Bandpass Enclosure - Is it Possible?

[mr_spanners]

As the title suggests I'm wondering if there's any practical way of making\using a bandpass enclosure for the NSX?

Having 'played' with various sub boxes in other cars (Sealed\Ported\Bandpass and even a monsterous Isobaric setup!) I'm interested to see what options are available as opposed to the sealed box in the passenger footwell.

Suggestions please....

~Phil.

 

[D'Ecosse]

Problem is the same old one of space Phil - you would need a much larger volume for a complete bandpass enclosure. The "sealed" part of the enclosure for the sub alone would need volume to be similar to that for 'normal' sealed box then you need the bandpass part of the enclosure on top of that.
It could certainly be designed exactly like the current footwell offerings with an additional enclosure coupled to the front of it - not at all practical though!

 

[lithiumus]

As D'Ecosse mentions, space is the biggest issue, not to mention weight if that matters to you.

Not much room for a bandpass in the passenger footwell unless you go with a much smaller driver i.e. 8" or 6.5" but then you'd be better off with a larger sealed, not to mention a much more linear bass repsonse / curve with a sealed enclosure.

Another option is to put large subs in the trunk but with the engine in between and no real porting into the passenger area, I can't imagine that you would get much sonic quality of the bass and rather just delayed vibrations.

I did an isobaric bandpass once with 2 Kicker C-12 (Old School back in the day). I used 1" MDF throughout with 1"x"1 bracing and a mix of bolts and wood screws. The damn box was so big I had to construct it INSIDE the trunk of my Accord. When I had to remove it, I had to break it apart to get it out...

Ported is probably the next order of box to try, but there just is not enough space to do anything more...

 

[mr_spanners]

Thanks guys - I guessed the lack of space would be the issue... but I'm still going to investigate this further as I really would prefer to have tuned\precise bass freqs. I'm not really interested in 'feeling the bass' as I'm looking for a true representation of the music and not a portable massage facility!!!! :tongue:

As a point of reference my PC has a 6.5" bandpass sub which is dual-reflex (rear and front facing ports) and that produces a superbly 'tight' sound. The case for this unit measures 12" deep x 10" high x 7" wide and should go into the footwell with minimal loses over and above the usual 8"\10" enclosures.

http://www.the12volt.com/caraudio/boxes6.asp

~Phil.

 

[01blacks4]

i have used an 8 inch ported in my old NSX, the sound was much better than the 10 inch sealedoptions i have heard. and much smaller. FWIW

 

[clr1024]

i have used an 8 inch ported in my old NSX, the sound was much better than the 10 inch sealedoptions i have heard. and much smaller. FWIW

interesting I have always found sealed boxes to be tighter and have a better frequency response than a ported box, i.e. flexible for more types of music. I always felt that ported boxes got "sloppy" when it comes to pushing the extremes, aside from their tuning point, I know they are more efficient in their range but I wanted something to produce a wide range of bass notes as I listen to all kinds of music. .

 

[mr_spanners]

I've done some more research today and it's looking like the bandpass in the footwell is viable.

Speaker (sub) options so far are the Focal 5WS or the JL 6WO - likely choice of power is the JL Audio 250/1. As for the box design and port placement - well, I think I need to do some more research and no doubt I'll have to do some 'trial and error' work to get something that produces the sound I'm looking for!

I'll post my findings here on Prime!

~Phil.

 

[mr_spanners]

Update: Further investigation has led to me think that running two Focal 5WS subs in a single reflex isobaric bandpass setup will be the best (only!) way. I will wire these in parallel producing a 2.5ohm load (the subs are 5ohm) which should work fine with the JL mono amp which is capable of running a stable 2ohm supply.

Given the tiny amount of space in the footwell the isobaric solution seems to make sense (well, at least to me anyway!!!)

... This is beginning to sound like it could be an interesting project!!!

~Phil.

 

[TURBO2GO]

In our home installs whenever we have no room we create a bandpass subwoofer in the basement or in another room, and run the port into the stereo room. This is one huge advantage of a bandpass sub in that since the sub is in its own sealed enclosure (there are different types of bandpass but this is one), the only thing needing to be vented into the listening area is a 3" to 4" port usually.

This eliminates the need for the sub itself to be vented so you don't have to do things like cut your floormats or worry about a subwoofer showing on the floor. Its a totally sealed enclosure with only a port that you need to worry about. They are also very tunable.

 

[TURBO2GO]

interesting I have always found sealed boxes to be tighter and have a better frequency response than a ported box, i.e. flexible for more types of music. I always felt that ported boxes got "sloppy" when it comes to pushing the extremes, aside from their tuning point, I know they are more efficient in their range but I wanted something to produce a wide range of bass notes as I listen to all kinds of music. .

This is true for the most part, but my suspicion is that the enclosures made for the NSX are not of an ideal material like thick MDF. Also the air volume may not be ideal, and don't forget down in that corner there is quite a bit of "coupling" going on, all of which affect the sound.

