Crown amplifier power calculator question

[0800 Dub]

https://www.crownaudio.com/en-US/tools/calculators#amp_power_required

The calculator gives the required amplifier power in watts, but how does this relate to amplifier power ratings? As I understand it the Required Amplifier Power figure should be used to find an amplifier with that amount of power at the impedance that matches the impedance rating of one's speakers, but should one be looking at amplifier power ratings done at 1kHz THD=1%, or 20Hz-20kHz with a much lower THD %, or something else entirely?

 

[SimpleTheater]

https://www.crownaudio.com/en-US/tools/calculators#amp_power_required

The calculator gives the required amplifier power in watts, but how does this relate to amplifier power ratings? As I understand it the Required Amplifier Power figure should be used to find an amplifier with that amount of power at the impedance that matches the impedance rating of one's speakers, but should one be looking at a power rating done at 1kHz THD=1%, or 20Hz-20kHz with a much lower THD %, or something else entirely?

Since most speakers are rated at 1kHz, 1 watt, this calculator works well. 20-20k would create too many variables because speaker resistance changes throughout the frequency range, and no two are the same.

 

[0800 Dub]

With all due respect, that doesn't answer my question...

I'm trying to find out which wattage ratings I should be looking at on amplifier spec sheets. Amplifier spec sheets typically have a couple of different ratings that have been derived in different ways. Take this spec sheet from a Hypex implementation for example:

Or this Yamaha amplifier for example:

The calculator just gives a figure in watts, which doesn't give me any indication of which wattage figure to be looking at on spec sheets (other than looking at the figure measured at the impedance closest to the impedance of my speakers).

Wait...

Since most speakers are rated at 1kHz, 1 watt, this calculator works well. 20-20k would create too many variables because speaker resistance changes throughout the frequency range, and no two are the same.

Are you saying the wattage figure from the calculator is at 1kHZ?

 

[SimpleTheater]

Are you saying the wattage figure from the calculator is at 1kHZ?

Yes. There is no way, without putting a specific speakers impedance rating for the entire frequency range and also the amplifiers own specs to determine the correct values, so they use 1 KHz. If you have the money, just get a Benchmark AHB2 and you’ll have no worries, otherwise a best estimate is your best tool.

 

[pjug]

https://www.crownaudio.com/en-US/tools/calculators#amp_power_required

The calculator gives the required amplifier power in watts, but how does this relate to amplifier power ratings? As I understand it the Required Amplifier Power figure should be used to find an amplifier with that amount of power at the impedance that matches the impedance rating of one's speakers, but should one be looking at amplifier power ratings done at 1kHz THD=1%, or 20Hz-20kHz with a much lower THD %, or something else entirely?

What do you already have? It seems tough to start from scratch and use a calculator to figure out how much power. The peak SPL depends so much on what you listen to and how loud. You can't go too wrong buying more power than you need, though.

That calculator is for just one speaker? 2 speakers gives 3dB more SPL. Here is another calculator with more parameters.
https://myhometheater.homestead.com/splcalculator.html

 

[Chrispy]

The Crown calculator is more a pro tool for large venues or outdoors, that homestead version can account for room influences....

 

[DVDdoug]

I guess there's no easy answer. If you want to be conservative just assume the lower power numbers. But realistically, music is dynamic so you can usually get more power on short term peaks. And with this calculation/estimation you are looking for the minimum necessary power so it doesn't hurt to get an amplifier with more power... as long as you don't burn-out your speakers. If you think you're going to be close to frying your speakers you should probably get speakers that can handle more power (or more efficient speakers).

The Hypex specs seem "unusual" to me... The Yamaha shows more power at 4 Ohms which is pretty common. The "High dynamic power" shows some headroom for peaks but with no distortion specified it's not that helpful. The 1% distortion usually means your at or near clipping and distortion will go-up greatly if you go higher and the distortion is usually lower when you go down a little in power.

These are approximations, and in most home-situations you don't really know exactly what SPL level you need, and as you may know, doubling of the power is only +3dB (and cutting the power in half is only -3dB). So I'd just use the calculations as general guidelines or as a sanity check and don't try to get exactly the required (minimum) power.

