I know many don't like Capacitors but...
04-03-2006, 05:52 PM
#11
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Posts: n/a
Originally Posted by loudtdi
Running 1/0 power wire to 1300 watts of amplifiers is massive over kill.
One 4 AWG would be acceptable with 1 or 2 farads of capacitance.
If you wanted to do it 'right' a 2 AWG would be best. Running (2) 4 AWG power wires is more work, harder to install and has more connections which is not ideal.
That being said, (2) 4 AWG wires is the equvilent of 1 AWG with the added advantage of lower ESR.
One 4 AWG would be acceptable with 1 or 2 farads of capacitance.
If you wanted to do it 'right' a 2 AWG would be best. Running (2) 4 AWG power wires is more work, harder to install and has more connections which is not ideal.
That being said, (2) 4 AWG wires is the equvilent of 1 AWG with the added advantage of lower ESR.
this is incredibly stupid advice that should be ignored. if loudtdi reads what he wrote and did a bit of math he would realize how incorrect his statements are. i hope he doesnt give audio advice often
04-03-2006, 05:57 PM
#12
Oh, sorry, you have a 2.4 farad cap already, It still wont make a difference.
Reality is that your alternator will supply almost all the current to the amp. When the amp wants more, the battery may kick in a bit, the cap stores a tiny amount of energy not to make any difference. For the cap to act as a true filter, You must have some resitance in the power cable from the battery to the amp. But adding the resistance by putting thinner wire increases the loss and reduces your overall power output.
Reality is that your alternator will supply almost all the current to the amp. When the amp wants more, the battery may kick in a bit, the cap stores a tiny amount of energy not to make any difference. For the cap to act as a true filter, You must have some resitance in the power cable from the battery to the amp. But adding the resistance by putting thinner wire increases the loss and reduces your overall power output.
04-04-2006, 12:33 AM
#13
0 Watt CAFz'r
Thread Starter
Join Date: Oct 2005
Posts: 35
Originally Posted by zoomer
Lets look at some numbers. You amps put out 600 watts rms, and assuming they are the pioneers GM510M, that is about 1000 watts peak into 2 ohms (from the datasheet/web site)
It is a class D amp, that is maybe 90% efficient, so that is 1100 watts power consumption. At 12 volts you then get
1100/12 = 90 amps peak current PER AMP. With 2 amplifiers that is 180 AMPS peak. First if you want to get that much power, you need to upgrade your altenator and battery. Bet lets assume you have or will. Lets also assume that you need 15 feet of wire to get from your battery to your trunk. AWG4 has .25 milliohms per foot, or 3.75 milli ohms total resistance. Using equation Watts= I^2xR we get 180x180x3.75mohms =121 watts of power dissipated in the 4 gauge wire. That is not trivial, but it only happens occasionally on peak demand, and certainly not while you are in the car, since your eardrums will blow if you are pushing 2000 watts peak thru the subs. Another calculation from ohms law (V=IxR) V=180X3.75mohms =.675 volts lost from the battery to the amp, when drawing peak current. The above calculations are approximate, but should be withing 10% or so. This is the way that you need to look at the issue. You need to put some data behind the guesses and opinions. You need to ask the questions; Why do you need this or that. The answers should be based on calculations that can be backed up and proven.
Using 2 AWG wire would halve the power dissipated in the wire and halve the voltage drop.
Here is a simple table of resistance per foot vs AWG size.
AWG mohms/ft
0 0.1003
1 0.1264
2 0.1593
4 0.2533
8 0.6405
10 1.018
So you decide. what you want to do. If this is an SPL car, then certainly run AWG1 or0 cable. But for everyday listening, AWG 2 or 2 runs of AWG4 is ok. AWG 2 will be cleaner, fewer fuses, connectors etc.
As for the Cap, there is no way that a 1 farad cap is going to make a shred of difference with 180 amps of current being drawn.
Here is a good general site to help you learn about car audio: http://www.bcae1.com/
There is a good section on Caps, and the author concurs with my opinion and others that do not make profits selling caps (most car audio shops make lots of profit selling caps) that caps don't do a thing. I know that the dealers reading this will not like to hear this, but they will not be able to prove otherwise. Bring the cap back to where you purchased it and trade it in for some lower gauge wire and good connectors, grounding block, fuse holder etc.
It is a class D amp, that is maybe 90% efficient, so that is 1100 watts power consumption. At 12 volts you then get
1100/12 = 90 amps peak current PER AMP. With 2 amplifiers that is 180 AMPS peak. First if you want to get that much power, you need to upgrade your altenator and battery. Bet lets assume you have or will. Lets also assume that you need 15 feet of wire to get from your battery to your trunk. AWG4 has .25 milliohms per foot, or 3.75 milli ohms total resistance. Using equation Watts= I^2xR we get 180x180x3.75mohms =121 watts of power dissipated in the 4 gauge wire. That is not trivial, but it only happens occasionally on peak demand, and certainly not while you are in the car, since your eardrums will blow if you are pushing 2000 watts peak thru the subs. Another calculation from ohms law (V=IxR) V=180X3.75mohms =.675 volts lost from the battery to the amp, when drawing peak current. The above calculations are approximate, but should be withing 10% or so. This is the way that you need to look at the issue. You need to put some data behind the guesses and opinions. You need to ask the questions; Why do you need this or that. The answers should be based on calculations that can be backed up and proven.
