Must read for all those running a BIG system
Oct 19, 2007, 09:19 PM
#1
Must read for all those running a BIG system
If you haven't upgraded your alternator yet, you should. Your system will sound better because you'll have constant power to your amps. It will be cleaner power which will be clearer sound.
Check this out...
https://www.evolutionm.net/forums/sh...d.php?t=300160
Check this out...
https://www.evolutionm.net/forums/sh...d.php?t=300160
Oct 20, 2007, 07:25 AM
#2
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Thank you adambl03,
Here are some selections from an article on audio system power design. The whole article can be found here:
http://caraudiobook.com/car_audio_el...al_systems.htm
Upgrading your alternator will also allow you to run a smaller battery with higher output stereo systems. I currently run a braile carbon fiber battery with just over 1600 W. prior to the alternator upgrade my bass amp was cutting out due to a low voltage and my headlights were dimming After the alternator upgrade, this all went away and my voltage is rock solid
Here are some selections from an article on audio system power design. The whole article can be found here:
http://caraudiobook.com/car_audio_el...al_systems.htm
Depending on your car's factory electrical system, you may not have enough power to run your aftermarket stereo system. You probably do unless you have a multi-megawatt system or an extremely tiny alternator. Generally systems under 500 watts will not need an upgrade.
If one battery is good then two must be better. Right? Wrong. Remember that the function of a battery is to start the vehicle and to provide power when the vehicle is not running. The only thing a second battery will help you with is "parking lot" listening time. Basically it will provide you the additional capacity to run your stereo longer without starting the vehicle. After the vehicle is started the second battery becomes another load on an already overworked alternator.
you may need to upgrade your alternator. Doing so will give you more juice to run all of your electrical components, including your stereo system, without looking to the battery for help. The problem is your alternator is undersized for your new electrical requirements and has to look to the battery to provide the extra power, resulting in shortened battery life.
Oct 21, 2007, 01:13 PM
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So, yesterday I did some testing on a friends Evo with 1000 Watts (between two amps), Stock battery, stock alternator, 1 1.5 Farad Capacitor, Constant engine speed at 3200 RPM
Output at constant RPM was above 14V
Lights on, dipped for a split second to 13.7V, then stablized immediately to above 14V.
Turned the stereo up, and voltage bounced between 10V and just under 12V. (depending on the bass in the song) Once stereo and lights were turned off, it took about 40 seconds before voltage returned to above 14V
This whole test was under 3 minutes. I have no idea how low the voltage would drop if we kept going with the stereo up.
I did take a video of his Volt meter with my camera phone, but it's too big for me to wirelessly transfer through E-mail and I can't find my data code.
When I get that, I will upload to a file hosting site to be viewed.
Output at constant RPM was above 14V
Lights on, dipped for a split second to 13.7V, then stablized immediately to above 14V.
Turned the stereo up, and voltage bounced between 10V and just under 12V. (depending on the bass in the song) Once stereo and lights were turned off, it took about 40 seconds before voltage returned to above 14V
This whole test was under 3 minutes. I have no idea how low the voltage would drop if we kept going with the stereo up.
I did take a video of his Volt meter with my camera phone, but it's too big for me to wirelessly transfer through E-mail and I can't find my data code.
When I get that, I will upload to a file hosting site to be viewed.
Last edited by TempeRacerGuy; Oct 26, 2007 at 04:34 PM.
Oct 24, 2007, 12:16 PM
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VERY interesting results. I always thought with my 1200w and stock electrical system I was fine, but your results make me question that assumption, even though I do not experience light dimming. The 10V dip has me concerned. . . . as does the 40 second delayed return to 14V. Maybe a HO alternator is in order.
So, yesterday I did some testing on a friends Evo with 1000 Watts (between two amps), Stock battery, stock alternator, 1 1.5 Farad Capacitor, Constant cruise at 3200 RPM
Output at constant cruise was above 14V
Lights on, dipped for a split second to 13.7V, then stablized immediately to above 14V.
