I am thinking of using Polk MM1040UM-SVC 10" subwoofer for an existing ported enclosure. It'd be two of this. The physical dimension would fit. I have measured the inside enclosure volume and the driver specs are below.
I do not have any experience in this. Would appreciate any comments if you think this would work well or not for a HT set up.
enclosure inside volume 1.45 ft3 (excluded port tube)
existing round port 3.5" diameter x 8" length
Amp power 150W RMS, 300W Dynamic, 4 Ohm
Subwoofer
Fs 35Hz
Xmas 3/4"
LE 2.3 mH
SD 35.65 ft2
Vas 0.54 ft3
Qts 0.6
Qes 0.7
Qms 5.5
Power Handling 350W Continuous, 700W Peak
Nominal Impedance 4 ohms
Efficiency 91 dB
Thanks!
I do not have any experience in this. Would appreciate any comments if you think this would work well or not for a HT set up.
enclosure inside volume 1.45 ft3 (excluded port tube)
existing round port 3.5" diameter x 8" length
Amp power 150W RMS, 300W Dynamic, 4 Ohm
Subwoofer
Fs 35Hz
Xmas 3/4"
LE 2.3 mH
SD 35.65 ft2
Vas 0.54 ft3
Qts 0.6
Qes 0.7
Qms 5.5
Power Handling 350W Continuous, 700W Peak
Nominal Impedance 4 ohms
Efficiency 91 dB
Thanks!
Last edited:
In a nutshell your existing box won't work well at all.
First off the EBP can go either way ported or sealed The sealed performance if you use your existing enclosure gets you an F3 of 40.84Hz....not good at all.
Optimal sealed performance is abysmal....really bad for sub-woofer performance.
Ported gets you far far better performance but you will need to build yourself a new enclosure.
Ported sims in at 56.7 Liters with an F3 of 20.26 Hz,.....well into true sub-woofer territory. with an odd 68mm diameter port tube, 297mm long, box tuned to 23.32 Hz.
Hope this helps......
_____________________________________________________Rick...........
First off the EBP can go either way ported or sealed The sealed performance if you use your existing enclosure gets you an F3 of 40.84Hz....not good at all.
Optimal sealed performance is abysmal....really bad for sub-woofer performance.
Ported gets you far far better performance but you will need to build yourself a new enclosure.
Ported sims in at 56.7 Liters with an F3 of 20.26 Hz,.....well into true sub-woofer territory. with an odd 68mm diameter port tube, 297mm long, box tuned to 23.32 Hz.
Hope this helps......
_____________________________________________________Rick...........
Hold up here, I'm switching back & forth units metric vs. Cubic feet....your existing box WILL work...wait a sec OK?
_______________________________________________________Rick.......
_______________________________________________________Rick.......
Ok, I forgot to do the conversion, with re-tuning the Fb...re-tuned to 26Hz for YOUR box we can get a -3.08 Db at 22.38 Hz........just fine.
Your port however would wind up being some 23 inches long....recalculating for a smaller port diameter has a diameter of 68mm by 13.22 inches long...should be able to fit inside...I still need to recalculate for the volume of such a long port however...........since we don't have all the driver parameters the port velocity MAY be too "fast" with "only" 68mm in diameter.
This is what I've come up with so far......It'll work out
________________________________________________________Rick.......
Your port however would wind up being some 23 inches long....recalculating for a smaller port diameter has a diameter of 68mm by 13.22 inches long...should be able to fit inside...I still need to recalculate for the volume of such a long port however...........since we don't have all the driver parameters the port velocity MAY be too "fast" with "only" 68mm in diameter.
This is what I've come up with so far......It'll work out
________________________________________________________Rick.......
Thank you Rick
I found a couple of port size calculators on the net and generated the following numbers:
Select Your Port Type: Round
Is this a slot port ? No
Quantity of ports: 1
Enter Enclosure Volume: 1.45 (ft3 )
Tuning Frequency: 41 Hertz
Round Port Diameter: 3.5 Inches
Vent Length: 8.08 Inches
Since I am using an existing enclusure (with amp plate) and it doesn't look like I can modify the port diameter. If the above calculation is correct, the F3 would be around 41Hz. Is that not good? I know 24Hz would be better since the driver spec goes from 24Hz to 200Hz. But I don't know what's the acceptable F3 range for subs.
I might be able to increase the port length by using a right angle coupler (like plumbing 😛). Would that work? Does it have to be straight?
