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#1
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Capacitors
When should you consider getting a capacitor for your car audio
system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#2
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Capacitors
people always get caps b/c there lights are dimming. i dont know why
they waist there money on them a 2nd battery will work better. upgrade the car battery to the biggest cca that you can fit then upgrade all wires to the alt and then upgrade alt .caps are a temp fix do it right the frist time and save the money from the cap and get the alt -- trex160s ------------------------------------------------------------------------ CarAudioForum.com - Usenet Gateway w/over one million posts online! View this thread: http://www.caraudioforum.com/vbb2/sh...hreadid=160387 |
#3
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Capacitors
Here is my experience: I had 500W Amp. + JLW6, when I cranked up my music without the cap., and whenever it came across strong bass, the amp. shut down by itself (underpowered) and then turned back on after 5 sec. so I installed a 1 Farad cap. and solved the problem! Side notes: I didn't see a lot light dimming, only slightly.. so light dimming wasn't a good indicator in my case. "Nathan" wrote in message om... When should you consider getting a capacitor for your car audio system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#4
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Capacitors
i had a 1 farad cap on my rf 800a2 and it didnt do didly squat -- capone ------------------------------------------------------------------------ Posted via RealCarAudio.com - The checkmate of the caraudio community. http://www.RealCarAudio.com capone's Profile: http://www.realcaraudio.com/forums/m...fo&userid=1723 View this thread: http://www.realcaraudio.com/forums/s...?threadid=9898 |
#5
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Capacitors
I eould highly reccomend againtst a cap. yeah some of them look cool and
unless you are planning on a show setup there aint no point to having one. In mine and most others opinion a second battery with an isolator and a higher amp capable alternator (or two or more even) will give you much better results. Even if you only change your stock battery to something like an Optima RedTop you might notice some performance gain. EFFENDI "Nathan" wrote in message om... When should you consider getting a capacitor for your car audio system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#6
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Capacitors
FYI, Adding a "stiffening" capacitor to a fully regulated amplifier won't
even help at all. You can tell if your amplifier has a fully regulated supply by checking to see if it has a secondary storage device in the amps PS. Usually, it will be another ferrite core wound with wire just like the PS transformer. I wouldn't recommend opening your amp up just to check, but I would tell you to contact your amp manufacture's tech support and ask them. Adding a second, isolated battery/alternator UG is always good. Keeps you from stranding you somewhere with a dead battery ( if done proper ) as well as adding capacity. Just be sure and use a sealed battery if you plan on placing it in the trunk. It is against the law in many states to put a vented battery in a "sealed" or passenger area. Vented batteries give off poisonous/corrosive/explosive vapors when charged. Taffer Garrett "Nathan" wrote in message om... When should you consider getting a capacitor for your car audio system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#7
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Capacitors
I have no first hand experience with Caps in my system. I never felt the
need for one. If my amps were overloading the electrical system in any way I wouldn't fix it with a cap. My choice would be a high output alternator. This is my understanding.... Its a product that many times does nothing to improve SQ or SPL. IMHO its used as a band aid, quick fix to try and cover up an overloaded alternator. Your SPL scores will not improve, if anything your SPL will decrease, as the cap is placing an additional load on the alternator. If your headlights are dimming, adding a cap will provide extra current for transient peaks, but at the same time youre adding a load to the alternator and taking precious power away from your amps. Again, I dont have first hand experience with caps in my system... unless someone can convince me they are worth the $$$ :~) If I did need an electrical system upgrade an alternator would be my choice.... fix the root cause. Garrett "Nathan" wrote in message om... When should you consider getting a capacitor for your car audio system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#8
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Capacitors
Just put .05f caps on your headlights if it bothers you so much
