Question Power and Impedance

[OMD]

Hi I'm new here. I have a question on calculating the output power of a power amplifier if the speaker Impedance is not matching. Currently I have a Rotel RB1582 Mk2 stereo power amplifier, which is rated at 200W rms pc at 8 ohms. I am thinking of getting Acoustic Energy AE520 floor standing speakers. These are awesome sounding speakers with a huge demand for power since they can handle up to 300W continuously. However, there is a slight problem in my mind, since the input Impedance of these is 6 ohms. I need to know how much more power will be drawn from the amplifier and will tjis be safe. I should add that the amplifier is compatible with Impedances as low as 4 ohms.

So am I correct with this calculation?

(8 ohms ÷ 6 ohms) × 200W = 266.67W

If this calculation is correct this means on paper the speakers will have the capability of drawing up to 266W of power from the amplifier. In reality it will not give out this much power. But would this set up be safe for the amplifier or is there the potential of overheating, clipping and damage to both components?

 

[Guitargonaut]

You'll be fine. Output will probably be a little higher. Either way - no danger to amp or speakers.

 

[nopiano]

Welcome! As above, this is a non-issue as you will surely regulate the output by listening at volumes below rock stadium level. So unless you live in an aircraft hangar you’ll be fine!

AE speakers, along with most others, quote a power handling capability. In use, you will mostly be bobbling along at 0.5 to 5 watts! But the reserve is there for musical climaxes.

Your estimate into 6 ohms holds good, though in practice, like many amps, your Rotel exceeds its spec. But I stress this is it’s maximum capability on a test bench.

Here’s a lab test of a similar integrated amp FYI.

Rotel RA-1592MKII Integrated Amplifier Lab Report

Lab Report The object of this lab report is not only to answer the question 'does the RA-1592MKII meet its specification?' but, more intriguingly, 'does this perform like a Michi X3 [HFN Apr '21] in a lower-cost case?'. The answer to both questions is 'yes, most definitely!'. Like the Michi X3...

www.hifinews.com

 

[OMD]

Welcome! As above, this is a non-issue as you will surely regulate the output by listening at volumes below rock stadium level. So unless you live in an aircraft hangar you’ll be fine!

AE speakers, along with most others, quote a power handling capability. In use, you will mostly be bobbling along at 0.5 to 5 watts! But the reserve is there for musical climaxes.

Your estimate into 6 ohms holds good, though in practice, like many amps, your Rotel exceeds its spec. But I stress this is it’s maximum capability on a test bench.

Here’s a lab test of a similar integrated amp FYI.

Rotel RA-1592MKII Integrated Amplifier Lab Report

Lab Report The object of this lab report is not only to answer the question 'does the RA-1592MKII meet its specification?' but, more intriguingly, 'does this perform like a Michi X3 [HFN Apr '21] in a lower-cost case?'. The answer to both questions is 'yes, most definitely!'. Like the Michi X3...

www.hifinews.com

Hi nopiano, thanks for replying.
I get what you're saying, so the continuous output would be fairly low but the reserves of power is there to handle the instaneous peaks, plus the fact that these speakers have a fairly high sensitivity providing 90dB @ 1W/m I would burst my eardrums before anything adverse was to happen to any of the components.
Oh and thanks for uploading that Lab test, it's very reassuring.

 

[plastic penguin]

Don't get too hung up on Impedance. Most amps and speakers will quote nominal impedance and minimum impedance.

My amp produces 80 watts per channel into 8ohms nominal and if the speakers are 4 ohms it produces around 150 watts per channel. Most amps are flexible when it comes to impedance. Just buy the speakers that matches the tonal qualities and enjoy your bundles.

 

[OMD]

Thanks for the reply.
Great advice, I intent to take my amp along to demo these and B&Ws for comparison.

 

[plastic penguin]

Thanks for the reply.
Great advice, I intent to take my amp along to demo these and B&Ws for comparison.

Let us know how the demo goes. Try and demo another brand of speaker around the price of the B&W, that'll give you a good comparison.

 

[nopiano]

Hi nopiano, thanks for replying.
I get what you're saying, so the continuous output would be fairly low but the reserves of power is there to handle the instaneous peaks, plus the fact that these speakers have a fairly high sensitivity providing 90dB @ 1W/m I would burst my eardrums before anything adverse was to happen to any of the components.
Oh and thanks for uploading that Lab test, it's very reassuring.

Exactly!