.

To counter this, you can cross the sub a little higher.
You can use larger mid bass speakers.
Reduce the gain on the sub
Eq out that big output bump.

Key thing is, since you have the wood and want to try it, do it! Build that box. Worst case is you don't like it. You can alway tune lower or higher. OR seal up the port ans see if a bigger sealed enclosure gives you what you want.

XBL-Steelhouse1

"No one wants to fight the naked guy."
cubdenno is offline  
post #7 of 28 Old 11-02-2012, 04:32 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

I've been searching around and most people do say Ported is louder and deeper.
But it seems like based on my set up the difference will be even more significant as I'm currently running way too small of a sealed box for my speaker.
5db is a pretty significant difference correct?

5db is ver significant...i guess the obvious question would be 5db at what freq? I would think you will have a 5db increase at say 20-35 hz....but if you play music that has no info at that freq then whats the advantage of going ported?

But overall when all things stay the same and the only change is switching from a sealed box that is too small...to a properly tuned ported box...you should notice a dramatic improvement in the impact of the subwoofer...you may lose a little of the tight cracking of say a drumstick on the drum skin....but you will make up for that in the impact of the bass foot pedal to the bass drum.

I am taking alot of liberties...and trying to explain it the best i can in the simplest of terms.

small sealed box can sound a little dry and not offer enough impact for most peoples ears...i tend to like that sound personally.

ported box will fill the car with bass much easier and louder...at the expense of some subtle detail....

So it will be a lot more fun....but maybe not quite so accurate.

Hope this helps....

Tim
tundrSQ is offline  
post #8 of 28 Old 11-02-2012, 04:48 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tundrSQ View Post

5db is ver significant...i guess the obvious question would be 5db at what freq?.

See the picture/graph I posted, it's straight from my Sub's manual. It looks like 5db across the entire range.

Quote:
Originally Posted by tundrSQ View Post

I would think you will have a 5db increase at say 20-35 hz....but if you play music that has no info at that freq then whats the advantage of going ported?
But overall when all things stay the same and the only change is switching from a sealed box that is too small...to a properly tuned ported box...you should notice a dramatic improvement in the impact of the subwoofer...you may lose a little of the tight cracking of say a drumstick on the drum skin....but you will make up for that in the impact of the bass foot pedal to the bass drum.

I shouldn't mind that. I like deep/strong bass.
Quote:
Originally Posted by tundrSQ View Post

I am taking alot of liberties...and trying to explain it the best i can in the simplest of terms.
small sealed box can sound a little dry and not offer enough impact for most peoples ears...i tend to like that sound personally.
ported box will fill the car with bass much easier and louder...at the expense of some subtle detail....
So it will be a lot more fun....but maybe not quite so accurate.
Hope this helps....

I'm willing to trade less subtle detail for louder/stronger bass.

Thanks!
passaturbo is offline  
post #9 of 28 Old 11-02-2012, 04:52 PM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by passaturbo View Post

Will bigger/proper size box for my woofer make it sound better.
And will going ported and increasing Cubic Feet x3 produce louder/deeper base.

you really shouldnt be expecting a person to answer the question without owning the subwoofer and trying it themselves.
the question is a per speaker answer.
i can say yes it CAN happen.. but maybe your specific subwoofer is the limiting factor.


any time you bring home a tool.. the tool will demand from you.
for instance,
if you bring home a socket, that socket will demand nuts and bolts.. you cant use it as a screwdriver no matter how much you demand from the tool (unless you grind the handle to become a flat-head screwdriver .. but that is physically altering the handle)


its the same thing with a subwoofer..
you bring it home and it has demands that it will ask from you.
you cant change those demands unless you physically alter the voice coil.

you know something that does happen..
people need a wrench and they grab (or buy at the store) one of those groove joint pliers to twist the nut with .. when they really needed one of those adjustable wrenches.
it also happens..
people use a philips screw driver that doesnt fit the screw very well.
those who own a cheap drill bit set get those adjustable philips screw driver bits and they work really good when the size is perfect for the screw.


it boils down to what the subwoofer wants .. and you let the subwoofer demand what it needs, or you get a subwoofer that gives you what you need and demand.
because maybe the subwoofer plays more clear in the small box.
maybe it plays more clear in the ported box.
that is specific of the subwoofer, not the box.


