TQWT for the TB W3-871S

[sergiusz]

Hello,

I'm observing this forum which is really great (!!!) for quite a time and am building my speakers (see http://mieszkoman.privat.t-online.de).

I would also like to start building a box using the TB W3-871S for my computer room. I am still thinking about the Buschhorn (MK2) or a TQWP (aka TQWT).

Do you guys have any plans for a TWQP enclosure using the TB W3-871s? Could I just take the Solo design (http://www.diyaudio.8m.com/Solo/solo.html) and put a 871s inside instead?

What would you prefer, the Buschhorn or a TQWP ?

Thanks for your help,
Sergiusz from Berlin/Germany

[joensd]

Hi sergiusz,
I´m soon about to finish a ML-TQWT with the TB speaker.
For a first look at the enclosure click and look here (it´s the tall one on the screen).

If you plan something like the SOLO from your link you certainly have enough space around the PC and might consider something bigger like the Gradient W160AL8 which has got a nice price as well. (the TB is actually quite expensive here in germany )
A ML-TQWT with the Gradient is my 2nd project on the bench at the moment.

Get back soon.
Regards
Jens

[Timn8ter]

For a single W3-871S driver folded pipe.

Line length ===== 26"
area at top ===== 3 sq in
area at bottom ==15 sq in
port tube =======1" diameter, 1" length
driver position ===12" from top of line
port position ==== 24" from top of line
enclosure tuned to 90 Hz.

[joensd]

For a single W3-871S driver folded pipe.

Line length ===== 26"
area at top ===== 3 sq in
area at bottom ==15 sq in
port tube =======1" diameter, 1" length
driver position ===12" from top of line
port position ==== 24" from top of line
enclosure tuned to 90 Hz.

Sorry bout the OT-newbie-question but what´s the point in building a folded pipe with (relatively) high tuning?
Looks like you use a sub with it? so why don´t go sealed for a more linear f/SPL ?
It also has quite a bump at resonance frequency; was that deliberate?

Mine will be :
Line length ===== 15.75"
area at top ===== 18.6 sq in
area at bottom ==18.6 sq in
port tube =======0.492" diameter, 1.18" length
driver position ===7.56" from top of line
port position ==== 14.76" from top of line

Probably not for very high output levels as it´s tuning is quite low (linear down to 70Hz).

Cheers
Jens

[Timn8ter]

The line length I used is to benefit from quarter-wave action inside a tapered pipe. The numbers would be pretty much the same were the pipe not folded. I just happened to have modeled this particular application and assumed that for computer speakers 30" tall speakers would be less desirable. Didn't notice a bump at Fs. I'll look again. For a BR ~16" is correct. I hope I didn't mix this up with my bipole design.

Edit: I ran the numbers again and they look correct other than the tuning frequency comes in at 85 Hz. With an Fs of 110 this is 77% of Fs which is about as far as I'm comfortable going.

[Timn8ter]

from MathCAD worksheet

[joensd]

I´m really sorry for confusing you.
It´s me that is confused.
Diameter is not the same as radius isn´t it?
Now I get your curve; still goes a bit over 90dB at Fres of driver but that might sound good anyway.
Do you use any circuitry (notch, series cap) with them or run a sub?

I made an error with my values BTW:
Diameter is supposed to be 0.984in.

[sergiusz]

First of all thank you very much for your prompt replies!!!!
I did not expect to have answers that early!!

I found Martin King's pages and will try to simulate a TQWP too.

The reason I chose the TB is because I read good things about it in the forum and would like to build some prototypes using cheap flake board. Now I think I'll try different enclosure types (closed, ported, buschhorn, TQWP) and will let the one live which I like most.

The MathCad sheet from Timn8ter at least looks very neat.

@joensd: I ordered my TB's from spectrumaudio.de. At least I did not find any other german internet shop selling these guys.

[Timn8ter]

I haven't built this exact application, just a model. I've built a few single and dual driver BRs with the 871. Usually they work fine without circuitry other than a low pass on the second driver. Might be interesting to experiment with John Krutke's notch filter though. I have used a sub with them and usually just run them full and use XO on the sub only.

[Chris8sirhC]

joensd, could you post some pics of the speaker your making? its sorta hard to see them since its basically a picture of a picture on a computer monitor.