Simple TL for cheap speaker to use as home cinema...

[ßart West-VL.]

Hello!

I'm about to cut the holes for FRS8-8 Ohm speakers for the surround speakers.
It 's basically a tube-like enclosure that's 1m22 long (the width of a sheet of MDF)
At first I would have put the speaker as high as possible but I found that the hearing height is about 90cm high.
There will be 2 drivers in the tube at the same height, next to each other.
If I calculate ruffly the frequency of 1m22 then it would be tuned to low I think, or not?
If I put the speaker at 90cm, will it change the resonance frequency a lot? For the better?

I hope I finally get this project going, been laying around far too long!...

Thanks!
Bart.

[picowallspeaker]

If you put the speaker at the end of the line ,it's a TL . The air mass inside the line if not de-coupled trough a chamber behind the speaker , resonates with the cone's movement ..and must usually well damped internally .
If the speaker is not at the end of the line ,the resonating air mass 'couples' differently to cone's movement ,and the air contained between the closed end and the speaker acts as 'damping' the mass of air to the open end .
That's a TQWT /tapered quarter wave tube ,which can be terminated with a duct like a reflex .
The only thing I fear ,is the vicinity of the two speakers ,as they can induce 'vibrations' in each other ...

[Crossblade]

Why don't you do a well known enclosure, such as the Cyburg's needle.
Cyburgs-Needle for Tangband W3-871S

I wouldn't really use the FRS8. And I don't think it can do it for home theater!

[sreten]

Hi,

As a straight pipe with no folds I cannot see what is wrong with a tuning
frequency of around 70Hz. Wiring your drivers as a 0.5 way may help.
Driver position does not change tuning, end offset smooths response.

rgds, sreten.

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

[ßart West-VL.]

Yes, I see what you mean and I have been pondering about that a lot for a long time with a lot of other things, but now I'm at a point where I just will build them and we will see from there, it's not that expensive that it needs much more detailed exploration.
As for the vibration they could induce, I'm not sure about it, they will be connected in parallel and the same height in the enclosure, I expect it to behave well.

Years ago, my interest started with the Bushhorn and from there on through the Cyburgs Needles and variants.
This would be my own design and that is where it stops, it is not well calculated at all and even less tested.

If everything is finished, there will be 10 frs8 speakers squealing around the TV, I think it will be enough for reasonable effects.
Besides, the sub I'm using now is not that great either, they might just match up!

There will be stuffing inside.
If it doesn't sound good at all, I can seal them and even make them bass reflex, the volume is just right.

okay, I'm refreshing the thread as I type and now I have doubts again as to what impact it may or may not have to move the drivers.

Thanks and keep it going please.

[ßart West-VL.]

sreten,

Thanks for that link.
If I understand it correctly, by that paper from Martin, then I'm within the border of driver offset.

[ßart West-VL.]

But then again;
Just looked at the Needle and that driver sits nowhere near those rules of driver offset.

[rjbond3rd]

That doesn't mean it necessarily sounds bad. It just means that more stuffing would be required to damp out the higher harmonics.

But more stuffing means less bass output, so obviously it's worth optimizing the offset. It is -definitely- worth getting Martin's software (bargain of the century).

Also check this out: Quarter_Wave_Resonators

[ßart West-VL.]

I'm going to build a prototype... finally!

How much distance should I leave between the floor and the TL. It's basically a tube standing upright on the floor but it's unclear what the minimum clearance should be, not to compromise the bass (if there is any).

Also, would you like to have a look at these questions, they are related to this project.

Thanks!

[Bjohannesen]

Could my design be an idea ? It is vey easy to build:

http://coolcat.dk/bjoern/TABAQ_TL_for_TB.pdf