 

[Chrispy]

Plus I suppose you'd look up the power at the distortion levels you can tolerate?

 

[MrPeabody]

You are concerned with two things: (1.) making certain that the amp you buy will not overheat when it supplies your speakers with the current they will draw when producing the sound power you require, and (2.) making certain that the amp you buy will not clip when it supplies your speakers with the voltage they require to produce the sound power that you require.

As for the first concern ...

I = (Power/Z)^(1/2)

When the current drawn by your speakers at the power you require is the same as the current implied by the amplifier specification (at the amplifier's rated power), this will be true:

power_required / my_speaker_impedance = rated_power / impedance_used_in_the_spec

rearranged:

power_required / rated_power = my_speaker_impedance / impedance_used_in_the_spec

For example, if the ratio on the right side of this equation is 1/2 (i.e., the impedance used in the amplifier spec is twice greater than the impedance of your speakers), then since the ratio on the left side will also be 1/2, this means that in this case the rated power of the amplifier will need to be twice as great as the power you require.

As for the second concern ...

V = (Z x Power)^(1/2)

When the voltage required by your speakers to produce the sound power you require is the same as the voltage implied by the amplifier specification (at the amplifier's rated power), this will be true:

power_required x my_speaker_impedance = rated_power x impedance_used_in_the_spec

rearranged:

power_required / rated_power = impedance_used_in_the_spec / my_speaker_impedance

For example, if the impedance of your speaker is twice greater than the impedance used in the amplifier spec, the rated power of the amplifier will need to be twice greater than the power you require.


Except for when the nominal impedance of your speaker is the same as the impedance used in the amplifier spec, exactly one of the two potential concerns will apply. You don't need to be concerned with which concern is the one that implies. Divide the smaller impedance into the larger impedance. Multiply this by the power you require, to obtain the implied amplifier power rating.

This is all very theoretical. If the calculator you used took into account the sensitivity of your speakers and the impedance of your speakers, and if it also factored in the "crest factor" (to compensate for the difference between the nominal power rating and the instantaneous power), it stands a chance of being useful. But I would still go more by my experience. If you've used an amplifier rated for 100 Watt per channel and you never had any issue with overheating or with distortion due to voltage clipping (or with not being able to turn it up higher than the volume control will permit), then you likely do not need more power than that, especially if the speaker sensitivity and impedance have not changed, but probably even if the speaker sensitivity and impedance have changed. Many audiophiles assume that their system will sound better if they replace the amplifier with a more powerful amplifier. Of course there will be specific cases where this will occur, but it is not true in any general sense that using a more powerful amplifier will improve the sound of your system. If the old amp sounded like trash because it was clipping, a new amp may fix that, or if the old amp got hot and shut down, a new amp may fix that, or if the old amp wasn't loud enough even when turned up all the way, a new amp may fix that. It is unlikely that the new amp will sound any different than the old amp sounded when the old amp wasn't turned up to the point where it sounded like trash because it was clipping.

 

[0800 Dub]

Yes. There is no way, without putting a specific speakers impedance rating for the entire frequency range and also the amplifiers own specs to determine the correct values, so they use 1 KHz.

I see. Maybe it's obvious to more techcnically-minded folks, but to me it wasn't. I reckon they should state that it's at 1kHz just to be 100% clear for everybody.

If you have the money, just get a Benchmark AHB2 and you’ll have no worries, otherwise a best estimate is your best tool.

Unfortunately I don't have enough money for a Benchmark AHB2.

What do you already have? It seems tough to start from scratch and use a calculator to figure out how much power. The peak SPL depends so much on what you listen to and how loud. You can't go too wrong buying more power than you need, though.