01BLACKS4 may have just had a scenario where his ported box was working better under these conditions where one of those paremeters was more ideal. It could have even been something like different amplifiers being used or the resonance frequencies in the car like tires, exhaust, etc.

So what you say is true, if you had two optimum boxes in an optimum environment. Certainly not the case in a footwell.

 

[TURBO2GO]

Update: Further investigation has led to me think that running two Focal 5WS subs in a single reflex isobaric bandpass setup will be the best (only!) way. I will wire these in parallel producing a 2.5ohm load (the subs are 5ohm) which should work fine with the JL mono amp which is capable of running a stable 2ohm supply.

Given the tiny amount of space in the footwell the isobaric solution seems to make sense (well, at least to me anyway!!!)

... This is beginning to sound like it could be an interesting project!!!

~Phil.

Phil if you need a source for Focal let me know.

 

[lithiumus]

Update: Further investigation has led to me think that running two Focal 5WS subs in a single reflex isobaric bandpass setup will be the best (only!) way. I will wire these in parallel producing a 2.5ohm load (the subs are 5ohm) which should work fine with the JL mono amp which is capable of running a stable 2ohm supply.

Given the tiny amount of space in the footwell the isobaric solution seems to make sense (well, at least to me anyway!!!)

... This is beginning to sound like it could be an interesting project!!!

~Phil.

Although in theory, an isobaric enclosure only requires 1/2 of the necssary enclosure volume... with such small boxes as the ones we are working with, the volume of the second driver can take up to or more than 50% of additional volume thus yielding only a 15 - 25% reduction in required speaker volume.

On the positive side, isobariv enclosures usually yield an overall lower distortion as the 2 speakers will cancel each others' distortion. Let us know how it goes.

 

[TURBO2GO]

If I may make another suggestion that works well for us...

If you can get a good set of speakers in the doors with some decent low-end frequency response, you can use a tactile transducer to let your body truly feel any bass down to below 10 Hz without taking up any room in the floor. You can mount one big one to the chassis or two smaller ones to the seats themselves.

A benefit is that once you step outside the car/seat, there is no booming bass. But as soon as you put your feet/butt down, you will feel there is a tremendous amount of low bass energy in the car. You will think there is a large subwoofer some place.

Guitammer makes several good units, one designed specifically for the car that comes with an amp, another is their new "mini" that is very small and can mount to or nearby the seat.

Also these won't weigh anymore than a sub and box, and in most cases a lot less.

here is a link:

www.thebuttkicker.com (see silent subwoofer)

pic of transducer:

 

[CL65 Captain]

I have two Buttkickers in my HT and they need buku power to work correctly... I am running 2000w to my pair. They are also pretty tall and will never fit under the seat.... would have to go in the sub spot in lieu of a sub.

A thinner solution that would fit under the seats would be one of the Clark transducers. http://www.clarksynthesis.com/home-products.php Another slim line that might work is the Crowson http://www.crowsontech.com/ but they are more expensive.

And finally the cheap way is the Aura bass shakers. I had four of these in a leather couch. They worked great, but more shake than impact than the Buttkickers. They were also a 1/10th the price.

These products can work great as an addition to a small sub, but really can't replace a sub. As well, some will be disapointed as they won't be giving you that "impact" that large subs moving air will. The key is blending them in smoothly so that they are transparent and you just think it's a bigger sub.

 

[TURBO2GO]

I have two Buttkickers in my HT and they need buku power to work correctly... I am running 2000w to my pair. They are also pretty tall and will never fit under the seat.... would have to go in the sub spot in lieu of a sub.

A thinner solution that would fit under the seats would be one of the Clark transducers. http://www.clarksynthesis.com/home-products.php Another slim line that might work is the Crowson http://www.crowsontech.com/ but they are more expensive.

And finally the cheap way is the Aura bass shakers. I had four of these in a leather couch. They worked great, but more shake than impact than the Buttkickers. They were also a 1/10th the price.

These products can work great as an addition to a small sub, but really can't replace a sub. As well, some will be disapointed as they won't be giving you that "impact" that large subs moving air will. The key is blending them in smoothly so that they are transparent and you just think it's a bigger sub.

I have worked with all of these and feel the buttkicker units are the best ones (I have not tried the Crowson, it looks good). CL65, you are really running a lot of power, but you can certainly do it with less.

I would probably look into using an effecient class D or smiliar amp for the car. They also have a new model called the "mini" which is much smaller, did you see this one? Its only 3" high!

I understand your points about impact, but there are also advantages here that you won't have with a sub. I am just suggesting this can be an alternative... something to look into.

 

[Malibu Rapper]

This is true for the most part, but my suspicion is that the enclosures made for the NSX are not of an ideal material like thick MDF. Also the air volume may not be ideal, and don't forget down in that corner there is quite a bit of "coupling" going on, all of which affect the sound.

