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Author Topic: How important is amplifier efficiency ?.  (Read 6596 times)

Mike Diack

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How important is amplifier efficiency ?.
« on: September 14, 2011, 05:01:30 PM »

OK this is something of a rant.
In my capacity as a serviceperson I look after the amps for several large council sports/general purpose stadiums. When these things were being fitted out, there must have been a particularly efficient Electrovoice salesman around because the amp of choice seems to have been the EV P3000. These things cycle through my workshop reasonably regularly, adding to my hernia and getting their control board capacitors replaced - as they have been cooked. I started asking the people in charge of such matters how often the amps were turned off (like when the facility was not in use, sometimes for weeks) and the answer was inevitably......never.
An idling P3000 pulls around 1.25 amps if correctly biassed (often lots more if it has drifted)
At 230 volts, thats 287 watts, giving 6.9 kWh/day
In NZ, power costs around $0.25/kWh, giving $1.72/amplifier/day
ie $629/amp/year just to slowly cook most of the time.
Most stadia have at least 10 of these amps ie >$6k/year.
When I pointed this out to one person in charge, his reply :
Oh, we also have to run the aircon to keep the equipment room cool.
I'm no greenie but this is just nuts.
M
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John Roberts {JR}

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Re: How important is amplifier efficiency ?.
« Reply #1 on: September 14, 2011, 05:26:33 PM »

I have done a little design work for fixed install and there is a temptation to run them slightly starved for class A bias to run a little cooler. For one in-wall amp, designed to be installed inside a breaker panel type metal enclosure, I even added an extra fan speed circuit, so it could run at high/low/off. Most fan circuits are just high and low speed, but when an amplifier does't even have an on/off switch, and is hard wired into the electrical circuits, you don't want to replace the fan every several years.

======

FWIW governments are more aware of parasitic current draw from products even when they are turned off, but in a rare example of good judgment they focus on saving a couple watts from millions of consumer products rather than a hundred watts from a few pro products.

This is one reason pro amps aren't already 100% PFC by law to save energy.

Stop me before I say something else positive about the government pukes.

JR
 
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Brian Ehlers

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Re: How important is amplifier efficiency ?.
« Reply #2 on: September 15, 2011, 12:48:24 PM »

Stop me before I say something else positive about the government pukes.
If it makes you feel any better, I recently read an article which stated that the government-mandated efficiency ratings for refridgerators do not apply to their internal ice makers, only to normal operation.  Yet it turns out that the ice maker consumes most of the energy used by the fridge.  (The high power is actually from the heater used to help release the ice from the mold.)  So we have millions of consumers making "green" choices based on completely inaccurate data and choosing refridgerators with ice makers just because they're too lazy to fill and empty the trays themselves.

There, I've restored balance within the Universe of Government Idiocy.   ;)
« Last Edit: September 15, 2011, 12:52:11 PM by Brian Ehlers »
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Brian Ehlers

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Re: How important is amplifier efficiency ?.
« Reply #3 on: September 15, 2011, 12:53:54 PM »

Back to the original post .....
It seems that such markets would be ripe for a salesman to promote to his customers "total lifecycle cost."  It's not just the purchase price, but how much will the equipment cost you over its life?  If you're the salesman who points out the annual savings by using the ultra-efficient amplifier YOU recommend, maybe you'll get the contract.
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John Roberts {JR}

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Re: How important is amplifier efficiency ?.
« Reply #4 on: September 15, 2011, 01:12:21 PM »

Back to the original post .....
It seems that such markets would be ripe for a salesman to promote to his customers "total lifecycle cost."  It's not just the purchase price, but how much will the equipment cost you over its life?  If you're the salesman who points out the annual savings by using the ultra-efficient amplifier YOU recommend, maybe you'll get the contract.

In broad stokes the efficiency of amplifiers is somewhat driven by product cost, and consumer buying patterns.

First Class G/H topology because it was more efficient, delivered the same output power from smaller power transformers and smaller heat sinks. Aluminum, iron, and copper cost money, so the customer got a more efficient amplifier as a consequence of buying the cheaper amplifier technology. 

We are now on another similar transition to class D, where we get some more efficiency in exchange for the increased complexity, allowing smaller again heat sinks and power transformers, but this time around the efficiency increases are not as large as the first round from class A/B to G/H.

Most customers do not think much of life cycle costs, while installers routinely look at reliability, since service calls are not profit centers for them but profit sinks. I have found customers pretty much deaf about efficiency, especially with loudspeakers, they want more power,,, just like captain Kirk. 

JR

PS: Don't get me started on government fails...  I'm trying to behave.
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TJ (Tom) Cornish

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Re: How important is amplifier efficiency ?.
« Reply #5 on: September 15, 2011, 02:14:44 PM »

Back to the original post .....
It seems that such markets would be ripe for a salesman to promote to his customers "total lifecycle cost."

