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# EMOTIVA Thread Q&A [TECHNICAL TALK ONLY] - Page 527

Class A is 25% efficient so it is possible it will draw 440 watts. 55 x 2 x 4 = 440

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Quote:
Originally Posted by rnatalli

Class A is 25% efficient so it is possible it will draw 440 watts. 55 x 2 x 4 = 440

When it is idling??

I'll have to find my Killawatt and measure the actual draw...

Yes, when it is idling if it is true/fully Class A then 440W, give or take, is in the ballpark.

Here is another way to consider it.

55W @ 8 ohms = 29.7Vp

55W @ 8 ohm = 3.71Ap

Since the amp's rail voltage needs to be, at the very least, as much as the output swing (actually more, but for sake of discussion) so +/-30V (or 60V).

60V * 3.71A = 222.6W

222.6W * 2 ch = 445.2W
Edited by whoaru99 - 3/26/13 at 6:28am
Quote:
Originally Posted by whoaru99

Yes, when it is idling if it is true/fully Class A then 440W, give or take, is in the ballpark.

Here is another way to consider it.

55W @ 8 ohms = 29.7Vp

55W @ 8 ohm = 3.71Ap

Since the amp's rail voltage needs to be, at the very least, as much as the output swing (actually more, but for sake of discussion) so +/-30V (or 60V).

60V * 3.71A = 222.6W

222.6W * 2 ch = 445.2W

It is Pure Class A, yes.

I wouldn't presume to argue with you as I have scant knowledge of such things, but it seems extraordinary to me that it would be using approaching half a kilowatt when it is idling. It's been switched on 24/7, excepting power outages, for over 20 years!  Mind you, my electricity bills are fairly large.... ;)

Quote:
Originally Posted by kbarnes701

Quote:
Originally Posted by whoaru99

Quote:
Originally Posted by kbarnes701

180 watts maybe at peak but at idle 55 watts isn’t it?  Most of the time it is on idle of course.

No, it should be more like 400 watts.

(55x2) / 0.25= 440W

55wpc is the output, but that is at a low ~25% efficiency so roughly four times more input power is required. Some are a little better, some a little worse in this regard.

There is no way it draws 440 watts when it is idling. Or, for that matter, when it is driving the speakers. It is a 55 x2 watt amp - it will never draw 440 watts.
It's potentially possible due to the inefficiency of Class A amps. I've seen a 35w Class A amp that constantly drew ~120-140w.

Max

Expensive :(

I looked at the XPA-1L review thread, the guy said the amp was drawing approximately 201watts at idle.
Quote:
Originally Posted by djbluemax1

Quote:
Originally Posted by kbarnes701

Quote:
Originally Posted by whoaru99

Quote:
Originally Posted by kbarnes701

180 watts maybe at peak but at idle 55 watts isn’t it?  Most of the time it is on idle of course.

No, it should be more like 400 watts.

(55x2) / 0.25= 440W

55wpc is the output, but that is at a low ~25% efficiency so roughly four times more input power is required. Some are a little better, some a little worse in this regard.

There is no way it draws 440 watts when it is idling. Or, for that matter, when it is driving the speakers. It is a 55 x2 watt amp - it will never draw 440 watts.
It's potentially possible due to the inefficiency of Class A amps. I've seen a 35w Class A amp that constantly drew ~120-140w.

Max

Gulp!  Where's the 'gulp' emoticon?? :)  I have to say that my electricity bills have always been fairly steep. When my daughters were growing up we had a very big house and lots of rooms in use all at the same time - my daughters both had TVs, we had more TVs in various other rooms - three women in the house meant that baths and showers were always being run (and baths filled to the brim with hot water). Washing machine and dryer seemed to be running all the time - I had several computers that were always on and so on and on.... but never in my wildest imaginings did I think that my Class A amp would be drawing close to half a kilowatt even when it was doing nothing!

I am not questioning you guys who know more about this than I do - but I am going to find that Killawatt and check this out!  440 watts!!!  When it is, er, doing NOTHING. Well, it does double as a room heater I guess, so that saves us a little.... hahahaha.

Quote:
Originally Posted by Milt99

I looked at the XPA-1L review thread, the guy said the amp was drawing approximately 201watts at idle.

The thing with my Class A amp is that it sounds really rough until it is thoroughly warm - at least 30-40 minutes of use. I have no idea why this should be so, and generally I don't believe that SS equipment should change sonically as it gets warmer, but it does. This isn’t a placebo type thing - it really does sound rough when it is cold. So I just left it on all the time. It's been on for 20 years, steadily drawing 440 watts unbeknown to me...

