Starting 1966 Factory Short Bed Build, Bagged, 383 Stroker and Muncie M20 4-Speed

[88Stanger]

Originally Posted by SkinnyG

I've used WinISD for designing boxes. Fun to play with, and it's free. http://www.linearteam.org/

DAMN! just loaded this, this is awesome! I am not messing around with it. Thank you brother, i really appreciate this!!

[88Stanger]

Funny i say all this and SkinnyG you got me thinking i better look a bit closer into this. so i am now. lol Thanks for checking in! Always good to verify what you are thinking...

[88Stanger]

SkinnyG I stand corrected, you are correct. The actual volume of each box is .75 cubic Ft of air space. This is a small amount and may just be to little for a ported box, damnit, but ok for sealed box. Looks like sealed box is what i will be doing....

[88Stanger]

Originally Posted by 88Stanger

SkinnyG I stand corrected, you are correct. The actual volume of each box is .75 cubic Ft of air space. This is a small amount and may just be to little for a ported box, damnit, but ok for sealed box. Looks like sealed box is what i will be doing....

Actually, so i redid the calc and I go back to my orginal statement that .89 cubic ft is the calc. I did get your number, and what i found is that if you are taking the box wedge design and split it into one box and one box cut in half to be a two triangles, you will use the box design outside numbers minus the board thickness of .75 x 2 BUT on the first box the bottom dimension is only 1 board thickness of .75. This will then get you the .89 rather than the .75.
not sure this makes sense, but i did the calc by hand then with two different software's and it comes up to .89.
Now with that said, i must take away the Speaker Volume.

[SkinnyG]

I'd run either two 10's in a sealed box as big as you can fit, or a single 10 in a ported box. They'd both likely play about as loud each.

Sealed they'd play pretty tight and handle good power. I'd wire them in parallel to 2 ohms and feed them with a Class D mono sub amp.

[88Stanger]

Originally Posted by SkinnyG

I'd run either two 10's in a sealed box as big as you can fit, or a single 10 in a ported box. They'd both likely play about as loud each.

Sealed they'd play pretty tight and handle good power. I'd wire them in parallel to 2 ohms and feed them with a Class D mono sub amp.

So with your thoughts here is the plan - I have a Lightning Audio LA-400M = 400 Watt Mono amp - to drive the the two 10-W1.v3 Subs. Now after looking at the numbers now i am thinking that maybe I Switch over to 12" W1.v3 in this box ported. I really prefer a ported box honestly.

[SkinnyG]

This is what I did:

Trapezoid inside dimensions

((a+b)/2)x(h)x(w)

((6.5 + 2.5)/2)x(14.5)x(48.5) /12/12/12

1.83 ft3

/2

0.9ft3

3x2.75x20 /12/12/12 (rough estimate of port area)

0.1ft3

sub: 0.05ft3 (typical)

0.9-0.1-0.05 = 0.75ft3 - but actually slightly smaller because I didn't take into account the separator board in the middle.

I ran both volumes through WinISD and there isn't a massive difference between the two. It will work. At .75 the box is tuned a few Hz higher.

[88Stanger]

Originally Posted by SkinnyG

This is what I did:

Trapezoid inside dimensions

((a+b)/2)x(h)x(w)

((6.5 + 2.5)/2)x(14.5)x(48.5) /12/12/12

1.83 ft3

/2

0.9ft3

3x2.75x20 /12/12/12 (rough estimate of port area)

0.1ft3

sub: 0.05ft3 (typical)

0.9-0.1-0.05 = 0.75ft3 - but actually slightly smaller because I didn't take into account the separator board in the middle.

I ran both volumes through WinISD and there isn't a massive difference between the two. It will work. At .75 the box is tuned a few Hz higher.

Ok I get it, You get the same .89 or .9 BUT i did not remove the port area... lol i get it. i am so dumb sometimes. Sorry for being such a dummy. lol
I was a bit lost in the program on where to enter all parameters for the box though.

