Umbra
Hobbyist & CA Tenderfoot
I've been looking forward to this project for some time and it's finally time to break ground. Granted it's a small, low budget project compared to the norm here, but I'm still excited.
I'll be driving around a minivan for a couple months (I know, I'm just glad it seats seven, given all the tail it's bound to pull). It's old - the stock speakers are shot and only a few buttons on the HU still work after the windows were left open when it was pouring out. I don't mind driving it, but I'm going to throw some of the CA stuff I picked up last year into it. I've got a few amps, some speakers, a couple barely passable head units, speaker wire, misc. wire accessories and a BNIB 8" MA Audio MA800XL sub I found on CL. I know, super exciting. It's a minivan so it's tempting to go nuts and fill 'er up with a huge box and some 15"s, but A) I'm only going to be using it for a short time, B) I'll occasionally need the space for passengers and/or large cargo, and C) I've already got most of what's needed. So I figure I'll just utilize the empty space between the front seats for a bit of bump. All I need is a wiring harness, power wire, a distro block, a box, and maybe some misc. mounting hardware and I'm good to go. That's the plan anyway.
The only problem is the box. I have the tools to build a box. I can build a box. I built one last year to great success, but it was a sealed box in a trunk. For this build I'd like to try a different design, pretty much anything but sealed (I think I have the space). I should probably keep it relatively simple with a ported box. The problem is I've never built a ported box. I have a couple pictures, measurements of the space and sub, and the T/S parameters as per the manual to illustrate what I'm working with.
T/S Parameters - MA800XL
Fo (Hz) - 30.33
QMS - 3.83
QES - 0.24
QTS - 0.23
VAS (Liters) - 18.06
REVC (Ohms) Parallel - 1.5
SPL @ 1W/1(dB) - 84.99
X-Max Linear pk-pk (mm) - 24
LEVC @ 1k Hz (mH) - 1.15
Sealed Enclosure
Minimum sealed (Cu. Feet) - 0.25
Fill Required (%) - No
3dB down point (-3dB Hz) - 108
Maximum sealed (Cu. Feet) - 0.5
Fill Required (%) - No
3dB down point (-3dB Hz) - 117
Ported Enclosure
Vented (Cubic Feet) - 1
Vented to (Hz) - 55
3dB down point (-3dB Hz) - 46
Port Diameter (inches) - 3
Port Length (inches) - 9
Number of ports - 2
Square Port Info
Port Area (square inches) - 14
Port length (inches) - 9
---------------------------------------------------------
I'd like to retain the use of the cup holder tray, but I can live if the box ultimately interferes with it. I'd also like to keep the box in the front, so as not to interfere too much with the area for the next row of passengers. The only concrete requirement is that is it doesn't impede the use of the e-brake. I think given the space I should be able to able to put something ported together. If I could leave some room towards the back to maybe stick the amps, or have it tall enough at the front to mount the amps on the sides that would be icing on the cake.
I have four questions I can call to mind:
1) If I were to build a ported box, where should the port be aimed for maximum effectiveness?
2) If I were to build a ported box, which way should the subwoofer cone face for maximum effectiveness?
3) The manual gives a build for a 55Hz tuning. Would it be unwise to tune lower if it better suits my musical preferences?
4) I'll probably use MDF. What thickness would be appropriate? I used 3/4" last time, I'm thinking that might be overkill here.
To expand on the tuning question: I listen to a variety of genres, but the most bass prevalent are Decaf's bass-boosted remixes, dubstep, rap, hip-hop - that kind of stuff. If I have to choose one range to focus on with a ported box it would be the low end. It'll only be for music, no burps or anything like that. The T/S parameters state the Fo is 30.33, is this the lowest note it can accurately reproduce? Again, I've never made a ported box, so I don't know what range to aim for. Some of the Decaf stuff dips into the 20s (a couple even south of that). I conscientiously avoid his songs that go below what the sub was designed to play. That being said, what's a good frequency to tune to? Something in the 30-40 range?
I apologize for including so much information, but I figure if anyone is able to help they'd have an easier time if they had all the important info upfront. I know this probably won't be addressed in one response, but I'm excited about this project, so I'll be checking in regularly, and if I end up with a usable design I'll be sure to post pictures. A design put together by someone competent would be great, but I really like learning about this stuff, so if a few kind souls could help me along the path I'd be so grateful.
