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Seriously?! .244 ?! That's like a third of my current box and seems very very small. Sundown themselves recommend .5-.75? Why so small?
It was what Bassbox Pro program suggested when I choose the option for it to do that so don’t put much faith in it. I’m going to guess Sundown can’t fit a vent in a box any smaller. For reference my JL Audio microsub with the 8W3v3 subwoofer was installed in a box just .35 cu ft tuned to 35 Hz by JL Audio. It’s only an 8” subwoofer after all. I normally put a 10” in a ported box around 1 cu ft such as the Alpine and Sundown SD3 10 I own.
 

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Precision Ports’ calculator compensates for their own ports’ flared area. Non-flared ports would be commensurately shorter (by something on the order of half the length of the flared portion(s), IIRC). Use this for non-flared ports: Port Length Calculator

Per Precision Ports’ calculator:
1a) .7 ft^3 at 34.6 Hz = 3” x 21.5” flared port (59.6 m/s)
2a) .7 ft^3 at 34.6 Hz = 4” x 38.5” flared port (33.5 m/s)

Per WinISD:
1b) .7 ft^3 at 34.0 Hz = 3” x 21.3” non-flared port (58.3 m/s)
2b) .7 ft^3 at 33.0 Hz = 4” x 41.3” non-flared port (32.8 m/s) GREEN

If you’ve only got 21.5” for a tube vent, and you want to keep all of that length within the cabinet, you’re stuck with 1a or 1b.

If you can locate the remainder of the vent (beyond 21.5”) outside the cabinet, then 2a or 2b would be preferable in terms of both output and vent noise.

At .7ft^3 you should have zero chuffing with a 4” Precision Port at any tuning. Lesser flaring will be accordingly less effective at reducing chuffing, so do the best you can in this regard.

.244 ft^3 is simply out of the question in terms of useful vent area and/or plausible vent length …while any such “High Fidelity” recommendation would seem to be very much at odds with the SPL design goals and capabilities of this driver (though, apart from vent noise issues, it seems OP has yet to weigh in on their own design goals/preferences in this regard). For example:

.244 ft^3 at 40 Hz = 3” x 46.4” non-flared port (34.5 m/s) BLUE

.244 ft^3 at 31.5 Hz = 3” x 76.2” non-flared port (30.5 m/s) RED

Bear in mind that, at a given vent area, vent velocity goes more or less hand in hand with cabinet volume and SPL (i.e. less cabinet volume = both lower SPL and vent velocity).

Response/SPL:


Vent velocity (m/s):
 

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If you give me dimensions A, B, C, and D, than I can model up any box you want with cut sizes. Also, give me an idea of the limits of your dimensions so I can play around with it. Just playing around with this sub some more I think Sundowns recommendations work best. Attached are two models with a vb of .5 cu ft and .8 cu ft (blue) for your comparison, and I used 3" flared port vents. Even with 3" flared ports I am having a hard time fitting them inside the box so again, I need those dimensions to play around with it.

Attached are the two PDF files for these boxes with all the details.
 

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Discussion Starter #24
Precision Ports’ calculator compensates for their own ports’ flared area. Non-flared ports would be commensurately shorter (by something on the order of half the length of the flared portion(s), IIRC). Use this for non-flared ports: Port Length Calculator

Per Precision Ports’ calculator:
1a) .7 ft^3 at 34.6 Hz = 3” x 21.5” flared port (59.6 m/s)
2a) .7 ft^3 at 34.6 Hz = 4” x 38.5” flared port (33.5 m/s)

Per WinISD:
1b) .7 ft^3 at 34.0 Hz = 3” x 21.3” non-flared port (58.3 m/s)
2b) .7 ft^3 at 33.0 Hz = 4” x 41.3” non-flared port (32.8 m/s) GREEN

If you’ve only got 21.5” for a tube vent, and you want to keep all of that length within the cabinet, you’re stuck with 1a or 1b.

If you can locate the remainder of the vent (beyond 21.5”) outside the cabinet, then 2a or 2b would be preferable in terms of both output and vent noise.

