Richiec77

iTrader: (3)

If you wish to skip the theory, scoll down. I have typed out some quick charts.



Wattage. It is Voltage time Amprage. (V x A) You'll see it 2 ways VA or W. It is the combination of the electromotive force and the size of the load. It is specific here because of Amplifiers and Deck Amplifiers.

To get Voltage divide by amprage. To get Amprage, divide by Voltage.

A quick way to see this is on a common Amplifier. 1000 watts output. Let's look deeper. Some people are fooled by bogus claims on the heat sinks of the amps. 1000 watts is a lot of power.

1000watts in a 12v enviroment works out like this.
(10 volts input) 1000w= 100.0A
(11 volts input) 1000W= 90.9A
(12 volts input) 1000W= 83.3A
(13 volts input) 1000W= 76.9A
(14 volts input) 1000W= 71.4A


Why is this important?????? Ampliers fall into 2 major catagories right now. Class A/B and Class D (no it does not stand for digital)

Class A/B amplifiers are roughly 55-67% efficient
Class D amplifiers are roughly 80-97% efficient

So on a 1000 watt amplifier the Protection Fuses should correspond to this.

IE. 1000W class D amplifier. 90% efficient. 10volts input.(to account for a voltage drop, Heavy Bass tone. Class D amps are GREAT Sub amps)

The Protection Fuses should equal a 1111W amplifier at 100% effieceny or 112 amps of protection. ( Bw x 0.90=1000w, simply divide output wattage by effieciency. 1000w/0.90=1111.111w. Now divide by 10 volts= 111.11amps.)
It should have 115-120 amps worth of fusing.


IE 100W class A/B amplifier. 65% effieciency. 12 volts input (not a heavy dynamic strain. Class A/B are Great Full range amplifiers. ALL Decks have these and most amps are of this design)

The protection Fuses should equal a 154W amplifier at 100% efficiency or 12.8 amps of protection. ( Bw x 0.65=100w, simply divide output wattage by effieciency. 100w/0.65=154w. Now divide by 12 volts= 12.8amps.)So it should have a single 15amp fuse.

Richiec77

iTrader: (3)

What do you all think. Is this type of info usefull??? I did this off the top of my head. If it's usefull I have more for all types of Car stereo related info. I'll just sum it up in a way that is easy to understand. Physics can be boring if you don't know how it relates to the real world.

Think your Sub is BAD ***. Plug it into a wall socket. No really don't do it unless it is a monster of a sub. Here an example of the Wattage out put to a sub pluged directly into a wall socket.

110volts 60 HZ (frequency of the AC signal, Similar to a Bass CD or Test Tone). 4ohm voice coil. Soooooo; With a 60 HZ tone bellowing, it is taking:

Peak= 4,279watts
RMS =3,025Watts

I've done this with an old L7 kicker (rep said it would take it NOPE), Hart L7 replica (yes) and an LVS sub from Memphis. (hell yeah and it didn't get too warm.

Here's a link to formulas used.
http://www.elec-toolbox.com/Formulas...l/formulas.htm

BigBadWolf

Wow... my brain hurts

badhoopty

nice avatar richie.

i designed it...

Richiec77

iTrader: (3)

Alright I'll do some common Wattage vs Fuse sizes for a quicker reference. I'm always trying to look out for people. I was burned very early on I have always hated that. So I try to not let that happen to me and I try to give all the free advice you normally might pay for.

What are some other common questions you would like answered? RMS vs Peak power? Alot of Info Links? Speaker design(maybe alittle to much),

Ok I'll make a newer thread that links to this and shows WHY you have to use certain GA wiring for amps. I've seen people try and run 2-4 amplifiers off an 8ga wire. That is just asking for something bad to happen.

I want input. I'm itching to educate. Been out of car stereo for about 2 years and miss it.

BigBadWolf

Ok, here are several questions for you. I don't know how far your expertise goes but let's try these...

Does the gauge of speaker (sub and non-sub) wire really matter?

If a speaker is rated at 60-150RMS, are you losing all that much sound pushing only 50 watts through them?

What the hell is the design difference between a free-air sub and one that requires an enclosure?