"sanitarium" wrote in message news:1065206183.423449@sj-nntpcache-5... I have no first hand experience with Caps in my system. I never felt the need for one. If my amps were overloading the electrical system in any way I wouldn't fix it with a cap. My choice would be a high output alternator. This is my understanding.... Its a product that many times does nothing to improve SQ or SPL. IMHO its used as a band aid, quick fix to try and cover up an overloaded alternator. Your SPL scores will not improve, if anything your SPL will decrease, as the cap is placing an additional load on the alternator. If your headlights are dimming, adding a cap will provide extra current for transient peaks, but at the same time youre adding a load to the alternator and taking precious power away from your amps. Again, I dont have first hand experience with caps in my system... unless someone can convince me they are worth the $$$ :~) If I did need an electrical system upgrade an alternator would be my choice.... fix the root cause. Garrett "Nathan" wrote in message om... When should you consider getting a capacitor for your car audio system. Would 800watts be helped out by a capacitor or would it just be a waste of money. |
#9
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Capacitors
"trex160s" wrote in message s.com... people always get caps b/c there lights are dimming. i dont know why they waist there money on them a 2nd battery will work better. upgrade the car battery to the biggest cca that you can fit then upgrade all wires to the alt and then upgrade alt .caps are a temp fix do it right the frist time and save the money from the cap and get the alt you do realize that if you don't upgrade the alt first you can make the situation worse. the proper setup should be, wire, alt, batt, and cap, in that order. |
#10
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Capacitors
caps are junk! -- capone ------------------------------------------------------------------------ Posted via RealCarAudio.com - The checkmate of the caraudio community. http://www.RealCarAudio.com capone's Profile: http://www.realcaraudio.com/forums/m...fo&userid=1723 View this thread: http://www.realcaraudio.com/forums/s...?threadid=9898 |
#11
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Capacitors
s.com...
people always get caps b/c there lights are dimming. i dont know why they waist there money on them a 2nd battery will work better. upgrade the car battery to the biggest cca that you can fit Not even close. All a bigger battery does is provide more engine off listening time. When the car is running the battery is nothing more than a load, just like a light or your defroster. then upgrade all wires to the alt and then upgrade alt .caps are a temp fix do it right the frist time and save the money from the cap and get the alt I agree about upgrading the alternator first, but a cap does a different job. you do realize that if you don't upgrade the alt first you can make the situation worse. Care to explain how? Cuz that's total BS. the proper setup should be, wire, alt, batt, and cap, in that order. Really? I've never change a battery in any of my cars, including my competition cars. Paul Vina |
#12
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Capacitors
Only if you're trying to get it to do something it wasn't meant to do. Caps
aren't meant to keep headlight from dimming, they're to provide voltage quickly when the alternator can't keep up, but only for very quick bursts. Paul Vina "capone" wrote in message ... caps are junk! -- capone ------------------------------------------------------------------------ Posted via RealCarAudio.com - The checkmate of the caraudio community. http://www.RealCarAudio.com capone's Profile: http://www.realcaraudio.com/forums/m...fo&userid=1723 View this thread: http://www.realcaraudio.com/forums/s...?threadid=9898 |
#13
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Capacitors
I'll second the opinion that additional batteries and/or
larger batteries are unnecessary. Batteries are for starting the car or running the system with the engine off - that's all. Furthermore, alternators only need to be able to keep up with the *average* current demand, not the *peak* demand. As long as you can drive around all day listening to music at your normal volume and not drain your battery, your alternator is sufficient. Now, for those large transient peaks that your alternator *can't* handle, that's where capacitors come in. Caps have an extremely low internal resistance, so they can provide huge bursts of current for short periods of time with almost no voltage drop. As long as your alternator can handle your car's average current requirements, it's not a "band-aid" or bad engineering to use a capacitor to handle the transients. Think of a typical toilet. When flushed, they have to be able to get rid of about a gallon of water in 10 or 15 seconds (about 4-6 gallons per minute). Now look at the water supply line coming in from the wall. Odds are, it's so small that it could never flow the required 4-6 gallons per minute to handle a flush. How do they get around this problem? The toilet tank that sits on top of the bowl holds a gallon or so of water in reserve. This tank is refilled from the small-diameter supply line in-between flushes. If you didn't use a tank, the only other option would be