Or maybe the salesman could also sell them a power switch.
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Ryan Lantzy

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Re: How important is amplifier efficiency ?.
« Reply #6 on: September 15, 2011, 02:24:34 PM »

If it makes you feel any better, I recently read an article which stated that the government-mandated efficiency ratings for refridgerators do not apply to their internal ice makers, only to normal operation.  Yet it turns out that the ice maker consumes most of the energy used by the fridge.  (The high power is actually from the heater used to help release the ice from the mold.)  So we have millions of consumers making "green" choices based on completely inaccurate data and choosing refridgerators with ice makers just because they're too lazy to fill and empty the trays themselves.

I think what you are referring to is the defrost heaters in refrigerators.  If there is a heater for the ice cube trays it wouldn't be on for more than a few seconds at a time.

The defrost heater cycles more often and runs for awhile to keep frost off of the evaporator coils.
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Jeff Bankston

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Re: How important is amplifier efficiency ?.
« Reply #7 on: September 15, 2011, 02:58:44 PM »

the quailty of the sound and durability is more important than "effeceincy" in an amp. same goes for cars. i love my nice comfortable ford f350. it gets about 14 mpg. i have a 65 mustang and a 68 torino. i'd rather be ride in comfort and spend a few extra bucks fo gas/diesel the drive some new little car that is very uncomfortable and hard to get in and out. i have riden in several new toyotas,nissans,etc that friends own. if there aint enough power plants you gotta build more. btw all this high efficient stuff of to day will probably very inefficient 10 years from now. where does it end ? will your stereo be a solar powered 9v transistor radio from the 60's ?
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Ryan Lantzy

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Re: How important is amplifier efficiency ?.
« Reply #8 on: September 16, 2011, 09:47:09 AM »

the quailty of the sound and durability is more important than "effeceincy" in an amp. same goes for cars. i love my nice comfortable ford f350. it gets about 14 mpg. i have a 65 mustang and a 68 torino. i'd rather be ride in comfort and spend a few extra bucks fo gas/diesel the drive some new little car that is very uncomfortable and hard to get in and out. i have riden in several new toyotas,nissans,etc that friends own. if there aint enough power plants you gotta build more. btw all this high efficient stuff of to day will probably very inefficient 10 years from now. where does it end ? will your stereo be a solar powered 9v transistor radio from the 60's ?

You and the rest of us in the US can afford to think this way (for the most part) do to the very low cost of energy here.  The OP quoted a price of 25 cents per kWh which if he converted to US dollars is about twice the price of electricity here.

Diesel and gasoline are 2-3x the price here per unit (higher in some places) and regardless of whether that's because of taxes, low supply, etc. it's something that really changes the way you think about your energy use.

I believe in building more power plants too, but only if they are nuclear and more importantly inherently safe designs.
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John Roberts {JR}

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Re: How important is amplifier efficiency ?.
« Reply #9 on: September 16, 2011, 11:15:52 AM »

Low cost energy in whatever form is a factor that supports industry which helps support employment and quality of life, so is pretty much a good thing.

To dwell on topic for a moment, I don't doubt that power amps will continue to get more efficient in the future but the improvements over class D will only be incremental (higher frequency, lower on resistance power devices, etc). The lion's share of amp efficiency improvements have already been harvested, at least wrt technology, while this hasn't completely filtered down to the cheapest amps yet, but that's coming. They already use tiny class D IC's in cellphones and music players to extend battery life. Connecting all the power points in between will happen.

I haven't taken a sharp pencil to this but a digital console should consume less energy than an analog console (with similar functionality). While this is not a significant energy user. Future energy savings in our industry will come from more efficient loudspeakers, with even more refined focus of where they throw that sound. Energy that is still heating up voice coils and sound that isn't hitting the meat in the seats, is wasted. 

======
There are still nuclear energy programs going forward but incredibly slowly. The Japanese tsunami was just another nail in the coffin, of public opinion that doesn't grasp technological issues very well, not to mention dysfunction when it comes to dealing with nuclear waste. The Japanese disaster was made worse by the common practice of storing nuclear waste on-site. Last I heard we are still squabbling over permanent storage here.

I was optimistic that new generation technology could be safer and generate less waste, but this industry is incredibly slow moving with high hurdles surrounding adopting new technology. I am watching the Indian program for experience with new technology nuclear reactors.

