Help a newbie match speakers to amp power

[hifidadbod]

Hi all,

Hoping I can lean on your expertise in getting a better understanding of power and driving my speakers. I really don't understand wattage, power, voltage, and the variables that drive a speaker. I have been looking for an amp to drive my current setup (KEF R3 Meta, Eversolo DMP-A8) and I'm leaning toward the Apollon NCX500 ST. It seems like it is way overpowered for the speakers (I have read that you can't overpower them, the danger is under powering), but I was hoping to get some clarity on that and see if you all think that is a good match.

Thanks for the help. Really appreciate it.

Hifidadbod

 

[nemanja_t]

Nice choice for Kef R3 Meta, enjoy your collection.
Clipping & Underpower

 

[staticV3]

Hi @hifidadbod! Welcome to ASR.

KEF publish power recommendations for each model, so that can give you a first clue about what kind of Amp you should be looking at:


Beyond that, you could measure your actual playback levels with an SPL meter, a calibrated mic like the UMIK-1, or an iPhone, then use a calculator like this to derive how much power you actually need.

A multimeter could also be used, along with test tones.

By saving some money on an Amp with appropriate power, that you could then spend on room treatment or room correction, you may achieve higher playback fidelity.

 

[DVDdoug]

I really don't understand wattage, power, voltage, and the variables that drive a speaker.

If your amp is rated to drive the speaker impedance you just need to know the wattage. Higher impedance speakers are OK, lower impedance speakers can put too much strain on the amplifier. Low impedance "draws" more current so you get more power if the voltage remains the same. (Your speakers drop to 3.2 Ohms somewhere in the frequency range but that's OK if the amplifier is rated for 4-Ohms.)

Speaker power ratings are "complicated". A speaker rated for 100W is supposed to be safe with a 100W amplifier that's hitting 100W (without clipping) on the program peaks. As you push it into clipping, the peaks are clipped/limited but the average power goes up and you can burn-out a driver. With a 75W amplifier that's clipping you can also get too much average power and burn-out the speaker.

Or you can usually fry a 100W speaker with constant 100W test tones, especially the tweeter which can't take as much power as the woofer.

Of course, some program material is more dynamic than others so the average is unpredictable.

In the real world speakers usually only get damaged when a drunk person or a teenager is allowed to adjust the volume... Even if your amplifier is "over-powered" for your speakers, you're usually OK.

 

[JeremyFife]

Nice system

It will work nicely - but just don't turn the volume up all the way and leave it there. Possible problem if small children or drunk adults can reach but nothing to worry about in real life.
The sound will be uncomfortably loud well before then and, if you go really extreme, the speakers will start to sound terrible and you won't want to listen that loud!

Things to avoid: stressing a low powered amplifier so that it 'clips' ... nothing to do with being underpowered but more about driving an amplifier out of its design specification. Not an issue normally.
When an amplifier is working normally, a watt is just a watt - high powered / low powered is all the same.

 

[hifidadbod]

Hi @hifidadbod! Welcome to ASR.

KEF publish power recommendations for each model, so that can give you a first clue about what kind of Amp you should be looking at:
View attachment 400750

Beyond that, you could measure your actual playback levels with an SPL meter, a calibrated mic like the UMIK-1, or an iPhone, then use a calculator like this to derive how much power you actually need.

A multimeter could also be used, along with test tones.

By saving some money on an Amp with appropriate power, that you could then spend on room treatment or room correction, you may achieve higher playback fidelity.

Thanks for all the incredibly helpful responses.

@staticV3 this is exactly where I get confused. The KEF recommendation is up to 180W. The Apollon is 600 watts at both 4Ohm and 2Ohm, and 380 watts at 8Ohm. Folks here seem to say that is fine. There is a delta somewhere!

 

[hifidadbod]

Nice choice for Kef R3 Meta, enjoy your collection.
Clipping & Underpower

Thanks, this is a helpful link.

