WinISD check please

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I have done some initial modelling in WinISD with the following driver and passive radiator -

Scan Speak 22W857 -
Seas SP22R -

The box is 42l.

I have modeled a closed box, Qtc = 0.55
Vented with a 7.5cm diam vent, 29.5cm long, tuning freq 30hz
Single PR with 50g of extra mass
Double PR with both having 70g of extra mass
I have added a 25hz 2nd order Butterworth high pass filter to restrict low frequency excursion.

For a 60W max power (the max of my amps) -

Cone excursion is within Xmax (9mm).
In the vented case air velocity is 17m/s.

Now, the question is, I would like to use a Passive radiator (I actually like the sound of speakers with them) but with just one PR the PR excursion is - 18mm which I think it too high (I need to reduce the watts to 20w to bring it down to 10mm, half quoted P-P). With the dual PR it is all OK.

So, is my assumption right that PR xmax in WinISD is half quoted P-P max excursion on data sheets. If so I will have to run two PRs which gives the same frequency response as vented so no real point doing it. One PR give a more gentle tail off and lower F10 which is preferable but has high PR excursion.

Can someone who is more knowledgeable at WinISD and speaker design check this out to see if I have missed anything or has suggestions how I would better implement the single PR.

Thanks in advance.

Plots attached. Blue = closed, Green = vented, Yellow = single PR and Red = double PR.


  • WinISD 22w SP22R Freq.JPG
    WinISD 22w SP22R Freq.JPG
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  • WinISD 22w SP22R ConeEX.JPG
    WinISD 22w SP22R ConeEX.JPG
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  • WinISD 22w SP22R PREX.JPG
    WinISD 22w SP22R PREX.JPG
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  • WinISD 22w SP22R VentAV.JPG
    WinISD 22w SP22R VentAV.JPG
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Optimal solution to your case is a vented cabinet that gives you great bass capabilities at reasonable cone movement, especially having a 25Hz BW high pass. PR presents unnecessary expense at no benefit, very restricted in PR movements at higher power input.
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@lojzek, I think I came to the same conclusion but good to have your confirmation, I do like PR and I have a difficult room to work with (almost square with lowish ceiling), but vented does look the best option.

Looking to match this with EM1308 and AMT19 in a 25w x 30d x 100t (external in cm) floor standers using active crossover (nanodigi + khadas tone boards).
The EM1308 has one of the most natural sounding midranges I've heard. Goes well with a Morel 308 or 338.

Will also suit your alu driver. Mine are SEAS L18, but I've used them with L22s too.

I'm currently using an EM1308 with an old MDT30 - I already have ET338s to replace them.
Thanks again. Do you have a morel tweeter you could recommend.

I have modelled these up with the Hiquphon OW1 which works really well or at the cheaper end the SB26CDC/ADC, any thoughts on these.

Waiting for info/measurement/reviews on the new SB MD60N mid dome as well.

Edit - thanks @Zuhl, posts crossed in the ether, will look into the morels.

The new single plate TM4055 looks interesting, like a MDM55/EM1308 plus 308 closely coupled.
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