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A40 power use
A40 power use
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Old Yesterday, 01:25 PM   #1
aagas is offline aagas
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Join Date: Jul 2013
Default A40 power use

I have a pair A40 stereo amplifiers each bridged to run in mono. Each drive a single DIY speaker.

I have had these amps for decades and had to replace a few parts along the way.
They still sound WONDERFUL.

I have usually just left them turned on 24/7 365 days a year.

So two questions:
(1) Do I understand correctly this circuit would draw the same amount of electricity at rest as when actually playing music?

(2) How much electricity do these 55 lb amps actually use in a year?
Old definition of an audiophile: A guy whose stereo costs more than his car.

Just wondering if I've already spent my future grandchildren's college fund on these beloved amps?

My wife keeps asking me about the electric bill ;-)
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Old Yesterday, 01:54 PM   #2
Mark Johnson is online now Mark Johnson  United States
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A40 power use
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Old Yesterday, 02:05 PM   #3
jameshillj is offline jameshillj  Australia
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From memory, I think my A40 (stereo) drew about 100W/channel (but it could have been more than this too) - so using the 2 amps, this would be about 400W/hr for both amps.

I remember being pleased that my F5, even biased to a high current, consumed less power and that's about 70w per channel.

And yes, they are class A amplifiers and draw this amount of power all the time - there isn't any real reason to not turn the amps off when not in use as they only take about 30 minutes to settle down from cold.

If your electricity prices are anything like ours here (about AUD $0.28/kwh), then leaving both amps on 24/7 will soon add up to about a grand per year, if my arithmetic is correct. Hopefully, your power cost is a lot more reasonable ....
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Old Yesterday, 03:12 PM   #4
aagas is offline aagas
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Join Date: Jul 2013

Thanks. Let me see if I've got this right...

The A40 output = 40W/channel, so you may have it spot on that they draw 100W/channel to produce that.

Draw per channel in KW ........................... 0.1
Number of channels ................................. 4.0
Power draw/hr in KW ............................... 0.4
Hours per year (24 x 365.25) ....... x 8766.0
KW/Year ............................................ 3506.4
Cost/KWH ............................................ x 0.21 USD
Power cost/yr TOTAL ........................ 736.34 USD

A lot, but not as much as I feared.
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Old Yesterday, 08:58 PM   #5
PRR is offline PRR  United States
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Location: Maine USA
The electric cost is enough to justify Mark's hint to buy a Kill-A-Watt.

This reports power use, and also KHW used over time (and with programming, dollars).

Aside from audio, you can check refrigerators, the rated power of LED lighting. I got a "refurbished" microwave oven and the power consumption was way higher than rated (it did cook real fast for 2 years but died this week.)
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Old Yesterday, 09:00 PM   #6
aagas is offline aagas
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Mark / PRR -- Much appreciated.
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