speaker sensitivity vs. speaker size


I would like to draw on all of you for your experience on this matter.

Here is my question:

If I have two pairs of speakers, one being a pair of monitors (bookshelf size) and a pair of floor standers (both from the same company, in this case) and they both have the same sensitivity rating (actually, in this case, the bookshelf is rated at 85db/w/m and the floorstander is rated at 86db/w/m), would they both be equally easy/ difficult amplifier loads (if the identical amp was used on either pair)? (sorry about the run-on sentence)

The larger speaker has a metal tweeter, a 6.5 inch midrange and an 8 inch bass driver. The smaller has the same, minus the 8 inch driver.

It is my inclination to think that, despite the ratings, the larger would be the more difficult load as it has more drivers to control).

I am calling on you guys to help with clarification on this matter.

thanks in advance
loose

Showing 1 response by audiokinesis

Loose -

Typically, the efficiency of the woofer sets the overall system efficiency.

And there is a trade-off relationship between bass extension, efficiency, and small box size - you can have any two of the three, but not all three.

Suppose you make a nice little 6.5" two-way mini-moniter. In order to get a good tonal balance, you might have to pad the midrange level down a tad, because the relatively small midwoofer is probably a bit weak in the bottom end. This lowers the overall system efficiency, but subjectively gives you a more balanced sound.

Now if you add a nice 8" woofer to do the bottom end, the midwoofer doesn't need to be padded down in the midrange any more. So the overall system efficiency can go up a bit without sacrificing the overall tonal balance.

This might be why the 6.5" two-way mini-monitor has a slightly lower rated efficiency than the 3-way floor-stander version.

Usually, a speaker's impedance curve is most challenging in the bass region. Without knowing the impedance characteristics of the 8" woofer and the 6.5" midbass driver, it's impossible to reliably predict which would be the "easier" load.

Duke