replacing speaker in a Wharfedale EVP-X12P

hello everyone,

the woofer in my Wharfedale 2-way monitor simply... melted :D and I had to change it fast, the best choice with a high q/p ratio was this one:

Fane International Ltd Loud Speakers

which I bought for peanuts, really, and it seems adequate for the job.

the only problem is that I don't know how many liters the internal volume is. I tried to calculate the resonance frequency approximately by trying to make out the cone excursion at each frequency by slowly sweeping a sine wave from 40 to 80 Hz, but it was useless.
I don't have any "professional" equipment (such as oscilloscopes and the stuff), but is there an easy way to calculate the resonant frequency of the cabinet, so that, with trial and error, I can be able to come up with the best combination possible in WinISD Pro?
 
that would be obvious, of course :D

but!

I don't know the internal volume of the cabinet. it has padding on the sides (which should artificially increase the cabinet's volume), there is a power amp, some bracing, in other words, the only way to really calculate the cabinet's volume would be filling it up with water and see how much water fills it up :D

so, knowing the parameters of my driver, is there any way to reverse-design a cab built for another driver? I mean, tuning the cabinet for my needs? I calculated that, in a range of 35-55 liters, a tuning of 49Hz would be ideal, how can I achieve this?
 
that would be obvious, of course :D

but!

I don't know the internal volume of the cabinet. it has padding on the sides (which should artificially increase the cabinet's volume), there is a power amp, some bracing, in other words, the only way to really calculate the cabinet's volume would be filling it up with water and see how much water fills it up :D

so, knowing the parameters of my driver, is there any way to reverse-design a cab built for another driver? I mean, tuning the cabinet for my needs? I calculated that, in a range of 35-55 liters, a tuning of 49Hz would be ideal, how can I achieve this?
1. You can use expanded polystyrene for the vol. instead of water. (And use a 110L garbage plastic bag)
expanded polystyrene (EPS)
2. By tunning the vol/filler and the port (length/diam).

That's the powered version (Wharfedale EVP-X12P Powered) with High/low EQ control, so adjust the ports by closing one of them (more LF extension) and testing.
 

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