anyone have measurements of TB 871?

[morbo]

Like the title says, does anyone have measured response/phase/impedance for the TB 871 driver that could be used in LSPCad? I have the T/S specs from creativesound, but LSPCad seems to need a measurement file to model it.

[morbo]

no one can help me out I know lots of you have used them...

[kelticwizard]

The frequency response graph is located at TangBand's site. If you click on the image, it enlarges.
http://www.tb-speaker.com/detail/1208_03/w3-871s.asp

The impedance curve can be gotten from that graph, or it can be simulated by Subwoofer Simulator, freeware written by our own member F4ier. it models about 20 curves or so, selectable, including System Phase, Impedance Phase and Impedance, among many others.
http://www.geocities.com/f4ier/speaker.htm


As you can see from the attachment below, there is good agreement between the Subwoofer Simulator and the measured response at TangBand's site for the impedance measurement. Notably, the ohms at 5,000 Hz and 10,000 Hz are almost exactly alike in the measured and the Subwoofer Simulator simulation. That means that you can pretty much rely on the Impedance Phase being accurate as well, don't you think?.

I would not use the SPL response curve of Subwoofer Simulator, I would rely on TangBand's own response curve. That is because Subwoofer Simulator shows the falling response of a speaker if it acted without cone resonances, etc. The measured response curve of TangBand is the way to go here.

I can give you some advice on setting up Subwoofer Simulator if you want to simulate it as well. The cursor moves up and down and gives exact readings per Hz.. Also, the files can be converted into FRD and ZMA files as well. Additionally,there is software called SPL tracer which many find useful in converting these fgiles to something else. That is located at the FRD consortium website.
http://www.pvconsultants.com/audio/frdgroup.htm


To simulate this, I simply input the numbers at TangBand's own website into Subwoofer Simulator. For a box, I chose a Sealed box of 280 liters-so huge that the program will essentially simulate the driver alone, unaffected by box volume.

The blue curve is the "system phase"-but remember, this is essentially in an Infinite Baffle, unaffected by box volume.

The orange line is the impedance phase.

The yellow line is the impedance magnitude.

I can give you advice on how to set up Subwoofer Simulator if you like-it took me a little while to get used to it.

Good luck!

Click on the attachment below. It will enlarge and y9u can then see the curves:

[morbo]

thanks kelticwizard I'll have a look at the FRD tools and subwoofer simulator. Quite an extensive set of programs there, I'll have to check out the step by step tutorial. I had thought of using the TB measured graphs, but having read that the specs on the TB website are way off I thought not to. I will certainly use them now. One question:

For a box, I chose a Sealed box of 280 liters-so huge that the program will essentially simulate the driver alone, unaffected by box volume.

Since this driver is going in a sealed subenclosure of known volume, should I still model the way you suggest?

[kelticwizard]

Morbo:

No, I would model it in the known subenclosure's volume.

However, please not the next post.

[kelticwizard]

Morbo:

I could be wrong, but I think LspCAD already does pretty much what Subwoofer simulator does in terms of simulating curves.

All I have is the sample LspCAD from Adire Audio, and it is set to model only Adire drivers. Yet, it simulates impedance, impedance phase as well.

Maybe I am wrong, but shouldn't you just be able to input the driver's parameters and have the program do the rest?

Here is a pic of Adire Audio's version of LspCAD and it's modelling of an Adire AV8 in a closed box, 60 liter cabinet. the solid line is the impedance amplitude, the dotted line is the impedance phase.

Please click on the thumbnail photo below.