The Emo amp may not sound rough when it is warming up so it can be switched off at the wall when it is not being used. It will also have a standby mode which my amp doesn’t have and in standby the Emo may have acceptable power use figures. 201 watts at idle doesn't really matter because when it is on it won’t usually be idling.  440 watts a day for 20 years. I am in shock I think :)

Suppose you could always hook up with a Krell KSA-250. They draw ~12A at idle from a 120V line (1,440 watts).
I came up with an estimate in my area of about 14 cents per month for 1 watt 24x7.
(720 watts = .720 KW ). My electricity costs about \$15 after delivery charges, etc.)

So I multiply that by the number of watts used my any device that draws constant power.
For example: TiVo = 25 watts = \$2.70 per month.

Emo XPA-1L: \$21.78
KBarnes701's Amp: \$47.52

- Rich
Quote:
Originally Posted by kbarnes701 The thing with my Class A amp is that it sounds really rough until it is thoroughly warm - at least 30-40 minutes of use. I have no idea why this should be so, and generally I don't believe that SS equipment should change sonically as it gets warmer, but it does. This isn’t a placebo type thing - it really does sound rough when it is cold. So I just left it on all the time. It's been on for 20 years, steadily drawing 440 watts unbeknown to me...  The Emo amp may not sound rough when it is warming up so it can be switched off at the wall when it is not being used. It will also have a standby mode which my amp doesn’t have and in standby the Emo may have acceptable power use figures. 201 watts at idle doesn't really matter because when it is on it won’t usually be idling.  440 watts a day for 20 years. I am in shock I think :)

Green gas effect!

Quote:
Originally Posted by RichB

I came up with an estimate in my area of about 14 cents per month for 1 watt 24x7.
(720 watts = .720 KW ). My electricity costs about \$15 after delivery charges, etc.)

So I multiply that by the number of watts used my any device that draws constant power.
For example: TiVo = 25 watts = \$2.70 per month.

Emo XPA-1L: \$21.78
KBarnes701's Amp: \$47.52

- Rich
\$40+ per month just keeping the amps on 24/7 (I'm assuming that the XPA-1L figure is for one monoblock)? Think I'll stick to my XPA-1's thanks (or upgrade to the XPR-1's if I want to do some structural integrity testing).

Max
Quote:
Originally Posted by djbluemax1

\$40+ per month just keeping the amps on 24/7 (I'm assuming that the XPA-1L figure is for one monoblock)? Think I'll stick to my XPA-1's thanks (or upgrade to the XPR-1's if I want to do some structural integrity testing).

Max

That is just for fun.
I would never keep them on 24/7.

- Rich
For me, \$0.089/kWh, so 440W 24/7 for a month would be about \$28.
Quote:
Originally Posted by whoaru99

For me, \$0.089/kWh, so 440W 24/7 for a month would be about \$28.

Here in MA, that is the generation charge. Then, you need to add delivery and taxes.

- Rich
There is a separate ~\$5 tax line on my last billing total of ~\$200, but that covers electricity, sewer, water, and garbage collection so it would be a mere fractional addition to the cost to run the amp. Overall, electricity is nearly 75% of the total but I run electric heat which is billed at a lower off peak rate.
Quote:
Originally Posted by whoaru99

Suppose you could always hook up with a Krell KSA-250. They draw ~12A at idle from a 120V line (1,440 watts).

Quote:
Originally Posted by RichB

I came up with an estimate in my area of about 14 cents per month for 1 watt 24x7.
(720 watts = .720 KW ). My electricity costs about \$15 after delivery charges, etc.)

So I multiply that by the number of watts used my any device that draws constant power.
For example: TiVo = 25 watts = \$2.70 per month.

Emo XPA-1L: \$21.78
KBarnes701's Amp: \$47.52

- Rich

20 years they have been on. 20 years!!  Hahaha - the electricity has cost more than the amp!

Quote:
Originally Posted by wse

Quote:
Originally Posted by kbarnes701 The thing with my Class A amp is that it sounds really rough until it is thoroughly warm - at least 30-40 minutes of use. I have no idea why this should be so, and generally I don't believe that SS equipment should change sonically as it gets warmer, but it does. This isn’t a placebo type thing - it really does sound rough when it is cold. So I just left it on all the time. It's been on for 20 years, steadily drawing 440 watts unbeknown to me...  The Emo amp may not sound rough when it is warming up so it can be switched off at the wall when it is not being used. It will also have a standby mode which my amp doesn’t have and in standby the Emo may have acceptable power use figures. 201 watts at idle doesn't really matter because when it is on it won’t usually be idling.  440 watts a day for 20 years. I am in shock I think :)

Green gas effect!

:)  I am a one-man contributor to global warming.... I plead Ignorance...

Quote:
Originally Posted by djbluemax1

Quote:
Originally Posted by RichB

I came up with an estimate in my area of about 14 cents per month for 1 watt 24x7.
(720 watts = .720 KW ). My electricity costs about \$15 after delivery charges, etc.)

