Speaker sensitivity

polkfan38

What factors determine a speakers sensitivity?

cristo

Lots of things:
enclosure design (folded horn more efficient than vented or passive radiator more efficient than sealed box),
voice coil structure, magnet structure, size, weight/density of driven material (cone, dome, electrostatic panel, etc.),
stiffness of surrounds, crossover design, . . . I'm sure there's more, but that's what I can think of just off the
top of my head.
Sensitivity is typically measured in db of spl (sound pressure level) averaged over a frequency range and measured
at 1 meter distance from the speaker when driven by 1 watt of signal (db/W at 1m).
It's sometimes specified as db at a particular input voltage, then you may need to know the impedance
to convert to db/W so you're comparing apples to apples.
2.83 volts (actually 2.8284....) with 8 ohm impedance is 1 watt (P = V²/R in this case)

The higher the efficiency of the speaker, the louder it will be when driven by a given amount of power.

polkfan38

The only flaw I see in your post is that "vented more sensitive than a sealed box" I have owned and seen many sealed designs with ratings over 100 dB. But I am sure the other components came into play here.

cristo

Yes, these are generalizations. Also, I guess I meant "acoustic suspension" instead of
sealed box, as a passive radiator design (like our beloved Polks) is technically a sealed box
but it acts more like a vented or reflex design.

TNRabbit

The type & quality of materials used in the crossover can also affect the sensitivity.

polkfan38

What gets me is that you see some high end stuff with sensitivity ratings in the low 80s. Wouldn't they strive to get it a little higher? For those prices?

TNRabbit

polkfan38 wrote: »

What gets me is that you see some high end stuff with sensitivity ratings in the low 80s. Wouldn't they strive to get it a little higher? For those prices?

It's a balancing act between all the elements. Some of the best sounding speakers in the world are a hard load for many amplifiers (Klipsch Jubilee excepted!). My guess is to get that extra something requires dipping down in the efficiency. I think Apogee Scintillas are @ 80dB (!) efficient & dip to 1 ohm impedance at certain frequencies, but are considered by many to present one of the finest sounds on the planet.

cristo

As far as type & quality of crossover materials, as long as you're keeping the same values,
different brands of resistors and capacitors should not affect sensitivity. Inductors can vary
regarding resistance for a given inductance value depending on wire gauge and construction, and this can affect sensitivity slightly.