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Speaker wpc ratings...please explain.


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17 replies to this topic

#1 of 18 OFFLINE   RobWil

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Posted April 17 2003 - 03:00 PM

If a pair of speakers are rated at 100wpc max, 500w peak what exactly does this mean? Does it mean you shouldn't run them at a full 100wpc and wouldn't this be a little extreme anyway?
Could you still drive them with a 200wpc amp, but you'd just have to be careful or what?
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#2 of 18 OFFLINE   Lewis Besze

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Posted April 17 2003 - 04:27 PM

The 100w means continious power handling[tied to the speaker's thermal limits],with 500w peaks which normaly lasts only a few seconds.
Yes you can hook up 200w amp,it's very unlikely,that you ever push the amp to that level,
It depends greatly on the sensetivity of the speaker,and the listening distance,and the input of the signal[gain].

#3 of 18 OFFLINE   Brett DiMichele

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Posted April 17 2003 - 04:31 PM

As Lewis said (you beat me to it D'oh!)

If a speaker is listed as 100Watts and 500Watts Peak. This
means the voice coils can sustain a 100 watt thermal load
without failure and momentary peaks of 500 watts. Every
speaker ever made has a range in which it will function
without failure from thermal overloading. If you send 1000
watts RMS to a driver rated for 300RMS it will go up in
smoke as the voice coils break down. (You can also do
damage to crossover components)
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#4 of 18 OFFLINE   RobWil

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Posted April 17 2003 - 05:56 PM

Thanks guys....I have a pair of Klipsch KG 5.2's, sensitivity 96db, at around 9 ft distance in a pretty small room. I'm thinking about driving each of them with an audiosource amp one, 200wpc bridged.
that's my story and I'm stickin' to it!

#5 of 18 OFFLINE   Dave Milne

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Posted April 18 2003 - 01:53 AM

Let's see... 96dB, 200W (that's +23dB), two of each (roughly +6dB, maybe more with room gain)...

= 122dB. Uh, that should do it.Posted Image

#6 of 18 OFFLINE   Brett DiMichele

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Posted April 18 2003 - 04:42 AM

LOL Dave

Yeah "Uhhh Yup" I think that'll work..

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#7 of 18 OFFLINE   RobWil

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Posted April 18 2003 - 08:36 AM

.
Quote:
Let's see... 96dB, 200W (that's +23dB), two of each (roughly +6dB, maybe more with room gain) ]= 122dB. Uh, that should do it....



Yeah..that was real constructive. I was worried about my speakers, not whether I had enough power a$$hole. The amp ones are only 80wpc , unbridged...I realize 200wpc is overkill, but guess what!....that just so happens to be what they are bridged! Just what I need ....another troll.
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#8 of 18 OFFLINE   Phil Iturralde

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Posted April 18 2003 - 09:04 AM

FYI: For a more precise & easy maximum SPL (loudness) @ your listening position (distance) vs. AMP power vs. speakers (number) vs. speaker sensitivity, ... use C. M. Collins 'excellent' SPL Calculator @ his website = How Loud Will it Go?

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#9 of 18 OFFLINE   Michael R Price

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Posted April 18 2003 - 09:16 AM

Rob,

It'll work fine. The RMS power rating is generally derived from the thermal power handling of the woofer. (I don't know where the "peak" rating comes from.) Of course, this usually does not count excursion limitations. Especially at low frequencies it might take a lot less than 100 watts to distort or damage the speaker.

The fact that you're using a 200 watt amplifier does not mean much. Especially since your speakers are so efficient, music and movies won't demand much power. Dave was trying to say this by showing that 200 watts put into those speakers would give you 122db, which is absurd. In other words, you won't ever need to use so much power that your speakers could be damaged. (I would be surprised if your ears could stand the volume produced by 10 watts continuous with your system.) Additionally, audible distortion should warn you that you're pushing the system past its limits well before damage occurs, if that ever happens.

#10 of 18 OFFLINE   Dave Milne

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Posted April 18 2003 - 09:45 AM

Sorry Rob for the sarcasm. As Michael pointed out, I was trying to illustrate that you shouldn't have a problem... since your ears would bleed first. The only possible route to trouble would be if you have inquisitive toddlers (like I do) who might inadvertently crank the thing to max.

In reality, more speakers are damaged by under-powered amps than overpowered, because the clipped output of an overdriven amplifier contains tons of tweeter-destroying high frequencies.

By the way, nobody caught my math error. 96+23+6 = 125 (not 122). :b No matter.

#11 of 18 OFFLINE   RobWil

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Posted April 18 2003 - 09:58 AM

OK....sorry I called you an a$$hole Posted Image
I was just hoping it WAS sarcasm and that I hadn't missed something!
No inquisitive toddlers...just dumbass big ones. How many times have you seen someone turn the volume up all the way becuase there was no sound? Of course it couldn't be because the wrong source was selected....that would make too much sense. It must be the VOLUME isn't turned up enough, even though you've already turned it up AS FAR AS IT GOES and there's still no sound!!! Posted Image
Would this hurt my speakers? Posted Image (just kidding)
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#12 of 18 OFFLINE   Chu Gai

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Posted April 18 2003 - 10:50 AM

Along the line of Mr. Milne's post regarding clipping and all that, this is a little gem that was recounted some time ago by Richard Pierce whom some may recall did the crossovers for the Rocket speakers.

Quote:
"Don't know where you spent your youth but remember some Boston stories. During my college days there got together with Danny Boynton who owned Audio Lab. He was wonderful -- he didn't get confused about the issues, but rather shamelessly sold on the psychological issues. ... His only redeeming grace was that he sold top of the line, quality material, and ... sold it to me at cost so I got a Mac amp and preamp early on."

