Another day, another idiot building a BP4
First post and of course, asking for help. I've done a ton of reading and I think I'm on the right track but really would like some sanity checking. The wife has a Can Am Defender (Side by Side) and wants some "boom boom". It's an open model and I'm putting the box in the bed so no cab. I'm pairing the subs with a set of wake tower speakers that come in around 60 Hz.
What I'm using:
TS Params:
I used these formulas to back my way into the following specifications:
Putting all of that into WinISD and then adjusting the port to somewhat reasonable air velocity got me here:
The above is modeling a single driver so when I build I'll double the diameter of the port thinking being it's two subs and WinISD is modeling one driver.
That brings me to the box design.
The box is 51" wide by 20.50" tall by 20" deep (front to rear). The port total width is 49.5" by 2" tall (inside dimensions) and 11.72" long.
Where I'm starting to struggle is first, is all of this in the right direction or have I gone badly wrong somewhere?
Second, I know port volume is not included in box volume, but if I change my port length to tune then the box volume will change which changes the port length which changes the volume, etc. Any tips? Or have I designed the port incorrectly by being above the speakers?
Should I redesign the box completely and fire sideway? Move the port? Should I just surrender and go back to IT a failure in the audio world?
First post and of course, asking for help. I've done a ton of reading and I think I'm on the right track but really would like some sanity checking. The wife has a Can Am Defender (Side by Side) and wants some "boom boom". It's an open model and I'm putting the box in the bed so no cab. I'm pairing the subs with a set of wake tower speakers that come in around 60 Hz.
What I'm using:
TS Params:
I used these formulas to back my way into the following specifications:
- fL 32.40750349
- S 0.6
- fH 74.74941047
- Qts 0.86
- Front Chamber 1.3968 (per sub, separate chambers)
- Fs 38.09
- Rear Chamber 1.448182937 (per) 2.896365875 (shared)
- fL Factor 0.7317
- Tune 49.22025233
- fH Factor 1.6877
- VAS 0.97
- Qbp 1.1113
Putting all of that into WinISD and then adjusting the port to somewhat reasonable air velocity got me here:
The above is modeling a single driver so when I build I'll double the diameter of the port thinking being it's two subs and WinISD is modeling one driver.
That brings me to the box design.
The box is 51" wide by 20.50" tall by 20" deep (front to rear). The port total width is 49.5" by 2" tall (inside dimensions) and 11.72" long.
Where I'm starting to struggle is first, is all of this in the right direction or have I gone badly wrong somewhere?
Second, I know port volume is not included in box volume, but if I change my port length to tune then the box volume will change which changes the port length which changes the volume, etc. Any tips? Or have I designed the port incorrectly by being above the speakers?
Should I redesign the box completely and fire sideway? Move the port? Should I just surrender and go back to IT a failure in the audio world?
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A box that size and weight in the back of a vehicle that small is going to definitely change the driving experience, LOL. And that box is going to boom at 50 Hz and provide very little output below that. What type of music does she listen to?
If I was looking at this scenario and response down to just 50 Hz, I'd probably be looking at a different solution, perhaps a neo-magnet pro audio 12" driver (to keep weight down) and a ~45 Hz TH box (similar to my POC3, just tuned higher), with 1/2" ply used for the larger sides, internal panels and bracing). Might not be as loud, but will sound better, and should be much lighter, so less impact on the driving experience.
If I was looking at this scenario and response down to just 50 Hz, I'd probably be looking at a different solution, perhaps a neo-magnet pro audio 12" driver (to keep weight down) and a ~45 Hz TH box (similar to my POC3, just tuned higher), with 1/2" ply used for the larger sides, internal panels and bracing). Might not be as loud, but will sound better, and should be much lighter, so less impact on the driving experience.
Thanks for the feedback. It's the Max version (6 seater) so I'm not terribly worried about the weight. All the gear combined should be about 200-230 lbs or one extra passenger. She normally drives alone so the vehicle can handle it. Music mostly pop, some country, some "hickhop". No house/trance/dubstep/etc.