 

[hifidadbod]

If your amp is rated to drive the speaker impedance you just need to know the wattage. Higher impedance speakers are OK, lower impedance speakers can put too much strain on the amplifier. Low impedance "draws" more current so you get more power if the voltage remains the same. (Your speakers drop to 3.2 Ohms somewhere in the frequency range but that's OK if the amplifier is rated for 4-Ohms.)

Speaker power ratings are "complicated". A speaker rated for 100W is supposed to be safe with a 100W amplifier that's hitting 100W (without clipping) on the program peaks. As you push it into clipping, the peaks are clipped/limited but the average power goes up and you can burn-out a driver. With a 75W amplifier that's clipping you can also get too much average power and burn-out the speaker.

Or you can usually fry a 100W speaker with constant 100W test tones, especially the tweeter which can't take as much power as the woofer.

Of course, some program material is more dynamic than others so the average is unpredictable.

In the real world speakers usually only get damaged when a drunk person or a teenager is allowed to adjust the volume... Even if your amplifier is "over-powered" for your speakers, you're usually OK.

I don't drink, but I've got young kids! I like on the Eversolo (and I imagine most newer products) I can really easily set the volume at a particular limit.

 

[JeremyFife]

Car analogies are terrible, mostly useless ... so here goes

Your car can probably exceed the speed limit, by a fair bit.
You don't drive like a nutter, you stay at reasonably safe speeds and you can enjoy driving.
If you actually floor the accelerator then driving becomes scary quite fast and you back off to a more sane speed before something breaks or you crash. You just don't drive like that.
You have a much smaller car, tiny engine, fine for short trips in town - out on the main roads you try to drive faster - the car complains, the engine is screaming and everything is rattling ... it's not nice and you slow down.

Driving sensibly, in the comfort zone for both car and driver and both cars are just fine

 

[hifidadbod]

Car analogies are terrible, mostly useless ... so here goes

Your car can probably exceed the speed limit, by a fair bit.
You don't drive like a nutter, you stay at reasonably safe speeds and you can enjoy driving.
If you actually floor the accelerator then driving becomes scary quite fast and you back off to a more sane speed before something breaks or you crash. You just don't drive like that.
You have a much smaller car, tiny engine, fine for short trips in town - out on the main roads you try to drive faster - the car complains, the engine is screaming and everything is rattling ... it's not nice and you slow down.

Driving sensibly, in the comfort zone for both car and driver and both cars are just fine

This is great. Helpful analogy. Thanks.

 

[MaxwellsEq]

@staticV3 this is exactly where I get confused. The KEF recommendation is up to 180W. The Apollon is 600 watts at both 4Ohm and 2Ohm, and 380 watts at 8Ohm. Folks here seem to say that is fine. There is a delta somewhere

You could use a 6 million Watt amplifier and still be OK. How many Watts enter your speakers is totally controlled by your volume control.

Speaker manufacturers' guidance is not terribly helpful. They aren't a strict limit, just a guidance on what the speaker can tolerate at the upper end. In most domestic listening conditions with many speakers you will probably run the speakers at about 5W. If you genuinely fed them 180W you probably wouldn't stay in the room long without ear defenders.

 

[hifidadbod]

You could use a 6 million Watt amplifier and still be OK. How many Watts enter your speakers is totally controlled by your volume control.

Speaker manufacturers' guidance is not terribly helpful. They aren't a strict limit, just a guidance on what the speaker can tolerate at the upper end. In most domestic listening conditions with many speakers you will probably run the speakers at about 5W. If you genuinely fed them 180W you probably wouldn't stay in the room long without ear defenders.

Thanks, @MaxwellsEq. So then what is the upside of going with a 400W amp like the Apollon over something that hits 180W or 185W and peaks there?

 

[coonmanx]

Thanks, @MaxwellsEq. So then what is the upside of going with a 400W amp like the Apollon over something that hits 180W or 185W and peaks there?

