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.
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.
"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..
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
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....
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..
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
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....
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®
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®
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.
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.
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!
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/index.php?showtopic=2495
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.
...but perhaps exemplified in the manner in which some of your "best practices" in response to some of these "myths" are myths themselves!
jdm5genlude said:
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/index.php?showtopic=2495
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.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.