[Gill]

Hi,
I am thinking of some changes in my setup, i shall be adding a Monoblock amp to my current setup.

Taking Reference from these links:-
http://www.team-bhp.com/forum/ask-gu...tml#post220127
& Recommended Power and Ground Cable Sizes
Taking the equation into account given in link by gunbir:-
I=(TP*2)/Vbatt(12V),
Calculating total power=
Amp-1 JBL 75.4, 416w@4ohms @14.4v and 568w@2 ohms @14.4v.Fuse rating 2*30A
Amp-2 Mono 500w@4ohms @14.4v and 900w@2ohms @ 14.4v.
Now calculating the max power should i take into account 4 ohms fig or 2 ohms fig.
On 4 ohms fig current draw is-152.6
on 2 ohms fig cuurent draw is-244.6
Though i will be using both the 4 channel amp in 4 ohms mode and in future i might run the mono on 1 Ohm load.
How should i go about slecting the Power wires.I have swift,what should be the lenght of power cable,the amp are mounted on rear seat back.
My current POWER KIT is Audison FPK 300 it's 8 AWG power & grond cable, 60 A fuse with it.If i upgrade how can i make use of it in this upgrade.
Can i run two seperate power cable from battery,so that i can use FPK300,and add a thicker cable for the mono.
If i missed out some information plz do ask.
Cheers!

[vebmetal]

I know we all get "excited" about ICE here, but do we have to go this far?

[Gill]

Originally Posted by vebmetal

I know we all get "excited" about ICE here, but do we have to go this far?

@vebmetal "excited" is not the right word my friend,this forum is all about getting basics right.
Those who have no idea about basics do tend to get "EXCITED" .

Cheers!

[vebmetal]

You didn't get the joke - look closer at the picture...

[Gill]

Originally Posted by vebmetal

You didn't get the joke - look closer at the picture...

had it mate in first go!!!!!
Comming to the topic,how should i go about it.

[Bass&Trouble]

Originally Posted by Gill

On 4 ohms fig current draw is-152.6
on 2 ohms fig cuurent draw is-244.6
Though i will be using both the 4 channel amp in 4 ohms mode and in future i might run the mono on 1 Ohm load.

Not cross-checked any of your calculations but if you are going to draw 244 amps, you need a 1/0 gauge cable.

In the future you will run at 1 ohm? So, the mono operates at 1 ohm? If so, then the current will be greater than the 244.6 you have calculated? Then go for 1/0 right away, I would say.

If you get a 1/0 gauge kit, you could probably use a small bit of the Audison 8 gauge cable to take a tap from the 1/0 cable to the speaker amp and for the earth. I dont see any other use for it.

[Gill]

I arrived on the figs as follwoing:-
On 4 ohms fig current draw is-152.6
I=(TP*2)/Vbatt== ((416+500)*2)/12=152.6
on 2 ohms fig cuurent draw is-244.6
((568+900)*2)/12=244.6

@B&T,sorry if i am getting it wrong,you mean to say that,i can use the 8ga wire to speaker amp(75.4) from distribution block.
what is double run of power cable?

[low_bass_makker]

Originally Posted by Gill

I arrived on the figs as follwoing:-
On 4 ohms fig current draw is-152.6
I=(TP*2)/Vbatt== ((416+500)*2)/12=152.6
on 2 ohms fig cuurent draw is-244.6
((568+900)*2)/12=244.6

@B&T,sorry if i am getting it wrong,you mean to say that,i can use the 8ga wire to speaker amp(75.4) from distribution block.
what is double run of power cable?

Sir the method is wrong...but which amp are you going to use AB class or D class as the later are more efficient and consume less current.

formula is

Current = Watts (output+ heat generated) / Voltage

The watts can be calculated as like for a amp max wattage figure whether it is 1 ohms or 2 ohms or 4 ohms. So let us assume a amp can give Max 100 watts so if it is a AB class double the load as they are 50 % efficient but if it is a D class they are 80 % (approx) efficient so the load figures will be 200 watts for a AB class and 125 watts for the D class not do the current calculation..

for AB class 200 / 12 = 16.6 Amps

for D class 125 / 12 = 10.4 Amps

So if your amp is 900 watts the If is a AB class it will consume max 150 amps and if it is a D class it will consume 90 amps.

[Gill]

LBM, went through few threads about these calculations,but couldn't make out the best way of doing it.even i didn't get, how you have calculated the watts,mono is a class d amp.
Is there any benchmark for efficiency(I presume heat generated) for amps of different class.
Or why one should consider heat generated(Thermal fig) into account while calucalating the wires
it will be lot easier for me if you suggest the wires n fuse i should opt for.
Better solve the problem rather making it more complicated.
I said so as there already had been a heated debate on this issue.let's have a swift solution.
NO offence meant to any one!

