[Carlos3]

I've been wondering how the power output of headphone amps compares to that of speaker amps, if calculated for the same output impedance (say 8 ohms) I've ordered a Rega Ear amp for my HD580, and these are its maximum output stats:

32 ohm load = 525 mW

600 ohm load = 55 mW

The question is, what would its projected maximum power output be at a hypothetical 8 ohm load?

 

[ServinginEcuador]

Quote:

Originally posted by Carlos3 32 ohm load = 525 mW 600 ohm load = 55 mW The question is, what would its projected maximum power output be at a hypothetical 8 ohm load?

I'm assuming that you meant 300 ohms, and not 600 since this makes the numbers come out weird. The formulas for calculating power are:

P=I*E power = current times resistance
P=E^2/R power = voltage squared divided by voltage
P=I^2 *R power = current squared times resistance.

So to make these formulas work when you have resistance and power, you'll need to figure out either voltage or current to make it workable to make the power you're looking for. So.... since you already have power and resistance, you'll need to figure out at least one more thing from that to make it work.

E=square root of P*R

At 32 ohms this is 4.1v
At 300 ohms this is 4.06v

So, when you have 8 ohms this amp can theoretically make about 2 watts of power at this rating. It may burn the amp out at this low of a resistance, but here's the numbers.

 

[Carlos3]

Thanks Doug.

According to Rega's stats it is 600. Here's the page:

http://www.rega.co.uk/html/ear_2001.htm

 

[ServinginEcuador]

Carlos3,

It really doesn't change much, but plug in 600 ohms to the equation and it still comes out pretty close to the same figures.

Glad ot help!!

 

[Carlos3]

Thanks again.

Could be a typo in their specs?

 

[ServinginEcuador]

It could be since the math doesn't work out when computing the numbers. That could be that it's harder to push such high impedance cans, but who knows.

I wouldn't try to push an 8 ohm load with a headphone amp. Might overheat and ruin it if run for any length of time. I think you were just curious, but I wanted to warn you just in case.

 

[Joe Bloggs]

You can't calculate projected power just like that. Just as you can't expect it to really output 2W into 8ohms, it may be able to provide more voltage swing at 600ohm than at 32ohms and so provide more power than projected using your calculations.

These changes are dependent on the amp design. Some amps have really high voltage swing capability but low current capability, so will output more power to higher impedance phones, while other amps are just the opposite and will output more power to lower impedance phones.

 

[ServinginEcuador]

Quote:

Originally posted by Joe Bloggs You can't calculate projected power just like that. Just as you can't expect it to really output 2W into 8ohms, it may be able to provide more voltage swing at 600ohm than at 32ohms and so provide more power than projected using your calculations. These changes are dependent on the amp design. Some amps have really high voltage swing capability but low current capability, so will output more power to higher impedance phones, while other amps are just the opposite and will output more power to lower impedance phones.

Joe,

That's why I made sure to put in the fact that my calculations were merely theoretical, nothing more. I used the figures that the manufacturer stated to come up with a good idea of what it can actually do to extrapolate what it could possibly do. Which I again made sure to state in my post that it is purely theoretical, nothing more.

 

[Joe Bloggs]

 

[ServinginEcuador]

Quote:

Originally posted by Joe Bloggs

Gotcha!!

Happy New Year Joe!!! But, isn't it going on the 2rd of January there since it's after midnight on the 1st here?? I always get it mixed up, but I thought that you were a day and like 15 hours ahead of us here?? What is the date/time difference anyway??? I am curious about that again.

 

[Joe Bloggs]

I don't think any place can be more than 24 hours ahead of another...

It's 5pm New Year's day here

 

[Budgie]

Quote:

Originally posted by Joe Bloggs I don't think any place can be more than 24 hours ahead of another... It's 5pm New Year's day here

I think your right about being ahead in time, Joe, but I have been to places that are years behind!