ported/vented box for 2 kenwood kfc w3011

Hi Brad.  First, you can never get optimal performance from a premade enclosure for any speaker unless you get really lucky.  That being said, go ahead and give your speakers a try in the enclosure you describe as I don't think it will harm them, nor do I think it will perform all that well..  It may or may not be any "louder" than the system you currently have, but if you must, try it.

The terms ported, vented, etc. are all just another way of describing a bass reflex enclosure.  They all do the same thing.

No, don't just add a port to your existing enclosures, it will most likely not work well at all unless you really know what you are doing.  And yes, the port must face open air, preferably the same air space the woofers face towards.

Thanks for your opinion.  I don't think I want to order it just to "hopefully" get better results because that would be a waste of $90. (:  How much money could I expect to have to shell out if I attempted to build a custom enclosure to the kenwood's specs for a dual 12" ported enclosure with each chamber containing 2.0 cubic foot air space?

Also, aside from the fact that it would be a premade box, would it be the length of the vent that would cause the above enclosure with my subs in it to not sound very good or what?  The sealed boxes that I have came from the same place as the vented box that I am thinking about getting and they make very good boxes.  However, the boxes that I have now are just sealed, not ported.  I guess it would be a lot harder to make a good ported box. (:

thank you very much.

Brad

You must use sealed enclosure for this sub.  EBP of 29.6, where anything under 50 should be sealed.  Find EBP by dividing Fs of 45 by Qes of 1.519    Re:  https://inform3.kenwoodusa.com/manuals/kfc-w3011.pdf

This sub and the rest of your gear may just not be suitable for your desired sound.  This sub is not built for low bass extension but you could likely apply a more powerful amp to make it louder.  Look at the response graphs shown by the manufacturer...peakiness between 60 and 70 Hz in either type of enclosure.

Bottom line:  save your $90 on that prefab box and take some time to sort out your priorities.

My gear consists of a Pyle Dryver 2000 amp (200 rms x 4 channels) I have 2 channels bridged on each sub giving them 400 rms each (this is their rated rms power,) of course the two subs above, 4 gauge amp wires, 1.2 farad capacitor, with a Sony CDX-R505 head unit.  Also, 6 other after market speakers in the factory locations of a Dodge Intrepid (1997.) 

I have looked at the WINlsd program this forum talks about so much, and if I have done it right I can build a 4 ft ^3 ported box with 2 x 4" diameter and 10.75" length ports to tune it to 35 hz and hit a flat 30 hz note with these subs.  I am not sure what a 30 hz note sounds like, but with what I have been reading the last 2.5 - 3 months is it is prreettyy low, which would be what I am looking for, i hope.  Is the WINlsd program accurate in what it says to build?  If I build this box that it recommends, will the box actually work to produce the sound it says it will?  How many of you have built a box with the WINlsd program and had it work like it says it will work?

Also, can any of you give me an average figure on what a box like this would cost to build?

Thanks to all that reply.

Brad

depending on how much the material cost in your area is what the final cost will be.  for me, i can build an enclosure myself for 60-80 dollars. this includes carpet, wood screws, mdf, glue,silicone,weather striping,terminal cups, and wire. 

bw40584, like Steve said those woofers will never really give you much extremely low output and they are best suited to a sealed alignment.  If you really want bone-rattling low end, you will have to get different woofers.  Oh, and get a real amp too while you're at it as Pyle is, well, appropriately named. 

WinISD is one of the best speaker enclosure design packages available and yes, for the most part you can "believe" what it tells you.  Realize that the actual installation will have a great deal of impact on the actual performance in a vehicle and you may or may not realize what any program shows you.  Another piece of excellent free software for designing subwoofers is called Unibox.

Hello.  I have decided that I need to build my own ported box for my KFC-W3011 Kenwood subs 2 12".  I was going to go with a prefab, but after discussing it on this forum and playing around with the WINISD program I decided to give it a go.  Here is what I plan to build:

Dual "common chamber" 12" ported box

Width:  37.5"     Height:  15.5"   Depth:   17.5"

Outside dem. volume:   5.88650  ft^3            Inside dem. volume:    4.66667 ft^3

Round ports:    Diameter:   4"    Length:   10.5"    Displacement=    .07636 ft ^3  x  2  =  .15272 ft^3