seriously..
if i was totally stuck with that subwoofer and forced to build a box for it to try and get the best i could out of it ... i think i would totally try this..
the minimum ported box size is 2.0 cubic feet
the maximum ported box size is 2.5 cubic feet

it doesnt say anything about the port size or tune.
so
i would build the box at 2.0 cubic feet .. and then make the port 0.5 cubic feet .. and it shouldnt fail because the given box size meets the 2.5 cubic feet.

what i dont know is..
will that box be smooth and flat in frequency response all the way down to the tune of the box.
maybe the box needs an equalizer to boost and cut some frequencies.
but
i would be using an equalizer anyways.

some people use the theile small parameters to input that data into computer software and build a box that fits the data .. and the computer software will tell you what the frequency response is going to be in that box.
i dont do it because i'm not heavily involved with building speaker boxes ... and the same question will come up ... does the owner need a flat response without an equalizer or do they use an equalizer that can help?

but i would still hold firm.. the first approach is to tune the box at the highest impedance point.
once you start to alter the port tune, you are building a box that is more advanced in terms of audio engineering.
and that could go as far as placing blocks of wood inside the box to alter the character of the box.

for example..
if you tuned the box lower than the impedance peak ... you might want to place a piece of wood in there that will help resonant the frequency of the impedance peak.
it is a multi-frequency tune that i would be after to get more than one 'correction' applied to the final result.

kinda like saying 'there is a hole here and a hole here'
and then building the box to fill in BOTH holes.
because sometimes people see 'there is only one hole if i tune it this deep.. and if i tune it any lower there is going to be two holes that need filled'
when they add the block of wood to help one of the holes, the entire size of the box needs to be adjusted to compensate for the block of wood.
and it might not be as simple as increasing the size of the box extra for the amount of space the wood block occupies.
you might need to find a compromised average between the two because of their interactions together, or because the box builder is trying to make smaller fine-tuned adjustments for the upper (or lower) portion of the frequency response.


i've seen situations where the amount of decibels coming from the cone was actually louder when it was sealed than when it was ported.
it is because the voice coil would rather shake the cone within a millimeter to produce output compared to the cone moving in and out half an inch.
anwaypasible is offline  
post #10 of 28 Old 11-02-2012, 05:01 PM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
oh..
i see now the first picture is from the kenwood subwoofer paper that came with it.

well..
it should be as easy as this..
which one of those bumps of extra decibels do you need in the car?
if you dont need any of them, then you dont need that specific subwoofer and you should be looking for a replacement?
or
do you look at the graph and use the three examples given, and see if you can continue moving in that pattern to get the bump in decibels flat?

you need to run the sine sweep to see what it sounds like in your vehicle .. that way you can compare it with those lines in the graph to really begin learning what it is your vehicle demands.
anwaypasible is offline  
post #11 of 28 Old 11-02-2012, 05:35 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

See the picture/graph I posted, it's straight from my Sub's manual. It looks like 5db across the entire range.
I shouldn't mind that. I like deep/strong bass.
I'm willing to trade less subtle detail for louder/stronger bass.
Thanks!

go for it...and there is no reason to think the ported box wont sound awesome...but you should make sure that you can filter out the frequencies below the tuning of the box....because basically below that the sub is considered "unloaded" and you could damage it if you play it too loud.

Your current amp looks like it does not have a subsonic filter....so you will need to address that....does your HU have one? There may be other ways to add the subsonic filter....but ultimately you may find it best to switch amps.

IMO not having a sub sonic filter on a ported box is a deal breaker....unless you are so underpowering the sub there is no chance for you to drive it to xmax below tuned freq...in this case i do not think you have that luxury.

Tim
tundrSQ is offline  
post #12 of 28 Old 11-02-2012, 06:06 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I think my head unit has a setting for Bass HZ. I have a Clarion CZ200.

So you are saying I don't want the Frequencies to go too low? (below boxes design which as per the screenshot in my original post is about 30hz)

But my sub is rated at 34hz so I don't think it can go below that?
passaturbo is offline  
post #13 of 28 Old 11-02-2012, 06:27 PM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by passaturbo View Post

I think my head unit has a setting for Bass HZ. I have a Clarion CZ200.
So you are saying I don't want the Frequencies to go too low? (below boxes design which as per the screenshot in my original post is about 30hz)
But my sub is rated at 34hz so I don't think it can go below that?

