Aren't passive radiators out of phase?

Sean (or anybody knowledgable about such things),

At what cabinet size and/or radiator size does hysteresis become an issue? I would think that in a big cabinet or with a big passive radiator, the response of the radiator to movement of the active would begin to lag, resulting in some potentially smeary sound. Is this an issue? Inquiring minds wanna know these things....

will

I've never spent much time playing with or learning about passive's although i have owned a pair or two over the years. As you probably know from some of my posts, i am a "sealed" kinda guy when it comes to boxes with TL's coming in second. Someone that is far more knowledgable in this area would have to help you out.

All i can say is that passive's allow a lower percentage of "out of phase" signal to play with speakers reproduction above its point of resonance than what a port or simple "slot loading" allows. Below the point of resonance, they are all about equal. Sean
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The dual 18" PR's in my HT SW really only kick in at very low frequency i.e. sub 30 HZ. Off the top of my head they each have a mass of around 1500 to 1800 grams. This is about 3.5 pounds. At these low frequencies the 15 inch driver's main job is to drive the PR's, not to produce direct radiated sound.

My 18" music SW is a 7.5 cu foot sealed box which I augment with a BASSIS. This avoids any potential problem with ports or PR's.

Mish, your HT sub sounds like a different yet probably more "technically correct" approach to using passive's than how most other designs go about it. What brand and model of sub is this ? Such a design doesn't ring any bells to me.

As to your "music" sub, have you ever thought about adding another driver in a push-pull or isobarik / compound arrangement ? Either of these can increase apparent box volume, lower FS, increase transient capabilities, lower distortion, etc... Only drawbacks to such designs is the lower impedance.

Is your music sub with the 18" a single or dual VC ( voice coil ) ? Sean
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PS... Sorry for getting off topic but it's not often that you get someone with BIG subs like that on a thread like this. Especially of such dis-similar designs : )

Thanks to all for the enlightening info.