to use a much bigger supply line that could handle the peak flow rate required for a flush. In a car, the supply line would be the alternator, the toilet tank would be the capacitor, and flushing the toilet would be an example of a peak transient. As long as your tank is big enough to handle the transient peaks, you can get away with a smaller supply line. Scott Gardner On Fri, 17 Oct 2003 22:06:22 -0400, "Tha Ghee" wrote: "trex160s" wrote in message ws.com... people always get caps b/c there lights are dimming. i dont know why they waist there money on them a 2nd battery will work better. upgrade the car battery to the biggest cca that you can fit then upgrade all wires to the alt and then upgrade alt .caps are a temp fix do it right the frist time and save the money from the cap and get the alt you do realize that if you don't upgrade the alt first you can make the situation worse. the proper setup should be, wire, alt, batt, and cap, in that order. |
#14
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Capacitors
I'll second the opinion that additional batteries and/or
larger batteries are unnecessary. Batteries are for starting the car or running the system with the engine off - that's all. Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. Oftentimes the amplifiers will shut off due to voltage below threshold. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. Furthermore, alternators only need to be able to keep up with the *average* current demand, not the *peak* demand. As long as you can drive around all day listening to music at your normal volume and not drain your battery, your alternator is sufficient. Now, for those large transient peaks that your alternator *can't* handle, that's where capacitors come in. Caps have an extremely low internal resistance, so they can provide huge bursts of current for short periods of time with almost no voltage drop. The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. As long as your alternator can handle your car's average current requirements, it's not a "band-aid" or bad engineering to use a capacitor to handle the transients. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? |
#15
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Capacitors
Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. That's a sure way of damaging your alternator. Oftentimes the amplifiers will shut off due to voltage below threshold. Yes they will, alternators do not respond fast enough to power peaks, causing voltage drops triggering under-voltage protecting in the amplifier, shutting it off . That's where a capacitor comes in to play. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. What is a poor battery, a faulty one ? . The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. True, most this voltage drop occurs between the battery and capacitor and not as much so between the capacitor and amplifier. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? Yes, Mid-grade amplifiers such as some Kenwood, Alpine amplifiers, use paper electrolytic capacitors that are way to small for their application. Not that long ago, I have bench tested a Profile 200 watt rms mono block amplifier after replacing a few burnt out output mosfets. At 14 volts with a current draw of about 18amps at peak the power led stated dimming. At that point i have ripped the amplifier apart again and upgraded the power hexfets to lager ones, I also doubled the size of the power capacitors and changed them from paper film to aluminum film capacitors, and that totally eliminated the power led dimming problem that this amplifier had at high volumes. |
#16
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Capacitors
Batteries do in fact supply current to the audio system. Try running a
system with the car on and the battery disconnected. That's a sure way of damaging your alternator. No it isn't. It can be damaging to your sensitive electronics, but you won't burn out your alternator. Oftentimes the amplifiers will shut off due to voltage below threshold. Yes they will, alternators do not respond fast enough to power peaks, causing voltage drops triggering under-voltage protecting in the amplifier, shutting it off . That's where a capacitor comes in to play. Or a battery. It's not a matter of alternators not responding "fast enough". They respond as fast as a battery, yet the battery hooked up still prevents the undervoltage state from occurring. It's a matter of the alternator simply not being able to supply enough current during the transients. As a result, the voltage drop is substantial. If the battery is hooked up, it can provide the excess current. If a capacitor is hooked up instead of a battery, it can provide the current assuming the transient is short enough. This is usually not the case. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. What is a poor battery, a faulty one ? Yeah. One that should be replaced. The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. True, most this voltage drop occurs between the battery and capacitor and not as much so between the capacitor and amplifier. Not sure what you mean here. There should be a very small voltage drop (less than a volt) between battery and amplifier/capacitor. But it doesn't take much at all for the capacitor to half-discharge in a very small time (shorter than a "typical" transient), in the process having a steep v drop. