Electricity is very important to car audo. Why is it not discussed more often?

[i2ain2thunder 10+ year member]

For being something that is so fundamental to car audio. I feel like actual principles of electricity get cast aside in the majority of discussions. It seems not enough people know enough about it, and the industry doesn't exactly paint the best picture of it, with it's misleading ratings.

For example most people I have talked to seem to think that electricity flows from + to - when it comes to a battery. When in fact it is the opposite, electrons are actually the - of the atom.

Are there any electrical engineers or experts in the house willing to shed some light onto this often misunderstood, and yet very important aspect of car audio?

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[i2ain2thunder 10+ year member]

Lets start with some basics.

What is voltage?

Voltage is the potential difference (the ability of an electric charge to do the work of moving another charge by attraction or repulsion) (- is attracted to +).

What are amps?

Amps (amperes) are a measurement of the current in an electric circuit measured as magnitude over time. Magnitude is the amount of electric charge a body possesses, and is determined by the number of electrons compared with the number of protons within the body. This is usually measured as Coulombs. 1 coulomb is 6quintrillion 250quadrillion electrons. (yeah, atoms are freaking tiny).

 

[germanyt 10+ year member]

So many people have no idea what an ohm is and why it changes power applied from the amp.

 

[big scott]

ya this is a good thread.

and most dont know this stuff and most may not need to know all of it.

but for me i like to learn everything about what ever.

this stuff is very interesting. i know a lot of this as i have been working on car for all of my life.

and ya ohms changes flow rate, less resistance.

power will flow easier with lower ohms ( resistance )

 

[seedlings]

For speakers, resistance in ohms, impedance, change based on the frequency. A speaker will have least resistance at it's resonant frequency (Fs), and increasingly higher resistance as frequency gets further from Fs.

Speakers (a coil of wire) and all loads/circuits with capacitance/inductance will have a different resistance based on the frequency. A resistor (theoretically) has no capacitance and no inductance, and therefore has the same resistance at every frequency.

AC voltage is measured at a frequency(ies). EG: USA's power grid is 120V at 60Hz. If you had a speaker that had 6 ohms resistance at 60Hz, and connected it to the power outlet, you would hear 120*120/6, or 2400 watts of 60Hz. (since power=voltage*voltage/resistance at that frequency).

DC voltage is 0 (zero) Hz. It has no AC component. This is why when you connect a 9V battery to your speaker to check polarity, it goes out and doesn't come back until you remove the voltage. It's called Direct Current because all the current goes directly across the load resistance one direction. With Alternating Current, the current goes one way, then changes to the other way at a given frequency.

CHAD

 

[fasfocus00 5,000+ posts]

For being something that is so fundamental to car audio. I feel like actual principles of electricity get cast aside in the majority of discussions. It seems not enough people know enough about it, and the industry doesn't exactly paint the best picture of it, with it's misleading ratings.
For example most people I have talked to seem to think that electricity flows from + to - when it comes to a battery. When in fact it is the opposite, electrons are actually the - of the atom.

Are there any electrical engineers or experts in the house willing to shed some light onto this often misunderstood, and yet very important aspect of car audio?

whoa there tiger. you are getting way ahead of yourself about what you think you know. firstly Conventional Current Flow Theory is what you are stating as a fact when it's just a theory. there is no way to determine if negatively charged electrons are determining the direction of flow or if the positive ions are attracting electrons causing the current to flow in the direction of the hole filled by the free electron. so that's out of the way.

next to why it's not discussed more in this industry. it's b/c it cost money. just look at polarized capacitors, they have been on the market for a long time yet people still keep with the thinking that you need 1 farad per 1000 watts of power. than you have the opposing crowd saying that capacitors are junk and you should just get a good "car audio" battery. than that crowd is split between all the brands. when the actual truth is that it's based on current draw and the only way to offset current draw is to have something that can provide current. the only think that produces current is your alternator and everyone tries to cheap out of upgrading their alternator by just adding more and more batteries. just look at the battery crowd, everyone talks about how awesome XS is yet more people buy Juice Box and Kinetik b/c it's cheaper. Than take a look at the Optima Yellow top. it has the highest resting voltage (13.1v resting) of all "car audio" batteries but all the noobs say that it's old technology and poor quality. if car audio is all about voltage than the Optima should win the battle of the "best battery" but it loses almost overtime. the 12v industry does not have a mandatory standard for installation practices and product advertising that the market gets flooded with so much junk and lies that we will never see a change in 12v. everyone on the forums think that MECP certification is a joke yet I'm MECP certified and I see all the crap that comes in from all these DIY'ers b/c someone on one of these forums said they know "dat music". as a professional I can say that the forums and eBay are the largest contributors of why the 12v industry is filled with so much crap.

 

[wew lad 5,000+ posts]

the problem is people lacking the motivation to go read up on this themselves, there's thousands of articles online available to you in mere seconds. obviously complex subjects need some clarification, but the information is there.

 

[i2ain2thunder 10+ year member]

For speakers, resistance in ohms, impedance, change based on the frequency. A speaker will have least resistance at it's resonant frequency (Fs), and increasingly higher resistance as frequency gets further from Fs.
Speakers (a coil of wire) and all loads/circuits with capacitance/inductance will have a different resistance based on the frequency. A resistor (theoretically) has no capacitance and no inductance, and therefore has the same resistance at every frequency.

AC voltage is measured at a frequency(ies). EG: USA's power grid is 120V at 60Hz. If you had a speaker that had 6 ohms resistance at 60Hz, and connected it to the power outlet, you would hear 120*120/6, or 2400 watts of 60Hz. (since power=voltage*voltage/resistance at that frequency).

