# Power Considerations



## a1161979 (Aug 26, 2007)

Hi guys. 

As far as i know this topic has not yet really been covered. I have noticed in other posts that many are using power amplifiers for each channel in surround and high powered pro amplifiers to drive LFE. Considering the level of current required by such devices i was wondering what considerations have gone into power supplies?

I was wondering if people would like to discuss the power requirements that modern Home Theater systems demand, also to want extent have members targeted power supply as a weak link in their Home Theaters. More often than not people focus on connecting cables, speaker cables and other factors yet power supply never seems to be targeted. Obviously a power amplifier (for example) will only be able to perform at an optimum level if it is being provided enough 'clean' power. Feel free to discuss anything related to power :T I was also wondering if anyone was using a Power conditioner and if so how it benefited their setup...

Considering the lengths that some have gone to over DIY subwoofers i'm sure many have tails to tell about their missions to correctly provide current to their Home Theaters. In addition do you really think that power should be considered on the scale that other aspects are? Anyone out their using 4AWG power cable for their power amplifiers? (I know someone who is :coocoo Personnaly i think power should be a serious consideration for anyone serious about Home Theater. 

Discuss...


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## Danny (May 3, 2006)

As I see it one 20 amp supply line would be enough (40amps for 120VAC)


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## a1161979 (Aug 26, 2007)

Depends on the equipment though, I know someone running 7 (yes 7) A500's for his 7.1 Home Theater as well as an EP2500 For his sub, Surely he has additional power consideration.

Also that is assuming that the line is a constant 240 volts which clearly it is not. Personally in Adelaide my voltarge varies from 238 to 247ish, this does have an effect on the operation of Home Theatre equipment...


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## bob1029 (Feb 26, 2007)

As far as im concerned, the power conditioners being sold under the guise of line noise supression are a complete waste of money. If there is truly any serious continuous drop in line voltage (serious being <90 volt on a 110 line), then line noise is the least of your concern. Most ac-dc power supplies on high-quality equipment can handle a wide range of instantaneous ac voltage inputs. If you think you have a noise problem with your equipment and confirm that its not ground-loop or component-based, then it would be a better idea to buy higher-quality equipment that properly isolates ac/dc components as well as high and low voltage power supplies. A power filter cannot solve problems with a poorly designed amp/tv/projector/reciever/stb. These are high-margin products being sold by electronic retailers to help compensate for the losses taken on highly competitive lcd tv sales. You will often see graphs showing frightening fluctuations around these products, but they are always lacking domain and range, as well as some sort of title showing what it is actually representing.

Now let me say that there is a significant difference between pseudo-science "noise filters" and line conditioners. If you are experiencing a significant and continuous drop in line voltage, then a variac is the best solution. These are capable of taking input ac voltage ranges between 80-140 volts and automatically adjusting the taps to maintain an output as close to 120 as possible. The only downside is that they consume power themselves and reduce efficiency of your equipment by about 10-20%.

If you are running SEVEN a500s and an ep2500 there may be some concerns. I am personally running 2x ep2500 and I notice the lights drop to about 3/4 normal brightness when I start to crank the bass. I always thought of this as "cool" :R, but I suppose that im losing some output in the process. I may grab one of those tripp lite 2400 watt variacs and see if it affects the bass output.

here is an example of one: http://nooutage.com/lc2400.htm
Something tells me that this probably has more power handling than some pricier monster products...


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## dynamowhum (Oct 3, 2006)

Having started down the ever spiralling path of hometheater about 4 years ago, I thought at the time that 1 dedicated 20 amp breaker would be adequate. Silly me I thought I was doing something great to build a room with a dedicated circuit for my rack. Now I am thinking of ways to run 2 more with my enterior walls and ceiling completeld and painted. I did put several double ganged outlets behing my rack area but all on the same circuit. Brilliant simply briliant. The pain begins to subside after I quit hitting my head of a post.


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## Wayne A. Pflughaupt (Apr 13, 2006)

a1161979 said:


> Depends on the equipment though, I know someone running 7 (yes 7) A500's for his 7.1 Home Theater as well as an EP2500 For his sub, Surely he has additional power consideration.


Probably is, but it might not be as much as you might think. For instance, if his receiver was “not quite there” before – barely clipping - he might need only another 1-2 dB of headroom, plus whatever the amp would use idling above what the receiver did. So, increased current demands in a case like this would be notable, but nothing drastic.

Of course, some amps use a lot of current idling – so-called Class A or B (forget which). But that type isn’t too popular. 

Now, if he’s running inefficient low-impedance speakers, then for sure, he’s chewing up the juice.



> Also that is assuming that the line is a constant 240 volts which clearly it is not. Personally in Adelaide my voltarge varies from 238 to 247ish, this does have an effect on the operation of Home Theatre equipment...


Nine volts is not an unusual variation here in the states with our 120-volt power. Virtually a non-issue for you. 



bob1029 said:


> I am personally running 2x ep2500 and I notice the lights drop to about 3/4 normal brightness when I start to crank the bass. I always thought of this as "cool" :R, but I suppose that im losing some output in the process. I may grab one of those tripp lite 2400 watt variacs and see if it affects the bass output.


Gee, for $400 I’d just have another circuit put in. I think that would give you a lot more bang for the buck. Need some help? 

Regards,
Wayne


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## dynamowhum (Oct 3, 2006)

Hey Wayne we are pratically neighbors, just a hop across the Louisiana border. No more than 160 miles or so. You say you like to crawl around in attics to run wire, man have I got a fun time for you. Come on over and see my frankenstiens monster. I even feed you and make whatever poison you are drinking. When done we will fire the system up and scare small children and make dogs howl. 
Just teasing actually but help of anykind is always welcome. Sorry for the thread still but couldn't resist.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hee hee – I try to avoid attics, unless it’s January or something. :yes:

Seriously though, have you seen my in-wall wiring thread? The same techniques apply to electrical, too. You could install the old work boxes and outlets in the home theater and run the romex from there back to the service panel, leaving plenty of slack. Then get an electrician to come out to route the romex into the panel and make the connections for you. Should be pretty cheap, since you’d have already done the _hard_ work!

Regards,
Wayne


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## dynamowhum (Oct 3, 2006)

Yeah I wired my room myself including terminating so I can do it. I just hate crawling around in the attic!Getting to old to play in those conditions. LOL


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