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? Yes, Mid-grade amplifiers such as some Kenwood, Alpine amplifiers, use paper electrolytic capacitors that are way to small for their application. Not that long ago, I have bench tested a Profile 200 watt rms mono block amplifier after replacing a few burnt out output mosfets. At 14 volts with a current draw of about 18amps at peak the power led stated dimming. At that point i have ripped the amplifier apart again and upgraded the power hexfets to lager ones, I also doubled the size of the power capacitors and changed them from paper film to aluminum film capacitors, and that totally eliminated the power led dimming problem that this amplifier had at high volumes. You don't know that this was an effective upgrade. An LED's performance is hardly indicative. First, the LED is not run off the rails; second, you don't know if LED flicker translates into an audible effect. I sincerely doubt it did. |
#17
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Capacitors
In article , Mark Zarella wrote:
Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. That's a sure way of damaging your alternator. No it isn't. It can be damaging to your sensitive electronics, but you won't burn out your alternator. Where did you get this infomation? Never operate an alternator on an open circuit. With no battery or electrical load in the circuit, alternators are capable of building high voltage (50 to over 110 volts) which may damage diodes and endanger anyone who touches the alternator output terminal. Yes, Mid-grade amplifiers such as some Kenwood, Alpine amplifiers, use paper electrolytic capacitors that are way to small for their application. Not that long ago, I have bench tested a Profile 200 watt rms mono block amplifier after replacing a few burnt out output mosfets. At 14 volts with a current draw of about 18amps at peak the power led stated dimming. At that point i have ripped the amplifier apart again and upgraded the power hexfets to lager ones, I also doubled the size of the power capacitors and changed them from paper film to aluminum film capacitors, and that totally eliminated the power led dimming problem that this amplifier had at high volumes. You don't know that this was an effective upgrade. An LED's performance is hardly indicative. First, the LED is not run off the rails; second, you don't know if LED flicker translates into an audible effect. I sincerely doubt it did. No the led is not run of the rails. But it is run off the internal power supply, which is feed in part from the internal capacitors. Your average (5mm) LED runs at 3.5- 5 volts DC with a current drain of 25mA. When the LED starts dimming, this is a sure sign of internal under-voltage. This creates DC ripples, need I say more? |
#18
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Capacitors
Captain Howdy wrote:
In article , Mark Zarella wrote: Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. That's a sure way of damaging your alternator. No it isn't. It can be damaging to your sensitive electronics, but you won't burn out your alternator. Where did you get this infomation? Never operate an alternator on an open circuit. With no battery or electrical load in the circuit, alternators are capable of building high voltage (50 to over 110 volts) which may damage diodes and endanger anyone who touches the alternator output terminal. Usually the regulator will prevent this from occurring. It's certainly not a "sure way" to burn out an alternator becuse it's happened to me several times and never did I burn out an alternator! (a computer, but not an alternator ) Yes, Mid-grade amplifiers such as some Kenwood, Alpine amplifiers, use paper electrolytic capacitors that are way to small for their application. Not that long ago, I have bench tested a Profile 200 watt rms mono block amplifier after replacing a few burnt out output mosfets. At 14 volts with a current draw of about 18amps at peak the power led stated dimming. At that point i have ripped the amplifier apart again and upgraded the power hexfets to lager ones, I also doubled the size of the power capacitors and changed them from paper film to aluminum film capacitors, and that totally eliminated the power led dimming problem that this amplifier had at high volumes. You don't know that this was an effective upgrade. An LED's performance is hardly indicative. First, the LED is not run off the rails; second, you don't know if LED flicker translates into an audible effect. I sincerely doubt it did. No the led is not run of the rails. But it is run off the internal power supply, which is feed in part from the internal capacitors. Your average (5mm) LED runs at 3.5- 5 volts DC with a current drain of 25mA. When the LED starts dimming, this is a sure sign of internal under-voltage. This creates DC ripples, need I say more? a) Undervoltage condition is generally indetectable by the human ear. b) This does NOT in and of itself create ripples in the rails. Especially in a semi-regulated supply, and global NFB design. Any ripple that did make itself through both barriers generally causes inaudible effects anyway. In other words, voltage fluctuations don't matter, unless headlight dimming really bothers you. In that case, there are other more effective ways of dealing with the issue. |
