75 watt RMS receiver into 50 watt RMS speakers

[Agentbolt]

So I've purchased this receiver on Newegg, the Onkyo 506

http://www.onkyousa.com/model....506&class=Receiver&p=s

75 W per channel (8 ohms, 20 Hz-20 kHz, 0.08%, 2 channels driven, FTC)

and I want to hook it up to 6 of these speakers

http://www.parts-express.com/p...cfm?Partnumber=300-682

*Power handling: 50 watts RMS/80 watts max *Impedance: 8 ohms *

So the 75W rating, for an Onkyo, I'm assuming is an RMS value. Which goes well above the RMS value of those speakers but doesn't quite hit the max value

So my question is, am I going to blow them up? I mean I'm sure I could be okay by just keeping the volume super low or whatever, but this receiver is being bought to play movies (not so much music) so loud explosions and stuff are kind of a must.

Any thoughts? Am I probably okay? Dayton tends to make good stuff, from what I understand, so I'm really hoping I don't need a new set of 6 satellites.

 

[spidey07]

Better to have too much power than not enough. Low power is what kills speakers.

You're fine. If you hear any noticeable distortion or it gets a compressed sound that means turn it down.

 

[alfa147x]

how does low power kill speakerS?

 

[spidey07]

Clipping the amplifier (overdriving) overheats the voicecoil in the speaker. Eventually melting it.

You're much more likely to overdrive an underpowered amp than a high power one.

 

[alfa147x]

Originally posted by: spidey07
Clipping the amplifier (overdriving) overheats the voicecoil in the speaker. Eventually melting it.

You're much more likely to overdrive an underpowered amp than a high power one.

melting speakers sound like fun...

 

[PurdueRy]

Originally posted by: spidey07
Clipping the amplifier (overdriving) overheats the voicecoil in the speaker. Eventually melting it.

You're much more likely to overdrive an underpowered amp than a high power one.

I believe clipping is more likely to damage the mechanical components of a speaker due to driving the speaker past its xmax rather than causing the voice coil to melt.

 

[spidey07]

I don't know Purdue. I've melted plenty of voice coils and crossovers. Was it do to clipping or just over driving? Don't know, but hard clipping sends brief DC to the voicecoil (chopped off wave).

Tweeters always went first. The dome ones and you could see the outer edge of the dome melted.

 

[taterworks]

Right, clipping blows voice coils because it causes the chopped-off parts of the sine wave to begin to look more like a square wave. Even though the amplifier no longer has the headroom to track the waveform beyond the ability of the amp's power supply rails to supply voltage, the amp's output will sit at the rails for a longer period of time, so while the amplitude of the signal doesn't increase, its RMS power level does.

A speaker's thermal power handling ability is based on power, but also time, as the voice coil heats up. A momentary 20ms peak of 75 watts won't blow your 50W speakers, but running them with an unclipped sine wave at 75W RMS for more than a few minutes probably will. Some of the best-sounding systems I've ever assembled had amplifiers that were capable of delivering between 1.5 and 2 times the rated power of the speakers, and that's because they had plenty of muscle on tap for sudden musical transients, but we never ran them into clipping or with anything more demanding than a typical music signal, so if you like to listen to 80 Hz sine wave tones instead of actual music, this approach may not work quite so well for you.

Short answer: You're probably good. And the Dayton speakers are inexpensive enough that if you do vaporize them somehow, you can afford to replace them if necessary. Just use your ears -- if, while cranking up your music, things start to sound ugly, then it's probably a good idea to back down on the volume knob just a little. Having a competent subwoofer can also give the sensation of more loudness without actually requiring the satellite speakers to play loud.

 

[taterworks]

Going a little further: A clipped sine wave causes tweeters to fry first because it introduces a great deal of upper-frequency harmonics to the musical signal (which occurs as a result of the hard 'knee' where the amplifier's output hits the rails). The tweeter's lightweight voice coil can't handle that kind of power, and it melts. Woofers are usually more robust and can take the abuse for longer before they're destroyed.

 

[cheesehead]

Originally posted by: taterworks
Going a little further: A clipped sine wave causes tweeters to fry first because it introduces a great deal of upper-frequency harmonics to the musical signal (which occurs as a result of the hard 'knee' where the amplifier's output hits the rails). The tweeter's lightweight voice coil can't handle that kind of power, and it melts. Woofers are usually more robust and can take the abuse for longer before they're destroyed.

Ribbon tweeters are the exception to the rule, though. Having a massive surface area for thermal dispersion might help a bit, and the transformer will likely saturate first anyway.


The big problem with all of these estimates is that they're often a load of rubbish. While I would wager those speakers can take close to 50W RMS, I severely doubt than any inexpensive "75WPC" receiver can actually deliver 75 watts RMS to even one channel.

That said, I'd spend a bit more on speakers. Those Daytons are good for $60, but $60 is not a lot of money. Perhaps you could step up to the Infinity Primus line?

