Dual Kicker Cvr Ported box Dilemma

[Frank88]

Hi everyone, I've been reading alot and mostly searching alot for the past week. I just ordered 2 Kicker cvr 12'' (with dual 4ohms voice coils to be wired in parralel) I will be driving those with a 2 channel (600W RMS max @ 2Ohms / channel).

The specs tell 1.75 to 2.25 ft³ per sub excluding port for vented boxes. I've found this forum by the free box plan thread by moe lester and I used Win ISD to verify few thing and all and im concerned about the fact that the design I was to choose put the two subwoofer in the same airspace and since the subs are powered by two different channels this could result in sound cancellation and also if one sub blow the remaining one get twice the volume. [My real question is above]

Im referring to this design here :

But there like 5 other design that are interesting for me in the cubic feet range I want. (about 2 to 2.2 per sub)

What you think about all that ? Should I put them in the same airspace and don't worry, or I should separate them and make 2 dedicated port or make a center port(if this is even possible in the way that doing so could result the same as putting them in the same airspace ???).

Another question : If I make 2 chambers, can I tune the ports differently for each sub (ex: one tuned to 30hz and the other to 35Hz) Will this give me a great result or just junk?

And finnaly : Im a little confused about the tunning frequency, which should a choose ? Do I need to get the closest to the fs (which is 26.1Hz) or it more matters on how I want it but you know, it's my first custom box and i know really know what difference it will make on the sound between let's say 25 30 35 hz tuned port.

I know there's alot of question and they maybee a little unclear as english is not my first language but thanks for reading and many thanks in advance for the answers !

Click to read more...

 

[BlactimusCrime 10+ year member]

idk what your listening prefs are but 30-33hz is where i like to be. and for combining chambers, according to a friend (nateberrier) you only have to use 2/3 of the total airspace for 2 subs (i.e.- 1.75cf/sub x 2 subs x .66=volume for 2 of your subs.) also, look at your amp and speaker specs, see if you can bridge your amp and wire all 4 coils of the 2 subs in parallel and not overpower the subs. this would take care of the possible cancellation you are worried about.

 

[Frank88]

The amp is bridgeable but with 2 dual 4ohms I don't see how I can get a 2ohms load, I would have picked dual 2ohms subs for this.

Im listening to a wide band of music but in my car I tend to listen to music with more bass because of the presence of the subwoofer. So im talking about House/electro music, hiphop and metal with good blastbeats but I often listen to good old rock as well (like Acdc, Pink Floyd and such).

I like subs in stereo because sometime double bassdrums are recorded mostly on one channel per bassdrum and give a stereo effect I like (this maybee in my head but each subwoofer have more time before the other kick because of not being in mono).

But thanks about the 2/3 airspace advice, so if I go with the two in the same airspace, that give's me around 2.7 cf net vol. (assuming I want 2cf per sub)

 

[THATpurpleKUSH 5,000+ posts]

I wouldnt go that small on 2, kickers like big boxes. Never heard of that 2/3 thing either...

 

[Frank88]

Ok thanks but anyway I think I will have to go sealed because I measered my trunk and It's quite small in size !! I was thinking I had more space but realised I was quite limited.

Im still gonna check if I can fit a ported one that goes with the specs (maybee by putting em in the same airspace and hope it sound's good.

If ever I go with the sealed one, Any recommandation for the driver (the best cf for this particular sub)

Many thanks again

Edit : If ever that could be usefull to help me, my car is a 2002 Mazda Protegé and I got about 15¾ inch high, 38 inch wide and around 15 inch deep of free space (i could go deeper but I need space for the amps and at 14-15 I would be using more than the half of the trunk) = 5.195 cf Gross Volume

With 3/4 mdf that give (with the divider) ----> 3.98 cf - woofer displ.(.14 for 2) = around 3.84 Net Volume without possible bracing

So here I think im answering to my own question : 1.92 cf per sub is in the specs but with the ports (let's say it equivalent to the volume of the separator (because port is L shaped and that we have 2 port (one per sub)) gives around 1.80 per sub and a Monster box in the trunk and im near the lower border of the specs.

So I guess I should stick with the sealed enclosure but Im still wondering what would be a great sealed airspace for thoses (specs are 1 to 4.6 cf for sealed)

 

[RAM_Designs 5,000+ posts]

I wouldnt go that small on 2, kickers like big boxes. Never heard of that 2/3 thing either...

x2 on the CVR's liking big boxes.

I practice something similar to the 2/3 rule, but it's definitely not that drastic. I normally do 10-15% smaller if doing multiple subs. Following the 2/3 rule and doing 8ft^3 for a pair of 18's instead of 12ft^3 just seems off...