#19
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Capacitors
On Sun, 30 Nov 2003 03:00:49 GMT, Mark Zarella
wrote: I'll second the opinion that additional batteries and/or larger batteries are unnecessary. Batteries are for starting the car or running the system with the engine off - that's all. Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. Oftentimes the amplifiers will shut off due to voltage below threshold. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. I agree that the battery will provide current when the alternator cannot keep up with the load. Unfortuneately, the battery is a poor candidate for this job, since it has a relatively high internal resistance. This resistance, combined with a high current drain, will cause a significant voltage drop. This is why it's acceptable for even a "good" battery to drop from 12V all the way down to 9.6V while cranking over the engine. Capacitors have a MUCH small internal resistance, so they can provide a larger surge of current without a corresponding large voltage drop. Furthermore, alternators only need to be able to keep up with the *average* current demand, not the *peak* demand. As long as you can drive around all day listening to music at your normal volume and not drain your battery, your alternator is sufficient. Now, for those large transient peaks that your alternator *can't* handle, that's where capacitors come in. Caps have an extremely low internal resistance, so they can provide huge bursts of current for short periods of time with almost no voltage drop. The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. Again, you're absolutely right. There is a voltage drop across the capacitor's terminals as a load is applied, but we can vary how quickly the voltage drops by varying the capacitance. Depending on our needs for a particular installation, we can make the discharge time constant equal to whatever we want by using smaller or larger capacitors. As long as your alternator can handle your car's average current requirements, it's not a "band-aid" or bad engineering to use a capacitor to handle the transients. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? I think the engineers do the best they can within the constraints of packaging size, cost, and the fact that they can't predict how exactly the amp will be used. They don't know how much capacity your car's alternator has, or what other loads are sharing that capacity. My guidance is that unless you know for certain that your stock alternator isn't up to the task (like trying to put 3000 watts of amplification in a stock Civic), give it a try without upgrading the alternator or adding a capacitor. If you can drive around all day playing music at your normal levels without discharging the battery, then your alternator is obviously capable of handling the *average* load you're putting on it. At this point, either everything's good, or you're getting some dimming of lights during large transients. Now, I would try a capacitor. Start off with the 1 Farad/kW estimate and go from there. If that still doesn't solve the problem, you have to find out which is cheaper - more capacitance, or a higher-capacity alternator. Some applications are cheap - you can get 150A alternators for Hondas for less than $250. For older or more offbeat cars, the choices are slimmer. I'm not saying that every installation needs a capacitor, and I'll admit that beyond a certain point, it becomes more cost-effective to put in a higher-capacity alternator. I'm just responding to the people that make blanket statements like "capacitors suck", or blindly follow rules-of-thumb like "one Farad per 1,000 watts amplifier power". Scott Gardner |
#20
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Capacitors
In article , Mark Zarella wrote:
Where did you get this infomation? Never operate an alternator on an open circuit. With no battery or electrical load in the circuit, alternators are capable of building high voltage (50 to over 110 volts) which may damage diodes and endanger anyone who touches the alternator output terminal. Usually the regulator will prevent this from occurring. It's certainly not a "sure way" to burn out an alternator becuse it's happened to me several times and never did I burn out an alternator! (a computer, but not an alternator ) Okay Mark, It seems that at this point, you agree on the fact that running your alternator without a battery will cause damage. For someone such as yourself that has been here for a long while, you are fully aware that this news group is mostly for newbies to have a place to go to for advice. Why would you tell someone to run their alternator without a battery when you know that you can do serious damage by doing so? For anyone in doubt, checkout http://www3.telus.net/DonsMiniSite/M...lternator.html http://www.tpub.com/content/construc...s/14273_51.htm http://www.allpar.com/eek/alternators.html a) Undervoltage condition is generally indetectable by the human ear. Undervoltage tends to overheat transistors, causing your amplifier to go in to thermal protection and shutting the amlifier off making this detectable by the human ear. It also creates distortion at lower power levels, which may damage your speakers. http://www.polkaudio.com/car/faqad/a...le=hownottowax In other words, voltage fluctuations don't matter, Are you totally sure? unless headlight dimming really bothers you. In that case, there are other more effective ways of dealing with the issue. Care to share? |
