# Find the tuning point of a passive radiator sub?



## pbc (Sep 3, 2007)

Just finished building a couple AV15H based PR subwoofers using a single AE AV15H and 2 18" Mach 5 Audio passive radiators.

Wanted to check the exact tuning point of the passive radiators, should be I think around 16-18hz, but not sure how I would go about doing that with REW?

Here is a naked close mic response with no HP and no EQ. Is the tuning 15hz where the phase changes?


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## pbc (Sep 3, 2007)

Also, first non sealed sub I've built so a couple questions on EQ. DSP software (ALLDSP) only allows adjustments at 20hz and up, so plan on setting an HPF at 20hz (assume with a 12b butterworth and not 24?).

If I wanted to lower the tune, would I add a low shelf at 20hz and add boost? Can REW help with that if I wanted to figure out how to set it to 18hz for instance?

Been about 10 years since I've build and measured subs so back to being a newb!


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## AEIOU (May 3, 2011)

pbc said:


> Just finished building a couple AV15H based PR subwoofers using a single AE AV15H and 2 18" Mach 5 Audio passive radiators.
> 
> Wanted to check the exact tuning point of the passive radiators, should be I think around 16-18hz, but not sure how I would go about doing that with REW?
> 
> ...


Port (Passive Radiators) output is maximum where woofer output is minimum, You can see this in the impedance curve


pbc said:


> Just finished building a couple AV15H based PR subwoofers using a single AE AV15H and 2 18" Mach 5 Audio passive radiators.
> 
> Wanted to check the exact tuning point of the passive radiators, should be I think around 16-18hz, but not sure how I would go about doing that with REW?
> 
> ...


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