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jdm5genlude 14th January 2004 09:24 PM

Really Funny car audio myths
 
Car Audio Myths

I received an email the other day that read:

"I suggest on the page about wiring a car audio system, that you
mention the importance of keeping the length of speaker wire
between paired Left and Right speakers nearly the same length.
This can be done to help keep the left and right channels in
phase."

Basically that says that electricity travels so slowly that
differences in the length of speaker wire can throw off the
phasing of the speaker system. Now there are several things that
will throw off a system's phase but speaker wire length is not
one of them. After pressing the author for the source of the
information I was informed that he was given that information by
a "senior" car stereo installer (whatever that is).

After explaining that this was not the case I got to thinking
about other good car audio myths I've heard. I think you'll find
them entertaining and also educational. Feel free to send me
your own favorites. I'd be glad to add them to my list.

Top Ten Favorite Car Audio Myths (in no particular order)

1. Amplifiers should be grounded at the battery

Generally the battery is the worst place to ground an amplifier.
The battery is where all of the electrical noise from the
vehicle's various parts ends up. Like a noise garbage disposal.
Connecting your audio components to this noise hub is a bad idea.

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.

3. Ground all of your audio components at the same place

Sometimes this works and sometimes it makes the problem worse.
When you ground any current carrying component to the vehicle
you create a circular field at that point. Poorly designed audio
components could pick up this field and introduce it as noise
into the system. When this is the case it's a good idea to
separate your components by six inches or more. The higher the
current (large amps), the more space I recommend.

4. Routing power cables on the opposite side of the signal
cables will prevent noise

Maybe. It will prevent the signal cables from picking up noise
inductively from the power cables. But it won't prevent them
from picking up noise from the vehicle's chassis or from other
electronic components along their path. It's a good practice but
doesn't guarantee noise pickup.

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.

6. Power capacitors should be fused

Bad idea. The purpose of a car audio capacitor is to deliver
large amounts of current very quickly (faster than a battery is
capable of). Adding a fuse, which is just a short length of very
small wire, will slow down this current delivery. And because
capacitors can discharge so quickly the fuse wouldn't blow
before the capacitor discharged.

7. Adding more speakers will increase the sound quality

Volume, maybe. Sound quality, no. The more speakers you add to a
system the greater the problems you will have due to speaker
interaction. Each speaker is a little wave producer and when the
waves from one speaker meet those of another speaker the results
are peaks and dips in the response. Generally less is more when
looking for sound quality. Look to the car audio competition
finals winners and you'll see that they use a small number of
high quality speakers.

8. Turning up all of the frequencies on an equalizer will
increase the system volume

The system volume is based on many factors including system
power and speaker sensitivity. The purpose of an equalizer is to
compensate for vehicle specific problems and not as a general
volume control. Boosting all of the frequencies won't make your
system louder, only more distorted.

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.

10. An amplifier's gain control should be set to maximum to get
more volume

The purpose of the gain control is to match the output level of
the component before it (head unit, equalizer, crossover, etc.)
Since car audio manufacturers don't use a standard output level
like home audio manufacturers do it is necessary to have an
adjustable input. Adjusting the gain too high will only cause
more distortion in the amplifier's output. Since our ears
perceive distorted and painful sounds as louder this is a myth
that has perpetuated.

Bottom line: Be careful who you listen to and what you believe
(good advice for life too). There are plenty of folks inside and
outside the car audio realm that will simply make something up
if they don't know the answer (don't want to look stupid). Then
there are those that have been told a lie, accepted it as truth,
and passed it along. When in doubt, get a second opinion.

Richard C 14th January 2004 09:40 PM

Re: Really Funny car audio myths
 
Quote:

Originally posted by jdm5genlude
Car Audio Myths

Generally the battery is the worst place to ground an amplifier.
The battery is where all of the electrical noise from the
vehicle's various parts ends up. Like a noise garbage disposal.
Connecting your audio components to this noise hub is a bad idea.


Really:confused: are you saying that the lowest impedance 0V point within the car is also the noisiest?

Tube_Dude 14th January 2004 09:41 PM

Re: Really Funny car audio myths
 
Quote:

Originally posted by jdm5genlude
Car Audio Myths

Top Ten Favorite Car Audio Myths (in no particular order)

1. Amplifiers should be grounded at the battery

Generally the battery is the worst place to ground an amplifier.
The battery is where all of the electrical noise from the
vehicle's various parts ends up. Like a noise garbage disposal.
Connecting your audio components to this noise hub is a bad idea.


