Bandpass design

[terra 5,000+ posts]

Whats a good place to tune to? 80, you said 50hz...you still stand by that? Justin? I'll make the sealed a tad bigger and change the tuning to get the strongest lows possible. Let me know

 

[TSGP]

50 hz?! jesus 80 no wonder you blew up all those woofers bro!!!

the tuning of a 4th order isn't where the slope of the pass band ENDS, its where it BEGINS.

Tune that ***** to 35/40 hz. Playing way under tuning will unload woofers, just like a normal ported enclosure

 

[terra 5,000+ posts]

50 hz?! jesus 80 no wonder you blew up all those woofers bro!!!
the tuning of a 4th order isn't where the slope of the pass band ENDS, its where it BEGINS.

Tune that ***** to 35/40 hz. Playing way under tuning will unload woofers, just like a normal ported enclosure

80 said that the box should be tuned in the middle of the pass band..or at least that's how I understood it. Justin, should it be tuned like a ported box would? I always have my boxes between 30-35hz so would I aim for that?

 

[TSGP]

If you tune in the middle of the frequencies you want to play...just like a normal ported box when you below tuning the subs freak out.

Not AS bad because they are in a sealed chamber, but overtime will still blow woofers.'

Thats why you end up having to play with tuning after you get it built to dial it in.

And 80....the pics I was talking about of TJs old setup were the 2 12s with the subs firing back and the port up toward the rear of the vehicle. He posted them on termpro. I don't post pics unless the builder does it first....believe me I have pics on my computer that would make a lot of competitors cream //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[terra 5,000+ posts]

If you tune in the middle of the frequencies you want to play...just like a normal ported box when you below tuning the subs freak out.
Not AS bad because they are in a sealed chamber, but overtime will still blow woofers.'

Thats why you end up having to play with tuning after you get it built to dial it in.

And 80....the pics I was talking about of TJs old setup were the 2 12s with the subs firing back and the port up toward the rear of the vehicle. He posted them on termpro. I don't post pics unless the builder does it first....believe me I have pics on my computer that would make a lot of competitors cream //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

So the final decision..

5 cubes sealed/8 ported at 33hz? Ok?

 

[TSGP]

I would honestly start out a little higher tuning then that...because a bandpass has a very narrow pass band, unless you just want a 35hz monster that slopes off pretty heavily.

Its easy to tune an enclosure lower //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif start out with the port as big as possible and then make it smaller or add length to it.

I'd tune around 35/40 hz...i mean 33 hz is probobly fine but you want some type of high frequencies out of it i'm sure.

Also make sure you build the enclosure SUPER strong. Any resonances in that enclosure is going to have a crazy effect on the output

 

[JG903 10+ year member]

I think the explorer build these guys are talking about is posted on Termpro.

Link : http://audioforum.termpro.com/topic/8/26992.html

 

[terra 5,000+ posts]

I would honestly start out a little higher tuning then that...because a bandpass has a very narrow pass band, unless you just want a 35hz monster that slopes off pretty heavily.
Its easy to tune an enclosure lower //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif start out with the port as big as possible and then make it smaller or add length to it.

I'd tune around 35/40 hz...i mean 33 hz is probobly fine but you want some type of high frequencies out of it i'm sure.

Also make sure you build the enclosure SUPER strong. Any resonances in that enclosure is going to have a crazy effect on the output

I'm struggling to come up with enough port. The sealed portion is 30 tallx41 widex9.5 deep external. Thats 5.5 cubes roughly. Then with the ported section i cant get enough port area while keeping the tuning down. Whats enough port area? I'm looking at like 150 sq. in. if i use a slot. If I use round ports, they can't be bigger than 8" and (2) of them to get in the box.

and how is it easy to tune an enclosure lower?

 

[terra 5,000+ posts]

for 8 cubes I need between 100 and 150 sq. in of port to be optimal im assuming...12-16 sq. in per cu. ft.

Still have no idea how to get that much port and still make the box fit. I have MAX for the ported section of 31 tall x 41 wide x 20 deep

Messing around on re audio calc..

a port 4 inches tall and the full way accross the box (39.5 wide) would get me 160 sq. in. of port, 35hz, and 10 cubes. That good?

I think I got the perfect balance. 150 sq. in. of port, 35hz tuning, and 9.5 cubes.

 

[TSGP]

I think the explorer build these guys are talking about is posted on Termpro.Link : http://audioforum.termpro.com/topic/8/26992.html

yes thats it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I couldn't find it when searching

 

[terra 5,000+ posts]

I think I got the perfect balance. 150 sq. in. of port, 35hz tuning, and 9.5 cubes.

5 cubes sealed. good to go?

 

[galacticmonkey 5,000+ posts]

We built a bandpass like that for 4 Chaos 15s in a Tahoe... It sucked. The whole ported chamber firing foward like that sucks.

It go with the ported chamber firing back.

 

[TSGP]

We built a bandpass like that for 4 Chaos 15s in a Tahoe... It sucked. The whole ported chamber firing foward like that sucks.
It go with the ported chamber firing back.

All depends how its built, I had one similar to that that would do a 150+ with 2 10s and a t3000.

I just didn't like not being able to see the woofers

edit...are you talking about the way he's doing his?

If so man, my truck was similar to that. And my buddy had a ranger with 4 W3 15s and 4 power 800a2s that could move the gravel under his truck

 

[galacticmonkey 5,000+ posts]

Well the one that we did was a sealed chamber on the bottom, ported chamber on the top, with the port firing foward.

He rebuilt it with subs up/ports back, much better now.

 

[TSGP]

Yeah bandpasses are finicky, gotta have it just perfect or you'll lose a ton of output.