I have a Yamaha A-S301. I would like to change amplifier for two reasons: 1) I would like an amplifier with a smaller physical footprint 2) I thought it possible my speakers might benefit from an amplifier with more power to fully reproduce all the dynamics in the music I listen to. Even if no. 2 isn't the case, no. 1 still applies. I have a USB audio interface with a volume knob and I recently acquired a passive preamp for my other sources so I'm pretty much exclusively looking at power amplifiers to get better value-for-money perfomance-wise. Class D seems to be the way to go for small physical footprint and Hypex seems to have the best performance in the affordable segment of the market, so I'm considering Hypex implementations by Audiophonics and Buckeye. The sticking point is the power. I don't want to needlessly over-spend, or get too little power because I was trying to save money. It's basically a toss-up between the NC502MP and the NC252MP. My current temptation is err on the side of caution sound-wise and go for more power, pending more investigation/thought/enlightening thread responses. *thinking emoji*

When I entered my values into the Crown calculator, I got a figure just below 500W. Although, I don't know what SPL I require so I just entered the SPL Erin entered in his video about this calculator - 85. I put amplifier headroom to 20 because I figured I sometimes listen to classical music and I have a rock album that has a quoted DR of 20 for one track so I figured maybe having plenty of headroom would be a good thing. It could also be overkill though, as I read somewhere that clipping that lasts for a very short duration is not really audible.

That calculator is for just one speaker? 2 speakers gives 3dB more SPL. Here is another calculator with more parameters.
https://myhometheater.homestead.com/splcalculator.html

Thanks. How come this calculator doesn't have an "amplifier headroom" field like the Crown calculator?

I guess there's no easy answer. If you want to be conservative just assume the lower power numbers. But realistically, music is dynamic so you can usually get more power on short term peaks. And with this calculation/estimation you are looking for the minimum necessary power so it doesn't hurt to get an amplifier with more power... as long as you don't burn-out your speakers. If you think you're going to be close to frying your speakers you should probably get speakers that can handle more power (or more efficient speakers).

Am I correct to understand that the risk of speaker burn-out is only when audio is being played at very high volumes? There's no risk just by virtue of having a high power amplifier when playing at reasonable volumes, right? Sorry if that's a stupid question.

The Hypex specs seem "unusual" to me... The Yamaha shows more power at 4 Ohms which is pretty common. The "High dynamic power" shows some headroom for peaks but with no distortion specified it's not that helpful. The 1% distortion usually means your at or near clipping and distortion will go-up greatly if you go higher and the distortion is usually lower when you go down a little in power.

These are approximations, and in most home-situations you don't really know exactly what SPL level you need, and as you may know, doubling of the power is only +3dB (and cutting the power in half is only -3dB). So I'd just use the calculations as general guidelines or as a sanity check and don't try to get exactly the required (minimum) power.

Yeah, it's really annoying that the Hypex's power at 1kHz is quoted at 1% distortion. Is that useful to anyone? The Yamaha's is at 0.7% which I'm guessing is also too high?

snip

Thanks!! Going to have to re-read this and go over the maths slowly.

The last paragraph makes sense. Is it possible that, if an amplifier doesn't have enough headroom to reproduce all the peaks in the music, there is some level of clipping that's not particularly audible to the untrained ear but dynamics are still affected which presents itself as a, sort of, compressed sound? Sorry if this is a stupid question.

The Crown calculator is more a pro tool for large venues or outdoors, that homestead version can account for room influences....

Ta.

 

[pjug]

I have a Yamaha A-S301. I would like to change amplifier for two reasons: 1) I would like an amplifier with a smaller physical footprint 2) I thought it possible my speakers might benefit from an amplifier with more power to fully reproduce all the dynamics in the music I listen to.

Great. So you can do a check on whether this amplifier is likely to be clipping, which is likely the only reason you would want more power. If you have an oscilloscope you can do it directly. Or you can use the Pano method to do it with a multimeter, as Archimago describes:

https://archimago.blogspot.com/2017/09/musings-how-much-amplifier-power-do-you.html

I think this is much better than trying to figure it out with one of these calculators.

 

[Andysu]

I often use this and don't use the harman crown calculator or whatever it is. I even find the crown architecture tedious enough as it is.

https://myhometheater.homestead.com/splcalculator.html