[88Stanger]

you know eventually i will stop this madness, lol. Ok, so after some thought i forgot that i have abandoned the idea of the using the shoulder harness bar, so that allows me to go up to 18" in height. After doing the calcs as you SkinnyG showed, i would end with .90 cubic ft of airspace for the two vented 10" subs, this is increasing the height to 18" and excluding the vent space. The calcs according to JL Audio appears that they want Volume Net Int. to be .90 Cubic Feet. Looking at their suggested ported box with vent i am very close. so not i am looking at maybe going 1" longer on base just to get a bit more volume.
LOL i am killling myself here, but this is what happens when you are anal about things and you have been locked up in the house for almost 2 weeks.... lol Sorry about all my confusion SkinnyG! I will owe you one... two ... three... lol

[SkinnyG]

No worries. We all learned our knowledge from somewhere. Spread the love to the next guy.

[53Sparky]

There are other ways to affect the way a bass reflex enclosure is tuned that is not directly related to volume. By varying the amount of polyfill that you use within the box, you can simulate a larger enclosure and achieve performance results that match a larger box with less fill.

In other words, while there is absolutely a precision level of science to all of this, which SkinnyG has so proficiently demonstrated, you also have some wiggle room with the size of your enclosure which complements the science with duct tape and bandaids.

[88Stanger]

Originally Posted by 53Sparky

There are other ways to affect the way a bass reflex enclosure is tuned that is not directly related to volume. By varying the amount of polyfill that you use within the box, you can simulate a larger enclosure and achieve performance results that match a larger box with less fill.

In other words, while there is absolutely a precision level of science to all of this, which SkinnyG has so proficiently demonstrated, you also have some wiggle room with the size of your enclosure which complements the science with duct tape and bandaids.

I do plan on installing poly fill. Thanks for the comments.

[88Stanger]

Here is the box so far

[88Stanger]

So after the great advice from SkinnyG, i redid a few of the dimensions, of course after cutting the front piece and now i need a complete new sheet, but live and learn. After all calculations are in, the box ended at free air (not including the vent) of 1.18 cubic Ft. Then taking the vent at .11 cubic ft from the i ended up with 1.07 cubic ft of air space per sub. I will be adding poly fill also to increase the "air Space" a small amount, but overall i am happy with it.

[SkinnyG]

Very cool. I have a similar slot port box in my '77 with a single 12".

There is talk that a "slot" port like that will act a little lower than a regular port in an "open" box, as the "walls" the port uses extend the tuning frequency lower than the actual "port wall" itself is cut to. I think you add half the port height/width to the tune length, but I've forgotten exactly.

However,

It's going to thump awesome. It'll work.

I'd stuff some poly fill in there regardless.

[88Stanger]

Originally Posted by SkinnyG

Very cool. I have a similar slot port box in my '77 with a single 12".

There is talk that a "slot" port like that will act a little lower than a regular port in an "open" box, as the "walls" the port uses extend the tuning frequency lower than the actual "port wall" itself is cut to. I think you add half the port height/width to the tune length, but I've forgotten exactly.

However,

It's going to thump awesome. It'll work.

I'd stuff some poly fill in there regardless.

Thank you sir, i plan to stuff some poly in it for sure. Just now we are waiting on the subs... hard to get...

[88Stanger]

Originally Posted by SkinnyG

Very cool. I have a similar slot port box in my '77 with a single 12".

There is talk that a "slot" port like that will act a little lower than a regular port in an "open" box, as the "walls" the port uses extend the tuning frequency lower than the actual "port wall" itself is cut to. I think you add half the port height/width to the tune length, but I've forgotten exactly.

However,

It's going to thump awesome. It'll work.

I'd stuff some poly fill in there regardless.

So I just wanted to give you a big shout out! since talking with you and then i increased the box size, I got a message back from JL Audio. The developer for their boxes emailed me back with what he thought about my dimensions for the entire box including the port. He said that the tuning frequency of the box will be right around 33.15 HZ and the response curve and port velocity should be great. So again, Thanks for your responses especially. I appreciate all the others too, but you really got me back into paying very close attention to dimensions.

[SkinnyG]

(big.grin)

[88Stanger]

Used a jig to get holes cut.

[88Stanger]

Part done

[88Stanger]

Done

[88Stanger]

Painted

[SkinnyG]

OEM-looking gas tank straps would be cool.

[88Stanger]

Originally Posted by SkinnyG

OEM-looking gas tank straps would be cool.

hmm.. Interesting thought there, i must look into this.

[jlsanborn]

Very cool build! Looking forward to catching up on this one.