Driver displacement:   .229 ft^3   x  2 =   .458 ft^3

Total inside box volume with ports and subs displacement =    4.05595 ft^3

Could someone tell me if the "common chamber" is a bad idea or not?  I keep hearing that you should seperate the chambers in case one blows.  However, WINISD says that you will get more SPL from using the "common chamber."  I would like to know the pros and cons of both methods if anyone knows them.  Will the "common chamber" cause my speakers harm?  This will be my first attempt at building a box for subs.  As a matter of fact, these Kenwoods are my first 2 subs period.    I also would like to know if I should use bracing for this 4.05 ft^3 box?  I have read that you should use 2 baffle boards and glue and screw them together for a sturdier box, if you do not brace it inside, and if you brace it inside, you should use a coulple 2" x 2" boards and glue and screw them along a couple of the seams on the inside.  Could someone tell me how to figure out how much volume either of these methods would take up, if I even need to do one of them? 

Here is a copy of the owner's manual:

https://akamaipix.crutchfield.com/Manuals/113/113W2511.PDF

These 2 subs are being pushed at 400 watts RMS each.  I have a Dodge Intrepid.

  I am really glad I can get help from this forum.  Thanks!

Sorry, I forgot to ask about port placement.  I know you should place the ports in the same direction as the woofers are firing, but does it matter where on the baffle board you should put them?  For instance, is it better to put both ports in the middle, or put the woofers close together and put the ports on opposite sides of each woofer?  Also, do the ports have to be a port diameter's length away from each other like they have to be away from a wall of the enclosure?

Thanks.

Yes, I did check with WINISD for the port diameter and length.  That is what it recommended for my box volume.  There will be 2 ports, and the vent mach is at .05 according to WINISD.  The only thing it did not recommend was the dimensions of the box itself, which I had to research and find how to manipulate.  Just to clarify, and please excuse me if I am being a little anal about this but, if I put 1" x 1" bracing inside the box, do I just put it along the length of the bottom dimensions of the box or both the top and bottom?  Also, if I go with the center brace, will this be a negligable volume displacement as well?  Should I do both, or is just one method ok?  If just one is ok, which is better?

Much appreciated.

If your design is with two ports, go ahead and put a solid center baffle in that box.  That will give good bracing stability in the most critical areas, and the ports will be distributed one to a woofer as appropriate.  And because of the box depth, the "stick" brace as DYohn suggested from side to side would also be important.  Measure the cubic inches of the baffles for displacement, but as DYohn suggested, the quantity is neglible.  There is no reason to have a common chamber box when two ports are incorporated, and the need for bracing is addressed with the common baffle wall.

You have plenty of room on a box of that width to place the ports away from boundaries.  They can be toward the outside or inside, either will do.

What's the tuning frequency?  About 35 Hz?  Re your earlier thread (***edit: topics merged***), I don't expect these subs to perform as you hope in a vented box.  I could be wrong, of course, so post a thread when you have it all hooked up and let us know how the performance is.

Edit:  I was doing some other things as I wrote this and missed your reply to DYohn's reply, but to answer about the bracing:  yes, it is critical to brace side to side in a box that size.  The brace should be from center to center, not along the bottom or top.  It is the center area of any baffle expanse that is most prone to flexing.  Here is an illustration I made a while back that shows the critical areas of a box that need to be stabilized (yellow areas):

In your case, using dual ports, I suggested a solid center baffle separating the two drivers/ports rather than what's illustrated here.  Center point bracing (as shown) is best, but just using an additional length of 1 X 1 wood along all edges is much better than using no bracing at all.

Stevdart, yes the tuning is at 35 Hz.  WINISD shows I should be able to hit a 35 Hz note pretty flat with these subs, so I am going to try it out.  Hey, if Solobarics are meant for sealed and sound good in a ported box, hopefully these will to.  It will be a little while before I build it, I got to wait until this semester at aschool is over (college.) 

Are you suggesting that I put a center brace with no holes in the middle?  I was going to do the "common chamber" because WINISD shows it will be more SPL this way instead of "seperate chambers."   I was going to use 2 ports because WINISD shows I will get less vent mach using 2 instead of 1, but the difference is only .04, so I might just use one instead.  But, how would I use the center bracing that way?  If I just use one port 6" Diameter, How would I brace the box then?  With the 1" x 1" along the edges?

Sorry, I wish I had more time, got to go to work.

• thanks.

I was thinking that I could use a 6" precision port tube and cut it to around 11" long and have a .09 vent mach.  Would I get much vent noise from this mach #?  Also I was thinking that I could use 2 of the center bracing boards with a 12" circle cut out of them on each side of the port, which would be in the middle.  How does that sound?  With 2 of these bracing boards in the middle, will the volume displacement still be negligable?

