How to use Martin J. King's software to design a TL loudspeaker?

[Bricolo]

and with an image:

[kneadle]

The dimensions will fall right into place, then. Enter a "4" in the SL "Area of the large end" Sd parameter, then a "1" in the SO "small end" Sd parameter.

After that, simply adjust pipe length, driver position, port radius and stuffing parameters until you see the desired tuning in the first graph and desired ripple in the response graph.

I'm assuming you're using the ML TQWT mathcad worksheet.

Bob Brines' website actually walks you through the mathcad worksheets, with full explanations and critique. http://geocities.com/rbrines1/

Dave

[Bricolo]

Originally posted by kneadle
The dimensions will fall right into place, then. Enter a "4" in the SL "Area of the large end" Sd parameter, then a "1" in the SO "small end" Sd parameter.

After that, simply adjust pipe length, driver position, port radius and stuffing parameters until you see the desired tuning in the first graph and desired ripple in the response graph.

I'm assuming you're using the ML TQWT mathcad worksheet.

Bob Brines' website actually walks you through the mathcad worksheets, with full explanations and critique. http://geocities.com/rbrines1/

Dave

I'm using the offset speaker worksheet
why should I use the ML TQWT one? If I understood correctly, TQWT are expanding transmission lines, with a port at the end.
My drawing shows a tapered TL

[planet10]

Originally posted by Bricolo
I'm using the offset speaker worksheet
why should I use the ML TQWT one? If I understood correctly, TQWT are expanding transmission lines, with a port at the end.
My drawing shows a tapered TL

All the worksheets are actually the same but with the input area set up a bit different. The ML-TQWT sheet has the set-up that would be most convienient to simulate the line you are proposing.

dave

[kneadle]

Originally posted by planet10


All the worksheets are actually the same but with the input area set up a bit different. The ML-TQWT sheet has the set-up that would be most convienient to simulate the line you are proposing.

dave

To add a bit, "expanding" and "tapered" depends on the Sd parameters you enter. If you want an expanding-QWT, then your closed end to open end ratio will be less than 1; whereas, if you want a tapered-QWT, your closed end to open end ratio will be greater than 1. Yours would be 4:1.

The T/S specs you entered in the top part of the worksheet include the Sd (surface area) of the driver, so the number you enter in the SO and SL fields are multiplications of the area of your driver.

Dave

**Edit** I should note that I'm using the term "tapered" and "expanding" to describe the shape of the pipe as it moves away from the driver. I think I'm using "tapered" backwards from the common use of the term.

[MJK]

All the worksheets are actually the same but with the input area set up a bit different. The ML-TQWT sheet has the set-up that would be most convienient to simulate the line you are proposing.

BUSTED! Yes, almost all of the worksheets are the same calculation algorithm but with different input areas. People were getting confused trying to enter some of the standard geometries so I set up "dedicated" worksheets with a minimal amount of input required.

The only worksheet that really works a little different is the bass reflex model. In the bass reflex model you can move both the driver and the port to different, but not the same, locations along the long dimension of the enclosure. This will allow optimization of the port location which is typically not done in most bass reflex software models.

Hope that helps,

[Bricolo]

so, if I have to use the TQWT worksheet even with my design

what do I enter in the port parameters? since I have no port

[MJK]

Enter the area of the terminus (open end) and set the length to 0.001 inches. This reduces the model to a standard TQWT configuration.

Hope that helps,

[Bricolo]

ok

but I don't understant why you made the open end, closed end, and offset driver worksheet if we always have to use the TQWT one

[MJK]

They are the same worksheet, you can use either one. But it is easier to "remove" the port from the ML TQWT worksheet then it would be to add a port to the offset driver worksheet. Use whichever worksheet you like best, the answers will be the same.

Hope that helps,