Cheers!

[low_bass_makker]

Originally Posted by Gill

LBM, went through few threads about these calculations,but couldn't make out the best way of doing it.even i didn't get, how you have calculated the watts,mono is a class d amp.
Is there any benchmark for efficiency(I presume heat generated) for amps of different class.
Or why one should consider heat generated(Thermal fig) into account while calculating the wires
it will be lot easier for me if you suggest the wires n fuse i should opt for.
Better solve the problem rather making it more complicated.
I said so as there already had been a heated debate on this issue.let's have a swift solution.
NO offence meant to any one!

Cheers!

The thermal figure is considered as they will also include while the load is calculated.

Yaar simple tell us the amp and we will suggest you the wires and also how we evaluate them. This way it will be easy to understand.

[Gill]

Amps shall be JBL 75.4 and Kenwood 9103D.Plz do consider the upgrade possibilities for a 4 channel amp.

Cheers!

[low_bass_makker]

Kenwood KAC-9103D Mono subwoofer amplifier 900 watts RMS x 1 at 2 ohms at Crutchfield.com

and

JBL Grand Touring Series GTO75.4 II 4-channel car amplifier 104 watts RMS X 4 at Crutchfield.com

both the amps has 30 x 2 amps fuse. Also the 4 channel will work on speaker duty that is with HPF, so the current consumption will be quite less of that amp. But anyways a simple logic you can go for a single 4 gauge cable as it is capable of handling 150 amps. (30+30 + 30+30 = 120 amps fuse total) as the 8 gauge will be less for your application.

Recommended Power and Ground Cable Sizes -> check the Power & Ground Cable Specs chart

Or

One can calculate the Ampere

For the Kenwood as it is D class I am assuming it to be 80 % efficient so the max current watts it will draw will be 900 watts + 20 % = 1080 watts

so 1080 / 12 = 90 amps

The above case will happen when you play a sine wave and never possible with music.

For the JBL amp Max it can give is 104 x 4 or 284 x 2 but since you are using it for 4 channel I will take 104 x 4 = 416 watts . Bening it AB class I will assume it 50 % efficent so the total watts drawn will be 416 + 50% = 832 watts

so 832 / 12 = 69.3 amps

Now one more important thing to consider here is that since you are using the amp in Speaker duty the peak current demand will be never 69.3 amps. so you can consider it less also. Anyways total demand is now 90 + 69.3 = 159.3 amps which can be considerd to be 150 easily. Which a 4 gauge (25mmsq) cable can easily handle without any problem.

So calculate it anyway you just need a 4 gauge (25mmsq) cable for the job even if you upgrade your speaker amp also.

[Gill]

Originally Posted by low_bass_makker

Now one more important thing to consider here is that since you are using the amp in Speaker duty the peak current demand will be never 69.3 amps. so you can consider it less also. Anyways total demand is now 90 + 69.3 = 159.3 amps which can be considerd to be 150 easily. Which a 4 gauge (25mmsq) cable can easily handle without any problem.

So calculate it anyway you just need a 4 gauge (25mmsq) cable for the job even if you upgrade your speaker amp also.

Thanks alot for detailed explaination LBM,So i need a 4 gauge power cable to the distribution block and then should i use a 4 guage or 8 guage can do for each amp,and power cable guage n ground cable should be same size? right. What should be the fuse size for the battery terminal and D-block?I think i can put the FPK300 in use if 8 gauge can be used to power each amp from the d block.

Cheers!

[Gill]

When one has a inline main fuse holder,simple distribution block will do!Or a fused d-block is required.

[low_bass_makker]

Originally Posted by Gill

Thanks alot for detailed explaination LBM,So i need a 4 gauge power cable to the distribution block and then should i use a 4 guage or 8 guage can do for each amp,and power cable guage n ground cable should be same size? right. What should be the fuse size for the battery terminal and D-block?I think i can put the FPK300 in use if 8 gauge can be used to power each amp from the d block.

Cheers!

You are welcome. Ya 4 ga is more than you require. I would sugest to use 4 gauge for the mono and 8 gauge for the 4 channel. The fuse at the battery terminal should be 120 amps. Both the ground and positive cable should be 4 ga.

Originally Posted by Gill

When one has a inline main fuse holder,simple distribution block will do!Or a fused d-block is required.

No need to use a fused D- block if there is inline main fuse holder.