Richiec77

iTrader: (3)

All votage is 12volts. Wattage is total through all the channels. The higher the Voltage the lower the Amps. The lower the Voltage the Higher the amps.

Class A/B amplifiers (50%-65%)
------------------------------------------------------------------------
100w= 15-20 amp fuse (12.8amps)

150w= 25-30 amp fuse (19.8 amps)

200w= 30-35 amp fuse/fuses (25.6 amps)

250w= 35-40 amp fuse/fuses (32.0 amps)

300w= 45-50 amp fuse/fuses (38.4 amps)

350w= 50-60 amp fuse/fuses (44.8 amps)

400w= 55-65 amp fuse/fuses (51.2 amps)

450w= 65-70 amp fuse/fuses (57.6 amps)

500w= 70-75 amp fuse/fuses (64.0 amps)

600w= 80-90 amp fuse/fuses (76.8 amps)

700w= 95-100 amp fuse/fuses (89.6 amps)

800w= 110 amp fuse/fuses (102.4 amps)

900w= 125-130 amp fuse/fuses (115.2 amps)

1000w= 140-150 amp fuse/fuses (128 amps)

1100w= 150-160 amp fuse/fuses (140.8 amps)

1200w= 170-180 amp fuse/fuses (153.6 amps)


As you can see that is a lot of juice. A bigger alternator and extra batteries become almost a deffiniate at the 500w + range. That is why there are Class D amplifiers. Fuses are usually set to be about 15-20% over the draw at 12v to account for the draw at 10v.

Richiec77

iTrader: (3)

All votage is 12volts. Wattage is total through all the channels. The higher the Voltage the lower the Amps. The lower the Voltage the Higher the amps.

Class D amplifiers (80%-97%)
------------------------------------------------------------------------
100w= 15 amp fuse (9.3amps)

150w= 20 amp fuse (14 amps)

200w= 25 amp fuse/fuses (18.6 amps)

250w= 30 amp fuse/fuses (23.25 amps)

300w= 35 amp fuse/fuses (27.9 amps)

350w= 35-40 amp fuse/fuses (32.6 amps)

400w= 45 amp fuse/fuses (37.25 amps)

450w= 45-50 amp fuse/fuses (41.9 amps)

500w= 50-55 amp fuse/fuses (46.6 amps)

600w= 60-65 amp fuse/fuses (55.85 amps)

700w= 70-75 amp fuse/fuses (65.15 amps)

800w= 80-85 amp fuse/fuses (74.45 amps)

900w= 90-95 amp fuse/fuses (83.75 amps)

1000w= 100-105 amp fuse/fuses (93.05 amps)

1100w= 110-115 amp fuse/fuses (102.35 amps)

1200w= 120-130 amp fuse/fuses (111.65 amps)


If you compair any 2 wattages from the class a/b amp to a class d amp you can easilly see which is more efficient. Class A/B amps are good for Full range and Class D is only good for Subs. (only JBL makes a full range Class D amplifier for Pro-Audio only (concerts ans stuff). They start around $20,000)

Richiec77

iTrader: (3)

Been doing it for about 12 years. Worked for Circuit City, Sounds good, Sound FX (Chicago area) then I just did it all for myself. Been Sponsor by Memphis (SPL) and did Sound Q for most of the time. Infact only 2 years ago did I even try my own hand at SPL. IASCA mostly. Learned most of this through years of reading and using the info.

Yes. and somewhat yes. For Subs. Regular use is fine with 12ga. SPL is squeezing every last ounce out so use 8ga power wire. For full range speaker 18ga-14ga works. Just remember It's hard to say when to switch, but here is a reason why you would use bigger wire.

Electricians deal with this principal when they design wiring for houses and business'. Wire has internal resistance. In a car the short runs let you get away with smaller diameter (larger wire #) wire. The heat generated by the wire's resistance is tiny, but goes up if the wire gets longer. In a car I did tests and could not hear a difference with a switch in wire size. Even up to 100 watts on my Dynaudio's I really couldn't say if there was a change or not. But the wiring was much Warmer with 18ga vs 14 ga. So I stuck with the 14ga wire. I didn't want to chance the insulation melting and being rubbed away and then Shorting out.


