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Old 14th January 2004, 10:44 PM   #11
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first of all...yaaaa...I thought it was funny...my post was not meant to disregard the humour

and...the chassis is the best grounding method....like the chassis ina amplifier
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Old 14th January 2004, 10:52 PM   #12
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Quote:
Originally posted by JOE DIRT®
first of all...yaaaa...I thought it was funny...my post was not meant to disregard the humour

and...the chassis is the best grounding method....like the chassis ina amplifier


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Old 15th January 2004, 02:47 AM   #13
Immo_G is offline Immo_G  Australia
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Yeah, on experience i'd have to disagree with #4, running the power cable on the other side of the car is what we do standard on installs.

You'd be amazed how badly shielded some car audio signal cables are these days, and you can actually hear a nice whine running the power on the same side on a lot of setups done that way.
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Old 15th January 2004, 03:11 AM   #14
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Default Re: Really Funny car audio myths

I don't by any means mean to pick on you, because your point was very very valid..
...but perhaps exemplified in the manner in which some of your "best practices" in response to some of these "myths" are myths themselves!
Quote:
Originally posted by jdm5genlude
[B]2. Adding a second battery to the vehicle will ease the load on
the alternator

A second battery will increase the load on the alternator, not
decrease it. With the vehicle running the second battery becomes
another load for the alternator to charge. Second batteries are
only good for engine off listening time.
[B]
Depending on the symptoms, adding a second battery will help, will be the correct path of action...
That is not to say that it will decrease the load on the alternator per se, but think about what's being said, anyway...
"the load on the alternator" isn't the problem... the symptoms of exceeding the load that your alternator can sustain is the issue.
And often it's not just adding a second battery, but capacitors that are called in to help.
Bear in mind that for both batteries and capacitors, they only present loads to the alternator when they are in a state of charge, not continuously.
If they are charging, that means they have been discharged, which means they have been in use in the past few moments, which means they are doing their job...

In light of that, having less battery reserve on hand could be counterproductive, in an install that's taking advantage of it.

What's going on is that for at least a transient peak (with today's high-power amplifiers can exceed even 200a - try to upgrade your alternator to that level... and see what kind of HP and mileage you lose ), you're exceeding your alternator's abilities...
Your car's voltage in turn drops from the 14.4v level of the alternator to the 12v level of the battery, so that the alt and batt can provide the needed current together.

If minimizing dash-light dimming is a priority (as bulbs are brighter on 14.4v than they are at 12v, obviously) installing a capacitor to help out may be a good option, as it will be fast enough to begin helping supply current as soon as the voltage starts dropping from 14.4v, until the point where the slow-reacting battery(ies) has risen to the call and is fully contributing whatever ovarage is being called for.

But the problem isn't that adding a second battery puts a larger load on the car...
...charged batteries aren't a load, and together they represent a single potential of charge, essentially.

No more will be discharged from two, or even three or four batteries, given the same system use...
...and therefore, no more will need to be replaced at recharge time.

Multiple batteries do buy you the potential to discharge a greater amount of charge, that must then be discharged, which would present a greater load on the alternator...
But is that really a downside? That's just a potential...

...like installing a larger gas tank in your car might cost you more to fill up at the gas station, potentially...
But if you top off at the same intervals, with the same car, it won't cost you any more to top off... the car won't magically use more gas because the tank is larger... you don't lower your MPG by installing the bigger gas tank.

That's the point.

Oh, and here's a thread to read some more of the more technical side, from a fellow moderator at this forum:
http://community.caraudiotalk.com/in...showtopic=2495

Quote:
[B]9. Tweeters should be placed as high up as possible

Tweeters should be placed as near to the midrange/woofer as
possible. The tweeter and the midrange/woofer are a matched pair
and shouldn't be separated. Imagine an electric guitar which has
a wide acoustical range. If the guitar is playing a riff in the
frequency range of the woofer and then switches to a riff in the
frequency range of the tweeter you'll likely notice the position
of the guitar jump. Now if the tweeter is placed near the woofer
the guitar position will remain in place.
[B]
This is a bit of a myth itself, from misunderstanding the true issues.

Locating the tweeter near the mid is an OK rule of thumb.
But it doesn't pay any respect to the reason you want to locate the tweeter as close to the mid as possible, which has everything to do with pathlengths to your ears.

Simply put, you want to keep the pathlength from the speakers to your ears as equal in distance as possible.

If the pathlengths are different in length, phasing issues will be created, a "comb filter" effect, if you will, because at some frequencies, the wavelengths will line up along those pathlengths in a way that will combine constructively, while at other pathlengths the wavelengths will line up and create cancellation nodes.

The greater damage is done in the subconscious realm, where your mind simply doesn't perceive the sound as "real"... essentially imaging damage is done, your subconscious isn't "fooled" into believing the sound is live, or real, if you closed your eyes.

So, if you were to examine two scenarios:
1) Midrange installed in stock door locations, tweeter installed immediately adjacent to it, at the 11:00 position on the drivers door, and 1:00 on the passenger's door.
2) Midrange installed in stock door locations, tweeter installed in the sail panel location behind the rear-view mirrors, which in this case let's say offers the same pathlength distance to your head as the midrange unit (as is the case with my wife's VW beetle).

The "rule of thumb" would seem to imply that scenario 1 would be superior.
In actuality, scenario 2 offers the more "equal" layout.

I wrote this article a while back, explaining this subject, primarily in the hopes that myths that are based on "rules of thumb" that people don't have an understanding of where that "rule of thumb" came from might simply cease to be someday (I'm an optimist ):

Check it out:
http://www.betteraudio.com/geolemon/Phasing/Phasing.htm
It's actually an easy read.
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Old 15th January 2004, 04:36 AM   #15
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geolemon....your post is pretty much on the mark....I was vague with my answers as I knew the thread was a joke in a way and all of this could go into further discussion as like alot of threads in this forum
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Old 17th January 2004, 03:52 PM   #16
maylar is offline maylar  United States
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Default Re: Really Funny car audio myths

Quote:
Originally posted by jdm5genlude
Car Audio Myths
5. A high output alternator will reduce the chance of noise

Actually it's the opposite. The larger the alternator the
greater the noise output. The noise increases with the power
output of the alternator.
The AC ripple content of a 3-phase full-wave rectified alternator is 4.2% of the voltage. Irregardless of the size of the alternator. If that's what you refer to as "noise", then size doesn't matter (at least in this case )
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