At .7ft^3 you should have zero chuffing with a 4” Precision Port at any tuning. Lesser flaring will be accordingly less effective at reducing chuffing, so do the best you can in this regard.

.244 ft^3 is simply out of the question in terms of useful vent area and/or plausible vent length …while any such “High Fidelity” recommendation would seem to be very much at odds with the SPL design goals and capabilities of this driver (though, apart from vent noise issues, it seems OP has yet to weigh in on their own design goals/preferences in this regard). For example:

.244 ft^3 at 40 Hz = 3” x 46.4” non-flared port (34.5 m/s) BLUE

.244 ft^3 at 31.5 Hz = 3” x 76.2” non-flared port (30.5 m/s) RED

Bear in mind that, at a given vent area, vent velocity goes more or less hand in hand with cabinet volume and SPL (i.e. less cabinet volume = both lower SPL and vent velocity).

Response/SPL:


Vent velocity (m/s):
Grinder and V8, your time is very much appreciated.

I agree this .244 business seems ridiculous. I want the output, and will stick with 0.7ft³. However the response of that blue line looks really nice, if only the peak was at 28hz instead of 45hz. Is this possible?

I'm fine with the port sticking out of the box, It's all under the rear seat and I'd rather get the absolute best performance I can out of it. At this point I'm going to cut the top off this box, remove the slot port and throw a tube in it.

My goals are a 60/40 split of SPL/SQ. I listen to everything except country. 75% of my vehicle listening is low heavy bass rap or electronic. But, I need to be able to throw on some Tool, Max Richter, Local Natives, Ben Howard etc and have it sound good. I want to still have decent output at 25hz if possible. I'm actually debating tuning it to 28-30hz.. cause what do I get, about 3 usable hz below tuning before she unloads?

I guess what I'm saying is I'd rather a wider playable range over a narrow range of huge SPL. But.. I want that range to start low.

Lower hz needs more power to generate the same db, right? So tuning lower makes sense? I guess I need to learn how to use this software so I can play with how much high end I lose by tuning so low.

I think my plan is to put a 44-45" 4" tube in this current box, with a coupler on the external portion and shorten it until I like what I hear?

I could spend all day modeling it in the software, but I already have a good 0.7ft³ box, I know I want to use a 4" port and a couple feet of it is going to stick out, so I might as well just go for it. haha.


Side question:

When it comes to flaring the internal part of the port, what is the best approach if the top and bottom of the box will contact the port? Should I flare the tube, stick a brace a few inches back from the flare, and then cut the flare flat on the top and bottom so it JUST fits in, and then like silicone the seams where the plastic contacts the wood? My only other option would be to put a bend in and turn the port toward the front of the box to allow more clearance. (cause it's a wedge shape).

Thanks again guys. This thing is pretty impressive as is, I can't wait to hear it with the proper port area! :)
 

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See my responses in red.

Grinder and V8, your time is very much appreciated.

I agree this .244 business seems ridiculous. I want the output, and will stick with 0.7ft³. However the response of that blue line looks really nice, if only the peak was at 28hz instead of 45hz. Is this possible? The high fs in my opinion is what is making it difficult to get the curve flat below the fs. I'm no expert here but I have noticed this a lot when modeling other drivers and I tried a box on my Alpine at 25 Hz Fb and it sounded muddy. That driver has an fs of 35 hz. I went back to a 34 Hz tune and it sound awesome now.

I'm fine with the port sticking out of the box, It's all under the rear seat and I'd rather get the absolute best performance I can out of it. At this point I'm going to cut the top off this box, remove the slot port and throw a tube in it. I recommend that you buy some PVC pipe and experiment with different tunes and volumes. you can shrink the vb of the box by just adding blocks to the inside of it. I do this sometimes before committing to a well built final box because although these programs are great, they are not perfect, and cabin gain makes a huge difference. BassBox Pro can model for cabin gain if you know what it is or I can guess based on vehicle type.

