Bookshelf TL design

[kctess5]

Hey now that I've been doing this a while I've discovered a market for well priced (my time is cheap) high quality speakers among my friends. Being in high school I could use the extra money to fund my own projects.

To keep price down I want to avoid crossovers and multiple drivers so full range is clearly the way to go.

I made two BR speakers yesterday and I already have two buyers lined up so for the second one I was thinking of making a folded transmission line box for the same Tang Band W3-881SI 3" to boost bass a bit more. I'm having trouble finding good small TL designs for a 3in speaker and I have no idea how to design one myself sooo....

Does anyone have plans for bookshelf transmission line speaker? Or know where to find the mother lode?

[Cowboyinthejungle]

Dude, I've been looking for the same info myself. I have found, and had some pretty decent luck with, two rules of thumb. Tune to the Fs of the speaker and the compression chamber needs to be 2X the Sd of the speaker and the opening at the end of the tube should be equal to the Sd of the speaker. I know this isn't exactly the scientific method, but it has produced some positive results for me thus far.

[planet10]

Originally Posted by Cowboyinthejungle

...I have found, and had some pretty decent luck with, two rules of thumb. Tune to the Fs of the speaker and the compression chamber needs to be 2X the Sd of the speaker and the opening at the end of the tube should be equal to the Sd of the speaker.

What you have described is a short version of "classic" design methodology. One can do a lot better than that now-a-days. I have been discouraging it sonce the advent od decent models from Martin King & Augspurger in 1999.

1st thing we know for instance is that since the line is tapered such that xsection at the terminal is smaller than the throat, the line has to be shorter to tune to Fs.

The 2 dominant 3" TLs are the Tabaque and the Cyburg Needle. Many drivers have been tried in them. They could be folde to fit on a desktop.

dave

[phivates]

Shorter line due to stuffing or to the taper? Back in the day I went with 2x > .5 not knowing that stuffing slows sound, so my seven foot lines were tuned way below fs. Ignorance equals low bass sometimes.

[planet10]

Due to taper.

In classic approach it was associated to the damping, but it has been clearly shown that this is not the case.

dave

[audiosteve]

kctess5, this may be the kind of thing you are looking for.
HiVi B3S in mini transmission-line

[Bob Brines]

A compact TL is possible if you don't need a lot of SPL. This one is 18" tall and 6 1/2" wide. Uses an Alpair 7.3 and is folded like the old "Weem's Pipe".

Bob

[speakerman19422]

I found using small drivers like Bose cube type drivers made by Sony worked in t-line at Fs 270 hz but could not play very loud due to excessive cone excursion. I had to cross them over to a sub. So I used old Audax 6.5 for the sub in another t-line. Trying to get a 6.5 tp play down to driver Fs will bottom out voice coils . Using a 6.5" down to 60hz a better choice. Fried did this in his C3l enclosures He used line lenght of 80hz that measure flat to 60hz due to stuffing density and line terminus area.