i dont know why they said it stops at 34hz
maybe it has something to do with distortion percentage of those lower notes.
maybe it has something to do with distortion percentage with notes above 34hz (like maybe the top end of the frequency range starts to distort)

chances are, the subwoofer cone will continue to move below 34hz
for what reason the frequency response says 34hz - 300hz .. i dont know.
maybe the reason is practical and rational .. maybe it isnt.
i dont know.


i told you why you wouldnt want to build the tune too low.
but i also told you to use the frequency response graph.
and i am telling you now.. just because the graph looks flat on paper from jumping up another box size.. that doesnt mean the subwoofer's real frequency response will be identical to what the theory is on paper.

you should of found out if one of those boosts in frequency response is going to help .. or if the increase in decibels is only going to make a different frequency more loud than the rest.

i realize you are focusing on the bass extension.
but it wont do you any good to get a small increase in decibels if you've got a 12dB peak somewhere else in the frequency response .. because then that 12dB peak will be drowning out the extended low bass and you wont be able to hear it (and maybe you wont be able to feel it either, unless the music is focused on that specific frequency without any other frequencies playing)

it is like there is a bunch of arguing going on and you dont care to scream and shout over the people yelling.
get them calm first.

i could easily tell you to build three different boxes and see which one works the best.
but that isnt cost-effective.
because you might want to sell the other two boxes, but there are more people that dont know what box size and tune they need.
they might buy the box and it might be the wrong one.

you might build three boxes and find out you want one in the middle between two box sizes.

i've given you all the rational instructions.
the only other option is to get one of those speaker building programs and input the data on that sheet into the program and mess around with the box size and port size until the frequency response looks like something you want.


**edit**

master box builders would probably look at the 25? hz resonant frequency response.
then put the speaker in a box that is most loose at 25hz and hear how it sounds.
then put the speaker in a box that is most tight at 25hz and hear how it sounds.

speaker box building is way more of an engineering task than building a box with four walls and a tube.
i've seen speaker boxes with dozens of little 1 inch x 1 inch cubes inside all put into a specific place to get the frequency response molded like a piece of clay into a pot or vase.

i know it can be done with math .. or it can be done with trial and error.
anwaypasible is offline  
post #14 of 28 Old 11-02-2012, 07:06 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'm not that anal.

Worse thing that can happen is I will blow the sub (which is no big deal, it only cost me 50 bucks and already have done MORE than that over past 2-3 years....and I can always put it in the sealed box.

And time it takes to make a ported box is actually quality father/sons project....so that's only a gain value.
passaturbo is offline  
post #15 of 28 Old 11-02-2012, 07:06 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

I think my head unit has a setting for Bass HZ. I have a Clarion CZ200.
So you are saying I don't want the Frequencies to go too low? (below boxes design which as per the screenshot in my original post is about 30hz)
But my sub is rated at 34hz so I don't think it can go below that?

i looked at the manual. i did not see where it had a subsonic filter. Yes it has a low pass for a subwoofer...but that is different...that blocks the high freq from going to the sub. What you need is something that block the ultra low freq from the sub.

Or you need to build the box so large that the tuning is below 20hz....but that is impractical, and probably will not be something you would want.

34hz is a decent tune for a auto sub....i did not see in your original post exactly what tune they were giving you in the box that had the 5db advantage....but whatever that tune is...you would want to block frequency below that tune...to protect the driver.

You could do this with a large cap designed to high pass at say 28hz....but they can be costly. Better to purchase something like the audio control epicenter if you can afford it. But i am not an expert in that type of processing...so it would be worth doing some research. You can email audio control directly and explain your set up and get a suggestion for subsonic filtering for a ported box.


The thing is most people use mono amps for subs...and they almost all have SSF's...where as 2 channel amps and HU's do not.

Tim
tundrSQ is offline  
post #16 of 28 Old 11-02-2012, 07:08 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

I'm not that anal.
Worse thing that can happen is I will blow the sub (which is no big deal, it only cost me 50 bucks and already have done MORE than that over past 2-3 years....and I can always put it in the sealed box.
And time it takes to make a ported box is actually quality father/sons project....so that's only a gain value.

cool beans...as a father of two girls...this is the best part.