Well, I was quite familiar with Mr. Boynton and some of his shenanegans, one of which is most amusing.

Audio Lab was quite fanatic about MacIntosh equipment. Any criticism of it (and I was more than willing to supply a lot of criticism!) was treated simply as heresy. The equipment was kept in a showroom noted more for its reverential hush than its suitable listening environment.

As expected, less than rational means were used to promote the equipment. One example that impressed many uninformed buyers was the EPI 100 loudspeaker kept in the MAC room. The grill cloth was burned out completely, the speaker cone was mere ash and portions of the front of the cabinet were charred. This speaker, according to the Audio Lab legend, was set upon by none other than the almight MacIntosh 2105 power amp. "So much power," it was told, "that the speaker literally caught fire!"

This seemed most suspicious to me. I inspected the speaker casually, and noted with great interest that in spite of all the apparent damage, the voice coil, the spider and the linen wrap on the speaker frame were in perfect condition!. It was, at this point, very apparent that the speaker had been burned, not by the
almighty MacIntosh, but by the lowly Burnz-O-Matic propane torch.

I decided to play a little trick of my own. I challenged Audio Lab to a bet. I said that I could do the same thing to a MacIntosh speaker with a mere Japanese receiver. They accepted willingly. I purposely selected the lowest power receiver around that also proved to be the most unstable into reactive loads (I think I finally ended up with a 25 watt Pioneer of some sort. We hooked it up to the Mac speakers, and I was given the helm.

My game plane was well established. I ran the volume to full level, selected (purposely) an album of Beethoven String Quartets, to make the situation even more ludicrous, and, with the cuing lever down, dropped the stylus onto the middle of the record at about a 45 degree angle, at a very impolite speed. The stylus bounced once, and then obligingly scooted across the record to land on the label.

Well, the first bounce absolutely destroyed the midrange, the skipping then promptly fried the tweeter with a most satisfying flash that was visible through the grill cloth! Now, as I had hoped, this poor little amplifier, clipping up the wazoo, was staring at a most awful reactive load, as the destruction of the drivers had now rendered the crossover something else entirely. The amplifier promptly latched up to the positive supply, dumping about 30 volts DC into the voice coil of the woofer. The speaker gave a couple of final squacks, and then was silent. The whole affair took, maybe, 4 seconds. Then, there was the unmistakeable odor of burning resins, and but the slightest hint of a curl of smoke coming through the grill of the speaker.

The staff was absolutely dumfounded. The scene must have been like that in biblical times, with the mauraders staring in horror as Goliath lay dead, bleeding by the temples, on the battlefield, slain by a mere boy. My only comment was, "When in Rome, don't f*** with the Gladiators."

You see, it was all quite simple. A small receiver, driven into clipping, can be most unstable, oscillating at high frequencies, suffering from power supply recovery problems, and so forth. I had a much better chance of killing the speaker with something small than with something big.

Needless to say, I was quickly made Audio Lab's official Persona-non-Grata for Life. And till their dying day, I made sure that everytime I was in Harvard Square, I was sure to pass by and wave. By the way, the poor little receiver that couldn't but did survived unscathed, and ended up in a friend's apartment where, as far as I know, it remains playing music to this day.


#13 of 18 OFFLINE   RobWil

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Posted April 18 2003 - 11:48 AM

So you're saying you think I'm OK then, too???? Posted Image
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#14 of 18 OFFLINE   Chu Gai

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Posted April 18 2003 - 12:03 PM

yes

#15 of 18 OFFLINE   DanaA

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Posted April 18 2003 - 12:21 PM

I also have Klipsch being driven by a pretty powerful amp. As a couple of watts can drive the speakers to 100 decibels, people might wonder why. The point is that I'm planning on keeping my power amp for a long time and power amps can last for a long time. I love my speakers, but I'm not married to them. If, for instance, I change my speakers down the line for less efficient speakers, I don't have to go through the burdon of picking up a new amp. This one will be a keeper for years to come, unless the unforseeable occurs. And, besides, I just like owning a lot of power.

Did anyone notice that most of you guys were also on Rob's other thread too. Posted Image

#16 of 18 OFFLINE   RobWil

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Posted April 18 2003 - 01:37 PM

Quote:
The point is that I'm planning on keeping my power amp for a long time and power amps can last for a long time. I love my speakers, but I'm not married to them. If, for instance, I change my speakers down the line for less efficient speakers, I don't have to go through the burdon of picking up a new amp.


I'm beginning to think along the same lines.

Quote:
Did anyone notice that most of you guys were also on Rob's other thread too.


Really? Gee....I hadn't noticed! Posted Image

I think it all comes down to one fact. I may be a dumbass about this sh!t...but at least I'm an interesting dumbass!
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#17 of 18 OFFLINE   Michael R Price

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Posted April 18 2003 - 03:16 PM

Dana,

I agree with your philosophy but I'm the other way around. I want to get high-efficiency speakers eventually, and my 400 watt amp will be waiting for them! Posted Image

But seriously I think it's a good idea to get a better sounding amplifier (if such a thing is possible) for the same price by sacrificing a bit of power output if you don't really *need* 100+ watts. Just don't go by my example unless you're really sure you need the power. (I wasn't.)

#18 of 18 OFFLINE   DanaA

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Posted April 19 2003 - 02:24 AM

There is a bit of Tool Time in all of this, isn't there? Men and their power amps and 300 horsepower car engines. Not something practical or at all reasonable, but there we are with out toys. Posted Image


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