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Discussion Starter · #1 ·
I live in an old house with **** wiring. As I start adding more equipment I don't want to spend too much on an electrician because I am renting.


Would using class d amps allow me to get more power to my speakers and subs without having them overdraw the circuit or run into its limitations before theirs.
 

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Maybe. I have to say that I hooked a Kill A Watt meter up to my receiver and played close to reference level. I would say peaks were over 90 dB at my listening position.


I doubt I saw power go over 200 watts. I had a whole thread on this topic, but that was a long time ago. Either the Kill A Watt can't respond very quickly to peaks, or very short peaks in the music drew needed power from the caps without a noticeable fluctuation in power draw. I did have a test to see intermittent peak power draw - a solo repeating kick drum would definitely pulse the Kill A Watt readout. There was a lag, which makes sense - the power was drawn from the caps which were then recharged a bit less than a second later. The Kill A Watt would spike during the cap recharge.


Why am I mentioning all this? Just so you get an idea of what the meter showed. If you listen to reasonable levels, your power draw from an AVR is probably no more than 100 watts, and probably less. It does not take much power to drive average speakers to reasonable levels. You want 90 dB average level ( with no regard for your ear canals,) then you might need over 100 watts consumption.


All this being said, it would be interesting to have two people play the same song movie with a similar set of speakers and measure power draw between a classic class B AVR and a class D Pioneer.
 

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Quote:
Originally Posted by noah katz /forum/post/16958641


Fact is class D is of little if any efficiency benefit in home use because average power demanded is quite low.


The 90+% efficiencies claimed is at full output.

Depends on your definition of "low", and the specific amps involved.


One amp I measured sucked just over 100W without playing anything, and around 110W avg when playing at reasonable levels. I've also seen stereo amps claiming something like 300W or more at idle.


A pair of class-D monoblocks measured less than 20W total both while idle and playing fairly loudly.


Multiply that for a 7-channel system, and I'd argue it's a significant difference.


Now, is it worth spending $2K more, just to save $20 per year? Not in my book!
 

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The biggest power consumption in many amps is wasted energy in the form of heat. Some amps generate 100W of heat or even more. A hot amp = inefficient amp. My 2000W Sunfire doesn't even have cooling vents and consumes about 15W at idle. Same for the old Carver amps, almost zero heat.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by goldenbear /forum/post/16958974


Depends on your definition of "low", and the specific amps involved.


One amp I measured sucked just over 100W without playing anything, and around 110W avg when playing at reasonable levels. I've also seen stereo amps claiming something like 300W or more at idle.


A pair of class-D monoblocks measured less than 20W total both while idle and playing fairly loudly.


Multiply that for a 7-channel system, and I'd argue it's a significant difference.


Now, is it worth spending $2K more, just to save $20 per year? Not in my book!

So basically it will not help because when it hits peak watts the AMP in the room and the circuit will still limit true output if it is not strong enough?
 

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Quote:
Originally Posted by goonstopher /forum/post/16960275


So basically it will not help because when it hits peak watts the AMP in the room and the circuit will still limit true output if it is not strong enough?

Your post is ambiguous. I still contend that you likely would draw a lot less power from a class AB receiver than you think. I don't think you have a problem.


A class D receiver like the Pioneer SC might let you play louder. So maybe it's worth considering.


I should point out that people regularly post that they have never tripped a breaker with a normal 15 am circuit with any number of AV components plugged into that same circuit. And my results with a Kill A Watt meter indicate why, in my opinion. People draw less power than they think.


If you are seriously going to play your system at reference level, which few receivers can even manage, or near reference level, maybe you will draw 100's of watts and might want to consider a more efficient receiver.
 

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Quote:
Originally Posted by rdgrimes /forum/post/16959234


The biggest power consumption in many amps is wasted energy in the form of heat. Some amps generate 100W of heat or even more. A hot amp = inefficient amp. My 2000W Sunfire doesn't even have cooling vents and consumes about 15W at idle. Same for the old Carver amps, almost zero heat.

