Experts what should I change..

[NickCR 10+ year member]

Hi All,

I'm trying to make a new box for my trunk as earlier post indicated that my trunk is cancelling frequencies and reducing my performance.

The biggest problem is that i'm really not the best when it comes to calculating all the specs and details of the air space in the box.

I will have a professional installer help me build the box and make all the mounts for the amps so the actual creation of the box will not be hard. I will be putting two Koiiler 10" DVC in the box. Each powered seperately by Koiiler AMP's. I have a capacitor with 5.6 or 5.7 joules (i think thats the rating name).

As it is the system sounds great, but I know i'm missing a lot of thump, the boxes are horrible and I doubt they are doing the best job they should.

Attached below I have included a diagram of my trunk. My plan was to punch a hole through the Ski Hole and use that space as the "port". I also was told by the installer that just making a hole without the port directed to the hole would accomplish what I want. Which is the best solution here? Just a regular port for both of the subs? I like crisp but deep bass. I'm not a big fan of dry bass, that you normally get from the sealled boxes. Any suggestions?

Thanks in advance.

Nick

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[Mr. Nipples 10+ year member]

1.get rid of the bungees

2.

 

[Volenti 10+ year member]

2.?

3. Profit!

You look to have enough room for a bandpass enclosure, standard tripple chamber with the center chamber vented through the ski hole. Would be my first option.

 

[NickCR 10+ year member]

Thanks for the initial comments...

The bungees are not my favorite. However I need access to my spare tire, located right below the box, but with that said I have moved the bungee supports around and made them much stronger and not in anyway touching the subs.

What benefits would a bandpass box have vs a regular ported box?

 

[Volenti 10+ year member]

The main advantage of a bandpass box for your application is the ability to direct all the bass through a small opening (the ski hole), something that's not easily done with a regular ported box.

You said in your inital post that the boot was causing problems with the bass response, in general I agree, the best way to eliminate the boot from the equation is to seal the box up to the back seat and directly fire the bass into the cabin space. When you only have a small opening available bandpass is a logical first choice.

Post the parameters of the drivers (or a link) and I'll see if they will be suitable for a bandpass design.

 

[NickCR 10+ year member]

Hi Volenti,

Thanks for the response, Sub specs are as follows:

Size: 10"

Frequency Respond: 20 Hz - 500 Hz

Sensitivity: 90 dB

Impedance: 4 ohm

Components Surround Material: Foam

Mounting Enclosure: Non-Enclosed

Top Mounting Depth : 5.31 In.

Bottom Mounting Depth: 5.31 In.

Mounting Diameter / Length: 9.84 In.

# Power handling:800 Watts Peak, 400 watts RMS

# Vented 4 Layer Dual 4 Ohm Voice coils

# Diameter: 2.5" Voice coil

# Nominal impedance: 4 ohms /per coil

# DC resistance: 3.2 ohms each coil

# Frequency range: 20 Hz-1.5 kHz

#Fs: 41 Hz

# Qts: 0.6360

# Qes: 0.7209

# Qms: 5.4047

# Vas: 26L

# Xmax: 11.9mm

# Sd: 0.0346m

# Mounting Depth: 135mm

# Mounting Hole Diameter: 250mm

# SPL: 86.54 dB 1W/1m

With a bandpass box with this sub will I get a nice crisp bass that i'm looking for or would it be different.

Thanks

Nick

The main advantage of a bandpass box for your application is the ability to direct all the bass through a small opening (the ski hole), something that's not easily done with a regular ported box.
You said in your inital post that the boot was causing problems with the bass response, in general I agree, the best way to eliminate the boot from the equation is to seal the box up to the back seat and directly fire the bass into the cabin space. When you only have a small opening available bandpass is a logical first choice.

Post the parameters of the drivers (or a link) and I'll see if they will be suitable for a bandpass design.

 

[Volenti 10+ year member]

Yes they are suitable, total enclosure volume is 3.5cuft, the outside sealed chambers are 1cuft each leaving 1.5cuft for the vented center chamber, vent size is 6'' in diameter by 5'' long.

While I can't predict the exact response it should have a little extra kick ~50hz that will eliminate any dry type sound, as for crispness it will certainlly be crisper with the bandpass then firing into the boot.

 

[NickCR 10+ year member]

Thanks for your reply. I really appreciate your comments and help. Now I was wondering the following. Would the BandPass provide more bass then a ported with my subs given the specs you provided.

Do others out there agree with the specs and suggestions?

Thanks All,

Nick

Yes they are suitable, total enclosure volume is 3.5cuft, the outside sealed chambers are 1cuft each leaving 1.5cuft for the vented center chamber, vent size is 6'' in diameter by 5'' long.
While I can't predict the exact response it should have a little extra kick ~50hz that will eliminate any dry type sound, as for crispness it will certainlly be crisper with the bandpass then firing into the boot.