I found a couple of port size calculators on the net and generated the following numbers:
Select Your Port Type: Round
Is this a slot port ? No
Quantity of ports: 1
Enter Enclosure Volume: 1.45 (ft3 )
Tuning Frequency: 41 Hertz
Round Port Diameter: 3.5 Inches
Vent Length: 8.08 Inches
Since I am using an existing enclusure (with amp plate) and it doesn't look like I can modify the port diameter. If the above calculation is correct, the F3 would be around 41Hz. Is that not good? I know 24Hz would be better since the driver spec goes from 24Hz to 200Hz. But I don't know what's the acceptable F3 range for subs.
I might be able to increase the port length by using a right angle coupler (like plumbing 😛). Would that work? Does it have to be straight?
First of all, let me say sorry to all the viewers that I created a twin post on this subject by accident (I think I refreshed my screen). Anyway, there are some comments in the other thread as well.
Back to the subject. It seems confusing to me that how can a smaller port (2" x 7" vs 3.5" x 8") can result a lower tuned freq? I used the calculator I found on carstereo.com and it seems smaller and shorted port should increase the tuned frequency when the enclosure volume stays the same.
Back to the subject. It seems confusing to me that how can a smaller port (2" x 7" vs 3.5" x 8") can result a lower tuned freq? I used the calculator I found on carstereo.com and it seems smaller and shorted port should increase the tuned frequency when the enclosure volume stays the same.
He-he...
You can, refer to port plugs like the ones used by B&W, they can reduce the diam., or use some DIY kind-off. Be inventive.
Is there one?! More important is if you using it inside (room size) or outside. There simulators for that, and some reading. More important some times (for me, if used inside) is the roll off; f3, f6, f12, f24...
No, usually is (straight) for best results and tunning. But it can hang outside where/when you don't see it. Just should not be in touch or ~< 1xport/diam. close to the back enclosure wall.
Hmmm
Maybe my copy of WinISD beta has some bugs.
I hope you got better answers on the other post.
I will look into this.
Maybe my copy of WinISD beta has some bugs.
I hope you got better answers on the other post.
I will look into this.
When you reduce port diameter, the length has to be reduced too to keep the same tuning frequency. Not in favor of port noise of course.
I think your T&S parameters are way off.
On there website:
MM1040 UM - Marine | Polk Audio
The current configuration of your box peaks with +6dB! at 41hz (-3dB@35hz) and the port has an air velocity of 47m/s@350Wrms: too high.
If you can fit a port in there of 4" diam. and a lenght 26,5", you'll reduce the port air speed to 29m/s@350Wrms and a resonance frequency of 31hz (-3dB@27hz)
If you want to use this driver in a car, I suggest to use a sealed box of 14l
It's 12dB down@31hz which will result in a flat response in a car, and it takes less space.
On there website:
MM1040 UM - Marine | Polk Audio
The current configuration of your box peaks with +6dB! at 41hz (-3dB@35hz) and the port has an air velocity of 47m/s@350Wrms: too high.
If you can fit a port in there of 4" diam. and a lenght 26,5", you'll reduce the port air speed to 29m/s@350Wrms and a resonance frequency of 31hz (-3dB@27hz)
If you want to use this driver in a car, I suggest to use a sealed box of 14l
It's 12dB down@31hz which will result in a flat response in a car, and it takes less space.
Attachments
Richard, Inductor, thanks for your help.
I've installed Winisd Pro and started playing with it a little bit. I still don't understand the most of it but can see how tunning the port size works.
Please use the following track for all future responses.
http://www.diyaudio.com/forums/subwoofers/238406-need-help-10-subwoofer-build.html
I've installed Winisd Pro and started playing with it a little bit. I still don't understand the most of it but can see how tunning the port size works.
Please use the following track for all future responses.
http://www.diyaudio.com/forums/subwoofers/238406-need-help-10-subwoofer-build.html
Bart, thanks for pointing out the correct driver parameters and I've called Polk to confirm (i.e. there are some errors in the manual). Here are all the numbers again:
Existing enclosure
inside volume 1.45 ft3 (excluded port tube)
single round port 3.5" diameter x 8" length
Amp plate 150W RMS, 300W Dynamic, 4 Ohm
Polk MM1040UM SVC Subwoofer
Fs 35Hz
Xmas 1"
LE 3.0 mH
SD 54.25 ft2
Vas 0.65 ft3
Qts 0.45
Qes 0.529
Qms 3.0
Power Handling 350W Continuous, 700W Peak
Nominal Impedance 4 ohms
Efficiency 91 dB
I've installed winisd pro and played with it a bit over the weekend. I can see how the port size can change tunning frequency but are still trying to understand all the other numbers and functions.
It seems that there are some options to consider and I'd hope to get some more guidance:
1. Should I go with sealed? It would mean that I need to block off more than half of the existing cabinet space. Due to the low amp output (150w RMS), I am not sure if sealed is the way to go. It could be the easiest cabninet mod for me though.