 

[Tiamat]

Should be fine. There are many generalizations that are typically made. One of which is that more power is better since supposedly the amplifier is rated to not send a clipped signal into the speaker. If you play too loudly and the amplifer sends too much power to the speaker, you can burn the voice coils.

Both are not great situations. If your speakers are inadequate for your room, upgrade the speakers. If your amplifier is not adequate, you will hear distortions and clipping, which severe enough, can burn out the tweeters (first to go).

 

[thomsbrain]

The "clipping amp" thing has come up many times and I'll just have to agree to disagree with some of the other folks here on it, but here's my take:

Considering most modern pop recordings are already square-wave clipped at the source and we all play them with no problems, I'm gonna guess that the speakers people are melting weren't really up to handling the amount of power their manufacturers were claiming and that's why they melted. You know, speaker manufacturers lie. That's what they do best, in fact. And think about it: the speakers died because they were fed signals too strong for them to reproduce properly, so they started to heat up. They had too much power. TOO MUCH power. Not too little. It may be true that a clipped signal is tougher to reproduce and therefore the maximum power handling of the speaker is lower for clipped signals than for clean signals. But the core problem was still that the speaker was couldn't handle the amplifier's output power. The speaker's power rating was a "best case scenario" rating and the real world isn't always best-case scenarios.

I have a conservatively rated 100-watt tube Marshall amp that I have upgraded with even higher-output power tubes and run at full volume (massive clipping), with a massively clipped input from the maxed-out preamp for hours at a time into a speaker cabinet rated for 120 watts, with no problems. The speakers in that cabinet were designed in the 1970's and use paper cones (Celestion G12H-30). Guitar speakers are purposely crappy because they need to "EQ" out a lot of low and high frequency garbage from the distorted amp. That means there is a lot of juice from the amp that gets absorbed as heat because it can't be reproduced. We were at a recording studio and I was feeding this setup pre-recorded guitar performances so that we could capture the sound of the amp at full volume. We literally fed it hours and hours of non-stop material with no issues.

The lesson is that if you have speakers that can handle their claimed ratings, you won't have problems. There's a reason that the guitar speakers are only rated for 30 watts apiece, despite being 12" and having massive voice coils. The manufacturer knows that the speaker will get abused, so they rate for worst-case scenarios. Now look at home speakers, where little bookshelf speakers are often rated for 75 watts or higher. Do you really think a little bookshelf speaker can really handle more power than a massive 12" woofer? No. Obviously the manufacturer is full of shit. So be smart, and don't feed small speakers 75 watts, clipped or not.

OP, the short answer is it is perfectly ok to have more amp power, but if you hear distortion, you should probably turn it down, because your speakers are overtaxed if they are distorting. Simple as that.

 

[Rubycon]

I've put 3000W unclipped power into a modestly rated 100W speaker before - a very very short burst. Some can take it, some cannot. Live music has a wide dynamic range (unlike modern recordings today - the majority of them) and thus amplifier power must be high to prevent "running out of steam" during a gig.

Most home speakers are quite fragile and some of the more better built ones can also mimic pro audio with over built voice coils, suspensions, etc.

Regardless of how a speaker is built and what its role is unless it's truly a pile of junk - ultimately its fate is in the hands of the operator/listener.

Occasional clipping is not going to hurt a loudspeaker BUT in the case of playing back commercial recordings - the overall average level is going to be high and a lot of that energy is going to directed to the tweeter or midrange drivers if present. These drivers are very fragile compared to a bass driver. Most dome tweeters can dissipate only about 10 to 15W thermal power. Ferrofluid helps prevent burn out with transients and reduces power compression which is rather a useless feature with most pop music these days. That was often touted in the early 80's with the term "digital ready". For today they need to have "loudness ready" speakers - woofers with four inch edgewound voice coils, large air inductors, and lightbulbs to protect the high frequency drivers. Pretty much standard on reinforcement type loudspeakers.

Bottom line is when the drums don't sound louder or start to sound like a different genre of music (rock to rap), then you're severely over driving. If the speaker system can handle to DC equivalent of the amplifier power supply then it could survive any kind of abuse with that equipment. Of course (unless you are essentially deaf!) your ears will tell you something is wrong well before this happens...I hope!

 

[Agentbolt]

Well I guess we'll see. As someone else has already pointed out, if I do blow these, it's not as if I'm out thousands of dollars.

 

[thomsbrain]

Originally posted by: Rubycon
Of course (unless you are essentially deaf!) your ears will tell you something is wrong well before this happens...I hope!

Yup. To borrow the motto of the rock band Weezer: "If it's too loud, turn it down."

 

[Googer]

Originally posted by: alfa147x
how does low power kill speakerS?

When an amplifier cannot keep up with the load demands, it will start pumping out square waves. It is square waves that will destroy a speaker. Since most speakers have an RMS (root means square) and a peak rating, A lager more powerful receiver, is better able to keep the sine wave going during periods of peak and high volume.

There's nothing wrong with having several 900 watt Krell amplifiers connected to a pair of 40 watt speakers.