Have any of you tried the Precision Port Tubes from Parts Express?  Is there any difference between using them and regular PVC tubing from Home Depot for the port?  If there is not a big difference between them, then I will use PVC tubing for the port, but how would I mount that to the box...there is no flange.

Here is a link to the Precision Port Tube:

https://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=268-352

Thanks.

Hello.  Stevdart, I have decided to take your advice on putting a center brace in my box to seperate the chambers, and port each chamber with a 4" x 10" port.  However, with my box being only 37.5" inches wide (maximum,) and the Precision Ports requiring about a 5.25" diameter hole for each port, this only leaves me with about 1" inch space between the driver and walls on the outside of the box.  The box is only 15.5" inches tall (maximum.)  Will this be ok because I keep reading how you should have a port's diameter away from any wall and the driver.  WinIsd suggests using this size port (It is the one that I can fit) to have an acceptable mach noise (.10).  If this will not work, then maybe I could face the woofers up, and put the ports facing the trunk.  How would that work?  Has anyone ever tried that?  How did it compare to the woofers facing the trunk?

Thanks!

bw40584 wrote:

---

this only leaves me with about 1" inch space between the driver and walls on the outside of the box.

---

Did you mean to say "between the port tube and wall..."?  I can't think of any reason this would cause an acoustical problem.  Just be sure you have 4 or 5 inches of free air extending straight out at port's end.

Well, I meant that between the port and driver, and between the port and side and bottom walls there will be about an inch of wood.  Also, yes, there will be about 8 inches between the inside port end and the back wall.  However, there will only be about an inch or so between the bottom and side of the box.  I am guessing by your response that this will work out for me.  Thanks for your help.

two 2" X 5" ports are completely different tuning than one 4" X 10" port.

aznboi had a typo above:  meant to say 12.56 sq in.  You can see, as he pointed out, that it takes a total of  four 2" openings to equal one 4" opening (4 X 3.14 = 12.56).  If port noise is okay with that then you had too large of a port opening modeled in the first place (not that there's anything wrong with that, it just takes up precious space needlessly).  You should also look at WinISD's calculated port square inch opening area when you are working under the "vents" tab in the project window.  It is shown as "cross area".

You are experiencing modeling difficulties that proves why slotted ports are popular in car audio.

Thanks for the replies.  You know, this designing business is ALOT more complicated than it would appear!  I do not know what version you are using Stevdart, but I do not see a "cross area" tab or anything on mine, I am running version (.44).  Here is what WinISD shows me for both sizes of ports.  The volume difference of the boxes is because I have subtracted the volume displacement for the port(s).  I have found some flared 2.5" x 8.5" ports, and that is why I have those instead of the 2" x 5" ports.  It would appear that I will get better sound and less noise using the two 2.5" x 8" ports per chamber.  DYohn, you told me that WinISD is a software that I could "believe" the results that it showed me, do you think what it is showing me right now is right or wrong?  Please let me know what you think.  Thanks guys!

Driver            : KFC-W3011
                    Vas : 26.6
                    Qts : 1.09
                    Fs : 45.00
                    SPL : 90.00
--
Project by        : Brad
Project for       : you
--
Number of drivers : 1
Box type          : Vented
Box size          : 2.140 ft^3
Tuning frequency  : 35.00 Hz
Vent              : 2 vent(s)
                    8.06 in length for each                                           
                    2.50 in round
 *edit*         MACH: (0.07)                                        
                                                            
             Relative                                      
Freq         Gain         SPL                              
[Hz]         [dB]         [dB]                             
20.00        -17.76       72.24                            
25.00        -6.34        83.66                            
30.00        -0.36        89.64                            
35.00        0.92         90.92                            
40.00        2.20         92.20                            
45.00        3.72         93.72                            
50.00        5.07         95.07                            
55.00        5.93         95.93                            
60.00        6.17         96.17                            
65.00        5.95         95.95                            
70.00        5.50         95.50                            
75.00        4.97         94.97                            
80.00        4.46         94.46                            
85.00        4.00         94.00                            
90.00        3.59         93.59                            
95.00        3.23         93.23                            
100.00       2.92         92.92                            

Driver            : KFC-W3011
                    Vas : 26.6
                    Qts : 1.09
                    Fs : 45.00
                    SPL : 90.00
--
Project by        : Karen Wehrli
Project for       : you
--

