ISO passive radiator reco's for Mid-Bass coupler design

[john61ct]

would going to multiple small PRs make this easier?

Might be able to fit 4x 5.5"

but 3x 3" might be enough

 

[Wolf]

I doubt that would help.

 

[voodooless]

What exactly is the real goal here? What problem is the PR supposed to solve? I think that selecting the right driver will mitigate any need for a PR in that frequency range in the first place.

 

[Wolf]

Honestly, I don't know.

 

[john61ct]

It's about getting some extra efficiency from a pretty tiny box ( < 1 cu ft, external 12.5" square HxW) Depth can go to maybe ~15", some leeway there.

If I can make good use of 200+ W, great.

I agree the choice of active driver will be critical, but I want to select the

low-mass/high-Fs, low-compliance/low-Vas high-Qms PRs first, likely 8-10" (if multiple smaller ones can't work).

Then their Vd spec will limit my choice pool of active drivers to half that.

If it’s about midbass, there are probably better ways to raise the efficiency of the system than a PR.

I'm open to suggestions that fit!

Shooting for 80-200Hz, so target Fb geometric mean center over 125Hz if possible. Is that mid-bass?

If I can eke out a bit more bandwidth I'd love to go a little lower F3, but then again I might need to crossover a little higher at the top end?

TBD once I see what REW has to say with a built prototype.

 

[john61ct]

I hope you use floor spikes, build heavy, or go dual-opposed for the subs, as they can shake themselves pretty hard.

Remember these aren't subs, F3 unlikely to go under 65Hz, so maybe not quite as much shaking?

I REALLY like the clean cyclops front-only design, so doubt I'd go dual-opposed PRs unless absolutely necessary, plus I'd require inset / flush mount, given the hard-limit 12.5" exterior width would I think reduce interior volume too much?

This is a mobile use case, but a soft surface is unlikely for spikes. I'm thinking maybe something like this underneath?

https://www.amazon.com/Rubber-Neoprene-12x12-Inch-Plumbing-Protection/dp/B071RYXTSW/

All constructive feedback welcome (from anyone)

 

[john61ct]

Remember these aren't subs, F3 unlikely to go under 65Hz

I've seen people insist that some powerful active drivers DESIGNED FOR trueSubs

"can be used" as drivers for dedicated midbass couplers, just because they have usable FR up past 300Hz.

But my understanding is, SPL efficiency would be better served by my selecting from the pool of purpose-designed MBM drivers, F3 / Fs well above, say 40-50Hz?

If not, it would be great building a whole set of MBM and trueSub boxen in the same HxW form factor, based on the same driver, and switching them as needed from one application to the other just by swapping enclosures and PRs!!

seems unrealistic to me...