There really is no advantage to one over the other if they both can do what you want them to do. The amp with more power will give you more headroom, but if you don't use it then it is meaningless. I used to think that the NAD amps were great because they advertised that their 40 watt amps could do peaks of 100 watts if necessary (3 dB of headroom). But I never really cranked it up like that and now that I no longer have that NAD I am using an MCS 3842 that is also basically a 40 watt amp with less headroom. The MCS does the job for me and I really don't crank the piss out of anything these days. So in the end it just depends on how you use your system.

If you get a dB meter you may find that you don't need a whole lot of power. If I crank my system past one watt it gets quite loud. So I rarely would even get close to that 40 watts being needed. I could probably get along with a 5 watt amplifier on most days...

 

[MaxwellsEq]

Thanks, @MaxwellsEq. So then what is the upside of going with a 400W amp like the Apollon over something that hits 180W or 185W and peaks there?

There's no obvious upside in a 400W vs 185W amplifier in these circumstances. Firstly, given the same gain, 400W will only be slightly louder than 185W! Doubling power does NOT double volume. A 60W, 80W and 100W will all be roughly as loud as each other!

Why have a bit more power? There are some people who believe peak, fast transients need a lot more instantaneous power to replicate the real energy of the sound than is immediately obvious from average power usage, even at lower volumes.

 

[coonmanx]

That being said, if you like the look of a certain amp and it ticks all of the boxes for features that you want and you can afford it...

Then by all means get it. It's your money and your choice.

 

[JustJones]

So then what is the upside of going with a 400W amp like the Apollon over something that hits 180W or 185W and peaks there?

The upside is if you ever change speakers to something a little harder to drive or move to a larger room and sit farther away you're probably not going to need to get a different amp.

 

[Whiskey the Cat]

Hi all,

Hoping I can lean on your expertise in getting a better understanding of power and driving my speakers. I really don't understand wattage, power, voltage, and the variables that drive a speaker. I have been looking for an amp to drive my current setup (KEF R3 Meta, Eversolo DMP-A8) and I'm leaning toward the Apollon NCX500 ST. It seems like it is way overpowered for the speakers (I have read that you can't overpower them, the danger is under powering), but I was hoping to get some clarity on that and see if you all think that is a good match.

Thanks for the help. Really appreciate it.

Hifidadbod

That’s an excellent system you are getting together. I have the KEF R3 Metas and an Eversolo DMP-A6 Master (not currently hooked up in the same system) and I considered the Apollon, but eventually went with the Benchmark AHB2. You can rest assured that you are not going to do any damage in any normal circumstances. If anything sounds off you can consider other factors – the recording itself, the room furniture, and speaker placement. The equipment will not be at fault.

 

[hifidadbod]

That’s an excellent system you are getting together. I have the KEF R3 Metas and an Eversolo DMP-A6 Master (not currently hooked up in the same system) and I considered the Apollon, but eventually went with the Benchmark AHB2. You can rest assured that you are not going to do any damage in any normal circumstances. If anything sounds off you can consider other factors – the recording itself, the room furniture, and speaker placement. The equipment will not be at fault.

Thanks! Appreciate the help. Was planning to switch the Eversolo out for a minidsp shd. I kind of want room correction integrated in the easiest and “best” way possible. Is that dumb and should I stick with Eversolo?

I’m actually changing up one thing: swapping the Eversolo for a minidsp shd. I want room correction integrated in the easiest and “best” way. Is that a crazy switch?

 

[Whiskey the Cat]

Not something I have any experience of, so I can’t help there.

 

[RayDunzl]

The KEF recommendation is up to 180W. The Apollon is 600 watts at both 4Ohm and 2Ohm, and 380 watts at 8Ohm. Folks here seem to say that is fine. There is a delta somewhere!

The difference in sound pressure level between 180 and 360 watts would be about 3dB.

That would be at a rather loud level, going from 110 to 113 dB.

Your speaker is rated 87dB at 1W, 110dB at 180W

Here is a somewhat crude chart showing Sound Level in Decibels (blue line) plotted against Watts and Amperes and Volts from the amplifier for an 87dB sensitivity speaker:

Less than a watt will cover most of your quiet listening.

But notice how the power requirement escalates with increasing volume.

That's why people have "more power" on tap.