Just speaking of the Zetoolman enclosure I have, it is a very sturdy fiberglass box. The entire box is fiberglass and is extremely stiff. Very close to the stiffness of MDF at least to the point where the difference in practice is probably inaudible. Fiberglass boxes are widely used in competitions. The air volume is not an issue because there are very good subwoofer options that only require .6 - .65 cubic feet. These have been available for the mobile environment for quite some time now. I can tell from your posts that you come from the home environment. You would be surprised at how good car subs are.

Regarding the Buttkickers, I used to run a set of Aura Bass Shaker Pro's in another car. They worked pretty darn good, I had them mounted under my seats. No room in the NSX for that. Also, the best way to mount them probably would have been to weld them in place. They always seemed to vibrate themselves loose even with strong bolts and nuts holding them in place. When they vibrate loose even just a little bit, you lose a lot of the output.

 

[mr_spanners]

Thanks for all the input!!!

My original aim was (and still is) to produce an enclosure that will produce a precise and detailed bass response.... as I recently tried to explain to a friend "I want it to go 'thud' not BOOM" :biggrin:

So, the need to "feel" the bass is not on the agenda (hence the avoidance of going the usual 10" sealed box route) but I would like to produce a sub that will compliment the Focal K2 Power components that I have lined up for the doors.

Turbo2Go - Thanks for the offer of sourcing the subs. Despite being out of production they are still available to buy over here in the UK (£100gbp each which is around $170usd) but there's a couple of guys that are selling used 5WS units so I might see whether I can bag me a deal there first!

As for the enclosure itself well, it will be a combination of of 18mm MDF and at least 2 layers of 450gm fibreglass so it should be very strong. The only thing I cannot be sure of (yet) is the port length and diameter as I need to try and find a way of accurately measuring the volume of the enclosure.

... let the fun begin!!!

 

[CL65 Captain]

I have worked with all of these and feel the buttkicker units are the best ones (I have not tried the Crowson, it looks good). CL65, you are really running a lot of power, but you can certainly do it with less.

I would probably look into using an effecient class D or smiliar amp for the car. They also have a new model called the "mini" which is much smaller, did you see this one? Its only 3" high!

I understand your points about impact, but there are also advantages here that you won't have with a sub. I am just suggesting this can be an alternative... something to look into.

In HT applications, I have tried all four (Aura, Croswon, Clark & Buttkicker). The Crowson gave the most impact, but it was also the most expensive solution requiring one for each recliner and two for the couch. The other disadvantage was it had to be placed under a recliner/couch leg. The Butkicker came in second but I could use one for the recliner platform and another for my riser with the couch. The Clark was more shake than impact. The Aura basshakers I got on clearance from Parts Express, so they were dirt cheap. Used 8 basshakers attached to the frame of my couch upstairs.... for the price, they worked great but more shake than impact. They also won't take alot of power.

How much room is under the NSX seat, I am guessing not alot. The only way I would do it, is if I could mount them directly to the seat.

 

[TURBO2GO]

Just speaking of the Zetoolman enclosure I have, it is a very sturdy fiberglass box. The entire box is fiberglass and is extremely stiff. Very close to the stiffness of MDF at least to the point where the difference in practice is probably inaudible. Fiberglass boxes are widely used in competitions. The air volume is not an issue because there are very good subwoofer options that only require .6 - .65 cubic feet. These have been available for the mobile environment for quite some time now. I can tell from your posts that you come from the home environment. You would be surprised at how good car subs are.

I am not doubting this, I was just making a point that if to someone their ported box seemed tighter, it could have been for any number of other reasons besides the box itself. There is some serious interaction going on between the car and the sub and it may have been the tuning frequency of the ported box favored that partcular setup/music more.

Correct me if I am wrong but isn't the fiberglass somewhat thin? I have a hard time seeing it as inert as an MDF box. When you knock on it, is it as dead as it would be with 3/4" MDF?

In the home environment some of the best in-walls use aluminum enclosures. 1/4" thick. It seems to be the best where MDF is too thick and takes too much space. Has anyone tried aluminum?

 

[Malibu Rapper]

Correct me if I am wrong but isn't the fiberglass somewhat thin? I have a hard time seeing it as inert as an MDF box. When you knock on it, is it as dead as it would be with 3/4" MDF?

The fiberglass is quite thick on my box. So thick I can jump on it and it probably wouldn't even flex. I believe it's around 1/4" around most of it. Knocking on it is not as inert as MDF.

How much room is under the NSX seat, I am guessing not alot. The only way I would do it, is if I could mount them directly to the seat

I'd guess maybe 1/2"-3/4" or so because you have to consider moving it forward and backward.

 

[mr_spanners]

Has anyone tried using a sound deadening spray or matting on the fibre (fiber!) glass parts of the enclosure???

I guess this would make more of a difference with a ported enclosure than a sealed unit though!!!

~Phil.

 

[CL65 Captain]

I sprayed sound deading spray all over the inside of the enclosure before I stuffed it with fill. Don't know if it made a difference or not, but had a can sitting there and figured it wouldn't hurt.