Agreed one of the 'bad' things of my 10channel denon poa amp is that it takes 279watts in idle more because of the ab design and the fact they don't even turn off channels not in use. One of the few downsides of this amp. As a result it becomes hot even at low levels. I do think Michael has a very good point in saying that people think receivers take a lot of power because it can do xxx watts into xx channels but in real use take very little to play at 90 or 95dB.


Daniel.
 

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The main thing is that even if you occasionally clip a 2000 W amp, that's only peaks, the average power is a small fraction of that.


"I should point out that people regularly post that they have never tripped a breaker with a normal 15 am circuit with any number of AV components plugged into that same circuit."


Yes, I'm one of those.


Not only can circuit breakers be overloaded for several seconds, but a lot of the energy for the peaks is supplied by the capacitors in the amp's power supply.
 

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Here is a breakdown by appliance type..

Key point is the continuous wattage rating plus the amount of time the appliance is being run...


•Aquarium = 50–1210 Watts

•Audio/Video Receiver= 70–400

•Clock radio = 10

•Coffee maker = 900–1200

•Clothes washer = 350–500

•Clothes dryer = 1800–5000

•Dishwasher = 1200–2400 (using the drying feature greatly increases energy consumption)

•Dehumidifier = 785

•Electric blanket- Single/Double = 60 / 100

•Fans

◦Ceiling = 65–175

◦Window = 55–250

◦Furnace = 750

◦Whole house = 240–750

•Hair dryer = 1200–1875

•Heater (portable) = 750–1500

•Clothes iron = 1000–1800

•Microwave oven = 750–1100

•Personal computer

◦CPU - awake / asleep = 120 / 30 or less

◦Monitor - awake / asleep = 150 / 30 or less

◦Laptop = 50

•Refrigerator (frost-free, 16 cubic feet) = 725

•Televisions (color)

◦19" = 65–110

◦27" = 113

◦36" = 133

◦53"-61" Projection = 170

◦Flat screen = 200

•Toaster = 800–1400

•Toaster oven = 1225

•VCR/DVD = 17–21 / 20–25

•Vacuum cleaner = 1000–1440

•Water heater (40 gallon) = 4500–5500

•Water pump (deep well) = 250–1100

•Water bed (with heater, no cover) = 120–380


Just my $0.025...
 

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For NEC electrical applications "continuous" is defined as three hours or more. Many of the items on M Code's list draw high power only intermittently.
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/16959209


300 watts at idle? Was that a class A amp?

Don't recall. I think it was one of the older Mark Levinson amps. I see plenty of AB amps (stereo) claiming around 200W at idle, so even assuming the 300W is an exception, there's still quite a difference in power consumption between AB and D amps. No one I know considers those types of numbers to be insignificant.


I guess my point is simply that even though most people will only need less than 10W or so per channel to get ear-splitting loud sound, AB amps have a significantly higher fixed power consumption when compared to D amps. So, there's definitely a noticeable difference in power consumption, especially if you're running multiple amps.


However, if you're looking at a D amps solely to save money (based on power usage), you need look at how much you pay for electricity vs the cost difference between the amps (D amps generally costs more than the many good, reasonably priced AB amps). I'm not going to get into the black-hole of a "discussion" regarding which type of amp uses less resources to produce, is easier to recycle, or any of the "Green" arguments.


As for the OP's concerns, I think it was more a concern of reaching the circuit's max power output. Well, it could still be a concern if you're running a bunch of AB amps that have a high idle power draw, plus other equipment on the same circuit. For example, if you have 7 mono-blocks that draw 100W each at idle (I'm just pulling numbers out of the air), that's already half what a 15-amp circuit can put out. Add a plasma TV, computer, Blu-ray player, and a few other components, you're already close to the circuit's limit. And that's just at idle.


But then, the more likely scenario is you'd run a 7-channel amp or receiver that draws maybe 300W at most at idle (probably quite a bit less than that). In that case, I don't think you need to worry about things as much.
 
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