T-TQWT design - Vifa 10"

[Jamii]

Hi DIY,

Looking for some help with a T-TQWT design for my Vifa 10" subwoofer, it is a car woofer (high Qts?) so hopefully It can be suitable. Specs as follows;

Vifa 10" Subwoofer Cat No. CS-2351
• Power handling:200WRMS
• Nominal impedance: 2 x 4 ohms
• Frequency response: 30Hz - 1kHz
• Sensitivity: 86.6dB SPL @1W, 1m
• Re: 3.6 ohms
• Qms: 6.13
• Qes: 0.83
• Qts: 0.73
• Vas: 42.8 litres
• Fs: 38.6Hz

I'm looking for a single fold design, size constraints only by the size limits of a sheet of Ply 2400x1200 (more than 1 sheet if need be)

I've had a play with hornresp but so far baffled on how to set it up for a T-TQWT.

Going to use a sub to augment my Cury Changs, I'm having to use too much EQ to get the sub bass level I'm after and obviously that's likely to be degrading sound quality.

See attached for a picture if you're curious.

Regards,
James

 

[Jamii]

The "Bjorno" style box is the one I'm looking to make, will anyone volunteer to help with Hornresp please 😕

 

[GM]

Greets!

Well, you could input one of bjorno’s designs into HR, then use the Loudspeaker Wizard to ‘slide’ your way into an acceptable design based on whatever will fit on a sheet of plywood. I’m guessing you’ll need several folds to get a long enough path-length to fit since the driver’s specs indicate a ~20 Hz tuning.

GM

 

[Jamii]

That sounds like a good idea, would you have a .txt file for the design? I'll try a thread search as well. ~20hz tuning would be good, hopefully get a reasonable amount of SPL too!

Thanks for the input.

James

 

[bjorno]

Hi,

FYI: No Assurance can be given for these suggestions. Properly TS should inputted into HR, use the input screens as templates when correct numbers are found:

b🙂

 

[Jamii]

Thanks very much mate, that is exactly what I needed! Now to chase down or measure the correct TS parameters. Champion!

James

 

[bjorno]

Forgot to post a suggestion that matches Post#2: 2 Drivers are a minimum for a T-QWP using the posted T/S parameters.

b🙂

 

[Jamii]

What about this design I came up with in BBP6, it's huge!. It's got the right frequency response but the group delay might be too high? It's above 24ms. 250L box for a 10" sub.

Might try and sim a box that's smaller, might reduce the group delay, the F3 will be higher though. Music doesn't have much (any) content below 30hz usually anyway, right?

I think this driver was intended to be used in a sealed box, don't really want to go down that path.

James

 

[Jamii]

Here is a much closer design to your BR in Hornresp, the frequency response is not as flat / different?

James

 

[bjorno]

Here is a much closer design to your BR in Hornresp, the frequency response is not as flat / different?

James

Hi James,

😱You are using T/S parameters for only one coil, when the coils are in series or parallel: Qes should be (Qes single coil)/2..

b🙂

 

[Jamii]

Whoops! it's going to be in series. Thanks for the help. Re-sim now,

EDIT: what if I drive a coil per ch. as I was going to use a Pro-Audio 2ch power amp? does QES = 0.83 then?

James

 

[GM]

Are you sure? The specs on the Jaycar site were similar to yours, but then here it was stated that those specs were wrong, so at this point I don't believe either and why I didn't bother to 'run the numbers' except for lowest practical tuning: http://www.diyaudio.com/forums/subw...eters-vifa-subwoofers-needed.html#post3208138

GM

 

[Jamii]

Ok so this is the sim I came up with with the coils in series,

James

 

[Jamii]

Thanks GM, I don't have the tools needed to measure TS parameters myself perhaps I should look at investing in one of those Dayton TS measurement kits.

James

 

[GM]

You're welcome! You could, but seems like using one of the freeware programs and a freeware computer signal generator would be the most cost effective: The Subwoofer DIY Page - Measurements
Measuring Loudspeaker Driver Parameters

GM