Transmission Line Questions

[Matttcattt]

I do not know anything about transmission line speakers (is that how they are described? ). i first got the idea from planet10 here. i have seen, and read the page about, El-Pipe-O. i would like to see, and read about, any other exapmples (maybe on a smaller scale ) of transmission line speakers.

i would like to know how i work out the box size, tube diameter and tube length for a set driver. can i use normal speaker software and input the tube as a port?

thank you very much for any info.

[MJK]

Hi Matttcattt,

I have recently added some classic transmission line alignment tables to my www.quarter-wave.com site. You can use these tables to quickly scope out a design for any applicable driver.

If you want more TL theory, there is a series of documents that derive the basic equations I use to model TL's in my MathCad worksheets. I have included a link to a free downloadable MathCad Explorer program which will run any of my MathCad Version 8 worksheets.

Also, there are four "quarter wavelength" loudspeaker projects that I have designed and built along with a gallery showing a number of other speakers DIYer's have built based on one of my designs or their own original design based on the MathCad worksheets.

Hope that helps,

[kneadle]

This Spiral Shaped Transmission Line Enclosure Project Complete is what I did with MJK's mathcad worksheets. A synopsis will be posted on the www.t-linespeakers.org website as soon as Planet10 has time to post it.

Good Luck!

Dave

[planet10]

Originally posted by kneadle
synopsis will be posted on the www.t-linespeakers.org website as soon as Planet10 has time to post it.

Hey Dave,

You wanted to go thru the text and tweak it and i need to embed the pictures.

Preview (ie work in progress) is here:

http://www.t-linespeakers.org/projects/davidduke/
The Seraphim -- Spiral TLS

dave

[planet10]

Besides my site, and Martin's mentioned above, one needs to go thru Bob Brines.

My site has ideas, classic designs, & some few based on Martin's ground breaking work. Martin's & Bob's cover modern TL design.

dave

[Matttcattt]

thanks, ill look through those.

[Matttcattt]

i looked at all the links posted, but i could not find any explination of how i work out the box volume, and tube length and diameter. i could not understand any of the graphs as they were not explained. can i use winisd or any other speaker calculator program to work out the box size, classing the tube as a port? i am interested in a box, with a tube, like el pipe-o.

[kneadle]

Right, that's just it. Transmission line design frees you from volume and such. It has to do with surface area and line length. Again, it's all about the quarter wavelength of the Fs of the driver. You want to design an enclosure that best supports that frequency while damping all the resonant frequencies. That's it! No more boxes! It's miraculous and so liberating.

Download the mathcad worksheets and start fiddling. Pick a driver, enter its attributes, then mess with the two Sd parameters, the stuffing density and the line length. And keep posting back here.

The graphs are hard to explain. I'll let someone else contribute.

Dave

[Matttcattt]

ok, ill have a look.

[Matttcattt]

can someone help me put the driver parameters into the mathcad worksheet?

the parameters are:

Eminence Model No. Beta 15
Nominal Chassis Diameter: 15", 318mm
Impedance: 8Ohms.
Power Rating: 350Wrms
Resonance: 35Hz
Usable Frequency Range: 35Hz to 4kHz
Average Sensitivity 1W @ 1m: 98dB
Magnet Weight: 34oz.
Magnet Gap Depth: 0.312", 7.94mm
Voice Coil Diameter: 2", 50.8mm
Mounting Information
Overall Diameter: 15.15", 384.8mm
Baffle Hole Diameter: 13.77", 349.6mm
Front Sealing Gasket: fitted as standard
Rear Sealing Gasket: fitted as standard
Fixing Holes Diameter (8 off): 0.25", 6.4mm
Fixing Hole P.C.D.: 14.56", 369.9mm
Depth: 6.05", 153.6mm
Weight: 9lbs, 4.08kg
Shipping Weight: 11lbs, 5kg
Thiele-Small Parameters
Resonant Frequency (fs): 35Hz
Impedance (Re): 6.32Ohms.
Coil Inductance (Le): 1.10H
Electromagnetic Q (Qes): 0.63
Mechanical Q (Qms): 8.10
Total Q (Qts): 0.58
Compliance Equivalent Volume (Vas): 334.6 litres
11.82 cu.ft
Peak Diaphragm
Displacement Volume (Vd): 327cc
Mechanical Compliance
of Suspension (Cms): 0.35mm/N
BL Product (BL): 11.5 T-M
Diaphragm Mass inc. Airload (Mms): 60 grams
Equiv. Resistance of Mechanical
Suspension Loss (Rms): 1.61N*sec/M
Efficiency Bandwidth Product (EBP): 55
Voice Coil Overhang (Xmax): 4.0mm
Surface Area of Cone (Sd): 823.7cm=
Impedance at Resonance (Zmax): 88Ohms.

here is the mathcad worksheet: