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Thread: For anyone with a SERIOUS audio system

  1. #1
    Low Bitrate rmjjensen's Avatar
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    For anyone with a SERIOUS audio system

    I've got an annoyance .....my alternator charges at a rock solid 14V all the time. However, when I start bumping the system the voltage drops (of course). This isn't really a problem, but if I adjust my settings to get some SPL output the voltage will drop so low that my computer will shut down. I have all the generic bases covered, but am considering adding an extra battery or two.

    It's very annoying. Does anyone else have problems where a "brown out" will freeze their computer? What power supplies are you guys using and how low has the voltage gone (if you know).

    Mine can go sub 11.2V then the comp will freeze up and restart itself.

  2. #2
    FLAC strohj's Avatar
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    most people who who go to such a high power output on sound... already run 2 or more batteries... AND a bigger alternator...

    I myself noticed that just the bigger alternator works for me... but then I am not pushing anything that hard...
    Pentium 4m 1.5GHz|MB896|Roadie Extreme|XM-Direct|Rikaline 6010|T-View 7"|Streetdeck|160gb Western Digital|1Gb DDR2-533 Ram

  3. #3
    Low Bitrate khemical's Avatar
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    Quote Originally Posted by strohj
    most people who who go to such a high power output on sound... already run 2 or more batteries... AND a bigger alternator...

    I myself noticed that just the bigger alternator works for me... but then I am not pushing anything that hard...
    I second that. You might be able to find a local auto shop that will be able to wind your current alternator to add about 100 more amps to it. That is what I did, but it does shorten the life of it. Already went through one of those on my ol' 95.

    steve

  4. #4
    Constant Bitrate lanman1's Avatar
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    Quote Originally Posted by rmjjensen
    I've got an annoyance .....my alternator charges at a rock solid 14V all the time. However, when I start bumping the system the voltage drops (of course). This isn't really a problem, but if I adjust my settings to get some SPL output the voltage will drop so low that my computer will shut down. I have all the generic bases covered, but am considering adding an extra battery or two.

    It's very annoying. Does anyone else have problems where a "brown out" will freeze their computer? What power supplies are you guys using and how low has the voltage gone (if you know).

    Mine can go sub 11.2V then the comp will freeze up and restart itself.
    What PS do you use on your CarPC?

  5. #5
    Low Bitrate Imagex's Avatar
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    Sounds like you could use a power cap in your system.
    James Tune
    CEO, Co Founder
    Hybrid Mobile Solutions, Inc

  6. #6
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    caps are a waste of time and money, unless they are BatCaps or the something like the new stinger 20+ farad caps, they discharge too quickly to do you any good and can actually hurt your sound/spl performance.

    This can be a problem of a few things...it could be that you have demanded too much of your alternator as it is. I will tell you to NOT take your alternator to a local audio shop, they won't know what to do with it AND chances are they will charge you too much to do it. Take it to an actual alternator shop and have them rewind it. You can also run a second battery if you want, but I would look at what kind of battery you are currently running. If it's not an optima red or yellow top, spend the money ($100 if you look a little) and upgrade. If you really want to go big, get a Stinger SP1700 ($450 MSRP last time i checked). That battery should give you all the reserve that you need. I was running two of them in my GTi when I was competing in SPL (http://www.stingerelectronics.com/we...ies_power2.asp), but then again I was pushing 4 12"s and a USAmps 2000 and a high and mid amp. I was able to run my car for 4 hours without the motor running before I drained those two batteries, and I was still able to start the car right up after that.
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

  7. #7
    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    Sorry for the following long post, but ask a complicated question & get complicated answers…

    A properly used stiffening cap is to your electrical system, what your shock absorbers are to your suspension. You could drive your car without shock absorbers but the constant pounding will ruin structural components & transfer the shock to the rest of the vehicle, causing your pc to shut down among other things. The stiffening cap will actually prolong the life of your alternator in the same way, by "absorbing" the big instantaneous demands for high current & smoothing them out to a certain point. Just because your caddy has shocks, doesn't mean you can go Baja it off road, obviously a stiffening cap isn't going to cure all & if the overall average draws of the system & the rest of the vehicle is higher than the output of the alternator the cap will not solve your problem. you can't expect a stiffing cap to supplement a true 1000+ watt system, & even a bunch of batteries will only prolong the inevitable of draining your reserves, to run a system that has big power demands you must increase the output of the alternator to meet these demands.

    The best solution is a combination of an aux battery close to the amps & a stiffening cap. A configuration like this will allow you to draw up to & even over your alternators output for short periods of time without a problem....


    I can't tell you how many bigger systems have been installed, only to need a new alternator within a month or so. This is actually common, especially if your working with a car that has had it's alternator in service for 5 years or more. The main goal here is to absorb the dips & spikes, the headlights dimming are only a symptom of the real problem.

    An amplifier instantaneously pulling up to 150 amps or much more in some cases, from your battery for a peak is almost as severe as intermittently shorting the terminals. This will not only overload the alternator, but can also screw with ecm's, bcm's, air suspension and/or suspension controls, not to mention a whole host of other electrical systems in a vehicle, Including your car pc, which doesn’t like an unstable environment, especially electrically.

    most of these systems are already being taxed by the fact that they are used in a mobile unstable environment in the first place, & most have been designed to live under these conditions, but add this much more stress & problems can & do occur. This is the main reason that automotive computer systems use say a 5v reference for sensors & such, because they can regulate it & attempt to maintain this constant voltage much more reliably than if they tried to run these systems at full battery voltage, which can easily vary by over 2 volts up or down depending on loads & usage.


    the cap can act as sort of a shock absorber, by providing the big instant hit of extra amperage at the right time, thereby taxing the electrical system that much less. Depending on how much is needed this may or may not make all the difference needed. an aux battery in the rear will kind of act as a spring, by being able to help deliver power under those same conditions, but for a longer period of time than a cap. The real difference is how "fast" the power demand is needed. Think of a cap as a sledge hammer, quick short bursts of power, but with a pause in between for recharging (backswing). Now think of the battery as a helper pushing. You will get the best results by having one guy pushing while the other swings away with the sledge hammer, all being perfectly timed by the physics of the demand at hand.

    I have built pro systems that will run at say 1,200 true rms, & powered it more than adequate with a 4 gauge run from the front to the rear battery, which is close to the amps. From the rear battery you would give each amp the power it needs, with even a 0 gauge for the sub amp & cap bank, 0 gauge ground to frame. Now keep in mind that the 4 gauges only job is to charge the rear battery, which in turn really supplies the system. The 4 gauge will not be overloaded because on average it is only providing the 30-50 amps required to maintain battery voltage in the rear, & the majority of the quick instant heavy short loads are handled by the rear battery & caps, never actually overtaxing the front of the vehicle itself. This is verified by the fact that I can run this system with an 80 amp breaker inline front 4 gauge without ever blowing it. Actually the only way to blow this 80 amp breaker is if the front battery went dead & then I tried to crank off the rear battery, or boost the vehicle from the rear. This system had a peak draw of almost 200 amps & it never saw the front of the vehicle.

    Anyone who tells you that a battery is better, or a cap is better, is not taking the whole picture into account. If I had to choose between one and the other in an install, I would pick the battery, but honestly they work best together. A batcap is kind of a melt between the two, but doesn't achieve the peak benefits of either; sometimes it can be a reasonable compromise when space is restricted...

  8. #8
    Low Bitrate rmjjensen's Avatar
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    Awesome replies!! So no one really has the problem I'm having ...dam.

    I think the main problem is that my car idle's at 500-650RPMs which is normal for it, but no alternator, even a high output one, will output it's peak current at idle. Here's some specs on my audio/electrical system:

    Stock Alternator: supposidly about 100amps
    Optima Yellow Top battery up front
    Upgraded 4 Gauge wire from alternator post to battery
    Upgraded 4 Gauge ground wire from battery to chassis and battery to engine block
    0 Gauge wire from battery to back of car
    5 Farad Capacitor in the back
    0 Gauge ground wire to a solid chassis bolt in the back

    Computer: VIA ITX board
    PowerCool 1U (Server style) 12V ATX power supply (I think it's 150 watts)

    Audio:
    Alpine PXA-H701 Digital Processor
    JBL BPx1100.1 Sub Amp
    JBL Px300.4 Full Range Amp
    2 Audiobahn Alum12Q subs (1.5cu ft each)
    Focal PolyK 165K V2 Speakers all around

    I install professionally and have never really had any electrical problems 'til I upgraded to that BPx sub amp ....It's most likely truely drawing at least the 1100watts RMS it's advertised at. When I drive it's fine ...it's idleing that sucks. Now, since it's fine at normal/high RPMs, is it safe to say the stock alternator will be able to charge two batteries. I'm thinking of using a isolator setup but I don't really want to try to fix this with "band-aids."

    I think maybe one of those stinger SP1700's in the back would do the trick. Maybe isolate my setup and put the computer on the vehicle's battery, and all the system stuff on that monster battery.

    Oh - and forget running the system with the car off, battery voltage severely drops during peak bass hits. .....so I think that maybe dual battery setups w/ an isolator might be the best bet. Yes or no?

    turbocad6: I saw your install page......wow! That's some amazing work right there. I love it.

  9. #9
    Constant Bitrate IonDokk's Avatar
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    Cool

    [QUOTE=rmjjensen]I've got an annoyance .....my alternator charges at a rock solid 14V all the time. However, when I start bumping the system the voltage drops (of course). This isn't really a problem, but if I adjust my settings to get some SPL output the voltage will drop so low that my computer will shut down. I have all the generic bases covered, but am considering adding an extra battery or two.

    It's very annoying. Does anyone else have problems where a "brown out" will freeze their computer? What power supplies are you guys using and how low has the voltage gone (if you know).

    Mine can go sub 11.2V then the comp will freeze up and restart itself.



    I run two harrison Labs 1600's to two rockford power 700 watt 12's, with two xtant 4004's 50x4channel with various focal and scanspeak drivers & tweets
    with two audiocontrol three.1 preamps.

