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Sub Amp Not Enough Power? 

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 6:54 am 
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Timmy Tim Tim, I think you need to look at Mobile Electronics Australia and some of the build's there.

Being an Electrician you should know that the alternator to battery should have a bigger cable than battery to amp. Stock wiring isn't sufficient, and should be the first thing upgraded along with a bigger ground to battery, nice solid ground to bear metal. There is NO NEEDED to run cable to the boot and no need to fuse a negative cable to whoever said that.

Before you get a CAP upgrade your Alternator to battery cable (fuse this run), your ground to battery and your engine to ground connection. This is called the Big 3 as recommended before, it reduces voltage drop across the system. YOU DONT NEED A CAP for your system. Look at getting your alternator tested to see if it is still making 70amps after all this time, i doubt it is.

http://www.mobileelectronics.com.au/forums/index.php?/topic/556251-capacitors/page__hl__capacitor__st__15
http://www.mobileelectronics.com.au/forums/index.php?showtopic=78792
http://www.mobileelectronics.com.au/forums/index.php?showtopic=42742&hl=capacitor
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 8:47 am 
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87SIlude wrote:
With the 5 alt and 14 2 volt batteries you'd expect it to be "rough" but with the time and money he'd spent he would have 0gauge connecting all the batteries and everything. (Well I would)
The less resistance through the bigger wire really "smoothes" out the power draw.
I think that's why the headlights draw so much power. Really small gauge wire with high resistance and a decent power draw.

It works like that dosnt it?


Sort of... I wouldn't call it smoothing power out... But the bigger the wire, for the same current, the less heat produced (H=I^2 x t), when you have less heat produced you have less resistance increase... When you have less resistance you have less voltage drop... Technically this is how it works for DC...

For filtering and smoothing power out, the only way I know is by use of an electrolytic type capacitor when by when you have a spike, you cap tends to absorb it as a charge and when you have a sudden drop you cap discharges to keep it as constant as possible... Same as the regulation stage of DC power supply I've ever fixed...

jrloz I do agree with you that for big gear then yes upgrade the alternator wire (no point running 4 gauge to a massive amp set up when the factory link between the alternator and the battery is 8 gauge)... And as you mentioned the same size (if not one size bigger wire) to a good clean spot on the chassis and preferably somewhere that will stay clean and not become corroded over time as this will only result in massive problems and headaches...

my point with the cap (note its not required on a small system, but even for the sake of filtering is not a bad idea to have) is that they can discharge quicker than a lead acid battery... If you run absolutely massive gear without a cap and the battery is "trying" to provide these short bursts of power to the amp (the alternator only charges the battery, not powers the whole car, in a complicated round about way, it looks at voltage for its output and is picked up off battery voltage, when it sees a drop across the terminals it provides higher output, or so I'm lead to believe)... A cap can do this impulse bursts without breaking a sweat... Whereas doing this to a lead acid will only greatly reduce its life and cause it collapse in less time.

Each to their own... I only run a 250watt (or something like that) amp for my parcel tray sub as I have never seen the need for a completely deafening sound system... I'm deaf enough as it is so it only ever stays at a reasonable level... I don't run a cap and don't see a flicker of any kind... Its only a tiny system... Even the one here from the OP is small... Probably not enough for a cap... But some of these big ones... The poor all old lead acid battery must hate its life... They were invented for a reason... and as I said for filtering and burst discharge features, DC power supplies use them...

If you don't wanna run a cap then hey I'm cool with that... Only trying to explain why you run one and how they work as there seems to be some misleading info about all this stuff on the first page, some wrong info and facts by my teachings and understandings...

Cheers,
Tim

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 10:53 pm 
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Ok im sober tonight.
Let me explain myself.

I DO know caps are usefull. Yes they are needed in a lot of thing.
But before using a cap why not fix everything else to actualy help the cap out and have better overall performance.
Bigger gauge power wires. Grounds. Battery. With all this done you usually will have minimal dimming with a small system like this one (wich we are discussing. Not all the fancy 40k gear)
I learnt a little in a auto ellecy inschool tafe course and I do understand more then you assume.
I didn't mean run 2 8gauge instead of 1 4gauge I ment rather then running 4gauge into a distro then into 2 8gauges (more connections more resistance right. Plus the resistance added by going from 4 to 8.) Just use 2 runs of what ever the gauge is you need. This is how all great systems are made.