Turned the stereo up, and voltage bounced between 10V and just under 12V. (depending on the bass in the song) Once stereo and lights were turned off, it took about 40 seconds before voltage returned to above 14V
This whole test was under 3 minutes. I have no idea how low the voltage would drop if we kept going with the stereo up.
I did take a video of his Volt meter with my camera phone, but it's too big for me to wirelessly transfer through E-mail and I can't find my data code.
When I get that, I will upload to a file hosting site to be viewed.
Output at constant cruise was above 14V
Lights on, dipped for a split second to 13.7V, then stablized immediately to above 14V.
Turned the stereo up, and voltage bounced between 10V and just under 12V. (depending on the bass in the song) Once stereo and lights were turned off, it took about 40 seconds before voltage returned to above 14V
This whole test was under 3 minutes. I have no idea how low the voltage would drop if we kept going with the stereo up.
I did take a video of his Volt meter with my camera phone, but it's too big for me to wirelessly transfer through E-mail and I can't find my data code.
When I get that, I will upload to a file hosting site to be viewed.
Oct 26, 2007, 04:31 PM
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OK, here's the video for you. Sorry the resolution is no good, but it was my palm treo at speed. The tick marks are 14 to the right, 12V straight up, and 10V to the left.
This was at the begining of the test, so it only dropped to 11V during this part. as the song went on, voltage continued to drop as the battery was going flat.
The song was Reel Big Fish "Take On Me" Short tight bass hits, lots of mids (horns). 1000 W stereo (400X4, 600X1) at approximately 75% volume (just before distortion)
Voltage test, stock electrical system 1000W
This was at the begining of the test, so it only dropped to 11V during this part. as the song went on, voltage continued to drop as the battery was going flat.
The song was Reel Big Fish "Take On Me" Short tight bass hits, lots of mids (horns). 1000 W stereo (400X4, 600X1) at approximately 75% volume (just before distortion)
Voltage test, stock electrical system 1000W
Nov 15, 2007, 09:15 AM
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You tested and saw no voltage decrease? If so, those must have been tiny tiny amps, or you were running them at very low.
Or are you guessing because your battery never went flat?
Or are you guessing because your battery never went flat?
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Nov 15, 2007, 09:55 AM
#8
Most amplifiers are expected to be 50% efficient. Even Class D amps that claim higher efficiency (>80%) are closer to 50% when the impedance is fully loaded down since the efficiency measurement is taken @ 4ohms and no one buys these amps to run that load.
So 500W x 2 (50% efficiency) = 1000W / 13.2V (lowest running batt Voltage) = 75A needed.
Music is dynamic and you can exceed this amount for peak musical transients. You run into problems when you are exceeding the alternators capability the majority of the time. There is no rule for what wattage requires an upgraded alternator because amplifier ratings are very subjective and output is dependent on frequency and the speaker impedance at that frequency. The setup (gain structure/clipping/other accessories/temp) all have a bearing on alternator performance too. For a properly desinged and setup system I would think 1000 clean Watts will be OK. Add the typical clipping of the sub amp and the number goes down. Square waves are a big drain, in many cases it would be beneficial and draw less current to use a 1000W amp that won't be driven to clipping instead of a 500W amp that is clipping on every note.
So 500W x 2 (50% efficiency) = 1000W / 13.2V (lowest running batt Voltage) = 75A needed.
Music is dynamic and you can exceed this amount for peak musical transients. You run into problems when you are exceeding the alternators capability the majority of the time. There is no rule for what wattage requires an upgraded alternator because amplifier ratings are very subjective and output is dependent on frequency and the speaker impedance at that frequency. The setup (gain structure/clipping/other accessories/temp) all have a bearing on alternator performance too. For a properly desinged and setup system I would think 1000 clean Watts will be OK. Add the typical clipping of the sub amp and the number goes down. Square waves are a big drain, in many cases it would be beneficial and draw less current to use a 1000W amp that won't be driven to clipping instead of a 500W amp that is clipping on every note.
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