Speaker Wattage Rating

[neo33]

How does wattage rating apply in general to any type of speaker (i.e. two-way, three-way)? Lets say a Heresy maximum wattage rating is 100 Watts RMS. If I feed 150 Watts continuously, I could potententially damage the speaker. But before I can even damage any driver, wouldn't the crossover go first? What about the Heresy II that have protection circuit? What about under wattage? What if I feed 20 Watts long term into the Heresy (aka listen at very low volume level), would it damage any driver at all?

[Guest " "]

in a lascala...... Power rating sine wave 0-40hz 50w, 40-400hz 150w, 400-4000hz 75w, 4k-20k 25w.

[Quiet_Hollow]

How does wattage rating apply in general to any type of speaker (i.e. two-way, three-way)?

It's a half-baked way of classifying audio components that affords companies significant marketing latitude.

In practice, watts are "real" power in the form of heat, which is by one of two ways a cone speaker can involuntarily stop making sound. The other way, is mechanical failure such as the cone tearing apart, or the cone tearing your neighbor a new ear-hole.

Lets say a Heresy maximum wattage rating is 100 Watts RMS. If I feed 150 Watts continuously, I could potententially damage the speaker.

How would you go about measuring this?

That's where the problem of using a power rating lies. Measuring instantaneous real power, as the total sum of heat in an entire speaker assemblage, is not practical.

What about under wattage?

There is no such thing. When the batteries in a flashlight die, the bulb goes dim, it doesn't explode. I can hook the headphone jack on an MP3 player directly to a La Scala and proceed to drive into a clipping frenzy, the big speaker won't bat an eyelash.

What if I feed 20 Watts long term into the Heresy (aka listen at very low volume level), would it damage any driver at all?

If you could measure it, 20 watts into a Heresy would be very loud. "Low" level listening is actually in the milliwatt region.

[8] The key is to measure the voltage instead. Using Ohm's law, you can calculate a reasonably conservative voltage using the manufacturer's stated power rating and nominal impedance.

With the above Heresy for a basic example: 100 Watt continuous / 8 Ohm would require a signal from the amp at 28V

So if you're listeing to some music, and you happen to place a voltmeter across the terminals...conservatively speaking, the speaker shouldn't have a problem handling a signal up to 28V. I'm sure you would also discover, 28V on a Heresy would be f*^#'n loud too.

Voltage is something we can actually keep tabs on using a meter.

[mustang guy]

...What if I feed 20 Watts long term into the Heresy (aka listen at very low volume level), would it damage any driver at all?

I have a 15 watt tube amp hooked to a pair of Heresy's, and all the way up, it is quite loud. 20 watts would make my head hurt! Low listening level would be 1 watt or less on a Klipsch Heritage speaker.

[Exponential]

My 10 Watt Jolida push-pull tube amp drives my Cornwalls to volume levels that will drive people out of the room. I am currently building a 2-Watt SET amp, which will be plenty of power, I am sure.

[neo33]

If 20 Watts is LOUD, then 100 Watts is IMPOSSIBLY LOUD! Why would Klipsch even make a speaker with that wattage rating?

[Don Richard]

So that it can survive the power output of amplifiers designed for the inefficient speakers that dominate today's market.

[Exponential]

If 20 Watts is LOUD, then 100 Watts is IMPOSSIBLY LOUD! Why would Klipsch even make a speaker with that wattage rating?

Because the drivers have that power handling capacity. The power rating is not related to listening level.

[Chris A]

If I feed 150 Watts continuously, I could potententially damage the speaker.

If you could stay in the same house while doing this, then yes, you would eventually fry one or more drivers. The SPL would probably be above 120 db© in the same room as the speakers.

But before I can even damage any driver, wouldn't the crossover go first?

Probably the tweeter first, then the woofer voice coil, then the midrange compression driver, in that order (a guess). The drivers would probably protect the crossover components []

What about under wattage? What if I feed 20 Watts long term into the Heresy (a.k.a., listen at very low volume level), would it damage any driver at all?

Twenty Watts (average) electric power into a Heresy would be outrageously loud, and would not be low level. Most Heresies are rated at about 98 dB (SPL) output at one Watt and one meter distance. For every doubling of power into the speaker, there will be a nominal 3 dB(SPL) increase in its output. So 20 Watts (average input) is like 112 db(SPL) at one meter for each speaker. Bottom line here is that that isn't very low output - in fact most dance clubs don't go that loud (my rule of thumb is like 110 db© maximum as on the verge of short-term hearing loss).

The only issue with "underpower" in amplifiers is the potential for amplifier clipping - where all the energy being fed into the speaker winds up going to the tweeter--which is least able to handle that kind of power, and results in blowing that driver. However, you'd not like the sound coming out the speaker long before that point.

Chris

[neo33]

Chris, you almost tell me what I wanted to know. I am using a wireless transmitter/receiver to drive my surround back Heresies in my 7.4 home theatre system. The wireless receiver output is only 42 Watts RMS into 4 Ohms or 21 Watts RMS into 8 Ohms per channel for two channels. My main receiver is outputing 80 Watts RMS into 8 Ohms per channel for 7 channels. 21 Watts may not be enough for the back sourrounds if I play at reference level but more importantly is that will it damage the Heresies in the long run?

[Chris A]

My main receiver is outputing 80 Watts RMS into 8 Ohms per channel for 7 channels.

Remember that there are eight(+) speakers running in a 7.1 setup, so "reference level" in your listening position for each speaker in that setup during reference-level passages is probably several dB lower (that is, measured one meter in front of each speaker).