I suspect in the near term we will see more NG power plants built to take advantage of the current surfeit of gas supplies well in excess of obvious demand, and relatively clean burning. Since we don't use oil to make electricity, this is likely to displace coal, which isn't a bad thing as burning coal is pretty toxic. There is a new clean coal plant being built near me in MS but I am not optimistic about the economics of this. I suspect it is much easier/cheaper to retrofit a coal plant for NG than convert to clean coal. While I don't feel good about ignoring our massive reserves of that relatively cheap and abundant energy source.

We shouldn't waste electricity or oil, just like we shouldn't waste water or food or money.... or time. I'm not too worried about running out (well I will run out of time).. When there's no more rosewood for finger boards, well come up with something else, just like ivory has been replaced in piano keybeds. Energy is everywhere around us, for the harvesting, when the time/price is right.   

JR
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Brian Ehlers

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Re: How important is amplifier efficiency ?.
« Reply #10 on: September 19, 2011, 07:26:27 PM »

I haven't taken a sharp pencil to this but a digital console should consume less energy than an analog console (with similar functionality).
I don't know .... which burns more power, a 5+ Watt DSP or the 4 dozen op-amps it replaces?  Besides, isn't the biggest power draw in a console (whether analog or digital) all the little LEDs?  And then there's the flat panel displays.

We shouldn't waste electricity or oil, just like we shouldn't waste water ....
I can appreciate the idea of water conservation in other parts of the country, but here in Michigan it's just not an issue.   8)
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Stu McDoniel

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Re: How important is amplifier efficiency ?.
« Reply #11 on: October 03, 2011, 10:53:24 PM »

OK this is something of a rant.
In my capacity as a serviceperson I look after the amps for several large council sports/general purpose stadiums. When these things were being fitted out, there must have been a particularly efficient Electrovoice salesman around because the amp of choice seems to have been the EV P3000. These things cycle through my workshop reasonably regularly, adding to my hernia and getting their control board capacitors replaced - as they have been cooked. I started asking the people in charge of such matters how often the amps were turned off (like when the facility was not in use, sometimes for weeks) and the answer was inevitably......never.
An idling P3000 pulls around 1.25 amps if correctly biassed (often lots more if it has drifted)
At 230 volts, thats 287 watts, giving 6.9 kWh/day
In NZ, power costs around $0.25/kWh, giving $1.72/amplifier/day
ie $629/amp/year just to slowly cook most of the time.
Most stadia have at least 10 of these amps ie >$6k/year.
When I pointed this out to one person in charge, his reply :
Oh, we also have to run the aircon to keep the equipment room cool.
I'm no greenie but this is just nuts.
M
Designers are getting better at this whole Class D amplfier thing and this is good.   I was looking at a youtube video of Behringers new Inuke class D amplifiers.  I have not heard one of these amps or seen one under a severe load
but 7lbs for weight and the low power consumption is a plus.   Even Crown has dabbled in the Class D amplifier thing.
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John Roberts {JR}

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Re: How important is amplifier efficiency ?.
« Reply #12 on: October 03, 2011, 11:55:57 PM »

Designers are getting better at this whole Class D amplfier thing and this is good.   I was looking at a youtube video of Behringers new Inuke class D amplifiers.  I have not heard one of these amps or seen one under a severe load
but 7lbs for weight and the low power consumption is a plus.   Even Crown has dabbled in the Class D amplifier thing.
Even Crown has dabbled in it... WTF?? ::) ::) If you did a little research you would find patents from Crown's dabbling in it. If it wasn't for companies doing original design work in class D (like Crown and several others), who would the cloners copy?  Class D didn't poop out of the chute at current power levels or ultra light weight. This is the result of decades of hard work developing the technology.

JR
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Tim McCulloch

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Re: How important is amplifier efficiency ?.
« Reply #13 on: October 04, 2011, 10:00:08 AM »

Designers are getting better at this whole Class D amplfier thing and this is good.   I was looking at a youtube video of Behringers new Inuke class D amplifiers.  I have not heard one of these amps or seen one under a severe load
but 7lbs for weight and the low power consumption is a plus.   Even Crown has dabbled in the Class D amplifier thing.

Your "idiot light" is glowing very, very brightly.
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Mike Diack

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Re: How important is amplifier efficiency ?.
« Reply #14 on: October 04, 2011, 04:06:22 PM »

Even Crown has dabbled in it... WTF?? ::) ::) If you did a little research you would find patents from Crown's dabbling in it. If it wasn't for companies doing original design work in class D (like Crown and several others), who would the cloners copy?  Class D didn't poop out of the chute at current power levels or ultra light weight. This is the result of decades of hard work developing the technology.

JR

MANY decades :-)
http://nvg.org/sinclair/audio/x-10.htm
(Lets hope Sir Clive does better with his latest venture [a 33YO lapdancer])
M
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Re: How important is amplifier efficiency ?.
« Reply #14 on: October 04, 2011, 04:06:22 PM »


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