Understanding speaker power rating vs sensitivity

[Petrolhead]

Hi

I will be upgrading my system as it is as I want a bit more sound than what I have. I am currently running the Klipsch RP-280F and looking to get the RF-7 iii speakers, but first I would upgrade amplifier setup.

The RF-7 is rated at 250W but with a sensitivity rating at 100dB. I am by no means any expert, but I cannot understand that these speakers would be able to take 250W of power as the volume would be over concert level? From what I learned back in the day, you should always select an amplifier that has more maximum output than speakers.

I want to be able to have the possibility to play the maximum volume, the speakers can output safely.

Amplifier recommendations would be greatly appreciated. Thanks

 

[TLS Guy]

Hi

I will be upgrading my system as it is as I want a bit more sound than what I have. I am currently running the Klipsch RP-280F and looking to get the RF-7 iii speakers, but first I would upgrade amplifier setup.

The RF-7 is rated at 250W but with a sensitivity rating at 100dB. I am by no means any expert, but I cannot understand that these speakers would be able to take 250W of power as the volume would be over concert level? From what I learned back in the day, you should always select an amplifier that has more maximum output than speakers.

I want to be able to have the possibility to play the maximum volume, the speakers can output safely.

Amplifier recommendations would be greatly appreciated. Thanks

A manufacturers speaker power rating is pretty much meaningless. The reason being that it never mentions what really counts, which is how much power and for how long, at what frequencies.
Sensitivity is more meaningful unless it is Klipsch who are well known for embellishing their sensitivity ratings.

Basically every 3db increase in sensitivity is equivalent to doubling your amp power. Bit that will not make it twice as loud as the db. loudness scale is a log scale.

Actually making a speaker that reliably achieves concert levels is a formidable task. As a home designer and builder, this is something you get the feel for.

A woofer has a bigger VC and thicker wire in the VC. But when you buy a completed speaker you have no idea how the VC is designed. On the other hand when buying a driver from a reputable manufacturer like SEAS for instance, then you generally do. So you get a feel for it. A tweeter for instance is going to have thin light wire, and so will not take a lot of power. However with a crossover 2.5KHz or above they don't have to take a lot of power. The huge problem is the mid range, where so many, if not all commercial designs are compromised.
There is an awful lot of power, in a lot of music between 80 Hz and 2.5 KHz and actually 3KHz. Although power is really concentrated in the speech discrimination band, between 350 Hz and 4KHz. If you look at where the power of music is, which I can do in real time on my rig, then you really get a feel for where power resources need to be provided. So the big shortcoming of, I would say most speakers, particularly three ways is deficient power handling in the speech discrimination band.

There is a word of warning about Klipsch speakers here. The crossover to the horn is bang in the middle of the speech discrimination band. This is not only a bad plan as it is right in the middle of the speech discrimination band, but the horn tweeter is taking a lot of power and they do burn out if you use monster amps and give them too much power.

Probably the most important take home of what I am telling you, is the chart I will place below.

This is an image you really need to study carefully. You will note the enormous concentration between 80Hz and 2.5KHz and even a bit above.

I honestly think that few designers of speakers really take that chart to hart. It seem to me that so often they must ignore it wantonly, or out of ignorance.

I will tell you, that you can not design a really good, reliable speaker to deliver concert levels without really taking that chart to heart. It HAS to be a major focus of your design approach. For far too many, it obviously is not.

 

[highfigh]

A manufacturers speaker power rating is pretty much meaningless. The reason being that it never mentions what really counts, which is how much power and for how long, at what frequencies.
Sensitivity is more meaningful unless it is Klipsch who are well known for embellishing their sensitivity ratings.

Basically every 3db increase in sensitivity is equivalent to doubling your amp power. Bit that will not make it twice as loud as the db. loudness scale is a log scale.

Actually making a speaker that reliably achieves concert levels is a formidable task. As a home designer and builder, this is something you get the feel for.

A woofer has a bigger VC and thicker wire in the VC. But when you buy a completed speaker you have no idea how the VC is designed. On the other hand when buying a driver from a reputable manufacturer like SEAS for instance, then you generally do. So you get a feel for it. A tweeter for instance is going to have thin light wire, and so will not take a lot of power. However with a crossover 2.5KHz or above they don't have to take a lot of power. The huge problem is the mid range, where so many, if not all commercial designs are compromised.
There is an awful lot of power, in a lot of music between 80 Hz and 2.5 KHz and actually 3KHz. Although power is really concentrated in the speech discrimination band, between 350 Hz and 4KHz. If you look at where the power of music is, which I can do in real time on my rig, then you really get a feel for where power resources need to be provided. So the big shortcoming of, I would say most speakers, particularly three ways is deficient power handling in the speech discrimination band.

