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Hi,I am considering buying a Jungson JA 88D power amp that's rated to be 80 Watts output into 8 Ohms in pure Class A operation. But I can not find any data or info on it's power consumption. A friend mentioned that it could be a real power hungry amp. And my utilities are very expensive to begin with. The manufacturer's website is not helpful. Any idea what it's power consumption might be? Thank you in advance.
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To further add to your confusion consider the PS Audio HCA-2. They call it hybrid class A. It has a small class A section which always pulls 16 watts and a digital section which varies from almost nothing to 600 watts depending on the note being played at the time.
My 60W Accuphase A-60's manual says that it draws over 300 Watts at idle.
Just opening the door on my non-running refrigerator draws more current than my ARC D130 at door-blowing levels. The amp draws 0.79A at Loud levels and 0.76A at more normal levels. So much for power hungry amps choking down the PLC.Very efficient speakers to be sure, but I was amazed at these readings...
I have a Killawatt meter which allows me to see how much power any electrical appliance is using. When one of my Bottlehead Paramounts 300B (rated at 9watts/channel) is plugged into it, it tells me that it is consuming 60 watts. This is at idle or when blasting out the 9 watts.
Not really the same thing. The JungSon appears to have a power consumption ranging from 180W to 600W, but not much info from the manufacturer. Should be some figures on the back of the units distributed in either the US or EU.
But what if say I have a 97 96 db speaker and only end up using say 5-10 watts of thsi 80 Watt Class A Amp:http://www.jungson.com.au/products/hifi/ja88d
A Class A amplifier consumes its'entire rated power at idle because both the positive and negative rails are turned full on at idle and there is, therefore, no signal output since, for instance with a 10A Class A amp a + 10A and a - 10A output = 0. This is why a Class A amp has no crossover distortion since there is no crossover from + to - output i.e. both + and - rails are full on at idle. To produce an output signal the output of one rail, either + or - is lowered causing the opposite rail to output a similar voltge. I hope this has totally confused you, as it did me for quite a long time.
I am confused to say the least but say the Jungson consoumes 1.5 Amp, how could one then calculate the watts consumed. It's 120 V version
A pure class A amp will draw the EXACT same power from your mains line at idle as it does as full ouptut capacity.This is the case with my Pass Labs Aleph 3 which is pure class A and it draws 250 watts ALL the time no matter if it is idling or pounding out it's rated 30 WPC into 8 ohms or 60 WPC into 4 ohms.
As the Aleph 3 idles at 4 times it's rated output, I think we can safely say that it is a "pure" class A design :-)
As per Nelson Pass: "The "purity" of class A has been an issue in the last few years, with "pure" class A loosly defined as an idling heat dissipation of more than twice the maximum amplifier output. For a 100 watt amplifier, this would be 200 watts out of the wall at idle"
Hope this helps,
~kenster
Depends, but you could probably figure around 400 watts power consumption at full power output if really running in pure class-A (not many do).
Yes, it's full class A. However, I probably would use it with an 88 db, 6 ohm speaker and I do not listen to loud levels. It's an integrated amp.
I believe I am right on this, when ON it will draw 80 watts, 1.5 amps, all the times it is on. That is the draw from your meter, so if it is on 24/7 it will draw 1920 watts a day. Any peak watt draws come from the caps and won't be reflected by the meter. An A/B amp has a low draw until power is needed, then demand goes up. The class A amp will all so produce more heat into the room. I use a class A Threshold 100 watt amp that runs the front speakers in my HT I like the fast responce that a class A amp delivers.
"The power consumption is unrelated to the output power: at idle (no input), the power consumption is essentially the same as at high output volume. The result: a considerable amount of power is radiated by the heat sinks." (Wikipedia)http://en.wikipedia.org/wiki/Electronic_amplifier
In real life, here are the specs for a pure class-A 150W/channel amp ...Technical Specification
Input Sensitivity 1.6v for full rated output
input Impedance 67 kohms
Slew rate up to 40v/us
Power supply at 4 ohms up to 16 amps
Instantaneous current supply up to 75 amps
Signal to noise ratio < 100dB
Power Consumption (idle) 175watts
Power Consumption (full rated power @ 8ohms) 720 watts
Power Output 20hz - 20Khz @8ohms 150 watts RMS per channel (both channels driven)
Weight 40Kgs
Dimensions 480 x 480 x 225mm
Does that amp run in pure class A?
That's kind of the point, there isn't a real definition. But yes, it is advertised as a pure class A amp, and doesn't differ in that regard from many other similarly advertised designs from big and small companies ...
So you won't be submitting a correction to Wikipedia?
just not necessarily right either :-)"Pure" is really a modifier that hasn't much meaning in this context. It might have been used at one time in an attempt to separate the shadier advertisers from the more consumer friendly advertisers, but nowadays it is just an advertising term. In the end, not many amplifiers, regardless of class-A "purity", consume the same power at idle as they do at full power, and at all loads. Bias levels change and adjust, and banks of transistors still change bias in most push-pull designs at high power levels when they aren't needed, unless it's just a resistor biased single-ended design like some of the very low power class-A amps.
The definition of Class-A is that the devices conduct current during 360 degrees of a sine wave cycle. This does not necessarily mean that the input power requirements are steady during variations in the output power. The belief in this relationship is due to circuit designs that are very old. These older designs generally have a bias point that does not intentionally change as the power level changes. Unfortunately this is not a very efficient design from a power consumption perspective or from a power vs. device cost perspective.As designs have developed over time techniques have been developed and utilized that allow compliance with the definition of Class-A that improve power efficiency and allow greater power output from a fixed number of devices.
"Power Consumption (idle) 175watts
Power Consumption (full rated power @ 8ohms) 720 watts
Power Output 20hz - 20Khz @8ohms 150 watts RMS per channel (both channels driven)"
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