Going over max power rating

[myriad1973]

While I've been shopping around for a receiver, one thing occurred to me: My surround speakers are rated for 120 watts. The receiver I want is 130 watts per channel with 150 watts dynamic power.

Would I take a chance at blowing the surround speakers or would setting the crossover over 100 Hz and/or lowering the speaker level make them less susceptible to blowing?

 

[markw]

You'll be fine.

Those ratings can pretty much be taken with a grain of salt.

First off, odds are that 98% of the time you'll be using one, maybe two watts. That will most likely be as loud as a sane person would want on a constant basis. The rest is reserve power for momentary peaks.

Second, speakers can absorb gobs of power as long as you use your head. If something sounds funky, fuzzy, bad, or "knocky", you should turn it down ....now.

I've been using speakers rated at 35 watts with a receiver that is rated for 70watts for several years and no problems.

Finally, odds are that receiver won't be putting out 130 watts per channel. Read the fine print.

 

[myriad1973]

I had a feeling that was the case. I just wanted to make sure my instincts were correct. Thanks for the help.... I'm rusty these days when it comes to amps.

 

[XEagleDriver]

Not a problem unless you intend to abuse ears & speakers

. . . surround speakers are rated for 120 watts. The receiver I want is 130 watts per channel with 150 watts dynamic power. Would I take a chance at blowing the surround speakers . . .

One other thought, many AVRs (e.g. Denon) allow you to set the initial start-up volume and to limit the max available volume--both usefull features to avoid any inadvertent ear/speaker pain.

XEagelDriver

 

[walter duque]

You're fine. I bi-amp my center which is rated at 220 watts with 350 watts X 2.

 

[FirstReflection]

Having a high-power amplifier is virtually never a problem. Current is "drawn" by the speakers, it isn't "pushed" by the amplifier. The speakers will attempt to "draw" as much current as is necessary to play as loudly as you are asking them to (via the volume knob on your receiver). The worst thing that can happen is that they draw enough power to "bottom out" the driver - which simply means that the driver (tweeter or woofer) goes as far out or as far in as it physically can.

What is FAR more likely to damage your speakers is not having enough power. If your amplifier does not have enough power, your speakers might try to "draw" more power than the amplifier can provide. This leads to the amplifier "clipping" the signal. A "clipped" signal can produce an extremely loud "slap" sound, which can damage your speakers.

Most amps these days have protection circuitry that will "soft clip" the signal if the speakers attempt to draw too much power.

When it comes to looking at specs for receivers, unfortunately, the number of Watts can easily be manipulated. What you really want to find out are the number of channels being driven when they are giving their spec and over what range of frequencies and with how much Total Harmonic Distortion.

The THD figure should be under 0.1%. The frequency range should be the full 20 Hz - 20 kHz, but you will often see the spec listed for 1 kHz and 1 kHz only! Most speakers are a fairly easy load at 1 kHz. You can expect a receiver that is only rated at 1 kHz to deliver about half as much power at some other frequencies where the speaker is a harder load to drive.

Some companies - like Harmon Kardon - list their Wattage with "All channels driven", while others - like Onkyo - list their Wattage with 2 channels driven. If you do not see how many channels are being driven, you can assume that it is 1 channel at full power with the rest at 1/8th of that power rating. With a little simple math, you can figure out how many Watts the receiver's power supply is ACTUALLY providing to your speakers.

So 35 Watts/channel All 7 channels driven into 8 Ohms with 0.08% THD from 20 Hz - 20 kHz means that that receiver can pump out 245 Watts at any given moment.

Meanwhile, an 100 Watts/channel 2-channels driven into 8 Ohms with 0.08% THD from 20 Hz - 20 kHz receiver can actually only pump out 200 Watts at any given moment. So even though the first receiver says it is only a "35 Watts/channel" receiver, it is actually more powerful than this "100 Watts/channel" receiver.

Then there are the 100 Watts/channel into 8 Ohms with 0.08% THD from 20 Hz - 20 kHz receivers, which do not say how many channels. We can assume it is 1 channel at 100 Watts and 6 other channels at 12.5 Watts each. So that means it can muster 175 Watts at any given moment. They call this a "100 Watts/channel" receiver, but it is less powerful than either of the other two!

Then we've got the ones that claim "100 Watts/channel", but go on to list that it is into a 6 Ohm load with 1% THD and only at 1 kHz! If we were to try and equal that out to the other receivers, you're probably looking at about 25-30 Watts into 1 channel at 8 Ohms with 0.08$ THD from 20 Hz - 20 kHz. Not even in the same league, but you'll still see "100 Watts/channel (!!!!!!)" printed on the box - so that's where you have to watch out!

 

[PENG]

I am sure your response is well intended but I suggest you read through some S&V, HT Mag, HCC bench tests of a few popular AVRs in addition to HK's.

 

[fredk]

Peng, can you expand on that? My understanding is the same as that of FirstReflection. If a manufacturer states its receiver delivers 100W two channels driven then the receiver will deliver at least this amount of power. Anything less puts it in violation of FCC regs.

Some manufacturers, like Denon, tend to rate their receivers conservatively, so you would get at least 100w x 2 channels driven, but often more.

 

[MatthewB.]

You'll be just fine. Especially since your inquiring about surround sound speakers. Depending on how large the speakers are (driver wise I mean) you will get very little bass. I have found that if you cross the bass over at 80hz (THX recommended) then 50-60 watts is all you will ever need. If you cross even higher 100-120hz you use even less. But if you are using speakers that are full range towers and you have full bass going to them, then even 100 watts will be just fine.

I run a very powerful system in my main HT system and have a simple 60 wpc stereo adcom amp pushing my rear DefTech Mythos gems (had to go small because of spce contsraints) and I listen at very loud levels and have never had my speakers distort with 60 watts crossed at 120hz)

So in your case you'll be just fine.