Sure a solid state can output all that is needed. But for a system like this. The one mentioned. It would do the job fine.

Basically what im saying is we went off track from the ops question and then everyone (espesially me) got lost.

But thanks for the info. Refreashed what I had learnt.

Caps are good yes. But not when you havnt fixed everything else.

Like squirting nos through a stocker. You won't get the same output. Better yes. But not how it should be.

Great thread to read. I've read it several times and it has a lot of good info in it.

Cheers.
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 10:58 pm 
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Now I agree with you...

Well put and makes a lot more sense now... that sober thing works well :wink:

Cheers,
Tim

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 11:05 pm 
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hmmmm upgrade the wire between alternator and battery?
what size woul be recomended?
i have just installed a 8gauge earth to body connection tonight so i now have the factory earth and the new 8 gauge earth

cheers bear

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 11:11 pm 
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all depends how much current all your boot gear needs...

Ford factory earths look to be around the 8 gauge mark, well on my ED anyway...

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Tue May 11, 2010 11:38 pm 
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Yea. Damn $20 dark and stormy 6packs. Haha.
Well if the alternators are around 70amp id say its 8gauge.
4gauge would surfice. Anything else would be overkill.
Would there be any point putting 0gauge from the alt to the battery if the alt only runs at 70amps.?
But do check your connections at the alt atleast. They get corroded and gross over time.
I havnt upgraded mine as I sold most of my sterio. But I did run some 8gauge from the battery to the chassis and I noticed even that stopped the dimming a tiny bit.
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 12:13 am 
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87SIlude wrote:
I didn't mean run 2 8gauge instead of 1 4gauge I ment rather then running 4gauge into a distro then into 2 8gauges (more connections more resistance right. Plus the resistance added by going from 4 to 8.) Just use 2 runs of what ever the gauge is you need. This is how all great systems are made.


No. Once again, no. You're wrong, just as wrong as you were before when you said the exact same thing earlier.

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 12:25 am 
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Ok krisdog how?
How is it worse to run a sepperate run of wire to each amp rather then one run and a t piece?
Sound pretty f**k right to me.
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 12:39 am 
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hey guys
been doing some research on the big 3 upgrade on YouTube

I decided to go the big 3 with gauge wire so it will be 4 gauge between negative battery post and chassis and negative battery post to engine block and 4 gauge between positve battery positive post and alternator.

reconditioning and cleaning of the alternator will be done as well.

will this be adequate in a small to medium install

cheers bear

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 12:46 am 
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Isn't it engine block to chassis not engine block to neg.batt. Altho its the same theory.

This will help any system. I think everyone should do this who has a half decent system. Aswell as good amp grounds and connections. Good luck with it and let me know how you go.
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 12:59 am 
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All the big 3 videos on YouTube had the both earth leads starting at the negative battery post

I may end up throwing one on between the block and chassis

I just wanna do my system once and do it right do and have it reliable

bear likes overkill LOL

I think the fella who started this thread has got way more info then what he asked for

cheers bear

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 1:50 am 
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87SIlude wrote:
Ok krisdog how?
How is it worse to run a sepperate run of wire to each amp rather then one run and a t piece?
Sound pretty f**k right to me.


Steady ED wrote:
4g csa is greater then two runs of 8g, not to mention it's alot easier to have one lug and one fuse at the battery.


In case you misunderstood, csa = cross sectional area.

Recommended max fuse size
8g = 50 amps
4g = 125 amps

Meaning you can get more power to the amps with 1 run of 4g than 2 runs of 8g!
Whats so hard to understand?

 

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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 9:24 am 
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I didn't say run 2 8gauges tho. Well I did orgianaly. But I ment run 2 4 gauges.
With what you said there when you go from 4 to 2 8s its doing EXACTLY the same thing isn't it. Restricting the power flow by increasing the resistance.

Bear.
It would be a good idea to do it right the first time. A lot of people don't then have grounds pop off and headaches later on.
But you probably don't need both the grounds off the block.
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 Post subject: Re: Sub Amp Not Enough Power?
Posted: Wed May 12, 2010 9:48 am 
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what are you talking about?!?!
you said run 2x 8 gauges because it's better then a single 4awg cable, now you are saying you meant 4awg cables?
Why would he run 2 4awg cables?

 

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