Help with Speaker "Lingo"

[brttlt]

When they're talking about:
SENSITIVITY: what should I look for, what is better, higher or lower? (most seem to be between 90-93dB)

CROSSOVER FREQUENCY: what?

NOMINAL IMPEDANCE: huh! (although most seem to be at 8 ohms)

Thanks guys!

[Sycho]

SENSITIVITY:

higher is better, less power required to push the speakers

CROSSOVER FREQUENCY:

the point where frequencies get divided between the drivers varies between speakers

NOMINAL IMPEDANCE:

8 ohms is probably best for most situations

[Ruined]

sycho did a good job of describing the lingo, though it must be noted that 4ohm and 6ohm speakers are also very common in addition to 8ohm speakers - 6/8 are fine for any recevier, though some receivers have a problem with 4ohm speakers (generally you'd want a power amp for these anyway likely).

However, even when you do know all the specs, you can't "read" a speaker. You can generally make assumptions about positive or negative qualities the speaker may have, such as if it requires a lot of juice to drive or has a poor frequency response, but in the end you're probably better off getting into as controlled as an environment as possible and comparing speakers A/B. It would be best if you went to a high end audio shop and had them let you take some demo speakers home on loan to test them out in your house.

The speaker with the best possible specs could actually sound worse than a speaker with inferior specs in a room with poor acoustics.

[Taxi]

Originally Posted by brttlt

When they're talking about:
SENSITIVITY: what should I look for, what is better, higher or lower? (most seem to be between 90-93dB)

CROSSOVER FREQUENCY: what?

NOMINAL IMPEDANCE: huh! (although most seem to be at 8 ohms)

Thanks guys!

Sensitivity is a description of the volume of the sound a speaker will make at a given power from a given distance. Usually measured using 1W at 1Meter. So, a speaker with a sensitivity rating of 93 will play a little louder than one rated at 90. This makes no guarantee about the quality of that sound, however, just the loudness of it.

Crossover Frequency is the frequency at which your speaker's crossover begins (or stops) sending signal to the drivers in the speaker. An example will probably help here.

Say you are getting full-range audio from your receiver. That's (usually) 20Hz-20kHz. If your front speakers are set to crossover at 90Hz, then all the frequencies below 90Hz are not sent to the drivers of that speaker. In other words, those frequencies won't be played by THAT speaker. (90Hz isn't a "hard" cut-off. Crossover's usually gradually lower the volume of frequencies close to their crossover point, but that's probably a little more detail than you're looking for.) Anyway, in that situation, you'd want to add a subwoofer, set to crossover at 80-90Hz, which would better at reproducing those low frequencies than your front speakers. The crossover in your sub would be called a "Low-pass" crossover, since it allows frequencies below it's crossover point to be sent to the amp/speaker, and the crossover in your front speakers would be called a "high-pass" crossover.

Nominal Impedance. I always do bad with Impedance. The thing to keep in mind is, make sure that your amp/receiver can handle lower impedance speakers. Most will say so in the manual. 8 Ohm speakers are typical for "consumer" grade electronics.

[Sycho]

Originally Posted by Ruined

sycho did a good job of describing the lingo, though it must be noted that 4ohm and 6ohm speakers are also very common in addition to 8ohm speakers - 6/8 are fine for any recevier, though some receivers have a problem with 4ohm speakers (generally you'd want a power amp for these anyway likely).

lol my bottom of the line yammy (rxv493) can do 2ohms

[Jellodyne]

I think the crossover frequency he's looking for is the crossover INSIDE the speaker -- Here's a lot more info than he or anyone is looking for:

Say I've got a 2 way bookshelf speaker with one woofer and one tweeter. The woofer can handle from, say, 80 Hz to 3500 Hz. The tweeter can handle 2000 Hz to 20KHz. There's electronics in the speaker which routes the correct frequency sounds to the correct driver. In this case, the crossover frequency could be anywhere between 2000 Hz and 3500 Hz, but would probably be more like 2500-3000 Hz so that both speakers are in their 'comfort zone' and not at the extremities of their range. Since this example has such a wide range available, a lower order crossover could be used, meaning a crossover which cuts the high frequency off to the woofer and the low frequency off of the tweeter more gradually. If the overlap area was less you would use a higher order crossover. In any case the crossover frequuency is the frequency at which the woofer is rolled off 50% and the tweeter is rolled off 50%, so they're equally producing the sound. Since 50% + 50% = 100%, the sound level is equal to another frequency out of the crossover range where the woofer is producing 100% of the sound and the tweeter is producing 0% or vice versa.

Now then, if one of the drivers responds more quickly than another in the crossover range you could have phase issues. It can also be difficult to get the crossover range perfectly flat because you're juggling so many variables. For these reasons, the crossover range can be less smooth than what's feeding one driver only. A higher frequency crossover point can get these problem areas above the typical vocal range, which is generally a good thing, though to be fair the quality and power handling of the drivers may make a lower crossover frequency more optimal, and I would say that driver quality and crossover component quality are more important to the sound than the crossover frequency.

Basically don't sweat it too much. And as been said before, specs only tell part of the story. As long as the specs aren't TERRIBLE, give the speakers a listen and judge on THAT basis.