With those specs I'd say you would be ok, but you can potentially damage the speaker by doing this. The speaker is an Electrical/Mechanical device. It translates electrical input into a Mechanical output (watts in, Speaker moves in/out)

The motor structure needs a minimum amount of current to work. MUCH like the pricipale of a Belt driven Super charger. It takes some power to get the speaker motor running per say. If you don't have enough power the voice coil will begin to get hot (bad) or can sometimes Short out (dead speaker)

I'll cover SPL in a second post for you.



Physical Speaker Design? Or enclosure requirements?

Physically the Free-Air speaker is designed with a suspension system that is much stiffer than normally required. This is to keep control of the cone of the speaker and to keep it from Ocillating (free movement in a bad way. Thing of it like worn out springs)

For car guy's, compare the responsibilities of the shock absorber (misnomer. Everywhere else in the world calls it a spring dampener) and the Spring (actual called a shock absorber everywhere else but here).

A Speaker in a free-air enviroment is like a spring without a shock. If not design to work like this it can over react and actually weaken the suspension. If this keeps on happening a waterfall effect happens. The shock is worm and continues in this direction it actually tears itself apart.

So the Free-air speaker is designed with extra stiff suspension to keeo this from happening.


Speakers designed to work in an enclosure is like having 2 spings in one. Like the dampener springs inside dual springs. (Dual springs are mostly made double to control oscilation. VALVE FLOAT)

The speaker has it's own suspension and the enclosure is designed to mimick a second spring. Tuned together they produce a good suspension for the speaker to work in. This goes way deaper, but I'll keep it simple for here.

Richiec77

iTrader: (3)

How a speaker works.

http://www.clubknowledge.com/page1.html

http://micro.magnet.fsu.edu/electromag/java/speaker/

http://www.ishtek.com/spkrs.htm

BigBadWolf

Wow... found that interesting. I'm sure I'll come up with some more questions for ya by tomorrow. Perhaps these could be compiled into a FAQ somewhere.

Thanks for the response.

Richiec77

iTrader: (3)

I promised some SPL stuff. This is off the top of my head. I'll have to search for the article for EXACT #'s


Pioneer did a study in what was once their new testing facility on the affect of distortion and SPL to the human ear. The results were interesting. The reason for this is because measurements are linear, straight line, our ears hear in a non-linear fashion.


SPL is usually measure in dB's. DeciBell's. It's a measurement of the Sound Pressure Level. It usaually experesed in #'s like this 121dB. Now the absolute #'s are really arbritrary. A person experience will say what is louder. What follows is mostly true for Subs. Mids and high's are different.

Now dB's do correspond or relate to power. For a 3dB increase you need either a doubling of power or a doubling in coneage area.

(i.e. To get 3 dB increase you would need to go from 1 12" 500 watts to either 2 12" 500 watts total or 1 12" 1000watts total.) or (2 15" 1000watts. Needs 4 15" 1000watts or 2 15" 2000watts.) 3 dB would seem to be twice as loud right???

Actually no. When Pioneer and others tested this, they found that the average person need ~10dB in order to perceive sound as being "twice as loud" to get a 10 dB increase takes a lot of power and lots of speakers. The least amount of increase for a person to notice a change is about 1 dB. Average amoun to hear a change is 3dB.

i.e. System with 1 12" sub 100watts. 10 dB increase you would need 10-11 12" speakers or ~1100 watts of power. For every 3 dB. double what was before. 1-2, 2-4, 4-8, 10.6. 100-200, 200-400, 400-800, 800-1100.



Let me 1st say that distortion is the #1 killer of speakers. It causes the the speaker to move in irregular motions and warps the cone and puts the driver out of alignment.

For distortion they fed test music with distortion embedded in it. starting at 0.5%. By 1-1.5% most listeners noticed the distortion comming from the tweeters. By 2%-6% most listeners noticed it comming from the midrange speakers. By 6%-9% most listeners noticed it comming from the Midbass drivers.

And from 10% (very few people heard it) to 20% distortion is when most listeners heard it comming from the subs. The ears may be the best test equipment you own but have limitations.