DC voltage is 0 (zero) Hz. It has no AC component. This is why when you connect a 9V battery to your speaker to check polarity, it goes out and doesn't come back until you remove the voltage. It's called Direct Current because all the current goes directly across the load resistance one direction. With Alternating Current, the current goes one way, then changes to the other way at a given frequency.

CHAD

Hi Chad.

Thanks for the added information. While we're on the subject, it is my understanding this is how speakers operate for those of you who don't know. A speaker moves up and down depending on what direction the current flow is going. A speaker is basically just a big coil of wire inside a magnetic housing, whenever the electricity passes through the coil on your speaker, your speaker moves.

Now lets add in how much the speaker moves and it's general movement path. Which you all have seen on a spectrum analyzer. The SA shows a graph of the signal the speakers are getting. The speakers will movements will be identical to this pattern.

Now I believe there are 2 different concepts of clipping. But I think one of them, input clipping, happens when the tops of the waves get cut off. Now immagine the way the speaker has to move if you cut off the top halves of the waves, there will actually be millisecond pauses in the speaker's travel. This can be a huge problem for the speakers as they rely heavily on venting to stay cool, and once a speaker's coil has gotten too hot, you have a blown speaker and a nice hot glue smell. Many of the community I'm sure has experienced this.

Please feel free to add/correct anything with regards to this thread, I claim no expertise myself, I just like to study.

 

[i2ain2thunder 10+ year member]

Something I am generally curious about. My newest amp has a clipping light built into the remote gain control. Does anyone know how this feature actually can tell when clipping is present?

My guess is that there is another circuit whose job is to tell if there is ever any pauses/breaks in the sound system circuit.

 

[seedlings]

Hi Chad.
Thanks for the added information. While we're on the subject, it is my understanding this is how speakers operate for those of you who don't know. A speaker moves up and down depending on what direction the current flow is going. A speaker is basically just a big coil of wire inside a magnetic housing, whenever the electricity passes through the coil on your speaker, your speaker moves.

Now lets add in how much the speaker moves and it's general movement path. Which you all have seen on a spectrum analyzer. The SA shows a graph of the signal the speakers are getting. The speakers will movements will be identical to this pattern.

Now I believe there are 2 different concepts of clipping. But I think one of them, input clipping, happens when the tops of the waves get cut off. Now immagine the way the speaker has to move if you cut off the top halves of the waves, there will actually be millisecond pauses in the speaker's travel. This can be a huge problem for the speakers as they rely heavily on venting to stay cool, and once a speaker's coil has gotten too hot, you have a blown speaker and a nice hot glue smell. Many of the community I'm sure has experienced this.

Please feel free to add/correct anything with regards to this thread, I claim no expertise myself, I just like to study.

This is pretty solid commentary assuming sine wave test signals. If we're talking about program music, there will be lots of limiting, compressing, and clipping in the music itself which can effectively clip off the top and bottom of the waves. Especially rock, alternative and music with synthesizers. For example, a rock (overdriven) guitar or bass guitar signal will be an almost square wave. Nice fat synthesizer wave forms are often based on square waves and that square wave is PWM (pulse width modulated) to spend more or less time on the 'flat top' of the wave. And yes, this will cause your voice coils to run hotter than they would with a sine wave test tone.

CHAD

 

[NightScreams 10+ year member]

I just know I hook a big OFC + to + and big OFC - to frame and I magically get 14 volts to amp with car running and sound comes out to my speakers then I'm happy.

 

[audiobaun 5,000+ posts]

Im always interested getting some info/facts.Tuned in!//content.invisioncic.com/y282845/emoticons/popcorn.gif.32dd9e22fd77e77bc3c907062768fcd2.gif

 

[big scott]

I just know I hook a big OFC + to + and big OFC - to frame and I magically get 14 volts to amp with car running and sound comes out to my speakers then I'm happy.

ya but wire does not make them 14 volts.

 

[gimling]

Is an interesting post im curious what difference the flow is in the case of car audio, its an argument that really has nothing to do with our systems other than what we hook our red and black wire to, but to more confuse or enlighten you yes Electrons flow from Negative to positive, but conventional current flows from positive to negative, its all relative and makes no difference. diagrams and circuit designers will use conventional due to how the items in the circuit were origionally thought to how current flows, Its just how and whos looking at it. 1+2 is the same as 2+1, Conventional Versus Electron Flow : Basic Concepts Of Electricity - Electronics Textbook its what is used as ground, or chassis ground, or Floating ground, thats whats important since neg is generally used as the ground that is why why fuse the positive terminal of the battery.

What Direction this thread should really head in is maximizing these principals for maximum efficiency, i.e voltage,current loss, wire resistance, I agree with Fasfocus00 your alternator is probly the most important part of your sytem. everything else is used to try and get the maximum efficiency of that alternator. Big 3, power wire size, length, speaker wire size, length, all decisions with those will never get you more than what your alternator can put out,

Batteries, can be seen as use in a few different ways, #1 if you dont got the alternator to keep up batteries may give you enough for your SPL burp or to impress your friends with max power for a limited amount of time, #2 just an extention of your alternator to maximize efficiency. and too keep your system at its max potential at all times.

Capacitors, generally in smaller systems , not so much to keep lights from dimming but more to keep consistant power going to your amp, not always needed most amps have these caps inside them just not as big, can be helpful and now days are pretty cheap.

The rest is just calcs that you can easily find on the internet that will tell you your power, wattage, current, etc loss on your wiring, You either spend the money on the wiring to not lose what your subs, speakers can handle or buy an amp that can put out more power to compensate for your loss. Which all of this can me tested with a DMM and a clamp.

 

[Slo_Ride 5,000+ posts]

i take it the search button still doesnt work