Port Velocity

[Boomintempo 10+ year member]

39.8 m/s at its highest...Tempted to just go for it, and try to flare the MDF (mdf port) at the ends.

Read on termpro that the highest Wayne Harris said you could go was 15% of the speed of sound...which is around 50 m/s...while everyone else says 17 m/s is what you should strive for.

Yay, nay?

Click to read more...

 

[PV Audio 5,000+ posts]

Are you asking a question or telling us something?

 

[Boomintempo 10+ year member]

Sorry! Guess I should have been more clear.

The box that I'm looking at making has a port velocity of 38.9 m/s, and I am just wondering if any of you who have experience with this think it's too high.

I've searched around, and some places say that it's too high and that the highest you should go is 17 m/s for port velocity. While Wayne Harris thinks around a 30-50 m/s port velocity is ok (old article I found searching around the internet).

What do you guys think? 39.8 m/s too high?

 

[galacticmonkey 5,000+ posts]

Personally I like boxes with smaller ports for music. Worse case you could always try an aero port.

 

[Boomintempo 10+ year member]

Yeah, trying to make the box ported through that armrest. It's not a huge port or anything...can't quite fit those 2 6" ports. Even if I did 2 6" ports, though, the velocity was still a bit high.

So, in your opinion, you think I'm safe?

 

[S.B.C. 10+ year member]

How do you plan on measuring velocity once the box is built?

 

[Boomintempo 10+ year member]

Good question...right now I'm using Win ISD and going off of that for the port velocity. I'm assuming it'll be the same once the box is built...however I know it'll go up whenever I get a new amp.

Just don't want any port noise...

 

[PV Audio 5,000+ posts]

Unless you're planning on fabbing an anemometer into your car, I dunno how that's gonna work //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Boomintempo 10+ year member]

Not too sure you're tracking what I'm trying to ask PV Audio...either way I guess I'll just build the box and hope for the best!

 

[ahardy17 10+ year member]

Yeah, trying to make the box ported through that armrest. It's not a huge port or anything...can't quite fit those 2 6" ports. Even if I did 2 6" ports, though, the velocity was still a bit high.
So, in your opinion, you think I'm safe?

you're making a box with the port through the hole behind the armrest in the back seat of a sedan? i'm working on something similar

BBP 6 tells me my vent velocity will hit 20.2 m/s...not sure if that'd be different from winisd but i can see what bbp6 says about your box if you tell me the specs/driver

 

[Boomintempo 10+ year member]

It's for my two 12" type x's. They're the swx-1242d model. I'm going with a 4 cf^3 for the sealed and 3 cf^3 for the ported section. I'm looking to tune around 50hz. Port is gonna be 5x8.75 inches. 10.19 inches in length.

What's BBP6? Does that stand for box builder pro or something...maybe I should use that program!

 

[ciaonzo 5,000+ posts]

50Hz?

 

[Boomintempo 10+ year member]

Yeah, someone told me what's worked best for them and I've been runnin' with it. If you have any suggestions, feel free to post 'em. I've tried all different plots in Win ISD, and 50hz doesn't seem so bad once you figure in cabin gain.

I also don't listen to a lot of rap, most my music is rock or electronic. The only rap I listen to is the GOOD rap from back in the 80's and 90's

 

[ciaonzo 5,000+ posts]

I'm going with a 4 cf^3 for the sealed and 3 cf^3 for the ported section.

Are you modeling a bandpass enclosure or just two separate enclosures for comparison?

 

[Boomintempo 10+ year member]

Wanna do a 4th order bandpass and port it through my arm rest