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Discussion Starter · #1 ·
Ok whats the deal with these?

Just in process of upgrading my soundsystem. Have bought a sub , amp and wiring kit and a 1.5 farad power capacitor (just in case)

Now looking at the wiring diagram of the power cap i can see that before live wiring hits the amp there is a distribution block which seperates the wiring, sends power to the amp, and also sends power to the capacitor , and cap is earthed to body.

Now ive done a search on ebay, noticed some are fused? why is this when the power cables fused already. Also there are AWG ratings. The wiring kit ive bought says its 4AWG, what does this mean? Also why do distribution blocks have 1 x 4AWG input / 2 x 8AWG output? Which one would suit me best.

Btw for now its a 1000w active sub with a 3000w 4awg wiring kit, 1.5 farad cap. Reason i went for these is the active amp is only for the time being as i plan on uprating when funds allow

Any help on this matter will be much appreciated, also if you require more info just say.

Thanks
 

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Hey fella! Glad to hear your getting your tunes sorted!

Right, a distribution block is basically a neat way of splicing a cable to give you two or more outputs from one wire.

The way I looked at it is to think of electric and cables like water and pipes... wherever the cables are connected the electric will go... therefore you can hook the live onto your power cap, then take another wire to the +ve amp terminal from the same power cap terminal. However, its neater to use a distribution block, so you have one wire going to the power cap +ve, and one wire from the -ve, rather than having more than one wire to each power cap terminal!

The reason you technically should use another fuse is the same reason you use one from your main battery... a power cap is basically like a mini battery that will step in and boost the amperage/voltage when you are cranking the system. Therefore, if the power lead from the power cap was to ground on the shell, it would burn-out, and obviously, fire is not good!!! So I would advise to fit another fuse in the power cap positive lead (/leads depending on your wiring), its best to be safe, not sorry!!

The AWG rating is the size/thickness of the wire, what RMS is the amp you are running? To do it correctly you should measure the length of wire you are using, and the amperage that will be drawn through it by the amplifier; that way you can check the wire is within its limits and will not catch fire. Squeezing alot of current down a thin wire is NOT good!

However 4AWG is a decent size, and I should imagine this will be fine, unless you have forked out for a mahoosive output amplifier!!! Also, by using decent wiring, the amp can draw the current 'easier' meaning it will work better!

Hope that helps and isnt confusing!!!

Andy [:)]

PS on another note Ive started getting my sound sytem back in too! Cant wait until its all in! Might not be a fast car... but maybe it can be the loudest... [:D]
 

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The way I normally do it is one PDB for +12 volts,and one for ground,but this is only really neccessary if you plan on having more than one amp.The power cap must be as close as possible to your amp,ideally six inches or less.I would run the 4 AWG power cable to the +ve terminal of the cap,and then something like thinner 8 SWG from the cap to the amp.Then I would run 4 SWG earth cable keeping it as short as possible (you could get away with 8 SWG for your main earth as the cable length will only be about very short) to the -ve terminal of the power cap,and then onto the ground terminal of the amp.Or if you are going to expand later,run the 4 SWG +ve wire to the PDB,then a short length of 8 SWG to the amp,and the same with the ground wire via it's own PDB.Then again keeping the wires as short as possible,connect the +ve and -ve terminals of the cap into the appropriate PDBs,leaving two more holes vacant to plug your extra amps into.
4 AWG is the thickness of the wire in American Wire Gauge,the smaller the number,the thicker the wire.4 AWG will carry about 150 amps continuous,and 8 AWG about 75 - 80 amps continuous,the longer the cable run the more voltage drop you will get,so the thicker it needs to be if you are going to be drawing any real amount of current.SWG is Standard Wire Gauge that we use over here,which is almost the same as AWG,but I can never remember if it's thicker or thinner.I don't think you need a fused distribution block,as you will have the main fuse near the battery protecting the car,and each amp will have its own fuse protecting itself.

And a final bit of maths you may be interested in,taking the average Golf alternator to be rated at 90 amps,or a total power of about 1200 watts and allowing 300 watts of power to run the car,you will only have about 900 watts to run EVERYTHING else,and as most amps are about 50% efficient,you can only expect a genuine 450 watts of power to drive everything in your sound system.The power cap will only really help if the alternator can keep it charged up,but if you draw so much power that it's output voltage starts to drop,it will do nothing.
 

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Discussion Starter · #4 ·
Ahah Andy, thanks mate.

So why cant i find a distributor block that will split single 4awg into 2 x 4awg?

As i said before, i have forked out on a pretty cheap active sub for the time being, just so i can enjoy a little bass until i can get the system i want.

This is the spec ,RMS Power - 300W ,Peak Power - 1000W

The blocks i find seem to always split into a larger AWG.

[edit] Thanks Imagewerx for clearing a few more things up, there may be a few more questions to come yet [y]
 

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They are about, you just gotta find them! [:)] Good luck with it, and hope you are happy with it! What size sub have you gone for?
 

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You wouldn't normally need to split 4 AWG into more 4 AWGs,for the shorter cable runs you can use the 8 AWG,that's why most PBDs are 1 x 4 AWG in,and 4 x 8AWG out.We do keep ones that are something like 0 AWG in,2 x 4 AWG and 4 x 8 AWG out for those really monster bass installs.

Chris.
 

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Oh and most amp power ratings are hopelessly overoptimistic,the true peak power rating is only 1.414 times the RMS,or average power output.

Chris.
 

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Discussion Starter · #8 ·
Its only a 12" fli active sub, but for £64 brand new + delievered i thought itd be alright for now.