There is a word of warning about Klipsch speakers here. The crossover to the horn is bang in the middle of the speech discrimination band. This is not only a bad plan as it is right in the middle of the speech discrimination band, but the horn tweeter is taking a lot of power and they do burn out if you use monster amps and give them too much power.

Probably the most important take home of what I am telling you, is the chart I will place below.

This is an image you really need to study carefully. You will note the enormous concentration between 80Hz and 2.5KHz and even a bit above.

I honestly think that few designers of speakers really take that chart to hart. It seem to me that so often they must ignore it wantonly, or out of ignorance.

I will tell you, that you can not design a really good, reliable speaker to deliver concert levels without really taking that char to heart. It HAS to be a major focus of your design approach. For far too many, it obviously is not.

Consumer speakers don't usually show a real world power survival rating because of the marketing department who, as we know, don't care about some details- they're a bit like a Social Media version where facts don't matter. Pro drivers are rated, in specifics- power/voltage input, type of signal and duration are shown because they're intended to be used for designing systems that are durable, dependable and the performance needs to meet the requirements, not get a good review in an ad revenue-driven magazine.

I have seen a chart with the info from the top, but never with the descriptives at the bottom- that should be shown to EVERYONE who works in live sound, so they can have a clue about what they need to do. The pros usually know, but the 'friend of the band' mixers don't.

I was at a club to see a band and the (un)'sound guy' would twiddle some of the controls, walk around the room, return to twiddle more knobs and walk the room. Having mixed in various rooms, I asked "Have you ever used an RTA?" and he answered with "I use my ears". I then responded with "Again, have you ever used an RTA? It really makes this much easier". He had been messing with the mixer and effects, then he started tweaking the FOH equalizers and I told him that he might want to leave those alone. He gave me that "What do you know?" look and carried on creating some of the worst sound I have heard.

Later, I told him about the graffiti I had seen with "E=MC²±3dB"- he said "I have no idea what that means".

 

[ski2xblack]

Excellent info from TLS.

When it comes to "understanding speaker power rating vs. sensitivity" with Klipsch, you must take into account that Klipsch plays fast and loose with their sensitivity ratings. For example, they rate the RF-7 at 100db/w/m, while their actual measured sensitivity by third party reviewers shows sensitivity to be a hair shy of 93 db/2.83v/m. Similarly, Klipsch rates the La Scala at 104, actual sensitivity measured at 101. Your current speaker's sensitivity is probably about 90 db/w.

Power ratings are a bit useless since, as the good Doc pointed out, there is no specified time duration for which they can withstand that power level. At best, the power rating is roughly a failure point, the power levels where it's inadvisable to flog the speaker any harder. If achieving your desired listening levels requires doing that, you should instead move to a more sensitive speaker.

The RF-7 are marginally more sensitive than your current model, so upgrading your amp may not be necessary if you only want "a bit more sound" as you stated. If you want live concert type loudness, you really need a speaker capable of that, like the La Scalas. And since 'Scalas are legit +10db higher in sensitivity, you wouldn't need a more powerful amp with those either.

Oh, just a word to the wise: hearing damage is cumulative and irreversible. Trying to replicate rock concert spls in your house can and will damage your hearing. Plenty of old Klipsch farts suffer tinnitus.

 

[Eppie]

Hi

I will be upgrading my system as it is as I want a bit more sound than what I have. I am currently running the Klipsch RP-280F and looking to get the RF-7 iii speakers, but first I would upgrade amplifier setup.

The RF-7 is rated at 250W but with a sensitivity rating at 100dB. I am by no means any expert, but I cannot understand that these speakers would be able to take 250W of power as the volume would be over concert level? From what I learned back in the day, you should always select an amplifier that has more maximum output than speakers.

I want to be able to have the possibility to play the maximum volume, the speakers can output safely.

Amplifier recommendations would be greatly appreciated. Thanks

It is common for people to make the mistake of thinking that they have to match the max power handling of their speaker. That rating is simply stating how much power the speaker can handle before being damaged. When considering amplifier power, you need to look at several things: speaker sensitivity (or efficiency), sitting distance and your target volume level in decibels. Members like to recommend using an on-line SPL calculator.