Number of drivers : 1
Box type          : Vented
Box size          : 2.110 ft^3
Tuning frequency  : 35.00 Hz
Vent              : 1 vent(s)
                    9.92 in length for each
                    4.00 in round
        *edit*     MACH:   (0.11)                                                    
                                                            
             Relative                                      
Freq         Gain         SPL                              
[Hz]         [dB]         [dB]                             
20.00        -17.73       72.27                            
25.00        -6.32        83.68                            
30.00        -0.45        89.55                            
35.00        0.82         90.82                            
40.00        2.12         92.12                            
45.00        3.65         93.65                            
50.00        5.02         95.02                            
55.00        5.90         95.90                            
60.00        6.17         96.17                            
65.00        5.96         95.96                            
70.00        5.51         95.51                            
75.00        4.99         94.99                            
80.00        4.48         94.48                            
85.00        4.02         94.02                            
90.00        3.60         93.60                            
95.00        3.25         93.25                            
100.00       2.93         92.93                            

WinISD version I use and a link to version history is covered in my WinISD Guide stickied in this forum.

Your results here are similar to the manufacturer's data:  +6 db peak in the 60 - 70 Hz region.

No, I don't believe it would sound good.  When there is a 6 db peak, you have to consider all else as relative to that level.  And depending on the vehicle this is going in, there will most likely be a further increase in that freq range due to cabin gain.  "Flat" is when all usable freqs run along roughly the same db level.  The 0 line is a point of reference.  Only if 30 Hz were close to being along the same db level as the other freqs would it be considered flat (with a +6 db bump at 60 to 70 Hz, the 0 reference line is the same as -6 db).  And...decibel step increments are equal whether they are below or above the reference line.  There is just as much of a difference in sound level from 0 to -6 db as there is from 0 to +6 db, or from -3 to +3 db.

If I were to allow a peak when modeling a sub that I intend to "sound good", I would keep the peak at less than 1.5 db, and at a lower freq than 60 Hz.  It is the subwoofer selection that allows you that latitude and nothing else is as important.  This model is an entry level SPL sub.  Like I said at the beginning of this hybrid thread, this sub will sound pretty much the same no matter what type of box you build for it.  You just might be able to get it louder.

Alright, that helps.  But, I was thinking that if my sub is rated at a SPL of 90, then it will play anything that is close to 90 db within 1db really good, and anything that is above that it will play better (as in how loud it gets at that level.)  When I plot 400 watts (in WinISD) it shows that my subs will play a 30 Hz note at 115.66db, when my sub is rated to play good at 90 db.  That is not  an inaudible db level at all, regardless of the peak at 60-70Hz level.  Also, doesn't the peak just mean that it will be louder at this level than at any other level throughout the audio spectrum.  The way you describe it, it is like the peak becomes the new 0db line.  If that is true, then why would they put the red and purple lines there in the first place?  

Thanks

Thanks for that Anzboi3064.  No, I didn't look there, but I have looked at other places.  Don't know why I thought that?  Now that you mention it, it does sound kinda crazy.  However, what I am trying to say is that since 30 Hz is REAL close to the red or 0db line (-0.36db,) then my subs will play that frequency at normal volume, and it will play the rest of the frequencies louder than normal. (Normal being 90db with 1watt of power applied to them.)  Also, the 6 db peak at the 60-70 Hz region just means that it will be louder than normal at those frequencies, not necessarily meaning my subs will ONLY play the 60-70 Hz region and the frequencies with 3db of it well....right?

thanks

Will someone please tell me if what I am thinking is right or wrong please.  At the end of the message above I meant to say (WITHIN 3 db of it well...right?)

I read the contents section on the winISD help section.  It did not say anything about having a peak will make the sub not sound good.  It only said that anything that dips below the -3db line, the sub box will not play very well and will be at half volume.

Thanks.  Could you explain to me about the peakiness, and how/why it would make my system not sound good with a 6db peak at 60-70Hz because I just don't see why it wouldn't sound good just because of that.

Also, could someone tell me what kind of subsonic filter I should get for this setup and where to get one.  Thanks.