    First thing is have an extra battery. Then be sure that your computer has a 1 farrad capacitor in front of it ( this is probably over kill but it will keep you from losing power) another 1 farrad capacitor will help your subs keep up as well but the xtra batt and the cap infront of the pc will make all the difference in the world!
    Epia M1000 1.2gig, Toshiba 40gb HD, Itronix 60gb HD, 512ram,PCR, Audigy2zs, 2 Xenarc 7" , FRODOPLAYER Trying RR frontend , 2@1600/w Harrison labs amps & Caps, Focal & MB-Quart midrange, Diamond Audio D6 Subs, Mb Quart Tweets, 2-Audiocontrol three.1 !

  10. #10
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    This is exactly true and why I specified that the heavy duty caps are just about the only thing worth a damn. (meaning these pansy little 1 farad and 1/2 farad caps aren't worth the money on their own) ESPECIALLY on heavy systems. Now to run those small caps on your computer, sure, but on an amp? I wouldn't suggest spending the money on it for most amps.

    Excelent reply, thanks for clearing it up.


    Quote Originally Posted by turbocad6
    Sorry for the following long post, but ask a complicated question & get complicated answers…

    A properly used stiffening cap is to your electrical system, what your shock absorbers are to your suspension. You could drive your car without shock absorbers but the constant pounding will ruin structural components & transfer the shock to the rest of the vehicle, causing your pc to shut down among other things. The stiffening cap will actually prolong the life of your alternator in the same way, by "absorbing" the big instantaneous demands for high current & smoothing them out to a certain point. Just because your caddy has shocks, doesn't mean you can go Baja it off road, obviously a stiffening cap isn't going to cure all & if the overall average draws of the system & the rest of the vehicle is higher than the output of the alternator the cap will not solve your problem. you can't expect a stiffing cap to supplement a true 1000+ watt system, & even a bunch of batteries will only prolong the inevitable of draining your reserves, to run a system that has big power demands you must increase the output of the alternator to meet these demands.

    The best solution is a combination of an aux battery close to the amps & a stiffening cap. A configuration like this will allow you to draw up to & even over your alternators output for short periods of time without a problem....


    I can't tell you how many bigger systems have been installed, only to need a new alternator within a month or so. This is actually common, especially if your working with a car that has had it's alternator in service for 5 years or more. The main goal here is to absorb the dips & spikes, the headlights dimming are only a symptom of the real problem.

    An amplifier instantaneously pulling up to 150 amps or much more in some cases, from your battery for a peak is almost as severe as intermittently shorting the terminals. This will not only overload the alternator, but can also screw with ecm's, bcm's, air suspension and/or suspension controls, not to mention a whole host of other electrical systems in a vehicle, Including your car pc, which doesn’t like an unstable environment, especially electrically.

    most of these systems are already being taxed by the fact that they are used in a mobile unstable environment in the first place, & most have been designed to live under these conditions, but add this much more stress & problems can & do occur. This is the main reason that automotive computer systems use say a 5v reference for sensors & such, because they can regulate it & attempt to maintain this constant voltage much more reliably than if they tried to run these systems at full battery voltage, which can easily vary by over 2 volts up or down depending on loads & usage.


    the cap can act as sort of a shock absorber, by providing the big instant hit of extra amperage at the right time, thereby taxing the electrical system that much less. Depending on how much is needed this may or may not make all the difference needed. an aux battery in the rear will kind of act as a spring, by being able to help deliver power under those same conditions, but for a longer period of time than a cap. The real difference is how "fast" the power demand is needed. Think of a cap as a sledge hammer, quick short bursts of power, but with a pause in between for recharging (backswing). Now think of the battery as a helper pushing. You will get the best results by having one guy pushing while the other swings away with the sledge hammer, all being perfectly timed by the physics of the demand at hand.

    I have built pro systems that will run at say 1,200 true rms, & powered it more than adequate with a 4 gauge run from the front to the rear battery, which is close to the amps. From the rear battery you would give each amp the power it needs, with even a 0 gauge for the sub amp & cap bank, 0 gauge ground to frame. Now keep in mind that the 4 gauges only job is to charge the rear battery, which in turn really supplies the system. The 4 gauge will not be overloaded because on average it is only providing the 30-50 amps required to maintain battery voltage in the rear, & the majority of the quick instant heavy short loads are handled by the rear battery & caps, never actually overtaxing the front of the vehicle itself. This is verified by the fact that I can run this system with an 80 amp breaker inline front 4 gauge without ever blowing it. Actually the only way to blow this 80 amp breaker is if the front battery went dead & then I tried to crank off the rear battery, or boost the vehicle from the rear. This system had a peak draw of almost 200 amps & it never saw the front of the vehicle.

    Anyone who tells you that a battery is better, or a cap is better, is not taking the whole picture into account. If I had to choose between one and the other in an install, I would pick the battery, but honestly they work best together. A batcap is kind of a melt between the two, but doesn't achieve the peak benefits of either; sometimes it can be a reasonable compromise when space is restricted...
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

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