Lets take a more realistic speaker sensitivity rating of 92dB, use an 80W amplifier and a 12 foot seating distance. That produces 105dB at the seating position which is considered more than very loud and is safe for only 1 hour. That's continuous volume, though, and most music is not the same volume through out, so the times are general guidelines. Also, music does not push the amplifier to constant maximum output. Power requirement is generally much less with occasional peaks nearing max power.

The point being, don't rush out to upgrade your amp when purchasing very sensitive speakers. Most modern AVRs can easily drive those speakers to high volume. Try the new speakers first and see how they perform. You want to make sure that you are not driving the speakers or amplifier into distortion, as that can damage the equipment. You can purchase an SPL meter or try an SPL meter app on your phone to measure sound levels.

 

[Verdinut]

It's not necessary to purchase an SPL meter to determine the possible peak SPL on a system. Only using this:

Peak SPL Calculator

Also, this other calculation site is even more detailed: https://www.crownaudio.com/en-US/tools/calculators

 

[-Jim-]

Here's my 2 Bits more. (The Gents above have done a good job putting @Petrolhead on the right path.) The real issue is specs published by OEMs are not held to any enforceable standard, like say IEEE, so what they give out wanders all over the place; and is often incomplete at best - and sometimes outright deceptive IMHO.

I suggest you look at speakers that fit your budget first, as there's little point in digging deep into unobtanium. Don't restrict yourself to brands at this point, look outside of the box. Then look for independent reviews with real measurements and not the Bullsh*t ones some folks spew on YouTube full of terms like "chocolatety" or "buttery" that are nonsense. Then try to listen to your chosen few if at all possible. In your room where you plan to keep them is best, as the room and speaker placement makes a significant impact on what you hear.

Remember it's all about what you like, and hopefully is something you can live with (and no WAF battles ). This is supposed to be Fun and enjoyable!

 

[Petrolhead]

Thanks a lot for your input everyone! And you TLS Guy for a very educational post. This helps me a lot.

I think people here are under the impression that I listen to a higher SPL than what is the reality. I think I am not able to go much beyond 100dB and then I have absolutely no headroom, and I don’t want to damage anything. 105dB would be sufficient and I do not listen at this level for prolonged duration. The room is quite large and with a lot of height under the ceiling. I am starting to be confident that my 80W Denon X1300W is my primary problem, as increasing speaker crossover , easing power consumtion seems to let them play louder.

I have not locked in to any particular brands and is completely flexible.

But just so I understand. If we take the RF 7 just for the sake of the discussion. And I want to select and amp and I do not want to be able to run it in to hard clipping, how do I figure out the power rating I need? I can’t use the 250W rating obviously (which as a consumer I think makes the whole number misleading). The sensitivity rating is wrong, and there is no maximum safe SPL rating either.

 

[TLS Guy]

Thanks a lot for your input everyone! And you TLS Guy for a very educational post. This helps me a lot.

I think people here are under the impression that I listen to a higher SPL than what is the reality. I think I am not able to go much beyond 100dB and then I have absolutely no headroom, and I don’t want to damage anything. 105dB would be sufficient and I do not listen at this level for prolonged duration. The room is quite large and with a lot of height under the ceiling. I am starting to be confident that my 80W Denon X1300W is my primary problem, as increasing speaker crossover , easing power consumtion seems to let them play louder.

I have not locked in to any particular brands and is completely flexible.

But just so I understand. If we take the RF 7 just for the sake of the discussion. And I want to select and amp and I do not want to be able to run it in to hard clipping, how do I figure out the power rating I need? I can’t use the 250W rating obviously (which as a consumer I think makes the whole number misleading). The sensitivity rating is wrong, and there is no maximum safe SPL rating either.

You won't do it with those speakers. How do you know that you are achieving 100 db. at the listening position? Did you take reliable measurements?
Those speakers crossover at 1.3KHz. If you significantly increase the power you WILL blow the tweeters, no doubt about it.

But lets assume your amp starts to clip at 100 db. at your listening position. So to get to 103 db. would require 160 watts per channel. To get to 105db. would require a 250 watt per channel amp.

So you will be in for massive expense for a start. You certainly will need new speakers and a mega amp.