What did you see to determine the response would cut out below 50 Hz? I'm genuinely trying to learn and understand and thought the f3 of 29-80 was the responsive range and 50 was the peak. The reference (0 gain) is around 32 Hz so I thought it would still have sound there. "Tuning" is still something I don't fully understand. Should I be tuning the ported enclosure lower? Most of the reading I did seemed in indicate to build the sealed portion tuned to the lower end and the ported to the top end but happy to learn the truth on building these.
What did you see to determine the response would cut out below 50 Hz? I'm genuinely trying to learn and understand and thought the f3 of 29-80 was the responsive range and 50 was the peak. The reference (0 gain) is around 32 Hz so I thought it would still have sound there. "Tuning" is still something I don't fully understand. Should I be tuning the ported enclosure lower? Most of the reading I did seemed in indicate to build the sealed portion tuned to the lower end and the ported to the top end but happy to learn the truth on building these.
The WinISD graph shows the FR curve passing 0dB at frequencies near those that you quoted, but there's a bit 6+ dB peak in the middle, so it's likely to sound boomy, particularly as there's no "cabin gain" to fill in the response at lower frequencies.
And that's the thing - seeing that there's no "cabin" to work with here, designs that might sound fine in a car audio environment will probably not work out so well here.
An example: Walker Hayes' "Fancy Like" (yes that tune from the Applebee's commercial) has a low bass tone that comes in around 46 Hz, and another at 35 Hz. With that design of yours, the first tone will sound significantly louder than the second one.
If I already had the drivers that you're planning to use, I'd probably just use a 35 Hz vented box and fix the response with EQ. Mount the drivers so they're down-firing if you want to protect them from damage without having to resort to grills.
Are the electricals for her vehicle up to giving that amp the current that it needs? 🙂
And that's the thing - seeing that there's no "cabin" to work with here, designs that might sound fine in a car audio environment will probably not work out so well here.
An example: Walker Hayes' "Fancy Like" (yes that tune from the Applebee's commercial) has a low bass tone that comes in around 46 Hz, and another at 35 Hz. With that design of yours, the first tone will sound significantly louder than the second one.
If I already had the drivers that you're planning to use, I'd probably just use a 35 Hz vented box and fix the response with EQ. Mount the drivers so they're down-firing if you want to protect them from damage without having to resort to grills.
Are the electricals for her vehicle up to giving that amp the current that it needs? 🙂
Added a second battery and isolator so it should have enough power. The wattage on the stator looks OK (no other electrical accessories and it's designed to carry winch, light bar, etc.) Looking at lots of other builds in these SXS vehicles there are guys with significantly more equipment without even a second battery. The goal isn't to drive around blasting so current draw should be manageable less that 2-3 minutes of "haha look what mine can do".
The other reason for Bandpass is that there is always the risk the box can get water up to midline. Going bandpass lets me have the bottom half of the enclosure sealed and then port the top. Much lower risk of water getting where it should not be. I could mount the drivers in the top firing down but then my coils are exposed to the elements, not ideal either.
Is there a way to level out that huge gain in the center by changing dimensions or ratios between sealed and ported? I noticed on WinISD changing the ratio from 1:2 sealed😛orted to closer to 1:1 smooths the response significantly, is that the correct direction to go? I've read both ways that you want 1:2 and inversely 2:1 depending on SPL vs SQ and then other's say ratio isn't important.
The other reason for Bandpass is that there is always the risk the box can get water up to midline. Going bandpass lets me have the bottom half of the enclosure sealed and then port the top. Much lower risk of water getting where it should not be. I could mount the drivers in the top firing down but then my coils are exposed to the elements, not ideal either.
Is there a way to level out that huge gain in the center by changing dimensions or ratios between sealed and ported? I noticed on WinISD changing the ratio from 1:2 sealed😛orted to closer to 1:1 smooths the response significantly, is that the correct direction to go? I've read both ways that you want 1:2 and inversely 2:1 depending on SPL vs SQ and then other's say ratio isn't important.