car head unit and amp in home
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=106303
Printed Date: April 26, 2024 at 11:23 PM
Topic: car head unit and amp in home
Posted By: mp2031
Subject: car head unit and amp in home
Date Posted: July 22, 2008 at 8:07 PM
im trying to use a 13.8v DC power supply rated at 75amps 1000w for a car head unit and 4ch amp just wondering if anyone has done this before
Miles 
Replies:
Posted By: DYohn
Date Posted: July 22, 2008 at 8:32 PM
Sure. What do you need to know? ------------- Support the12volt.com
Posted By: mp2031
Date Posted: July 22, 2008 at 8:38 PM
well i'd like to power a 4ch amp rated at about 4x75w at 4ohms , head unit and possibly another sub amplifier if possible or maybe a 4ch amp 2 run speakers and bridged rear as sub just wondering what would be best and would this all work or do i need another/bigger power supply
Posted By: haemphyst
Date Posted: July 22, 2008 at 9:31 PM
Do the math.
A head unit (not driving speakers) will pull 5-7A
75X4=300/.5=600 (running WFO)
600 watts in / 13.8V = 43A
43A + 7A = 50A
75A - 50A = 25A
25X13.8=345W left over
A Class AB amplifier would be 175WRMS or a Class D amp would be around 300WRMS. That's how much additional you MIGHT have, depending on the honesty of the manufacturer of the power supply. A cheapie Pyramid? Not honest at all, and QUITE over-rated. An expensive Astron? A bit under-rated. What have you ACTUALLY got in a power supply?
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: July 22, 2008 at 9:32 PM
Well if your power supply is rated for 1000 watts I'd suggest powering amplifiers/head unit totaling no more than about 500 watts audio output power. Should be fine. ------------- Support the12volt.com
Posted By: mp2031
Date Posted: July 22, 2008 at 9:55 PM
ah k , i have 2x soundstream 6x9 sst6.9 (2x150Wrms) , 2 x focal polyglass 165 V1 (2x70Wrms) , 12" mtx sub (1x300Wrmx) (might upgrade that sub) , and a 13.8 v DC power supply 1000w 75amps . no amplifiers or head unit yet , just wondering to power all this would i need another powersupply or will this do ?
Posted By: haemphyst
Date Posted: July 23, 2008 at 3:09 PM
Again... It doesn't matter what the speakers are rated. If you are planning on running them WFO all the time, then you need to size your amplifier(s) appropriately, but if not, then you have to take DYohn's suggestion, and decide on no more than 500 to 600 watts of RMS (and I do mean RMS - disregard c o m p l e t e l y any "peak" or "max" numbers...) amplifier power. That's all you are going to be able to run on that power supply, 500 to 600 watts, whether you are using 50 watt speakers or 1.21 gigawatt speakers.
And you STILL didn't mention what kind of power supply you have. We'll need to know that to determine if ANY of the information we have provided can REALLY be accurately applied to your situation.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: bullseye753
Date Posted: July 23, 2008 at 3:24 PM
GREAT SCOTT! did you just quote back to the future!?
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Posted By: megaman
Date Posted: July 23, 2008 at 3:54 PM
haemphyst wrote:
.... That's all you are going to be able to run on that power supply, 500 to 600 watts, whether you are using 50 watt speakers or 1.21 gigawatt speakers.
WHAT THE #@$% IS A GIGAWATT?!?! lol
Posted By: mp2031
Date Posted: July 23, 2008 at 7:21 PM
haha sorry mate forgot to mention that , its custom made a mate did it for me and believes it puts out 1000w , as for the amp i would get around 400w for the speakers and i guess il have to wait for another power supply to power the sub + another amp.
thanks for your help guys
Miles 
Posted By: mp2031
Date Posted: July 23, 2008 at 7:25 PM
has anyone here done this kind of thing ? , as i would like to get a more suitable power supply for this maybe something that can put out around 1000w with no trouble
Miles
Posted By: advanced_audio
Date Posted: July 23, 2008 at 7:29 PM
Is it fused? If so what size fuses are in there?
Posted By: haemphyst
Date Posted: July 24, 2008 at 10:28 PM
If you want to run 1000 watts of amplifier power, then you need 2000 watts of power supply. While that is not a hard and fast number, it is a good rule of thumb.
2000\13.8=145A
That's a HUGE power supply. I have a 100A power supply in my garage, and it is welded to a 4 wheeled cart. It weighs somewhere in the vicinity of 175 pounds!
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: mp2031
Date Posted: July 24, 2008 at 10:43 PM
oh yeah i see , can i use 2x13.8v1000w power supplys ? or will this not work ?
Posted By: haemphyst
Date Posted: July 24, 2008 at 11:43 PM
Analog (meaning big, heavy) power supplies don't care about their outputs being paralleled. No issues with doing that.
Switch-mode power supplies... Ummm... not so much. Before you try to parallel those, check to be ABSOLUTELY CERTAIN it can be done.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: mp2031
Date Posted: July 25, 2008 at 7:19 PM
ok , im getting a tailor made power supply @ 2000w 13.8 v Dc 145 amps ,
i will let you know how it goes .
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