Using 2 AWG wire would halve the power dissipated in the wire and halve the voltage drop.
Here is a simple table of resistance per foot vs AWG size.
AWG mohms/ft
0 0.1003
1 0.1264
2 0.1593
4 0.2533
8 0.6405
10 1.018
So you decide. what you want to do. If this is an SPL car, then certainly run AWG1 or0 cable. But for everyday listening, AWG 2 or 2 runs of AWG4 is ok. AWG 2 will be cleaner, fewer fuses, connectors etc.
As for the Cap, there is no way that a 1 farad cap is going to make a shred of difference with 180 amps of current being drawn.
Here is a good general site to help you learn about car audio: http://www.bcae1.com/
There is a good section on Caps, and the author concurs with my opinion and others that do not make profits selling caps (most car audio shops make lots of profit selling caps) that caps don't do a thing. I know that the dealers reading this will not like to hear this, but they will not be able to prove otherwise. Bring the cap back to where you purchased it and trade it in for some lower gauge wire and good connectors, grounding block, fuse holder etc.
Yes, I have read the bcae1.com website and it's been a great reference many times over.
again, awesome.
Thanks
04-04-2006, 11:18 AM
#14
this is incredibly stupid advice that should be ignored. if loudtdi reads what he wrote and did a bit of math he would realize how incorrect his statements are. i hope he doesnt give audio advice often
Dave,
Please expand.......As you know, there is more than one way to do anything, your thoughts please so I may defend!
Some relevant info:
http://en.wikipedia.org/wiki/America...gauge#Formulas
Kevin
Dave,
Please expand.......As you know, there is more than one way to do anything, your thoughts please so I may defend!
Some relevant info:
http://en.wikipedia.org/wiki/America...gauge#Formulas
Kevin
Last edited by loudtdi; 04-04-2006 at 11:37 AM.
04-04-2006, 12:56 PM
#16
Guest
Posts: n/a
loudtdi, to say that 1awg is overkill is just wrong. the voltage loss could be in the area of 1/3 of a volt over a 17 foot between 1awg and 2 4awg, so your statements are incorrect. overkill and car audio shouldnt be said in the same sentence. in spl 1/3 of a volt is alot
04-04-2006, 01:16 PM
#17
Originally Posted by mike bisson
I have noticed caps making improvements to many systems, especially systems that are comprised of amplifiers with unregulated power supplies.
One cannot make general statements and assume that they apply to all cases. Yes, a Resistor-Capacitor or Inductor-Capacitor network does make a low pass filter to filter out power supply ripple. It is found in almost every power supply including car amp switching supplies. But it is the values of the R-C or L-C that determine the effect of the filtering. A 1-2 farad cap, combined with the fraction of an ohm resistance in the wire from battery to cap plus the load of the amp does not make an effective low pass filter to eliminate the drop in voltage caused by the repetitive boom boom boom of the music.
A 10000uF cap in a pulse width modulating power supply switching at 100000 cycles does work.
04-04-2006, 09:54 PM
#18
Originally Posted by defro13
loudtdi, to say that 1awg is overkill is just wrong. the voltage loss could be in the area of 1/3 of a volt over a 17 foot between 1awg and 2 4awg, so your statements are incorrect. overkill and car audio shouldnt be said in the same sentence. in spl 1/3 of a volt is alot
My Bad!
I know 1/3 of a volt drop in SPL competition is a bad thing. I have seen a van with 6 runs of 1/0 and dead equal voltage front to back.
If money was not an issue and install ease was not an issue, I would suggest everyone use 1/0. Like many have said, it makes the upgrade path in the future much easier.
Regards
Kevin
04-05-2006, 12:36 PM
#19
Go to Princess auto and buy 0awg welding cable for 1.99/ft or less if you can talk nicely to the sales rep. I love welding cable, it is so flexible,and easy to work with compared to many audio brands...and cheap.
04-05-2006, 12:39 PM
#20
Originally Posted by zoomer
Mike
One cannot make general statements and assume that they apply to all cases. Yes, a Resistor-Capacitor or Inductor-Capacitor network does make a low pass filter to filter out power supply ripple. It is found in almost every power supply including car amp switching supplies. But it is the values of the R-C or L-C that determine the effect of the filtering. A 1-2 farad cap, combined with the fraction of an ohm resistance in the wire from battery to cap plus the load of the amp does not make an effective low pass filter to eliminate the drop in voltage caused by the repetitive boom boom boom of the music.
A 10000uF cap in a pulse width modulating power supply switching at 100000 cycles does work.
One cannot make general statements and assume that they apply to all cases. Yes, a Resistor-Capacitor or Inductor-Capacitor network does make a low pass filter to filter out power supply ripple. It is found in almost every power supply including car amp switching supplies. But it is the values of the R-C or L-C that determine the effect of the filtering. A 1-2 farad cap, combined with the fraction of an ohm resistance in the wire from battery to cap plus the load of the amp does not make an effective low pass filter to eliminate the drop in voltage caused by the repetitive boom boom boom of the music.
A 10000uF cap in a pulse width modulating power supply switching at 100000 cycles does work.
Bring your car to North Shore Audio Video -- play your subwoofer system without a Cap, then I will hook up a 1 mfd cap -- if it is louder you buy the cap, if it is not I will give you the cap -- otherwise I shall continue to disagree with you.