I listen to classical music, orchestras, large choral works, organs operas and other solo recitals.

Now some of those works there is a massive orchestra and choirs, with a 1000 performers on stage at times, with a huge pipe organ thrown in for good measure. They do not play loud anything like all the time. Often there is just a solo flute or clarinet for instance

However, I have designed and built a reference system that will produce those concert level peaks when required and never exceeds the limits of the system.

However, the front three speakers use five power amps and active electronic crossovers are used. The system is 7.2.4 Atmos and uses a total of nine two channel power amps, providing 3,200 watts of power.
That is all because increase in spl. is a logarithmic curve and NOT a linear one in terms of the power requirements.

If you listened to pop/rock etc. a system like this would be a very bad idea, because the dynamic range of the program is relatively small. For my program the dynamic range is huge, especially with modern digital recording and media. The majority of it is relatively low down the dynamic scale. I will admit though, when the power is called for it is thrilling.

So the way you describe your room, you are going to need powerful well designed speakers which will be at the higher end of the price scale and and the power amps to drive them. It is not a simple task of just connecting up a big power amp.

 

[highfigh]

(and no WAF battles ).

 

[Petrolhead]

You won't do it with those speakers. How do you know that you are achieving 100 db. at the listening position? Did you take reliable measurements?
Those speakers crossover at 1.3KHz. If you significantly increase the power you WILL blow the tweeters, no doubt about it.

But lets assume your amp starts to clip at 100 db. at your listening position. So to get to 103 db. would require 160 watts per channel. To get to 105db. would require a 250 watt per channel amp.

So you will be in for massive expense for a start. You certainly will need new speakers and a mega amp.

I listen to classical music, orchestras, large choral works, organs operas and other solo recitals.

Now some of those works there is a massive orchestra and choirs, with a 1000 performers on stage at times, with a huge pipe organ thrown in for good measure. They do not play loud anything like all the time. Often there is just a solo flute or clarinet for instance

However, I have designed and built a reference system that will produce those concert level peaks when required and never exceeds the limits of the system.

However, the front three speakers use five power amps and active electronic crossovers are used. The system is 7.2.4 Atmos and uses a total of nine two channel power amps, providing 3,200 watts of power.
That is all because increase in spl. is a logarithmic curve and NOT a linear one in terms of the power requirements.

If you listened to pop/rock etc. a system like this would be a very bad idea, because the dynamic range of the program is relatively small. For my program the dynamic range is huge, especially with modern digital recording and media. The majority of it is relatively low down the dynamic scale. I will admit though, when the power is called for it is thrilling.

So the way you describe your room, you are going to need powerful well designed speakers which will be at the higher end of the price scale and and the power amps to drive them. It is not a simple task of just connecting up a big power amp.

Measurement was taken at 3ft/1m as per -Jim- instructions not listening position.

Sorry for being a novice, I just want to be able to select the correct power for my amp at a reasonable cost

 

[highfigh]

Measurement was taken at 3ft/1m as per -Jim- instructions not listening position.

Sorry for being a novice, I just want to be able to select the correct power for my amp at a reasonable cost

Big numbers impress people, whether they're accurate, or not.

The reason speakers need to be able to handle higher power is due to the cause of failure- heat. Power is a calculated value, based on Voltage and Resistance (speakers are measured for Impedance because resistance changes with frequency when using Alternating Current) and current creates heat in conductors. If the power reaching speakers is high but only for a short time, the effect isn't as great as if it lasts a long time. When a conductor's temperature increases, the resistance increases, which can become apparent if the power is very high, over a long period. If it continues, the level can decrease, measurably but that may be a moot point because our ears don't perceive sound as well if they have been bombarded for too long- this is called 'hearing threshold shift' and if it occurs too frequently and for too long, it can become permanent.

I would consider the length of time you'll listen at high levels- if you plan or expect to use high SPL often and if the speakers can actually handle 250W continuously for long periods of time, more power will be necessary because amplifiers have limits to their power output headroom- at low levels, a 200W/channel amp may be able to cruise along and produce peaks of more than 200W and the sound will be very dynamic but if the amp is producing more than 100W continuously and the music demands the same peak as before, the difference won't be as apparent and the amplifier may not be able to produce the signal peaks without distorting. This is important because the distortion isn't always audible and since it creates frequencies that are higher than the audio signal, it can damage the speakers, mainly the tweeters.

