need help with tapped horn calculation...

[morpheus82]

Hi guys,
I have a Sintel 10 inch subwoofer who needs a box, so I decided to build something "new" for me, a tapped horn.
So I learned how to choose the parameters and made some simulations on Hornresp.

Driver parameters are:

model: 90.25E8
Re(ohm): 7.2
Le(mH): 0.67
Fs(Hz): 63
Qes: 0.52
Qms: 8.14
Qts: 0.49
Mms(g.): 25
Cms(mm/N): 0.36
Vas(litri): 60.1
Xmax(mm.): 3.5
Bl(Tm): 9.6
G(m/s^2 A): not available
h(%): not available
SPL/2.8V(dB): 92

Now, I've chosen a S2=sd/2, so 150cm2 and an S3=2*Sd.
Put L12 and L34 = 15cm for construction and L12=200cm.
Then simulated and used the wizard to see the result...




I think not really good...and with just 50w, displacement is too high...
Response absolutely not flat...

So, where I am wrong?
I tried to modify the values, but there is no way for me...
Maybe the driver is not good for a tapped horn?
Thanks a lot in advance guys!

[oublie]

Try this, not great but a start. With 3.5mm of xmax your not going to get loud and low.

[morpheus82]

Thanks mate, but now we have a much bigger enclosure, and just 10w of power.
And we're still on the limit for the xmax...

[oublie]

your not going to get great response from a driver like this.

what are your requirements?

box size, frequency response, db lvl?

[morpheus82]

I know, but the driver is here looking at me...for free...!
Let's say max 80 liters, 30-100Hz would be great, dB level not really important...
Which box do you think it's good for this driver?

[tb46]

Hi Y'all,

The Sd looks a little small for a 10" driver, you might want to check that because it affects the following calculations if you use Hornresp to calculate Cms etc.
Also, it would be better to use Par for the horn taper, as it more closely reflects a horn path with 2 parallel sides. If you double-click Sd in the Edit mode it gives you the Thiel-Small parameters Hornresp is using in the calculation, they should agree with your measured parameters (or the manufacturers).

Regards,

[morpheus82]

Thank tb46,
well, for the measurement, do I have to consider only the cone diameter? Or also the foam?

[tb46]

Hi morpheus82,

A general method to establish Sd is to measure the diameter of the cone plus 1/3 to 1/2 of the surround on each side, then it's just Sd = D^2 * pi/4.

For a volume below 100L you may be best of with a simple bass reflex (vented) enclosure.

Regards,

[morpheus82]

I've tried some simulations with vented, but I have lower efficienfy and higher cutoff frequency...Cannot reach nothing under 55Hz...

[morpheus82]

actually I measured again, effective diameter is 212mm, so Sd is 350cm2 more or less.
This helps more than what I expected!I will post some results later.
The behaviour of the response is still not so good, but I can put 100w without destroying the driver and reach 30Hz...Not bad...