Wrong!! The battery is the cleanest point to connect an amp in a car!!
´
Cheers

Richard C 14th January 2004 09:44 PM

Snap!!!:)

Tube_Dude 14th January 2004 09:45 PM

Quote:

Originally posted by Richard C
Snap!!!:)

In time!!!;)

leadbelly 14th January 2004 09:49 PM

Re: Really Funny car audio myths
 
I did smile as I read your post, but probably not in the way you intended :)

SkinnyBoy 14th January 2004 10:14 PM

Re: Really Funny car audio myths
 
"I suggest on the page about wiring a car audio system, that you
mention the importance of keeping the length of speaker wire
between paired Left and Right speakers nearly the same length.
This can be done to help keep the left and right channels in
phase."

ok, yes.. its not the phase, but its so the speaker impedences match, and therefore they are the same volume... I have experienced this in my room.... one speakers polyswitch will cut out alot sooner than the other, because the other speaker had longer wire on it...

Top Ten Favorite Car Audio Myths (in no particular order)

1. Amplifiers should be grounded at the battery

Battery is totally the best idea.. it prevents nearly every chance of ground looks in the system...

2. Adding a second battery to the vehicle will ease the load on
the alternator

If the second battery is closer to the amp you don't have to worry about losses due to long high current cables, also, often the battery in a car (with a sound system) will only get discharged when you are drawing more current than the alternator can supply, if you have 2 batteries, there will be more current available so the batteries will keep their voltage higher better, and therefore, when under heavy load, there will be less system voltage drop, and therefore less load on the alternator...

3. Ground all of your audio components at the same place

I really have no idea what your talking about in your reply to this... but if you ground evertything to a common place (the chasis of the car is NOT common, the battery is) then you will avoid many many problems...

4. Routing power cables on the opposite side of the signal
cables will prevent noise

"prevent noise" is wrong, I agree, but it will prevent the horrible high frequencies generated by the alternator from being induced into the audio leads...

5. A high output alternator will reduce the chance of noise

I'm not going to argue with you on this.. cos I wouldn't have aclue.. :p

6. Power capacitors should be fused

fuse where? lol personally, in my oppinion, if you fuse something, you put the fuse BEFORE it... which in this case you should do..... AND.. all amplifiers have fuses on the DC input, so your suggestion goes up in smoke :p

7. Adding more speakers will increase the sound quality

I suppose agree with you on this too.. lol

8. Turning up all of the frequencies on an equalizer will
increase the system volume

agreed too... lol

9. Tweeters should be placed as high up as possible

I personally agree that tweeters should be places as high as possible... it creates a higher sound stage, and now I am just making up stuff cos I figure no one will read this far.. lol

10. An amplifier's gain control should be set to maximum to get
more volume

what if all you want is SPL? then setting the gain control to 75% is reccomended....

JOE DIRT® 14th January 2004 10:23 PM

I would like to comment on this because I was a former design/builder for IASCA sanctioned vehicles once upon a time...here goes it from jdm5genlude original post:

speaker cable length in a car audio environment between left and right channels does not change phase BUT adds delay in imaging (we tested this)
myths

#1 amplifiers should not be grounded at the battery because this involves long lground leads that are susecptible to noise and who the hell wants to run massive amounts of 4ga wire up to the battery

#2 correct

#3 ground all high current amplifiers if in close proximity to a single star ground and all signal level components the same

#4 true...buts its good practice because of the high currents involved with the amplifiers

#5 yes and no....a high current alternator that has been properly wound and rectified will not produce more noise (expect tp pay $800 for a decent one)

#6 correct.....a fuse should be placed at the battery and then separate fuses for each device (rules are rules)

#7 correct....more can be worse in a small chamber (vehicle)

#8 correct....most people have no idea how to use one

#9 correct...in a car audio environment it is best to keep the front channel as low as possible so the distance remains the same between left and right channels (hint: place two speakers on the floor in front of the driver and passenger seat and compare the imagining from your door speakers)

#10 correct....thats the reason why we use line drivers with low impedance to deliver maximum signal and a lower noise floor to the amplifiers so we can turn the gain down....remember 12 volt audio amplifiers are stressed out as it is in their power supplies


that is my synopsis on that post...take what you want and throw the rest away..LOL


Cheers!!The DIRT®

jdm5genlude 14th January 2004 10:38 PM

ohh man i didnt kno you guys were gonna take this serious.. i jus foudn this and thought u guys might enjoy a good laugh...:D

Tube_Dude 14th January 2004 10:40 PM

Quote:

#1 amplifiers should not be grounded at the battery because this involves long lground leads that are susecptible to noise and who the hell wants to run massive amounts of 4ga wire up to the battery
So the grounding of the amp must be connected to the chassis near the amp, that shares lots of noisy currents from others car appliances???:scratch:


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