Driver            : KFC-W3011
                    Vas : 26.6
                    Qts : 1.09
                    Fs : 45.00
                    SPL : 90.00
--
Project by        : Brad
Project for       : you
--
Number of drivers : 1
Box type          : Vented
Box size          : 2.140 ft^3
Tuning frequency  : 35.00 Hz
Vent              : 2 vent(s)
                    8.06 in length for each                                           
                    2.50 in round
 *edit*         MACH: (0.07)                                        
                                                            
             Relative                                      
Freq         Gain         SPL                              
[Hz]         [dB]         [dB]                             
20.00        -17.76       72.24                            
25.00        -6.34        83.66                            
30.00        -0.36        89.64                            
35.00        0.92         90.92                            
40.00        2.20         92.20                            
45.00        3.72         93.72                            
50.00        5.07         95.07                            
55.00        5.93         95.93                            
60.00        6.17         96.17                            
65.00        5.95         95.95                            
70.00        5.50         95.50                            
75.00        4.97         94.97                            
80.00        4.46         94.46                            
85.00        4.00         94.00                            
90.00        3.59         93.59                            
95.00        3.23         93.23                            
100.00       2.92         92.92                            

Driver            : KFC-W3011

Thanks man.  Would you consider this to be a "smooth peak?"  Can anyone answer the subsonic filter question?

Thanks

With a Qts that high these woofers should work better in IB alignment than in any sort of vented system.  Like was said EARLY in this thread, I'd use it sealed.  But if the numbers you keep posting are correct, you do not have a +6db peak, you have about a +3db elongated peak around 60Hz.  Your enclosure model looks something like this:

This system will sound really boomy although since the peak is centered on the approximate resonant frequency of most passenger cars, it should seem pretty loud.  It will not be very musical since it will be approx. twice as loud at 60Hz as it will be at 40 or 80 Hz.  Subsonic filters should be set at or just below the tuning frequency of a vented enclosure, so set yours to 35Hz.

Thanks DYohn!  The way I see it, is...how much "music" are you going to get out of a 12" subwoofer anyway?  Right now I have both of them in sealed hatchback 1.4 boxe(s) stuffed with 1.25lbs of polyfill each.  They sound very good, but I want louder and lower bass hits from the subs then what I am getting right now.  On all the rock songs and stuff, they don't miss a beat.  But, on some rap songs, you can tell they are not hitting everything.  I bought these subs in haste, and am now stuck with them.  But, they are not bad subs at all really.  But if I had not have bought them before knowing what I do now, I would by the Kicker CVR 2 ohm 12".  I do not have a subsonic filter on my amp.  I have been looking around and all I can find are the FMODs.  I think a 30Hz high pass would do because they only have a 20, 30, and 50, etc... How many would I need for two subs....2 packages of 2, or Just 1 package of 2?  Do you connect them to the white and red RCA's for each line in?  I am assuming you do, but I don't know.  If I have to buy 2 packs, that will be about $65.  Does anyone know a cheaper route?

I really appreciate everyones help, thanks.

You get a lot of "music" out of any subwoofer.  That's the whole purpose of using them!  If I owned those subs I'd use them like you already have them until I could afford to purchase something better.

Yes, FMODs are passive line-level filters and you use one set of 2 in line with the RCA signal coming into your sub amp.  There are other options if you want something a little more effective than the FMODs.  I like the HP-SUB from Harrison Labs.

Ok, what I mean is that they're there to boom, that's it.  If they weren't, why would people buy them?  Anyway, I don't know if you are yelling that at me or what because of the exclamation point.  I hope not.  But on those HP-SUBs, do the bypass jacks mean that I could just buy one of those and use it for both of my subs? 

I am planning on building this box to see how they sound before I think about buying new speakers.  If they don't sound good in the box, I will just have a good box for the next 2 subs I buy down the road.

bw40584 wrote:

---

Ok, what I mean is that they're there to boom, that's it. 

---

If that's all you want then sure, go ahead and do whatever.  We are trying to help you do something that sounds good, which has nothing to do with boom.

DYohn, When you say "musical,"  do you mean the loudness of the subs relative to the loudness of the other smaller speakers.  Basically, my subs will be overpowering everything else, making my music not sound good.  Is that what you mean? 

P.S.  I apologize for my ignorance on this subject if I am getting on you guys' nerves.  However, I do think you ALL do everyone an invaluable service with your advice and your time. 

Thank you, and happy holidays to everyone on the forum.

Brad

Ok, I am beginning to understand.  My subs right now, in there present enclosures (sealed,) do not over power the rest of the speakers.  I was using that statement as a hypothetical situation to give to you and see if I was on the right track of understanding. 

Would I need 2 of those PFMODs that you suggested earlier (one for each sub's RCA cords) or just one and use the bypass for the other set of RCA's?

If I used a crossover that has 2 high pass filters at 32-800Hz, with a 18db/octave slope, would that be doing the same thing that the PFMOD does...as far as the subsonic filtering?

thanks