Alright so I have a Sundown SA-10 in 0.56 cu/ft of space sealed in my car. Its all I have room for. Its actually a track car mostly.
Anyways..... I have learned a bit how to use winISD and was playing around with adding a port
The blue graph is the sub in the current sealed box it is in
The green graph is if I add an external 2", 24" long, port onto the box. This is without changing the size of the box at all. Same size enclosure
Clearly the port gives me a way better frequency response.
Is my work correct here?
I also know cone excursion is an issue but that graph doesn't show anything. What parameters do I need to add to get that information?
Can I just get some flared ports and use some 2" PVC pipe to make the external port? I might have to wind in with at least 90 degree bend. Is this OK or does this screw up the port? I don't think port velocity is going to be an issue for me. At least, that is what the software says.
Thanks for the responses. I am just a beginner audiophile.
Anyways..... I have learned a bit how to use winISD and was playing around with adding a port
The blue graph is the sub in the current sealed box it is in
The green graph is if I add an external 2", 24" long, port onto the box. This is without changing the size of the box at all. Same size enclosure
Clearly the port gives me a way better frequency response.
Is my work correct here?
I also know cone excursion is an issue but that graph doesn't show anything. What parameters do I need to add to get that information?
Can I just get some flared ports and use some 2" PVC pipe to make the external port? I might have to wind in with at least 90 degree bend. Is this OK or does this screw up the port? I don't think port velocity is going to be an issue for me. At least, that is what the software says.
Thanks for the responses. I am just a beginner audiophile.
To check port velocity and excursion, click “signal” and input whatever wattage for your equipment.
Putting bends in a port is usually fine.
Putting bends in a port is usually fine.
Sorry to say that, but your enclosure is too small for a vent. With 24" the port length will not work well. With such a driver maybe a passive radiator could do, but this also would profit from twice the volume, if driver tsp permit. You shold show the winISD page with the TSP parameter of your exact chassis, the ones I found do not match your simulation. Also, give some more information about your car. Does it have a full interior, where ist the sub, what kind of inclosure, build material, amplifier etc.
Please understand the relation volume and lowest frequency have, such a small enclosure needs extreme power to move the cone out. So maybe your amp doesn't have the power to drive your cone to the excursion that is needed for a lower low response.
Please understand the relation volume and lowest frequency have, such a small enclosure needs extreme power to move the cone out. So maybe your amp doesn't have the power to drive your cone to the excursion that is needed for a lower low response.
Generally car audio manufacturers quote the smallest possible enclosures for their subs, they recommend 1 cube ported which probably needs a port volume half the size of that box to not chuff with 19mm xmax... hence your 2" port would be a whistling Billy
If you can efficiently fold a tapered transmission line into your available space, this might be worth giving it some thought. There are different options available. this one is about 30 litres. The ripple in the higher frequencies can be minimised with filling if necessary. The line dimensions could be adjusted (eg shortened) as necessary and effect simulated in hornresp.
It is reflex box.
Fun comparison in same box.
you can see what magic extra bass.
Is just puff puff of port.
With vehicles in general the " cabin"
creates huge bass response peak
around 45 to 55 Hz
And that is what you hear regardless.
for car sub with 10"
just use 2x drivers in largest sealed box
you can make.
otherwise just use one 12"
because it is same box.
2x 10" = 2 cubic feet
1x 12" = 2 cubic feet
after many car systems
I can tell you 2x 12" in 3 cubic.
the end. sealed
Fun comparison in same box.
you can see what magic extra bass.
Is just puff puff of port.
With vehicles in general the " cabin"
creates huge bass response peak
around 45 to 55 Hz
And that is what you hear regardless.
for car sub with 10"
just use 2x drivers in largest sealed box
you can make.
otherwise just use one 12"
because it is same box.
2x 10" = 2 cubic feet
1x 12" = 2 cubic feet
after many car systems
I can tell you 2x 12" in 3 cubic.
the end. sealed
I think this is what you are asking for. Did I enter something wrong in here? It auto calculates some of the measurements. When it calculates them one or two of them is different from what they state on the sundown website.