So I multiply that by the number of watts used my any device that draws constant power.
For example: TiVo = 25 watts = \$2.70 per month.

Emo XPA-1L: \$21.78
KBarnes701's Amp: \$47.52

- Rich
\$40+ per month just keeping the amps on 24/7 (I'm assuming that the XPA-1L figure is for one monoblock)? Think I'll stick to my XPA-1's thanks (or upgrade to the XPR-1's if I want to do some structural integrity testing).

Max

I switch my Eno amps into standby when they are not in use - they seem to be good to go from the moment they are powered up (as I'd expect from SS gear really). The only reason I left the pure Class A (that description always makes me smile) on all the time is they sound dog rough for the first 30-40 minutes otherwise - and sometimes my 'listening window' is just one album of about 40 minutes, so if I started from cold the album would just be over by the time the amps got 'on song'. My way is expensive but the system is always ready to go.... I have decided to leave it on all the time even now I know the cost - I figure if it's been like that for 20 years and never bothered me, what the heck... :)

I have to say, I do not understand the warm up thing with Class-A.
It makes more sense with Class-AB which take time to warm up. Class-A warms up in no-time

- Rich
Quote:
Originally Posted by RichB

I have to say, I do not understand the warm up thing with Class-A.
It makes more sense with Class-AB which take time to warm up. Class-A warms up in no-time

- Rich

It doesn't make any sense to me either - SS equipment shouldn't need any 'warm up' time at all - they're not tubes! IMO full performance should be available immediately on switch-on.

But it isn't the case with my Class A amp. It sounds awful until it has been powered on for at least 30 minutes. This is not a subtle thing - it sounds rough until it has warmed up. You say it should warm up in no time, but in my case this is not so. The amp starts to get warm as soon as it is powered on of course - but the heat sinks do not get too hot to touch until about 30 minutes have elapsed. From that point it is fully useable and sounds so sweet.  All my other amps are Class A/B and I can use those immediately they come out of standby and there is no amelioration of the SQ after they have been on for a while.

I think you got a bad cap somewhere, it's taking too long to charge and not holding, think car battery with and endless alternator.
Quote:
Originally Posted by datranz

I think you got a bad cap somewhere, it's taking too long to charge and not holding, think car battery with and endless alternator.

Don't think so - it's been like this since the day I bought it. The 'audiophile' store I got it from told me to expect it to be this way.

I spend over \$4,800 in electric bill a year :( I could buy an amp every year!  The pool is a electrical sucker, I never use the air conditioning, a bit of heat in the winter in January, February and that's about it as I live near the coast in a temperate climate but the electric company is highway robbery!

Quote:
Originally Posted by wse

I spend over \$4,800 in electric bill a year :( I could buy an amp every year!  The pool is a electrical sucker, I never use the air conditioning, a bit of heat in the winter in January, February and that's about it as I live near the coast in a temperate climate but the electric company is highway robbery!

That is a heck of a bill!  Even with my Class A I'm nowhere near that - but then neither do I have a pool (unfortunately) :)

Quote:
Originally Posted by kbarnes701 That is a heck of a bill!  Even with my Class A I'm nowhere near that - but then neither do I have a pool (unfortunately) :)

Yes, it is a friend of mine pay over \$12,000 a year in electric bill! His house is 7,000 square feet

Quote:
Originally Posted by wse

Quote:
Originally Posted by kbarnes701

That is a heck of a bill!  Even with my Class A I'm nowhere near that - but then neither do I have a pool (unfortunately)
Yes, it is a friend of mine pay over \$12,000 a year in electric bill! His house is 7,000 square feet
I wonder what \$12,000 (or say, \$36,000) worth of solar technology would do to that bill?

Max
Hard to say only with the price of the solar system. You'd have to know the typical output of those solar systems in your locale, the amount of electricity consumed, and the cost of electricity in your area.

There is some tricky lingo used when looking into this. One of them is "energy payback" which is only the amount of time it takes to produce the same amount of energy as it took to make the system. That is usually 2-5 years. However, that's misleading because that's not the payback time of the cost of the system vs how much utility electricity demand/cost was reduced. Some say the true payback in the later regard is very long...
Edited by whoaru99 - 3/28/13 at 11:47am
Yes, I looked into solar it ' s more like ten plus years
Quote:
Originally Posted by wse

Yes, I looked into solar it ' s more like ten plus years

And if the sun is not out, you are not allowed to listen to you HT.
Not at all good for night viewing

- Rich
Quote:
Originally Posted by wse

Yes, I looked into solar it ' s more like ten plus years

That was my point. It's more like 30 years, maybe more, if you look at the total picture not just some "energy payback" mumbo jumbo.
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