Tim
tundrSQ is offline  
post #17 of 28 Old 11-02-2012, 07:15 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tundrSQ View Post

i looked at the manual. i did not see where it had a subsonic filter. Yes it has a low pass for a subwoofer...but that is different...that blocks the high freq from going to the sub. What you need is something that block the ultra low freq from the sub.
Or you need to build the box so large that the tuning is below 20hz....but that is impractical, and probably will not be something you would want.
34hz is a decent tune for a auto sub....i did not see in your original post exactly what tune they were giving you in the box that had the 5db advantage....but whatever that tune is...you would want to block frequency below that tune...to protect the driver.
You could do this with a large cap designed to high pass at say 28hz....but they can be costly. Better to purchase something like the audio control epicenter if you can afford it. But i am not an expert in that type of processing...so it would be worth doing some research. You can email audio control directly and explain your set up and get a suggestion for subsonic filtering for a ported box.
The thing is most people use mono amps for subs...and they almost all have SSF's...where as 2 channel amps and HU's do not.

The box I was going to build (as per the screenshot) is tuned to 30hz (about).

I'm still struggling to understand the entire thing (to be honest). Are you saying that the sub is not good for a ported enclosure or the size of the box is too big. Explain the entire frequency/filter thing to me.....it's hard to understand (sorry I'm not that big of an audiophile)

Reading thru this...
http://www.decibelcar.com/menuelectro/119.html

It seems like that's needed on a sealed box as well.


Seems like my amp does have some kind of a filter (see below). Just not sure if it's "subsonic". Is that what you were referring to?
http://www.kenwoodusa.com/Car_Entertainment/Amplifiers/KAC-7205

"High-pass (12 dB per octave) and low-pass (24 dB per octave) filters variable from 50 to 200 Hz"
passaturbo is offline  
post #18 of 28 Old 11-02-2012, 07:29 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

The box I was going to build (as per the screenshot) is tuned to 30hz (about).
I'm still struggling to understand the entire thing (to be honest). Are you saying that the sub is not good for a ported enclosure or the size of the box is too big. Explain the entire frequency/filter thing to me.....it's hard to understand (sorry I'm not that big of an audiophile)

Not saying that the sub is not good for this box, or for going ported.

I am saying that all ported boxed need some kind of filtration to block frequencies below the tuned freq of the box.

Trying to keep it simple....woofers need to be controlled by something....or they will flap uncontrolled and burn up.

Sealed boxes by design roll off the ultra low frequencies and protect the woofer...no sub sonic filter needed.

ported ( tuned ) boxes use the port inside the box to balance the volume of air inside the box to the volume of air outside the box...and the amount of port used in relation to the size of the box creates a tuning point.

Above that point and the box controls the woofer...no burned voice coils.....but below that point...in your case 30hz....the woofer is considered unloaded or uncontrolled.....and if you play music frequencies below 30 hz...the woofer will not be able to handle them....causing the driver to over reach its mechanical or thermal limits...and either rip or burn.....both things are bad.

Now a subsonic filter does not eliminate the low freq...just rolls them off at 3db per octave....the same as a sealed box does. So you aren't losing anything ....you are just protecting the driver..

Tim
tundrSQ is offline  
post #19 of 28 Old 11-02-2012, 07:57 PM
AVS Special Member
 
cubdenno's Avatar
 
Join Date: Dec 2008
Location: Cham-Bana Illinois
Posts: 1,486
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Liked: 62
Thankfully most music doesn't have much information below 30 hertz.

The nice thing about ported enclosures is the reduction in distortion. The more a speaker moves excursion wise, the more nonlinear distortion begins to creep in. And at low frequencies, playing loudly the more the cone has to move. Porting reduces the movement of the woofer cone with the majority of sound coming from the port. Believe it or not, but a well designed ported enclosure actually sounds better than a sealed enclosure playing at the same output level.

There are stand alone units you can add to get crossover functionality that are cheap an dork very well. The minidsp can be added to a car and it offer excellent SQ, incredible features like the ability to equalize or add some time alignment,phase control on top of the sub sonic filter. Plus it comes highly regarded on this forum. Search it. A lot of the DIY guys use it. Heck I use it! Works great implementing multiple subs in my home theater.


The spec of 34 hertz that was given is the fs of the woofer in free air. This is the woofer by itself. Now the system fs will change once you install the woofer in the enclosure of your choice. Different enclosures will cause a different fs for the woofer enclosure combination. The woofer/enclosure combo can end up having a higher or lower fs depending on the design. So yes, the sub can play lower than 34 hertz.

