I believe you Dave, as I have been grounding direct to the battery for many years. Not just for noise reasons like most people think that a ground wire is to prevent, but for reistance on the ground return. If I cannot get that resistance down by upgrading the battery to chassis and my amp to chassis ground etc., then I will ground to the battery with a proper ground wire.
Most installers do not bother to check resistance on the ground return as they are commission based and want the next job in the shop. They also do not want the hassle of trying to explain and sell it to the customer that needs it. How many of you installers out there actually check the ground return resistance?

 

Dukk, that is the problem, you are only checking for noise, not a problem that can lead to failure of the amp.

 

There is no valid electrical argument against doing either. There is only the financial argument of which is cheaper and that is easy.
Now what is left the argument over which is better since they are both good enough. The additional cost for running an extra line to the battery will be pretty small relatively speaking (amps, HU, BA woofers, etc.). I don’t think this has solved too many ground loop issues (but it could if you have a poor chassis like in a.... Mopar). Hey I haven’t tried it, I never have seen the need for it. Has anyone had better SQ or SPL from doing it?

 

Like I said, I am not checking for noise, I am checking for a resistance on the ground return, if it cannot be lowered by changing to a different ground point and or upgrading the grounds at the battery, basically throwing the book at it to try and solve the problem, it is then left to ground to the battery.
What I'm trying to get across is that if you are putting 100 amps of positive current into the amp and electricity is an alebra equation that states what you do to one side you must do to the the other, the ground is as equally important.
What would happen to the power line if there was a high resistance on it, would the amp operate properly? The ground wire is the same thing. Do you use a large guage power wire just because it is what you were led to believe, no you don't, you use it because it is what you must use to complete the equation. If an amplifier has a high resistance on the ground return, bad things will happen to an amplifier, it's only a matter of time. I happen to take the time to check this in order to prevent smelly power supply down the road. This has nothing to do with SPL,SQ,noise, ground loops, the customers bank book or the price of rice in china.

[ February 20, 2004, 04:23 PM: Message edited by: MR2NR ]

 

Interesting concept MR2NR well here is an easy way to check... you can extrapolate (don’t you love big words that sound like sex acts) the chassis resistance. [img]graemlins/jack.gif[/img]

Measure terminal voltage at the battery.... measure terminal voltage at the amp (from your + cable to your ground point (not you ground cable)) if the voltage is different from your batteries terminal voltage it is due to resistance in the + cable and the - chassis. Note no capacitors can be hooked into the system (this includes amplifiers, they must be unplugged). To complete the ‘theory to practice’ you would then run a cable to your - terminal and compare. I don’t think the difference will be significant but it could be in some vehicles (old and rusty, or with poor electrical systems).
[img]graemlins/deal4u.gif[/img]

 

MR2NR, I would imagine you have seen cases where resitance through the chassis is more than say through a wire back to the amp but if you look at the entire unibody floor pan as the ground plan I would think it would have way more area than say a 4 or 1 ga. wire would have. [img]graemlins/dunno.gif[/img]