This enclosure is inside the car behind the drivers seat over the fuel tank. It is mounted to the chassis and hidden away. Its the only way I can pass tech inspection at the track and still have a booming subwoofer. A lot of tracks will make you take it out before you can go out.
My amp puts out 1100 RMS at 2 ohm. This sub is a 750 rms and it is handling full power just fine. I did see something about maybe being able to push higher power to a sealed unit. Is this true? Can you push more power to the sub when it is sealed? Could I get away with running another 500 rms to it?
Why does the enclosure need to be bigger to use a vent? Isn't this program here to show us what would happen? Why can't I just run the vent? Will the sub blow?
I could fold onto the back of it. I have another 12" of space behind the box to work with. What program is this?
What do you mean by "whistling"? The port is going to make tons of noise? Can this not be minimized by the tapered horn or another feature?
Hornresp freely available at www.hornresp.net. There is an ongoing thread in the subwoofer forum https://www.diyaudio.com/community/threads/hornresp.119854/post-1462861. There are related threads about software to help design an enclosure to translate one’s simulations by Brian Steele and lordsansui which look to be useful tools too.
Last edited:
There are a number of tutorials on WinISD, They mention that it will select a large vent diameter. You can reduce that diameter and adjust the length to maintain the tuning F. Reducing the diameter will reduce the length. Then the port velocity needs to be considered. There are limits mentioned in these tutorials. The TS parameters also need to be entered in the correct order as it will calculate some itself and where that happens you need to leave as is even if the data sheet states different,
Such a long thin port will just blow out compressed air not bass. The simulation sees only the energy, but this is not converted into sound waves, but very fast puff's of air. Like an engine with lot's of HP, but only first gear. You need the right transmission with sound, just like with a car. A thin vent is short, if you make it larger, it get's longer. Too long means too much volume, too thin too much losses passing through the pipe.
With your small box volume you will not get any usefull tuned vented system.
If you want to keep the volume small, you have to equalize the drop off to lower frequency. Which means large cone excursion, using extreme power.
I fear your car will not represent the normal passenger car, which is damped by seats and interior parts, panels etc. So it may not show the normal in car pressure chamber effect, which leads to insufficent bass response, overpowering the road and engine noise.
Good music reproduction in light wheigt cars is not that easy to get right.
With your small box volume you will not get any usefull tuned vented system.
If you want to keep the volume small, you have to equalize the drop off to lower frequency. Which means large cone excursion, using extreme power.
I fear your car will not represent the normal passenger car, which is damped by seats and interior parts, panels etc. So it may not show the normal in car pressure chamber effect, which leads to insufficent bass response, overpowering the road and engine noise.
Good music reproduction in light wheigt cars is not that easy to get right.
Its a physics thing forcing a large volume of air forwards and backwards at 25~50 times a second in a small diameter tube will create huge turbulence at its inlet and outlet.
In Winisd, once you have decided on your ideal box volume and port tuning, click on the port air velocity graph this will show you how much port air speed in meters per second 17Msec is a general rule of thumb to stay under to stop any port chuffing sound.
Winisd by default signal input is at 1 watt, Im pretty sure your going to feed these subs more than 1 watt
Now go to the signal tab down by the box/port tabs and increase your input wattage to the actual Wrms power of your amp and take another look at the graph, you need to balance your port dia and find a happy medium. In reality you only hit max power rarely so if youre the sort who just likes nice smooth not over powered bass, open the SPL graph and change the signal input to the level you think appropriately represents the max Db level you desire in your car.
Go back to the port velocity graph and see if its close to 17Msec, if not play around with box volume/port tuning and sizing... hint if you change from 1 port too 2 ports(keeping same dia)the port length needed will double and the Msec will halve on the air velocity graph, like wise if you halved the port area it'll halve the length for the same tuning and double the air velocity.
Its all a balancing act and compromise, the guys who are interested in only being stupidly loud probably don't care about the port noise and true SPL guys probably only worry about compression in the port a highly resistive port would limit SPL, they look generally for the tuning frequency of the car and work from there.