21 Watts may not be enough for the back sourrounds if I play at reference level but more importantly is that will it damage the Heresies in the long run?

Surround channels usually limp along at the lowest average output, probably by 10 dB or even more for a typical soundtrack. Twenty one Watts into each surround channel is a whole lot for Heresies. And that's just where the amplfier begins to distort due to its output limitations. Klipsch speakers don't take a lot of input under even very high SPL conditions in the room. I'd be worried more about the subwoofer channel than the surround channels (i.e., "LS", "RS", "LBS", "RBS"), due to the acoustic inefficiency of typical direct-radiating HT subwoofers.

I'd say "don't worry about it...you're there already". If the surrounds sound like they're distorting on reference-loud passages, then its time to worry about the surround amplifier channels: the speakers will survive otherwise.

Chris

[neo33]

I am not sure I understand that.

And that's just where the amplfier begins to distort due to its output limitations. Klipsch speakers don't take a lot of input under even very high SPL conditions in the room. I'd be worried more about the subwoofer channel than the surround channels (i.e., "LS", "RS", "LBS", "RBS"), due to the acoustic inefficiency of typical direct-radiating HT subwoofers.

Also at reference level, the two back surround channels are active on the main receiver, but the power outputted on the wireless receiver will not be the same.

[Chris A]

Also at reference level, the two back surround channels are active on the main receiver, but the power outputted on the wireless receiver will not be the same.

I'm not sure what you are saying here myself.

The comments that I made were about:

1) capability of your surround amplifiers to support the surround channels to "reference level". Some amplifier designs can provide much higher output for short periods of time, even though they might be distorting more than specified % distortion levels,

2) the ability of your surround back speakers (Klipsch Heresy) to handle the electric power input from your surround amplifier(s) however they are driven by pre-amps (wireless or not),

3) the electrical power input and acoustic power output requirements for the surround channels relative to the LCR and sub channels is always much lower on average, and

4) the total acoustic power output required from each speaker is lower than the total SPL required for "reference level" at your listening position since you have 8+ speakers in a small interior room.

Chris

[mustang guy]

Neo, what are your mains and center channel gonna be? Are you using your khorns, and something like a Belle? In that case, 80 watts potential demand there, and limiting Heresy's to 20 would be a misfit if it is a pretty big room, because you may actually be pushing the voltage up, and you will have a db gain adjustment for the rears (Heresy's) due to their lower efficiency. If the room is smallish, or the mains were gonna be Heresy's, then you should be good to go.

[Guest " "]

But before I can even damage any driver, wouldn't the crossover go first?

fuses...maybe....crossover parts...rarely. The caps in Heritage xovers are rated for over 250 volts. so the mid driver and tweeter would be long gone. inline woofer coil can handle a couple hundred watts...much more than the woofer voice coil.

[neo33]

This should really be in the Home Theatre section but...

Here's what my current 7.4 setup looks like:

Main: Klipschorns.

Center: La Scala.

Surrounds: Cornwalls.

Surround Backs: Heresies (for now, Cornwalls later).

Plus two front Epik Empires and two back Epik Empires.

All seven channels are active and driven by the main receiver of 80 Watt RMS into 8 Ohms per channel. I am feeding the surround and surround back channels into two wireless transmitters (total of 4 channels). The surround and surround back speakers are driven by two wireless receivers (2 channels each) of 21 watts RMS into 8 Ohms per channel. So while the main receiver is feeding full power into the surround and surround back channels at reference level via the transmitters, I am not get the same power outputs from the wireless receivers for the surround and surround back channels. Will this under wattage (lack of amplification power thereof) damage my speakers in the long run?

My reason for doing this is because I don't want to run lots of wires from the front to the back of the room.

[mustang guy]

Wow! Sounds like it's gonna be a killer setup.

Nothing you mention would damage speakers. I would imagine the wireless receiver amps have clipping protection built in, so your tweets will be safe on the Cornwalls and the Heresy's. You can check the transmitter/receiver manual for this.

If you ever decide to run wire to the back, consider a single 4 wire to the surrounds, and a two wire to the rear from the surrounds. Something like this:

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10239&cs_id=1023902&p_id=4039&seq=1&format=2, then this:

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10239&cs_id=1023902&p_id=2820&seq=1&format=2

You can either run this on the floor, or in the walls, as it is rated as such. You could also run the 4 wire to the back then split it to the rear speakers. Then use the 2 wire to run to each surround.

[derrickdj1]

Listening to music and movies will not give you a continuous output. Speaker companies derive that number using special sound signal to stress the speaker for a particular rating. Surrounds usually receive 1/2 of the voltage as the front 3. I have used VS 14 surrounds rated 50/200 rms/peak with a 200 watt amp and never came close to stressing them even near reference level which is extremely loud in the home setting. Long term hearing is suspect if one uses that type of volume regularly. You may damage the surround amp before the speakers. Far as speaker damage it is usually the voice coil that goes or mechanical damage to the driver. The xo most likely will survive.

[bobdog]

I have to disagree with most here and say that I believe you are underpowered to all channels. You have some great speakers give them a little love and feed them well.

[mustang guy]

I have to disagree with most here and say that I believe you are underpowered to all channels. You have some great speakers give them a little love and feed them well.

There are definitely times that I crank up my system to the limits. My Integra DTA-70.1 pumps 150 watts into each of my six LaScalas, and my Crown XLS-202 pumps 400 watts into my two THT subs. It's very musical, and very loud. If I did not have that capability, I admit, I would still be shopping.

I agree with you, but I also know it is a very personal thing. There is absolutely nothing wrong with 1 watt into an efficient speaker, but when you wanna rock, ya gotta feed them babies! []