If you download an audio app to your phone, you should be able to measure SPL (Sound Pressure Level) and if you find that it's not higher than about 95dB on a regular basis, you probably don't need a power amp that's rated higher than 100W. This all depends on the music/program material- if the music has very little dynamic range, that places less demand than high dynamic range program material.

Think of headroom in literal terms- if you're jumping on a bed in a room with the ceiling at 8', it's easy to hit your head but you won't, with a higher ceiling. The height is equivalent to the signal level.

 

[-Jim-]

Measurement was taken at 3ft/1m as per -Jim- instructions not listening position.

Sorry for being a novice, I just want to be able to select the correct power for my amp at a reasonable cost

Mmm... I don't remember advising you to take SPL at 3ft/1m. (It certainly isn't in this thread.) Please advise.

Perhaps it best to give the folks here all the details, room dimensions, listening positions, and preferred speaker placement on a sketch; as well as equipment make and model numbers so the advice going forward will be of practical use to you.

You said "105dB would be sufficient and I do not listen at this level for prolonged duration." I wonder how you determined that number. A SPL meter on another system?

Like others have cautioned you here, damaging volume levels to your ears are not repairable, so proceed with caution when listening at high levels. You can use "Deadphones" or ear plugs while testing. Always protect yourself and those who will be using the system.

 

[TLS Guy]

Measurement was taken at 3ft/1m as per -Jim- instructions not listening position.

Sorry for being a novice, I just want to be able to select the correct power for my amp at a reasonable cost

I suspect you are chasing rainbows. Those are high efficiency speakers, so upping amp power will probably result in a blown tweeter more likely that not. Those speakers are not a good design in my view. Crossing at 1.3KHz has two strikes against it. It is right in the major midrange power band and also right on the middle of the speech discrimination band which is poor design in my view.

So an spl. reading at your usual listening position would be very helpful. My hunch is that to do what you are asking will more likely than not require different speakers and amplification.

Getting high spl. levels at the listening position is not an easy engineering task. In addition if it is rock, pop and electronic music you are listening it is most unwise. Having the power to listen at concert levels to the finale of Mahler's symphony No.2, the Resurrection is one thing, blasting rock music quite another. Hearing damage follows a spl./time curve.

Clean high powered systems can not be engineered on the cheap.

 

[Petrolhead]

Mmm... I don't remember advising you to take SPL at 3ft/1m. (It certainly isn't in this thread.) Please advise.

Perhaps it best to give the folks here all the details, room dimensions, listening positions, and preferred speaker placement on a sketch; as well as equipment make and model numbers so the advice going forward will be of practical use to you.

You said "105dB would be sufficient and I do not listen at this level for prolonged duration." I wonder how you determined that number. A SPL meter on another system?

Like others have cautioned you here, damaging volume levels to your ears are not repairable, so proceed with caution when listening at high levels. You can use "Deadphones" or ear plugs while testing. Always protect yourself and those who will be using the system.

Yes it was from another thread.

Get a Sound Meter and see what the level is 3 feet away from the speaker just as it starts to distort. If you don't have a meter, use a free App on a Cell phone. Please advise the level you obtain and we can go from there.

I came to the number 105 from my own speakers as they can do it but it is right at the limit of where the sound distort. So therefor I have concluded I want a little bigger system so I can achieve it without pushing my equipment.

Thanks a lot for your input so far.

I am using ear protection when testing.

I don’t know the SPL at my listening position but it is of course less.

The room is about 9 x 8 meter and high ceiling. The equipment unfortunately needs to be located towards one corner.

 

[TLS Guy]

Yes it was from another thread.



I came to the number 105 from my own speakers as they can do it but it is right at the limit of where the sound distort. So therefor I have concluded I want a little bigger system so I can achieve it without pushing my equipment.

Thanks a lot for your input so far.

I am using ear protection when testing.

I don’t know the SPL at my listening position but it is of course less.

The room is about 9 x 8 meter and high ceiling. The equipment unfortunately needs to be located towards one corner.

That is not an especially large room. I would have thought those speakers would get loud enough. If you must have more, then you need more capable speakers and more powerful amplification. Keep front of mind that loudness is a log function and NOT linear, so more power takes more resources from amp to speakers. Much more than I bet you imagined. Every 3 db. requires a doubling of amp and speaker resources. That is why truly clean powered rigs are a very big budget item. Even when you build it yourself it does not come cheap.