2. Make the port diameter smaller (~2") to lower tunning freq. This I can do. However, I understand air velocity would increase and I don't know if it would be an issue. Sorry, I don't have all the numbers and how to get it in winisd.
3. Make the port length longer (~26"). It does not look like possible because the existing port is right under the driver magnet vertically (down exiting), there is really no room to extend the tube upward. Using a 90 degree elbow is possible but only for maybe 5" to 6" longer.
4. Open a second port? I can open a second vertical port for upto 12" long but I am not sure if this would help.
This is intended for a room of roughly 33' (W) x 15' (D) x 18' (H) for both music listening and HT. I wish not to get a boomy or muddy sound. Would appreciate any suggestions of what would be my best choice.
Many thanks!
Existing enclosure
inside volume 1.45 ft3 (excluded port tube)
single round port 3.5" diameter x 8" length
Amp plate 150W RMS, 300W Dynamic, 4 Ohm
Polk MM1040UM SVC Subwoofer
Fs 35Hz
Xmas 1"
LE 3.0 mH
SD 54.25 ft2
Vas 0.65 ft3
Qts 0.45
Qes 0.529
Qms 3.0
Power Handling 350W Continuous, 700W Peak
Nominal Impedance 4 ohms
Efficiency 91 dB
I've installed winisd pro and played with it a bit over the weekend. I can see how the port size can change tunning frequency but are still trying to understand all the other numbers and functions.
It seems that there are some options to consider and I'd hope to get some more guidance:
1. Should I go with sealed? It would mean that I need to block off more than half of the existing cabinet space. Due to the low amp output (150w RMS), I am not sure if sealed is the way to go. It could be the easiest cabninet mod for me though.
2. Make the port diameter smaller (~2") to lower tunning freq. This I can do. However, I understand air velocity would increase and I don't know if it would be an issue. Sorry, I don't have all the numbers and how to get it in winisd.
3. Make the port length longer (~26"). It does not look like possible because the existing port is right under the driver magnet vertically (down exiting), there is really no room to extend the tube upward. Using a 90 degree elbow is possible but only for maybe 5" to 6" longer.
4. Open a second port? I can open a second vertical port for upto 12" long but I am not sure if this would help.
This is intended for a room of roughly 33' (W) x 15' (D) x 18' (H) for both music listening and HT. I wish not to get a boomy or muddy sound. Would appreciate any suggestions of what would be my best choice.
Many thanks!
With the new parameters I still get a 5dB peak using 3.5" x 8"L
But with a port of 3.5" dia by 17" it runs almost flat until it cuts off sharply
Set this in WinISD by setting the port dia and adjusting the tuning in the box tab.
Have fun.
🙂
But with a port of 3.5" dia by 17" it runs almost flat until it cuts off sharply
Set this in WinISD by setting the port dia and adjusting the tuning in the box tab.
Have fun.
🙂
posts from duplicate thread merged in Thanks for all the help. So I plotted 3 scenarios with images attached. Please tell me which one is better for me? What do I need to consider? (Please note the amp is only 150W RMS)
Green - port 4" x 26" Fb = 30Hz
Blue - port 4" x 20" Fb = 33.1Hz
White - port 4" x 38" Fb = 26.1Hz
What happened is it dawned on me that I actually can extend the vent very long. The subwoofer is actually part of a tower speaker. It takes the whole lower half of the enclosure plus a narrow (5" x 5.5") long space behind the upper drivers (see drawing).
I think I can (and have to) open the vent wider (changing from 3.5" to 4" diameter) in order to lower the air velocity. However, because the vent has to go through that long space with the opening at the top, will that give me any negative results?
Thanks!
Green - port 4" x 26" Fb = 30Hz
Blue - port 4" x 20" Fb = 33.1Hz
White - port 4" x 38" Fb = 26.1Hz
What happened is it dawned on me that I actually can extend the vent very long. The subwoofer is actually part of a tower speaker. It takes the whole lower half of the enclosure plus a narrow (5" x 5.5") long space behind the upper drivers (see drawing).
I think I can (and have to) open the vent wider (changing from 3.5" to 4" diameter) in order to lower the air velocity. However, because the vent has to go through that long space with the opening at the top, will that give me any negative results?
Thanks!
Attachments
Can someone tell me if it will be an issue for the vent tube to go through that long narrow space?
What's the length of the port? Under a meter is no problem.
Your air speed velocity seems OK if it's in ft/s 😉
Sharp edges and short turns can give problems.
So at least, try to round all edges in the port.
Your air speed velocity seems OK if it's in ft/s 😉
Sharp edges and short turns can give problems.
So at least, try to round all edges in the port.
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