I'll be driving around a minivan for a couple months (I know, I'm just glad it seats seven, given all the tail it's bound to pull). It's old - the stock speakers are shot and only a few buttons on the HU still work after the windows were left open when it was pouring out. I don't mind driving it, but I'm going to throw some of the CA stuff I picked up last year into it. I've got a few amps, some speakers, a couple barely passable head units, speaker wire, misc. wire accessories and a BNIB 8" MA Audio MA800XL sub I found on CL. I know, super exciting. It's a minivan so it's tempting to go nuts and fill 'er up with a huge box and some 15"s, but A) I'm only going to be using it for a short time, B) I'll occasionally need the space for passengers and/or large cargo, and C) I've already got most of what's needed. So I figure I'll just utilize the empty space between the front seats for a bit of bump. All I need is a wiring harness, power wire, a distro block, a box, and maybe some misc. mounting hardware and I'm good to go. That's the plan anyway.
The only problem is the box. I have the tools to build a box. I can build a box. I built one last year to great success, but it was a sealed box in a trunk. For this build I'd like to try a different design, pretty much anything but sealed (I think I have the space). I should probably keep it relatively simple with a ported box. The problem is I've never built a ported box. I have a couple pictures, measurements of the space and sub, and the T/S parameters as per the manual to illustrate what I'm working with.
T/S Parameters - MA800XL
Fo (Hz) - 30.33
QMS - 3.83
QES - 0.24
QTS - 0.23
VAS (Liters) - 18.06
REVC (Ohms) Parallel - 1.5
SPL @ 1W/1(dB) - 84.99
X-Max Linear pk-pk (mm) - 24
LEVC @ 1k Hz (mH) - 1.15
Sealed Enclosure
Minimum sealed (Cu. Feet) - 0.25
Fill Required (%) - No
3dB down point (-3dB Hz) - 108
Maximum sealed (Cu. Feet) - 0.5
Fill Required (%) - No
3dB down point (-3dB Hz) - 117
Ported Enclosure
Vented (Cubic Feet) - 1
Vented to (Hz) - 55
3dB down point (-3dB Hz) - 46
Port Diameter (inches) - 3
Port Length (inches) - 9
Number of ports - 2
Square Port Info
Port Area (square inches) - 14
Port length (inches) - 9
---------------------------------------------------------
I'd like to retain the use of the cup holder tray, but I can live if the box ultimately interferes with it. I'd also like to keep the box in the front, so as not to interfere too much with the area for the next row of passengers. The only concrete requirement is that is it doesn't impede the use of the e-brake. I think given the space I should be able to able to put something ported together. If I could leave some room towards the back to maybe stick the amps, or have it tall enough at the front to mount the amps on the sides that would be icing on the cake.
I have four questions I can call to mind:
1) If I were to build a ported box, where should the port be aimed for maximum effectiveness?
2) If I were to build a ported box, which way should the subwoofer cone face for maximum effectiveness?
3) The manual gives a build for a 55Hz tuning. Would it be unwise to tune lower if it better suits my musical preferences?
4) I'll probably use MDF. What thickness would be appropriate? I used 3/4" last time, I'm thinking that might be overkill here.
To expand on the tuning question: I listen to a variety of genres, but the most bass prevalent are Decaf's bass-boosted remixes, dubstep, rap, hip-hop - that kind of stuff. If I have to choose one range to focus on with a ported box it would be the low end. It'll only be for music, no burps or anything like that. The T/S parameters state the Fo is 30.33, is this the lowest note it can accurately reproduce? Again, I've never made a ported box, so I don't know what range to aim for. Some of the Decaf stuff dips into the 20s (a couple even south of that). I conscientiously avoid his songs that go below what the sub was designed to play. That being said, what's a good frequency to tune to? Something in the 30-40 range?
I apologize for including so much information, but I figure if anyone is able to help they'd have an easier time if they had all the important info upfront. I know this probably won't be addressed in one response, but I'm excited about this project, so I'll be checking in regularly, and if I end up with a usable design I'll be sure to post pictures. A design put together by someone competent would be great, but I really like learning about this stuff, so if a few kind souls could help me along the path I'd be so grateful.
