My opinion is that resonator systems of any kind are bad. But I understand their effect (net benefit) is ok with passive 3-way woofers and subwoofers. PRs have more radiating area but are bad with high excursion, it is a good rule to use double number of passives to active(s). Location of the port or radiator should be on the backside or downside towards floor.
My simple measurements above have only anecdotal value, but give reason for further studies.
My simple measurements above have only anecdotal value, but give reason for further studies.
There is something 'in-between' a passive woofer and a passive radiator >
It is what I call an "Actively Assisted Rear Radiator". ( a form of bass reflex )
The basic concept is that of using a decent quality 4ohm Car Sub. of low Fs driven by a very high mH + high DCR inductor.
The 3 or 4 ohm DCR of the inductor raises the very low frequency impedance and renders the 'rear sub' as semi-driven. ( assisted )
Apon experimentation, I have found it extremely effective at producing VERY LOW FREQUENCIES. Rear mounting appears to be key.
Experimental tuning IS obviously required.
PS. High value inductance but also high DCR keeps cost low.