 

[phantom240 5,000+ posts]

bandpass will not... i repeat WILL NOT have the same bass response as a normal ported box, and wont even come close to a sealed box... as far as "crispness" goes that is. Bandpass boxes are known to produce "muddy" bass, more suitable for heavy bass rap-type music, not so much for drum kicks and such with fast basslines. Of course, it is harder to hear distortion with bandpass boxes, which, to many people, is a bad thing because you cant tell when your subs are distorting, which kills the sub. But, on the flip side, bandpass boxes are known to get hella loud for people who dont have the experience/skill to build a proper ported box.

And please read the stickied thread at the top of this forum about differences in box designs (sealed vs ported vs bandpass vs infinite baffle)

 

[Volenti 10+ year member]

Thanks for your reply. I really appreciate your comments and help. Now I was wondering the following. Would the BandPass provide more bass then a ported with my subs given the specs you provided.

Nick

Oh with the particular response curve I modeled it's not that much different to what you would get with a vented enlcosure from ~40-100hz, the main difference is the bandpass can be easily vented into the cabin space through the small ski hole while a ported enclosure is more troublesome and un-predictable, especially with dual drivers. (bacause you need a coupling chamber with dual drivers you can get 6th order effects which can cause issues)

Note that this is addressing the particular suitation that you face with your vehicle, if you had a hatch or a SUV there wouldn't be this problem and you would happily be using a typical vented box.

 

[NickCR 10+ year member]

Guys thanks agian,

Would I be better off looking to just open a hole in the back-top area between the seat back and the window? Would this also create the effect i'm looking for with the bass increase only with a vented box.

My usual music listening is: Rap, R&B, Rock, Reggeton. Sometimes I listen to different music types but not often. I don't really know what i'm explaining with the crisp vs muddy. Really I know i've had some ported boxes in the past and I really like the way they sounds vs sealed.

 

[phantom240 5,000+ posts]

Oh with the particular response curve I modeled it's not that much different to what you would get with a vented enlcosure from ~40-100hz, the main difference is the bandpass can be easily vented into the cabin space through the small ski hole while a ported enclosure is more troublesome and un-predictable, especially with dual drivers. (bacause you need a coupling chamber with dual drivers you can get 6th order effects which can cause issues)
Note that this is addressing the particular suitation that you face with your vehicle, if you had a hatch or a SUV there wouldn't be this problem and you would happily be using a typical vented box.

...nice... you put a lot of thought into that.

Problem solving skills are always a plus in car audio...pos rep for that!

Anyways, being that you have prefered the vented over sealed, and your preferences in music, i'd say that Volenti hit the nail on the head... and about cutting a hole in your rear deck, thats called porting your rear deck. It is a VERY powerful tool, but its a very hard thing to do CORRECTLY. You have cabin resonant frequencies, port volume, blah blah blah. For the average consumer, its more hassle than its worth

 

[PowerNaudio 10+ year member]

i suggest going with a well tuned ported enclosure. if not go sealed but again size it correctly. i listen to the same type of music you do, but mostly reggaeton and rap. as long as you build the enclosure to match the specs of the sub and tune it to get low. but still hit some like 80Hz, youll like it.

i aim to build the boxes to go from 120Hz to at least 25Hz, if the sub allows it if i can get it to be close to a flat frequency response. that way all music will sound good. but that just me.

 

[NickCR 10+ year member]

Guys,

You've provided some great feedback and i'm looking forward to choosing an enclosure and having it designed. There was one other thing that I just thought about and I wonder what you think. My cabin is very well sealed. This is just the way these car are built. Now my question is if I have a direct port to the cabin when I open or close the doors would I create and problems with the sub reflex and make a sub pop or something?

I think making the right size port in my rear deck is possible as i'm not going to be doing a DIY install, i'm going to get some help from a professional. What would be best in that case Ported or Bandpass. BTW I like where the comments of the bandpass have lead and I also like the fact that the bandpass will hide my subs in the box so I don't have to worry about them being ripped or damaged from things in my trunk.

Nick

...nice... you put a lot of thought into that.
Problem solving skills are always a plus in car audio...pos rep for that!

Anyways, being that you have prefered the vented over sealed, and your preferences in music, i'd say that Volenti hit the nail on the head... and about cutting a hole in your rear deck, thats called porting your rear deck. It is a VERY powerful tool, but its a very hard thing to do CORRECTLY. You have cabin resonant frequencies, port volume, blah blah blah. For the average consumer, its more hassle than its worth

 

[Volenti 10+ year member]

Guys,
My cabin is very well sealed. This is just the way these car are built. Now my question is if I have a direct port to the cabin when I open or close the doors would I create and problems with the sub reflex and make a sub pop or something?

Nick

With the 4th order bandpass the sealed chambers will prevent any pressure based damage from opening or closing the doors, you would cause structural damage to your car long before you created enough pressure to damage the drivers, it's not an issue.

Regarding the vented v bandpass, remember if you go vented you need to have both the vent and the driver/s radiating into the cabin space, if you only have the vents directed into the car with the drivers still firing into the boot you end up with a leaky mis-tuned bandpass box.