Sorry I tend to drone on. biggrin.gif

XBL-Steelhouse1

"No one wants to fight the naked guy."
cubdenno is offline  
post #20 of 28 Old 11-02-2012, 08:50 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tundrSQ View Post

Not saying that the sub is not good for this box, or for going ported.
I am saying that all ported boxed need some kind of filtration to block frequencies below the tuned freq of the box.
Trying to keep it simple....woofers need to be controlled by something....or they will flap uncontrolled and burn up.
Sealed boxes by design roll off the ultra low frequencies and protect the woofer...no sub sonic filter needed.
ported ( tuned ) boxes use the port inside the box to balance the volume of air inside the box to the volume of air outside the box...and the amount of port used in relation to the size of the box creates a tuning point.
Above that point and the box controls the woofer...no burned voice coils.....but below that point...in your case 30hz....the woofer is considered unloaded or uncontrolled.....and if you play music frequencies below 30 hz...the woofer will not be able to handle them....causing the driver to over reach its mechanical or thermal limits...and either rip or burn.....both things are bad.
Now a subsonic filter does not eliminate the low freq...just rolls them off at 3db per octave....the same as a sealed box does. So you aren't losinganything ....you are just protecting the driver..

Starting to make sense now.

So looking at my amp specs here, does this mean that it has Subsonic filter?
High-pass (12 dB per octave) and low-pass (24 dB per octave) filters variable from 50 to 200 Hz
From
http://www.kenwoodusa.com/Car_Entertainment/Amplifiers/KAC-7205

Also under Specifications I found
Low Pass Filter Frequency
(-12 dB/oct.)
50 Hz - 200 Hz (variable) Low-Pass Filter Frequency
passaturbo is offline  
post #21 of 28 Old 11-02-2012, 11:37 PM
AVS Special Member
 
cubdenno's Avatar
 
Join Date: Dec 2008
Location: Cham-Bana Illinois
Posts: 1,486
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Liked: 62
http://www.kenwoodusa.com/Car_Entertainment/Amplifiers/KAC-9105D

This amp has an infrasonic filter. This is the sub sonic filter or SSF that has been discussed. It's a high pass filter/crossover. This is what helps keep your sub from unloading below the tuning frequency of the port.

Your amp, which is very nice by the way, does not have the SSF or infrasonic. It has instead the common high pass or low pass selectable. Most two channels do not have it. Heck most four channel amps don't have it either.

XBL-Steelhouse1

"No one wants to fight the naked guy."
cubdenno is offline  
post #22 of 28 Old 11-03-2012, 07:16 AM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I sent an email to Kenwood just to confirm.

THat amp is really nice. Incredible bank for the buck. 900watts RMS at 2 ohms. THat will be my next amp to go along with the following:

http://www.amazon.com/Pioneer-TS-W3002D4-Champion-Series-Subwoofer/dp/B001P71I6C/ref=sr_1_3?ie=UTF8&qid=1351948494&sr=8-3&keywords=12%22+pioneer

Anyways, so what are my choices as far as subsonic fiters go? Or what options do I have?

Would this work?
http://www.amazon.com/FMOD-Crossover-Pair-High-Pass/dp/B0006N41CO/ref=sr_1_1?s=electronics&ie=UTF8&qid=1351949173&sr=1-1&keywords=crossover+with+subsonic+filter\
passaturbo is offline  
post #23 of 28 Old 11-03-2012, 11:51 AM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by passaturbo View Post

I sent an email to Kenwood just to confirm.
THat amp is really nice. Incredible bank for the buck. 900watts RMS at 2 ohms. THat will be my next amp to go along with the following:
http://www.amazon.com/Pioneer-TS-W3002D4-Champion-Series-Subwoofer/dp/B001P71I6C/ref=sr_1_3?ie=UTF8&qid=1351948494&sr=8-3&keywords=12%22+pioneer
Anyways, so what are my choices as far as subsonic fiters go? Or what options do I have?
Would this work?
http://www.amazon.com/FMOD-Crossover-Pair-High-Pass/dp/B0006N41CO/ref=sr_1_1?s=electronics&ie=UTF8&qid=1351949173&sr=1-1&keywords=crossover+with+subsonic+filter\

that fmod thing should work fine. just plug into the RCA inputs at your sub amp.

I have never used them....so i am only saying that this is what they are designed to do...and should work fine.

Tim
tundrSQ is offline  
post #24 of 28 Old 11-03-2012, 03:48 PM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I ordered it.

