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View Full Version : Curves vs 45's and kerfed ports



mendon mafia
12-08-2009, 01:15 PM
Is it better to put 45's on the port bend corners or use curves?

I was going to cut a piece of 8" sono tube to use in the corner of my 4" port but if a 45 performs better i will rather do that.

also what about for kerfed ports, can you just use 45 flares or must it be curved?

also regarding kerfed ports would it be beneficial to add a kerf to the inside opening as opposed to just the external opening?

Finally regarding kerfs, do you include any of the flares as port length?

PV Audio
12-08-2009, 02:49 PM
Is it better to put 45's on the port bend corners or use curves?

I was going to cut a piece of 8" sono tube to use in the corner of my 4" port but if a 45 performs better i will rather do that.

also what about for kerfed ports, can you just use 45 flares or must it be curved?

also regarding kerfed ports would it be beneficial to add a kerf to the inside opening as opposed to just the external opening?

Finally regarding kerfs, do you include any of the flares as port length?
Somebody has come with a lot of questions! :)

1. 45s are the cheap version. If you can use a curve, then use a curve. Sharp angles are air's worst friend. Some speaker builders even include sonotube sections in the rear of their enclosure so that the crosssection when looking from above looks like a wigwam. It helps to reduce the number of parallel walls and thus standing waves.

2. An angled port is not the same as a flared port. Contrary to the belief of 98% of the people on here, a kerf isn't really helping you all that much. The radius of the flare must be mathematically derived given the enclosure size and speaker. Opening gradually isn't enough; there are relationships that you need to use to get the most benefit.

3. Flared ports are only helpful if they're done on both ends. An aero has a flare on both ends. Flaring one end isn't the same and can't be called an aero, since aero is just a genericized trademark for a double flared port. Thus, if you want the full benefit, flare both inside and out.

4. Yes, the flare changes the tuning. Your port tuning without a flare is about 1.125 - 1.25 times more to have the same tuning as one with a port flare. For example, a 6" flared port will tune the same as a straight port between 6.125" and 6.25" with the same given length.

GAM3OVR
12-08-2009, 04:42 PM
Somebody has come with a lot of questions! :)

1. 45s are the cheap version. If you can use a curve, then use a curve. Sharp angles are air's worst friend. Some speaker builders even include sonotube sections in the rear of their enclosure so that the crosssection when looking from above looks like a wigwam. It helps to reduce the number of parallel walls and thus standing waves.

2. An angled port is not the same as a flared port. Contrary to the belief of 98% of the people on here, a kerf isn't really helping you all that much. The radius of the flare must be mathematically derived given the enclosure size and speaker. Opening gradually isn't enough; there are relationships that you need to use to get the most benefit.

3. Flared ports are only helpful if they're done on both ends. An aero has a flare on both ends. Flaring one end isn't the same and can't be called an aero, since aero is just a genericized trademark for a double flared port. Thus, if you want the full benefit, flare both inside and out.

4. Yes, the flare changes the tuning. Your port width without a flare is about 1.125 - 1.25 times greater to have the same tuning as one with a port flare. For example, a 6" flared port will tune the same as a straight port between 6.125" and 6.25" with the same given length.


math fail?

mendon mafia
12-08-2009, 06:50 PM
Somebody has come with a lot of questions! :)

1. 45s are the cheap version. If you can use a curve, then use a curve. Sharp angles are air's worst friend. Some speaker builders even include sonotube sections in the rear of their enclosure so that the crosssection when looking from above looks like a wigwam. It helps to reduce the number of parallel walls and thus standing waves.

2. An angled port is not the same as a flared port. Contrary to the belief of 98% of the people on here, a kerf isn't really helping you all that much. The radius of the flare must be mathematically derived given the enclosure size and speaker. Opening gradually isn't enough; there are relationships that you need to use to get the most benefit.

3. Flared ports are only helpful if they're done on both ends. An aero has a flare on both ends. Flaring one end isn't the same and can't be called an aero, since aero is just a genericized trademark for a double flared port. Thus, if you want the full benefit, flare both inside and out.

4. Yes, the flare changes the tuning. Your port width without a flare is about 1.125 - 1.25 times greater to have the same tuning as one with a port flare. For example, a 6" flared port will tune the same as a straight port between 6.125" and 6.25" with the same given length.

Thanks a lot! hahaha yea i usually ask like 10 questions at once i appreciate you hitting upon all of them, usually some get skipped over and i have to end up making a new thread.

Not sure what a wigwam is but I think you mean just add sono on the corners rather than 45's. Ive heard standing waves don't really matter for sub enclosures due to the frequency range (80hz ~ 4.29meter long wave)

Im just going to ignore the flares and when calculating the port length, o well if it tunes a bit low. i guess i will just shoot for 36hz then adding flares should drop me to 35 or so.

PV Audio
12-09-2009, 10:47 AM
Thanks a lot! hahaha yea i usually ask like 10 questions at once i appreciate you hitting upon all of them, usually some get skipped over and i have to end up making a new thread.

Not sure what a wigwam is but I think you mean just add sono on the corners rather than 45's. Ive heard standing waves don't really matter for sub enclosures due to the frequency range (80hz ~ 4.29meter long wave)

Im just going to ignore the flares and when calculating the port length, o well if it tunes a bit low. i guess i will just shoot for 36hz then adding flares should drop me to 35 or so.A wigwam is a Native American shelter that's got either a round base or a rectangular base, and a domed roof. For our purposes, consider it to be a rectangulat base so that when you look at it from the front, it looks like 3 sides of a square, then the top is domed. That's what you see if you use a sonotube in the back of your enclosure. :)

PV Audio
12-09-2009, 10:49 AM
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math fail?Nope, run some numbers! A flare makes the port area slightly larger. I find that a flared port's effective tuning is usually about 1.25x greater than the same diameter straight port (6" aero vs. 6" straight), thus, the tuning for the flared one is higher. :)

rosshimself13
12-10-2009, 11:11 AM
i think he was referring to you saying that a straight port is 1.125-1.25x greater in length, then using an example of a 6 inch flared port and a straight port being 6.125 and 6.25 where it would actually be 6.75 and 7.5...