Tang Band W4 design options

[ApaX]

Hey Jed,

I have been reading this thread for some while. I like the design but i do have some questions.

What kind of alignment did you chose? I do not understand why your tuning frequency is so low, whit the typical QB3 alignment i can only get a Vb of 3.7 liters (0.13 cu.ft) and a Fb of 90 Hz. F3 is around 90 Hz as well.

I have build a test box of this size and it does exactly the same as predicted. When entering the parameters in a simulation program it does the same, it show a nice respons from 90 Hz (-3dB) to 200 Hz. Afther 200 Hz it starts to rise 3 dB due to baffle step i think.

Can you explain how and why you chose a Fb of around 70 Hz?

Thanx

EDIT BY MODERATOR, This was split from the Lineup Maxx Build thread

[Jed]

Welcome to the forum!

Unless the TS parameters changed since I last modeled or tested it, a box tuning of 70hz is perfectly flat in the size boxes I used, as per Unibox's simulation and my measurements of the port opening. According to Unibox, the alignment you suggested creates a 2db peak in the response around 100hz.

[ApaX]

Welcome to the forum!

Unless the TS parameters changed since I last modeled or tested it, a box tuning of 70hz is perfectly flat in the size boxes I used, as per Unibox's simulation and my measurements of the port opening. According to Unibox, the alignment you suggested creates a 2db peak in the response around 100hz.

Thanx for your response! I think i know what the "problem" is, I used way to mucht damping materials, I had a loss factor Qb of 2,9. I removed some and did the measurements again, i got a loss factor of about 6. with some tweaking i might get it higher, towards 15 or 20. With a loss factor of 6 i already got down to 82 Hz for Fb.


For now i am going to aim for a qb3 alignment, this would be relative easy.

[Jed]

Thanx for your response! I think i know what the "problem" is, I used way to mucht damping materials, I had a loss factor Qb of 2,9. I removed some and did the measurements again, i got a loss factor of about 6. with some tweaking i might get it higher, towards 15 or 20. With a loss factor of 6 i already got down to 82 Hz for Fb.


For now i am going to aim for a qb3 alignment, this would be relative easy.

The W4 isn't exactly a bass champ so a little extra from 90hz-150hz isn't going to hurt anything, that's for sure.

Which design are you building?

Jed

[ApaX]

The W4 isn't exactly a bass champ so a little extra from 90hz-150hz isn't going to hurt anything, that's for sure.

Which design are you building?

Jed

non of them... I bought some measurement equipment and i would like to try to design something else. I picked the W4 1337 because it was cheap at parts express, i liked the driver for a long time because of its sexy looks.

In the end i might end up with a design similarly to yours. But I want to go through the entire development process myself. Basically just a learning process. That is way i ask the question of the tuning frequenting..., trying to couple a physical meaning to all the box parameters.

Anyway, thats way I had some question. For now I am going for the qb3 alignment as described in the book of dickason. What where your design targets for the D4's?

I want to use the new vifa neo titanium tweeter, but i am not sure jet, it looks nice for a good price.

[Jed]

non of them... . What where your design targets for the D4's?

I want to use the new vifa neo titanium tweeter, but i am not sure jet, it looks nice for a good price.

Yeah the new vifa looks good.

The design targets for the D4 are documented in the 1st couple posts where you can see all the LSPcad measurements and responses- including final system measurements.

Basically you are looking at a bass reflex design, F3 of 70hz, 4th order acoustic slopes with a Fc at 2.5k, flat final power response and easy impedance load for most receivers.

I rarely use "textbook" formulas because they don't account for the driver's actual performance in the real world. That said, when I was calculating the slot ports I DID use a slot port calculator to determine the desired tuning frequency and dimensions of the port, BUT after I modeled the TS parameters in Unibox to obtain the correct values. Finally, I measured the port to make sure it was working properly. In the D4s case, some poly fill is required lining the back wall all the way to the bottom of the cabinet to get rid of a little peak in the port response (again- this is documented in the build).

[ApaX]

Hey,

I have downloaded unibox, it is a nice little program. For simulation i have been using BoxSim, developed by visaton. At this time i did not find a better program. But it is only availible in german, so thats a pitty.

Anyway, for the W4's i am going to build a couple of different boxes and use different alignments. I just want to see how it sounds. For these speakers i do not want bas performance, I am going to use them as monitor's in a HT system.

I did some experiments today, removing most of the damping material, only leaving some foam in the back, against the back of the box. I can's seem to get the loss factor above 7. I am 100% sure that there are no leaks, and there is only minimal fill of damping material. Could it be that there is a lot of loss in the reflex pipe? It is a little on the small side, 3,2 cm (1,25 inch).