# Mechanical (excursion limited) power handling of a woofer in free air or open baffle

#### sujat

Dear Veterans & Fellow Enthusiasts!

I have gained valuable clarification, refinement and augmentation in my amateurish understanding of loudspeaker design through your insights and experience shared here.

I still have a basic question due to my being quite a lay person in this field. Unfortunately, even extensive searching for this answer over the internet has failed me, hence i take resort to this forum.

I do understand that irrespective of the quoted thermal power handling of a driver, its mechanical (excursion limited) power handling becomes relevant/dominant when used in applications like open baffle as well as sealed enclosures where Vb is much > Vas.

Q.1: For a usual entry level 8" mid-bass driver (eg: Goldwood or GRS driver as sold by Parts-Express; where Fs=60 hz; Qts=0.9; Cms=0.4; Xmax=3 mm, Vas=25 litres), what can i take its "mechanical power handling" to be in free air (or open baffle) when fed with a signal at its Fs? I am looking toward a modest open baffle application.

Is there a formula or equation that can give such value for any mid-bass driver?

Q.2: Would this mechanical power handling be higher in an open baffle considering it is fed with music which is non-synthesised (i.e. only acoustic instruments used as in heavy orchestral and folk)? - [Note: i will be driving it direct and full-range.... without any crossover component, with only a high-pass for a tweeter.]

Q.3: Given the same driver above, how much increase in its mechanical power handling can i estimate if as an alternative, i mate it with a sealed enclosure (in an extreme case) with Vb 150 litres (i.e. Vas * 6)? Is there an equation that gives such a figure for a given Vb as relative to driver Cms-Qts & Vas, so that it may enable me to calculate MECHANICAL power handling of a woofer for a range of sealed enclosure sizes?

Could you please shed some light on this? It would greatly help me gain clarity into this issue. I eagerly look forward to your insight and guidance!

Thanks and regards!
Sujat

#### fatmarley

The very best way to find out is to model the driver in software.

#### sujat

The very best way to find out is to model the driver in software.

Thanks fatmarley, i was really hoping there must be some guideline or indicative 'rule-of-thumb' that could be taken as a base though.

I agree with u.. what i am seeking may not be the best way, but probably a workable way that can be taken as a guideline.

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