How do I convert power ratings between amplifiers and speakers?

[passenger19]

Sorry in advance.

I'm looking to buy new speakers. The specs on my receiver quote 6 ohms (see below).

Minimum RMS Output Power per channel
[Front, Center, and Surround]
1 kHz, 0.1% THD, 6 Ω .......................... 80 W
1 kHz, 10% THD, 6 Ω ........................... 110 W
[Subwoofer]
50 Hz, 6 Ω .................................... 110 W

Power Supply .................................. AC 120 V, 60 Hz
Power Consumption ............................. 220 W/240 VA​

My goal is to purchase speakers (either a 2.1 or 5.1 system) with RMS (continuous/nominal) ratings that match the RMS ratings of my receiver as closely as possible. My thinking was this would let me squeeze as much volume out of my speakers as possible without risking damage or sacrificing audio quality.

My question is how do I calculate the ratings of speakers when their specs quote something other than 6 ohms (typically 8 ohms)? For example, if I want a stereo system (left/right), and my receiver is rated to output 55 W per speaker at 6 ohms, what wattage should I look for in a speaker that quotes a nominal impedance of 8 ohms? What's the math/rationale?

 

[KenM10759]

Don't concern yourself with that kind of matching thing, at all. First select the speakers which you like best, for whatever reason you like them. It could be you like the sound, the looks, the size, or the cost. And likely a combination of all of those factors. The one thing which can make a big difference in how loud a speaker can get for a given amount of amplifier power is the sensitivity rating of the speaker. Something like typical Klipsch speakers are very efficient and can sound quite loud with very little power. I myself don't care for a loud Klipsch...nor a quiet one for that matter but that's a different discussion. Other speakers are a lot less efficient and need more power, though may actually sound better.

What receiver do you have that is stating a power output for a subwoofer? I suspect your receiver is one that was part of a home-theater-in-box package and may not be happy driving other speakers.

Get speakers you really like, then worry about how you can get the most out of them.

 

[TLS Guy]

Sorry in advance.

I'm looking to buy new speakers. The specs on my receiver quote 6 ohms (see below).

Minimum RMS Output Power per channel
[Front, Center, and Surround]
1 kHz, 0.1% THD, 6 Ω .......................... 80 W
1 kHz, 10% THD, 6 Ω ........................... 110 W
[Subwoofer]
50 Hz, 6 Ω .................................... 110 W

Power Supply .................................. AC 120 V, 60 Hz
Power Consumption ............................. 220 W/240 VA​

My goal is to purchase speakers (either a 2.1 or 5.1 system) with RMS (continuous/nominal) ratings that match the RMS ratings of my receiver as closely as possible. My thinking was this would let me squeeze as much volume out of my speakers as possible without risking damage or sacrificing audio quality.

My question is how do I calculate the ratings of speakers when their specs quote something other than 6 ohms (typically 8 ohms)? For example, if I want a stereo system (left/right), and my receiver is rated to output 55 W per speaker at 6 ohms, what wattage should I look for in a speaker that quotes a nominal impedance of 8 ohms? What's the math/rationale?

The power rating of a speaker means virtually nothing. They are all way optimistic. If you gave any of them their full rated power for more than a few seconds they will all smoke and their voice coils be a burnt offering. ( speakers for high power professional application excepted.)

 

[M Code]

IMHO...
Power handling specs for loudspeakers do matter...
But the pertinent point is the amount of distortion, if the distortion factor is high such as in a compressed MP3 stream and the volume level is high the loudspeaker's motor structure (voice coil, gap clearance) is under high stress.. Also note this is more likley with a low power rated amplifier rarther than a high one...

Just my $0.02...

 

[TLS Guy]

IMHO...
Power handling specs for loudspeakers do matter...
But the pertinent point is the amount of distortion, if the distortion factor is high such as in a compressed MP3 stream and the volume level is high the loudspeaker's motor structure (voice coil, gap clearance) is under high stress.. Also note this is more likley with a low power rated amplifier rarther than a high one...

Just my $0.02...

They should matter, but they don't, as condition of use is never mentioned. What I'm getting is that a power specification of a loudspeaker is totally meanin less, as the dimension of time is never mentioned. In addition the frequency spectrum is never stated or the frequency envelope. I can assure you that any domestic speaker fed 10 watts pr more continuously at 10 or 15 kHz will have a fried tweeter pronto.

So yes, as nearly always stated they do not matter and are meaningless.

 

[lovinthehd]

As was said, the power ratings are more a melting point than anything useful in most cases. If you're going to look at speakers rated at 4 ohms or lower then your avr should also be rated for 4 ohms ideally (it likely would work but might shut down at higher volume levels for self-protection).

It does seem you have a passive subwoofer since your receiver has a powered output for the sub; most subs are active (self-powered with an on-board amp) and only use a pre-amplifier ouput (pre-out) from the receiver (which is all most receivers provide, the htib type sets is where you find the passive subs, i.e. needs external power amp).

Maybe time to look at all your components and consider what you'll be doing with them down the line...

 

[M Code]

They should matter, but they don't, as condition of use is never mentioned. What I'm getting is that a power specification of a loudspeaker is totally meanin less, as the dimension of time is never mentioned. In addition the frequency spectrum is never stated or the frequency envelope. I can assure you that any domestic speaker fed 10 watts pr more continuously at 10 or 15 kHz will have a fried tweeter pronto.

So yes, as nearly always stated they do not matter and are meaningless.

U are correct continuous power connected directly to a tweeter can/will destroy it..
However...
A typical quality hifi loudspeaker does not have a direct, straight-through connection for the tweeter..
Inside is the x-over network is a capacitor that functions to block lower frequencies as well as a varaiable resistor to vary its HF level. So even if a full 10W RMS is piped into the loudspeaker, the actual power that drives the tweeter is much lower, maybe only 2-3W...

Just my $0.02..

 

[highfigh]

They should matter, but they don't, as condition of use is never mentioned. What I'm getting is that a power specification of a loudspeaker is totally meanin less, as the dimension of time is never mentioned. In addition the frequency spectrum is never stated or the frequency envelope. I can assure you that any domestic speaker fed 10 watts pr more continuously at 10 or 15 kHz will have a fried tweeter pronto.

So yes, as nearly always stated they do not matter and are meaningless.

Have you never seen the specs for the speakers used in fixed installation?

http://www.jblpro.com/www/products/installed-sound/control-contractor-series/control-28-1#Specs