Accuphase power output vs power consumption

[hybridauth_facebook_100000321009226]

Hi all,

I am looking into buying an Accuphase amp and while browsing through their specs I am somehow confused about their power input/output ratio.

For example the specs on E-470 claims the following.

Rated Continuous Average Output Power (both channels operating simultaneously, 20 - 20,000 Hz) 260 W/ch 4-ohm load

Power Consumption 92 watts idle 420 watts in accordance with IEC 60065

Accordin to these numbers the amplfier will give an output power (260*2 = 520W ) higher than the consumed one (420W) which should not be feasible.

Does anyone know more about how Accuphase is rating their specs on this matter?

Thanks!

 

[andyjm]

Hi all,

I am looking into buying an Accuphase amp and while browsing through their specs I am somehow confused about their power input/output ratio.

For example the specs on E-470 claims the following.

Rated Continuous Average Output Power (both channels operating simultaneously, 20 - 20,000 Hz) 260 W/ch 4-ohm load

Power Consumption 92 watts idle 420 watts in accordance with IEC 60065

Accordin to these numbers the amplfier will give an output power (260*2 = 520W ) higher than the consumed one (420W) which should not be feasible.

Does anyone know more about how Accuphase is rating their specs on this matter?

Thanks!

Linear amps are very inefficient - that's why they get hot. I would guess that your amp wouldn't get much above 50% efficient (power out / power in), so something must be adrift in the numbers.

There are a few weasel words in the spec - 'continuous average output power' either its continuous, or its average - it won't be both. Have you read IEC 60065? what does it say about how the amp is driven when the measurements are taken?

I am afraid this is typical of amp specs which are more about marketing than technical details.

An amp spec should have maximum continuous (at least 30 minutes) output for a wideband signal (say 20Hz to 20KHz) at a specified level of THD - 0.1% seems a good idea to me. I think you would be surprised at how the quoted output numbers in marketing material would be greatly reduced if this approach was adopted.

Measuring the power consumption of the amp driven this way would give a meaningful measure of power usage, and would likely be at least twice the power output.

I had a look at IEC60065 - which is primarily about safety, not amplifier specs, and the main body of the doc is behind a paywall so I couldn't get the details. A guess would be that the IEC spec is a true measure of consumption, and the real continuous output of the amp would be below half that - so approx 105W per channel. It could be even lower than this if distortion levels and heat sink dissipation was taken into account.

 

[drummerman]

I also seem to remember having read somewhere that manufacturers dont have to quote full power consumption, only 80% or so.

Someone correct me.

 

[Macspur]

Don't worry about the figures too much... just buy the E470, you won't regret it.

Mac

www.realmusicnet.wordpress.com

 

[Vladimir]

They haven't stated how long the bursts are while they measure (no manufacturer does). Could be 50ms, enough to show the best power output using the energy reserve in the PSU main filter capacitors.