Will a 110 watt receiver power 120 watt speakers?

Yes. Here’s how to think of it—it’s not that 120 watt speakers draw 120 watts, it’s that they can handle up to 120 watts.

The important thing is to make sure the impedance is matched; that is, most home speakers are rated for either 8 Ohm or 16 Ohm loads; the wattage changes depending on the load.

When you check the specifications of the amplifier portion of the receiver (in the manual under specifications), look for both numbers: i.e., “110 watts per channel at 8 ohms/channel” and if your speakers are rated for 8 ohms, then you would be able to get that yield of wattage.

Keep in mind that the wattage is an “average” number not the peak wattage, in most cases; if the spec says “110 watts RMS” then that means that it “averages” around 110 watts per channel. RMS is usually about 60 percent or so of the max wattage, so if you’re trying to properly match wattage between components, you want to make sure that the RMS is close to the wattage rating for the speaker.

If it’s way off, then what will happen is that when you try to “crank” up your speakers, at louder levels, the speakers are “asking” for more power (I try to picture Scotty from Star Trek saying “We need more power”), and the amp can’t deliver it because it’s maxed. The main contributor to damaged drivers on a speaker is under-powering them, as opposed to over-powering them, meaning, powering them with an amp that doesn’t supply enough wattage when driving the speakers to the max levels.

You can actually hear evidence of under-powering, when you play a loud-volume signal, the speaker makes an odd crackling especially in the low-to-mid range; as opposed to a speaker being “over-powered” where you’d actually hear the speaker clipping or “cutting out”, crackling is actually indicative of under-powering. Under-powering can actually damage both the speaker and the amp under “ideal” conditions.

Sorry so technical…I guess you can say I’m an audio-geek!

Another thing to consider besides impedance is that people often think that if you’re amp is rated lower wattage than your speakers that you can’t blow your speakers. What “blows” speakers is clipping…driving the volume louder than your amp can produce, and causing clipping, i.e, a square wave. A square wave is esentuially pure DC, which a speaker can’t handle and will burn out your coils.

@HungryGuy is right! I realize in my description, that I actually had it backwards…the clipping is produced by under-powering the speakers, not the broadband/harmonic distortion I was describing.

You do hear the harshness with the clipping though. The amp can’t keep up with the amplitude gain, and has a “cutoff” of the wave, producing the square wave instead of retaining the curvature around the peaks….nice job @HungryGuy.

@sndfreQ That’s what was amazing when I was trying to my house speaker system off a vintage Marantz! Sounded like I blew the speakers, but really the amp didn’t have enough power!

Yeah I did that once! Story back from my college days over at CalArts, we were doing a sound design for a theatre production and were installing a large subwoofer cabinet that was about 9’ x 12’ and had 12 15” drivers, and being a neophyte designer, I was trying to drive it with a 600 watt amp. I tried to test it with some sound effects of thunder, and the cabinet started to make this odd crackling/boiling sound, like the sound of a needle scratching across a record lengthwise. I thought we blew all 15 of the woofers in the cab and I started to freak out. My teacher went to the amp rack, and re-patched the cab into two bridged 2500 watt amps (per channel x 4! @2 Ohms) and that thing shook the whole building (10000 Watts versus 1200Watts). About 10 minutes later, someone from the library on the floor below us ran up to the theatre and told us that the sub literally shook the whole building, and not knowing what was going on, they evacuated and sounded the fire alarm because they thought they felt an earthquake! But the sub was rockin’ (literally) from that point on. We had to phone the library whenever we did that show for the next week after that.

@sndfreQ – Right. It’s actually easier to blow your speakers with an under-powered amp than with an over-powered amp because the under-powered amp is more likely to be driven to clipping.

The clipping is the physical “squaring off” of the waveform; basically disrupting the smooth in/out motion of the driver cones, and the abruptness of disrupting very loud (strong) movements is what generates the heat in the coils…can also shred the cone material in some cases.

@sndfreQ – That’s absolutely correct. In extreme clases of clipping, you’re basically sending high-power raw DC electricity into your speakers. Ouch!