Im going to be cheeky now but could either of you knock up a simple wiring diagram in paint + stating wire thickness etc

So id be best with a 4awg input split to 2 x 8awg? I understand it now , thought the bigger awg would be fatter.
 

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It is better if you can keep the thicker wire right to the amp though, the smaller wire will strangle the current flow! Well, to what it could be with the thicker stuff right through.
 

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I would run one of these; with 4AWG right through, and 40amp fuses. Thinking about it, the fused distribution block would make more sense [:)]

Posted Image


PS sorry for the quick messy style! [:)]
 

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It is better if you can keep the thicker wire right to the amp though, the smaller wire will strangle the current flow! Well, to what it could be with the thicker stuff right through.
Over this short a distance it won't make any difference,the current demands of incar amplifiers aren't anywhere near as high as most people seem to think.Voltage drop is not only proportional to thickness,but also to length,and the amount of current that is drawn by the load,you'll get more voltage drop across all those extra fuses than you will along about a foot or so of 8 AWG cable,trust me I've been doing this for a very long time.There's no reason why you can't use the thicker cable all the way through if you feel the need,but that's the reason why they make PDBs the way they do with the outputs a lot smaller than the input.As I said previously,the standard charging system in a Golf has it's limits and can at the most give about 60 amps safely to run the sound system,which 8 AWG cable is more than capable of handling,and unless you fit a higher output alternator,you will never,ever have any more current available to run the system.

Chris.
 

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Quick question trolledgon.. why do you need a distribution block in the first place.. also as imagewerx has said keep the power cap as close as possible to the amp.. i.e. the shorter the wire distance the better.. also for the amount of power you'll be using for the fli sub and amp you'd only really need a 8awg amp kit but as you have said you have baught a 4awg one as you want to upgrade later that is better.. but once you go over 1000w rms then id go for 0awg wiring as sonny had to rewire his setup from 4awg to 0awg as the amp just kept burning the 80amp fuses for a joke.. so he installed a 300amp fuse with 0awg and that helped big time... also if your gonna upgrade later.. you'll probs be looking at another power cap.. if you do buy another power cap just buy another 1.5 farad one and run it in series (i think iirc) with the exsisting one and you'll have a combined farad rating of 3..

hth

Sat [y]
 

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if you do buy another power cap just buy another 1.5 farad one and run it in series (i think iirc) with the exsisting one and you'll have a combined farad rating of 3..

hth

Sat [y]
Actually you need to wire them in parallel,you'll halve the capacitance in series.

Chris.
 

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Ok, but I personally do everything I can to keep the current up, hence why I would use the thicker gauge right through. Also, you should use a fused distribution block on your positive, as if you manage to short your main power cable running through the interior from the front, ok, ur protected from your main battery, but the power cap will make a connection with ground; and the most probable result is a fire.

Its exactly the same as adding extra batteries in the back, and the reason you double fuse between the front and rear.
 

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If the +ve lead to the cap shorts to ground,the fuse at the front will blow,and the cap will make a big spark and discharge all the power that's stored in it in a very short period of time the way it is designed to do,i.e. a fraction of a second,it cannot possibly supply enough energy over a long enough period of time to cause a fire,unless of course an open container of petrol is nearby at the time.As I said,there is no reason not to use the same size cable all the way through except that you don't have to.I've worked on hundreds of cars that come into me with problems with their sound systems (this is my full time job by the way)and measured voltage at every single point I can,to know that you do NOT get a voltage drop along a short length of thinner cable.Even a fairly hefty bass amp that is fused for say 80 amps would only draw that under extreme circumstances,it's avergage current draw will be less than half that.Long cable runs yes,keep it as thick as possible to minimise voltage drop,but short runs (i.e. half a metre or less)will not be a problem.
And batteries in the back of the car will not,and can not under any circumstances make up for an alternator that can't supply enough current,it will almost certainly make matters worse,again I know this because I speak from experience.

Chris.
 

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Fair enough, but their is still a risk of a fire from a cap, no matter how fast they discharge their current.

I wasn't trying to say that an extra battery would solve the problem of a little alternator... 'fill your boot with batteries fill your hood with alternators'!

Anyways, I dont want to argue about it!! I was just saying how I would do it personally.... [:)]
 

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Discussion Starter · #18 ·
Thanks guys and calm down. [:p]

This thread was created just so i was sure what they were about. I saw a simple wiring diagram for the power cap and saw there was a DB in it. I was just curious to what they are, how to use them because im no expert on electrics and its the first time ive seen them installed on sound system.

The wiring kit i bought is a 3000w 4awg, so i thought this would most certainly power my next set up as im only looking for 2 x 1000w subs + suitable amp to power it (its not by all means going to be a MEGA install) I will come to all this when i get to it but its probably going to be 6 months down the line. If i have to buy better wiring and another cap then so be it.

am i right in saying that 8awg is half the size of 4awg? also are wiring kits labelled to what awg they are on the insulation?

i think either way i am going to follow imagewerx`s diagram, it seems the most sensible idea.

Oh and im looking to be running 40amp fuses throughout?

Any more tips just shout.
 

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Discussion Starter · #19 ·
Looking at imagewerx diagram, is that illustrated so i need 2 PB`s or is it possible to do that through one?. Another thing i dont get is im looking at these blocks.... take for example "one input and 3 outputs"...then looking at the diagram you can see three inputs and 3 outputs.

Im lost to what i need now. anyone point me in the right direction.
 

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if you do buy another power cap just buy another 1.5 farad one and run it in series (i think iirc) with the exsisting one and you'll have a combined farad rating of 3..

hth

Sat [y]
Actually you need to wire them in parallel,you'll halve the capacitance in series.

Chris.
hence the 'I think' as i couldnt remember .

Sat [y]
 
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