MJK's 'Classic TL' paper

PeteMcK · 5th August 2008, 12:22 AM

I'm trying to work through this paper, http://www.quarter-wave.com/TLs/Alignment_Tables.pdf ,
a little difficult given my limited maths...
First Question, is 'rho' in the formula at bottom of p3 merely standard air pressure, or is Martin using it to deal with stuffing density (or does he just assume a standard value for stuffing density throughout the paper)?
(I'm not sure which paper is referred to on p2 when he mentions "page 6 of the "Method Derivation" section")

If I understand the paper correctly, then to simplify Martin's 41 pages down to a few lines

, the design method is as follows:

1: Choose SL/So
2: Lookup Leff, Dz, Dr (Tables pp10-12)
3: Calculate So/Sd (formula bottom p3)
4: Calculate Lactual (formula p14)
5: Choose offset.

How am I going so far?

MJK · 5th August 2008, 12:46 AM

Quote:

Originally posted by PeteMcK
First Question, is 'rho' in the formula at bottom of p3 merely standard air pressure, or is Martin using it to deal with stuffing density (or does he just assume a standard value for stuffing density throughout the paper)?

The rho in the formula at the bottom of page 3 is the density of air, use 1.21 kg/m^3. A standard "constant" in acoustics is the expression (rho x c) where rho is the density of air and c is the speed of sound.

Quote:

(I'm not sure which paper is referred to on p2 when he mentions "page 6 of the "Method Derivation" section")

That would be the following document.

http://www.quarter-wave.com/TLs/Method_Derivation.pdf

Quote:

If I understand the paper correctly, then to simplify Martin's 41 pages down to a few lines, the design method is as follows:

1: Choose SL/So
2: Lookup Leff, Dz, Dr (Tables pp10-12)
3: Calculate So/Sd (formula bottom p3)
4: Calculate Lactual (formula p14)
5: Choose offset.

How am I going so far?

I think you have it correct. If you follow the sample problem on page 13 and 14 those are the steps.

Hope that helps,

PeteMcK · 5th August 2008, 04:38 AM

Thanks for the prompt reply Martin, good to know I'm on the right track. Daresay I'll have more questions as I get time to read more...
Cheers,
Pete McK

PeteMcK · 5th August 2008, 11:49 PM

attached is Martin's table3 in Graph form; the relationship isn't linear, but should be close enough for intermediate values of Qtd and Dz?

PeteMcK · 8th August 2008, 03:30 AM

I've created a simple spreadsheet which make the calculations from Martin's paper easier. It still requires the user to use the lookup tables.

Apparently I can't attach an Excel spreadsheet here

...
If anyone wants a copy send me an email
petermckelvie at optusnet dot com dot au

PeteMcK · 10th August 2008, 09:33 PM

Here's an attempt to zip the spreadsheet:

PeteMcK · 27th August 2008, 06:25 AM

Well, I stuffed that up, forgot Martin's Tables use inches...

attached is a zipped update, still enter the inch figures from Martin's tables, but the result will be in meters (& much more sensible...)

5th August 2008, 12:22 AM	#1
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	MJK's 'Classic TL' paper I'm trying to work through this paper, http://www.quarter-wave.com/TLs/Alignment_Tables.pdf , a little difficult given my limited maths... First Question, is 'rho' in the formula at bottom of p3 merely standard air pressure, or is Martin using it to deal with stuffing density (or does he just assume a standard value for stuffing density throughout the paper)? (I'm not sure which paper is referred to on p2 when he mentions "page 6 of the "Method Derivation" section") If I understand the paper correctly, then to simplify Martin's 41 pages down to a few lines, the design method is as follows: 1: Choose SL/So 2: Lookup Leff, Dz, Dr (Tables pp10-12) 3: Calculate So/Sd (formula bottom p3) 4: Calculate Lactual (formula p14) 5: Choose offset. How am I going so far? __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

5th August 2008, 04:38 AM	#3
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	Thanks for the prompt reply Martin, good to know I'm on the right track. Daresay I'll have more questions as I get time to read more... Cheers, Pete McK __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

8th August 2008, 03:30 AM	#5
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	Classic TL calculations spreadsheet I've created a simple spreadsheet which make the calculations from Martin's paper easier. It still requires the user to use the lookup tables. Apparently I can't attach an Excel spreadsheet here ... If anyone wants a copy send me an email petermckelvie at optusnet dot com dot au __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

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