1/4 wave/transmission line?

[Smanleyman 15]

I want to try out a transmission line box or quarter wave, whatever its technically called, and want to know if im off to a good start...

I want to use a 10" Fi BL Dual 1 so 41.5fs with an sd of 310cm^2 = 48in^2

1130/41.5/4*12 = 81.7 inches... so my design looks something like this...

I dont know much about these kind of boxes it just sounds like a fun project, If it turns out horrible I only lose a few hours and a little off my wood stockpile...What do you guys think about this design and these measurements?

Edited November 17, 2008 by fiq15pwnsnoobs

[Smanleyman 15]

Any opinions?

[fritosaregood 0]

it looks like you didnt account for the width of the wood for where the woofer sets.

[Smanleyman 15]

not 100% what you mean... Do you mean the "chamber" where the sub is in should be smaller? This was the only thing I wasnt sure about since with a 6.25 mounting depth I cant really make this a true TL... should I make the line shorter to account for the volume where the sub sits?

[fritosaregood 0]

where its 13.5 x 7 x 12. is 12 across? it look like that but you 3 ports but wood. with would make 13.5. but you also have 13.5 up. its just hard to tell since there are dimension lines. But I invert my subs when the depth is an issue. and i start my lines at the point farthest from the opening, including where the woofer is since that really should be part of the line.

[Smanleyman 15]

ohh ok I get you... no 13.5 is across and 12 is up, 13.5 up includes top and bottom wood... I guess I can change 7 to 5.5 since the sub is 6.25 mounting depth minus .75 from wood... and then I should shorten it maybe 12-14 inches to include the sub chamber(So maybe 17 deep)?

[fritosaregood 0]

it seems like it should. Do you not have space to invert the sub, and have the magnet on the outside of the box?

[fritosaregood 0]

here is how i would make one,

its just a quick drawin in at. imagine line is the samw width all the way through.

[Smanleyman 15]

Personally I dont like the look of inverted magnets, and this would be my daily setup, if it sounds good anyway, so the less space the better... Do you think going from 6x12 or so suddenly down to 4x12 would affect it to much and make it not perform as a TL? Better yet I could try to taper it down since ive read sometimes thats better for performance anyway...

[fritosaregood 0]

Personally I dont like the look of inverted magnets, and this would be my daily setup, if it sounds good anyway, so the less space the better... Do you think going from 6x12 or so suddenly down to 4x12 would affect it to much and make it not perform as a TL? Better yet I could try to taper it down since ive read sometimes thats better for performance anyway...

that small of a difference might not affect it. but i made one and my chamber for the sub was too big and turned the box into a regular ported box tuned to 22 hz. but the box is still loud. it did a 140.1 at 25 hz..with 800watts. But i like the look of inverted subs. so thats how ive been making them now. Ive tried a reverse tapperein from very small line are to the full line area at the end, but ive never started bigger and ended and the line area it should be. but i know its been done for this exact reason.. but what ive done is build scale models for some 7 in woofers to see what is better.

[Smanleyman 15]

lol @ 22 hz... I measured it as a ported box and its around 80hz... so Im a little worried as to how it will sound, and considered just increasing the chamber large enough to make it a 35hz or so as a ported box, but with the line length of a TL... and hope for the best.

I think I can trust it if I taper it off as is... what do you use to model the boxes? I saw the mathcad software on martin kings website but cant figure out how to use it or where to find the worksheets

[fritosaregood 0]

for mine i didnt have the right line area either.. it was for a 15 goin in a accord. thats why it was so low. It would be better to taper it than increase the chamber to make it like a normal ported box. as for my models I didnt mean a program, i just build a box out of 1/2in mdf