Thanks everyone, I will keep you posted on results. I'm shooting for 30hz tunning on the ported box.
passaturbo is offline  
post #25 of 28 Old 11-16-2012, 06:36 AM - Thread Starter
Member
 
passaturbo's Avatar
 
Join Date: Jan 2007
Posts: 53
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
So I finally finished building the box. This thing is HUGE. About 3x the size of my sealed box.

It's also HEAVY. I didn't weigh it but it must be at least 40-50lbs.

I used an entire 6x4 sheet of MDF 3/4 inch board.

I took my time letting the glue set and sealing it on the inside and outside (also letting it cure for over 2 days). I also didn't use a speaker terminal, just drilled a hole > ran a speaker wire thru it and sealed it up with silicone.

Just put the speaker in yesterday, installed the FMOD (30hz) on the RCA on the amp side and readjusted the gain (using Multimeter and 60hz tune) just to make sure everything was nice and dandy. Bass Boost stayed all the way down as always and EQ/Treb/bass on the head unit is default.

First impression. It's a big difference. I can finally hear higher end bass much better than before (before it was just ......flat/almost non existent). Puny would be a better word I guess.

As for the low end bass, it is much deeper and stronger now. Heck it feels/sounds better with the seats up than it did with the sealed box+ the seats down.

I would say the chart I posted in the OP from Kenwood is pretty much on point.

Thanks to everyone for warning me about the none existent subsonic filter on my amp!
passaturbo is offline  
post #26 of 28 Old 11-16-2012, 03:17 PM
AVS Special Member
 
tundrSQ's Avatar
 
Join Date: Nov 2006
Location: Vermont
Posts: 2,217
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
glad it all worked out...and as you know people here give away free advice for only one reason...WE WANT TO SEE PICTURES!!!smile.gifsmile.gif

Tim
tundrSQ is offline  
post #27 of 28 Old 11-20-2012, 06:29 AM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by passaturbo View Post

It's also HEAVY

first thing i thought of was the box being 3x bigger, but instead of the cone dropping 3 times in tone .. the cone only went down halfway and you can clearly tell it sounds like it is floating even though the box is huge.
kinda like calling out a timbre.
for example...
you hear a tire rolling down the road, but you could say if it sounded higher or lower like a semi tire or a car tire.
anwaypasible is offline  
post #28 of 28 Old 11-20-2012, 06:39 AM
 
anwaypasible's Avatar
 
Join Date: Aug 2010
Location: illinois
Posts: 391
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by passaturbo View Post

Bass Boost stayed all the way down as always

i read this and i thought to myself.. did you adjust the bass boost and it still didnt help with filling in anything, or did you hear the same note in two different boxes with the knob?
did you realize just how deep the tune is, and thus learned the 'as always' trick about going even lower to get more gut belching from the cone?
or
was the 'as always' type of wording used maybe as turning the bass boost with 60hz going to the multimeter and it didnt make the voltage go up much because 60hz didnt get touched much?

***edit***

i learned a little something with my box and cones the other day.
i had these pointed towards the front seats:
http://www.sonicelectronix.com/item_10592_Dual-XOBP12D.html

then i took the glass off on each side and pointed the box upwards towards the trunk lid.
sounds more detailed than towards the front with the glass off.

only getting 150 watts RMS from a dual amplifier.
can you believe i think i heard these subs blow from a 150 watt rockford fosgate amplifier from the 1990's ?!!!
i think either the 150 watt RMS from the other amplifier was distorting, and the little dual amplifier is at it's limits too .. or maybe my power cord has too much oxidation on it.
i need a capacitor awfully bad because the amplifier has 30 volt capacitors inside, but there isnt many of them and i cant expect the coil to suck up amperage the capacitors could be holding.
it wont go through the line to the battery and get all the long thump.
if it would, then the lights wouldnt dim.

i seen a new 2 farad for like $25 shipped to the door on ebay.
something about it with a 20v surge .. i dont know if i wanted to use a toroidal coil and bump it up from 14v to 20v .. or if it has simply been tested for 20v .. or if the cap will squirt out 20v ....... maybe give the toroidal coil a few capacitors for the bumping, then try to give it a rectifier, because that will put the electricity through once and kinda hold it there and not let it go back towards the alternator .. but that might be too much amperage from the capacitor .. gotta know the caps full output to keep the rectifiers safe, then you are ready to shove some voltage into the amplifier.
should probably look again at some of the other parts max voltage .. maybe remove the coil in the amplifier completely ????!
anwaypasible is offline  
Reply Car Audio, Video, and Nav

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off