Check my WinISD entry

[xyrium]

For some reason, WinISD doesn't like my data entry. Manual entries are in green I suppose, while the calculated entries are in blue. You can see the error message I get, but it doesn't explain to me why. I've entered the data from the Madisound site, as well as the Scanspeak pdf for this driver. I'm just trying to calculate port dimensions should I decide to port this box (1 cu ft, tune to 40Hz since my cab is 8 liters less than John's original ZRT design).

[evilskillit]

Ok, best piece of advice I can give you is consult the help files as to what order to enter the parameters in.

With auto calculate unknowns checked enter these params in this order and let it figure out the rest.

MMS, CMS, RE, BL, LE, SD, XMAX, PE, QES, QMS.

That is from memory, check the documentation under (entering new drivers) or something like that. If you are missing one of those params just keep going and at the end try entering an extra Q parameter instead.

If you do it this way it will auto calculate all the ones that could possibly conflict so you can't end up with an error. You should clear the whole thing first just to make sure it doesn't have any values hanging around in memory. If you need any more help let me know, but thats how I do it, and I learned to do so from the help file. Haven't had any problems since.

[xyrium]

Thanks Matt. I'll re-enter the data. I entered in tab order, which seemed logical, though maybe improper. I also unchecked the autofill option but still got the error, but like you said, maybe the data is in memory or some sort...

Looks like Unibox provides the following port size for 30Hz tuning in a 30l box.

Design by Vb, Fb and Q
Physical Vb 30.0 l
Absorption, Qa 80
Leakage, Ql 30
Port, Qp 80
Alpha, a 1.933
Vb 30.5 l
Fb 30.00 Hz
F3 35.32 Hz
Response peak 0.43 dB
Peak at 72.44 Hz
Port min dia. 6.72 cm
Port length 43.00 cm
Port 1. resonance 364 Hz
Include effect of port resonance

[xyrium]

Ok, WinISD os giving me a port length of 7.14" using a 2" port for tuning at 30Hz in a 30l cab. Any larger diameter port produces lengths beyond my cabinet depth. Hmm, port resonance is at 947Hz. Does this sound ok to you guys?

[evilskillit]

I've noticed that a lot of designs seem to have port resonances that are within the woofer's passband and no one seems to complain, so I guess they're ok.

You could probably get away with using a 1.5" port if you used a flared one. It would probably still have some port resonance within the woofer's pass band however.

Don't forget about slot ports as well, you can bend them around corners. Tho I guess if you're using an already built and finished cabinet that is out of the question, eh?

[impulse]

I would not recommend to use a 1,5" port. Air velocity should be kept under 17 m/s (5% of sound velocity). At about 25watts air velocity will exceed 17 m/s from 48Hz and down (40 m/s at 30 Hz).

A 2" portdiameter (length = 7,36") will handle much better.

25 watt is about what this speaker can handle run fullrange before cone-excursion becomes an issue.

[xyrium]

Thanks guys, good feedback. Porting them all depends on how soon I plan to build that sub. I was hoping to use the Seas LROY, but we shall see. I have a Crown Cdi1000 that will be pressed into duty for that purpose. Regardless of whether I port these or not though, I will always high pass them at 50Hz. They really do a nice job below that, but it comes at a price when at 90dB or higher.