# I want to build a Transmission Line/ T-Line Subwoofer Enclosure

I have been wanting to build a Transmission Line subwoofer enclosure to house 2 10 inch subwoofers. I'm not exactly sure what subwoofers I will be using yet, or the specifications on them yet either. The only thing that I am worried about while constructing this box, is the calculations. I am good in math, and geometry and all of that stuff, but I don't know where to start. If someone could take a moment and explain to me what the calculations and the steps that would be needed to construct such an enclosure, it would be much appreciated.

Thank you.

Thank you.

active| newest | oldestHow to calculate the Qts and Vas using more than 1 driver depends on how they are used. If they are coupled in an isobaric configuration (face to face, sealed as a physical unit), the Vas stays the same, but the Qts is divided by the number of drivers. If you mount the drivers side by side and they are not coupled, the Vas is multiplied by the number of drivers and the Qts stays the same. I'll have to look back in my notes to verify that, but that is the way I remember it.

Qa

do you still have the Qbasic design?

See below.

Qa

I have two Focal Polyglass subs from around 1992 ish and would live to work up a TL for one or both!

Please send a link to the file .

kcluse@gmail.com

Thank you in advance for your help.

Kevin

Qa

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PRINT : PRINT : PRINT : PRINT : PRINT

PRINT " WHAT IS THE FREE AIR RESONANCE FREQUENCY OF THE"

INPUT " DRIVER (Fo) IN Hz"; FO

PRINT : PRINT

INPUT " WHAT IS THE DIAMETER OF THE DRIVER IN INCHES"; D

LET A = (1130 / FO) / 4

LET F = 1 + (.5 / .074)

LET F = SQR(F)

LET F = 1130 / F

LET B = (F / FO) / 4

LET XS = (D / 2) ^ 2 * 3.14159

LET XF = XS / 144

LET BV = XF * B

LET WS = BV * .5

CLS : PRINT : PRINT : PRINT : PRINT : PRINT

PRINT " FOR A DRIVER OF"; D; "INCHES IN DIAMETER,WITH A FREE"

PRINT " AIR RESONANCE FREQUENCY OF"; FO; "Hz,AND AN ENCLOSURE PACKED WITH"

PRINT " DAMPING MATERIAL AT 1/2 LB. PER CU.FT.,THE BASIC"

PRINT " SPECIFICATIONS FOR A TRANSMISSION LINE ENCLOSURE ARE:

PRINT

PRINT " LINE LENGTH ="; B; "FEET"

PRINT

PRINT " LINE CROSSECTIONAL AREA ="; XS; "SQ.IN."

PRINT

PRINT " APPROXIMATE BOX VOLUME ="; BV; "CU.FT."

PRINT

PRINT " WEIGHT OF DAMPING MATERIAL ="; WS; "LBS."

PRINT

PRINT " FOR A HARD COPY PRESS THE <PRN SCRN> KEY"

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If you need to convert the Diameter from metric to imperial (mm or cm to inches), use one of the many online unit converters.

Enjoy!

Qa

I never new what t-line subwoofers were until now. Thanks.

www.diysubwoofers.org/tls/