My goals are a 60/40 split of SPL/SQ. I listen to everything except country. 75% of my vehicle listening is low heavy bass rap or electronic. But, I need to be able to throw on some Tool, Max Richter, Local Natives, Ben Howard etc and have it sound good. I want to still have decent output at 25hz if possible. I'm actually debating tuning it to 28-30hz.. cause what do I get, about 3 usable hz below tuning before she unloads? You get two peaks basically as the Vb goes up. One at the fs (should say above fs) of the driver and the other is for the tuning frequency of the box/port

I guess what I'm saying is I'd rather a wider playable range over a narrow range of huge SPL. But.. I want that range to start low.

Lower hz needs more power to generate the same db, right? So tuning lower makes sense? I guess I need to learn how to use this software so I can play with how much high end I lose by tuning so low. true to a point but as the box gets bigger, the power needed to get the same SPL goes down because efficiency goes up. Tuning lower with a smaller box for this driver gives you that flatter curve as you see in Grinders blue one.

I think my plan is to put a 44-45" 4" tube in this current box, with a coupler on the external portion and shorten it until I like what I hear?Yes, test first in car until you get what your ears like and then build the box to those specification. The modeling software gets you close.

I could spend all day modeling it in the software, but I already have a good 0.7ft³ box, I know I want to use a 4" port and a couple feet of it is going to stick out, so I might as well just go for it. haha. I say go for it and have some fun!


Side question:

When it comes to flaring the internal part of the port, what is the best approach if the top and bottom of the box will contact the port? Should I flare the tube, stick a brace a few inches back from the flare, and then cut the flare flat on the top and bottom so it JUST fits in, and then like silicone the seams where the plastic contacts the wood? My only other option would be to put a bend in and turn the port toward the front of the box to allow more clearance. (cause it's a wedge shape).There are a ton of youtube videos on how to do this. There are also flared ends for the tubing for sale on Parts Express. I highly recommend spending the money for the Precision Port kit with tube extensions. Its a little bit of money, but it makes for a nice SQ/SPL setup.

Thanks again guys. This thing is pretty impressive as is, I can't wait to hear it with the proper port area! :)
 

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I would echo much of this ^^^^^

Adjustable port length (and Vb, via added displacement) in conjunction with in-car experimentation is the best way forward. Even if you don't achieve the results you're after, you'll be a lot closer in the end, and you'll learn a whole lot in the process. According to WinISD, smaller Vb will reduce Fb peak, while higher Fb will also flatten response of this driver. Here's a great thread on Fb and cabin gain (as you probably don't need as low an Fb as you think) https://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/38784-given-cabin-gain-reality-do-we-need-low-fs.html
 

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IDK if you are open to changing drivers but I own the love my SD3 10 and have it ported. Look at the comparison between the SD3 10 vs that SA 8 in the graph. I'm willing to bet this gets just as loud if not louder than the SA-8 (but check with Sundown) and it is all SQ. Love, love, love mine!

Box spec for this SD3 10 is .98 net tuned to 32.5 Hz.

Edit: adding the same SD3 10 sealed in light blue so you can see comparison in .8 cu ft sealed.
 

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Based on apparent height of OP's cabinet, there doesn't appear to be adequate vertical height (or horizontal clearance) for a 10"

If it were me, and if I could afford it, I might be looking to replace this driver with one that would seem to be more in line with my SQL preferences. However, I might be equally inclined to hold-off and experiment, and learn whatever I could ...and in the end, perhaps even end up with something that I'd be quite pleased with.
 

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Discussion Starter #29
Based on apparent height of OP's cabinet, there doesn't appear to be adequate vertical height (or horizontal clearance) for a 10"

If it were me, and if I could afford it, I might be looking to replace this driver with one that would seem to be more in line with my SQL preferences. However, I might be equally inclined to hold-off and experiment, and learn whatever I could ...and in the end, perhaps even end up with something that I'd be quite pleased with.
This is correct, I can't fit the 10 or I would have for sure gone that route.

I'm happy with the SQ and performance of the SA. Will report back when I get time to rework the port. Thanks again for you guys help!
 
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