# dual woofer transmission line

#### Fradbut

Hi Guys.
I was planning a speaker project and wondered if anyone could help me with the calculation for a dual-woofer transmission line design.
I can find online calculators for single woofers but not dual, so I'm thinking I need some advice from your expertise
Many thanks for considering my request.

#### planet10

Paid Member
On-line TL calculators should be considered a joke. Like any other box, it should be modeled, TL modelers thou are scarce on the ground. There is much more design space than for typical modelers.

For a dual driver TL, double the Vas. Fs, Qt remain the same. Zd should be set the average position of the drivers.

Do you have drivers in mind? What are your goals?

One of ours:

dave

1 user

#### Fradbut

Hi Dave.
Thanks for your reply.
I'm hoping for *2 CA22-RNY's with a mid and tweeter.

1 user

#### Fradbut

Looking at something with a big, clear, classic speaker sound but compact enough to keep my wife happy. That's why I thought of the *2 TL design

#### GM

Then best overall to use a tiny 'FR' driver for the mids/HF as he did.

1 user

#### woodo

Nice looking driver. Hornresp can model 2 drivers if you go that way. And spicytl too I believe.

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#### planet10

Paid Member
The Q is perhaps a bit low, and with a Vas as large as it is, likely a pretty big box.

dave

#### Guerilla

Are American drivers affordable in the UK?
CHEERS

#### GM

Seems tiny to me , especially once stretched into a MLTL if no significant series R and/or use the late Professor Leach's preferred Qes and even then only pumps it up to 112.64 L/3.98 ft^3/38 Hz Fb:

T/S max flat alignment:

Vented net volume (Vb) (L) = 20*Vas*Qts'^3.3 = 30.86 L*2 = 61.71 L/2.18 Ft^3

Vented box tuning (Fb) (Hz) = 0.42*Fs*Qts'^-0.96 = 45.4 Hz

F3 (Hz) = Fs*0.28*Qts'^-1.4 = 51.4 Hz

(Qts'): (Qts) + any added series resistance (Rs): http://www.mh-audio.nl/Calculators/newqts.html

1 users

#### Fradbut

Cheers chaps. I'll check out hornresp for modeling 2 drivers.
Yep we can get USA drivers in the UK cheaply but why when we've got so many European and Chinese choices.

1 user

#### woodo

The Seas unit does a pretty good job. The TLDesign tool gives convenient starting options for the sizing of the enclosure if you don't already have something in mind. Longish line length can be reduced by a reasonable taper. The ripple can be modelled and smoothed to taste.

#### ernperkins

Like @planet10 said "Zd should be set the average position of the drivers.". This covers both wiring options:

1 users

#### Arthur Jackson

I followed the Lynn Olson Ariel project and adjusted fire as required.

#### Fradbut

Thanks, Guys, much appreciated. Being a newbie this will give me plenty to add to my design and much to think about