#21
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Capacitors
Batteries do in fact supply current to the audio system. Try running a
system with the car on and the battery disconnected. Oftentimes the amplifiers will shut off due to voltage below threshold. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. I agree that the battery will provide current when the alternator cannot keep up with the load. Unfortuneately, the battery is a poor candidate for this job, since it has a relatively high internal resistance. This resistance, combined with a high current drain, will cause a significant voltage drop. This is why it's acceptable for even a "good" battery to drop from 12V all the way down to 9.6V while cranking over the engine. Capacitors have a MUCH small internal resistance, so they can provide a larger surge of current without a corresponding large voltage drop. Batteries are an integral part of the audio system. Certainly moreso than a capacitor. The benefits of added capacitance do not significantly contribute to the alternator's net output. The same cannot be said of batteries. Although the output impedance of a battery is greater than that of a capacitor, the amount of energy it stores and therefore can deliver is much greater. Capacitors are useless for trying to keep up with musical transients, which tend to last longer than the usable discharge time of a 1 to few farad capacitor. The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. Again, you're absolutely right. There is a voltage drop across the capacitor's terminals as a load is applied, but we can vary how quickly the voltage drops by varying the capacitance. Depending on our needs for a particular installation, we can make the discharge time constant equal to whatever we want by using smaller or larger capacitors. Yeah, and for practical applications, this requires a pretty huge amount of capacitance. And for what benefit? As long as your alternator can handle your car's average current requirements, it's not a "band-aid" or bad engineering to use a capacitor to handle the transients. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? I think the engineers do the best they can within the constraints of packaging size, cost, and the fact that they can't predict how exactly the amp will be used. They don't know how much capacity your car's alternator has, or what other loads are sharing that capacity. My guidance is that unless you know for certain that your stock alternator isn't up to the task (like trying to put 3000 watts of amplification in a stock Civic), give it a try without upgrading the alternator or adding a capacitor. If you can drive around all day playing music at your normal levels without discharging the battery, then your alternator is obviously capable of handling the *average* load you're putting on it. If your battery is discharging, there's no amount of capacitance that will help. At this point, either everything's good, or you're getting some dimming of lights during large transients. Now, I would try a capacitor. Start off with the 1 Farad/kW estimate and go from there. If that still doesn't solve the problem, you have to find out which is cheaper - more capacitance, or a higher-capacity alternator. Some applications are cheap - you can get 150A alternators for Hondas for less than $250. For older or more offbeat cars, the choices are slimmer. I'm not saying that every installation needs a capacitor, and I'll admit that beyond a certain point, it becomes more cost-effective to put in a higher-capacity alternator. I'm just responding to the people that make blanket statements like "capacitors suck", or blindly follow rules-of-thumb like "one Farad per 1,000 watts amplifier power". I know of no practical applications where a capacitor is a more viable option, aside from trying to prevent dimming by putting them as close to the headlights as possible. Yet the reasons most often attributed to adding capacitance tend to be to improve sound in some fashion by mounting them as close to the amplifiers as possible - total bull. |
#22
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Capacitors
Captain Howdy wrote:
In article , Mark Zarella wrote: Where did you get this infomation? Never operate an alternator on an open circuit. With no battery or electrical load in the circuit, alternators are capable of building high voltage (50 to over 110 volts) which may damage diodes and endanger anyone who touches the alternator output terminal. Usually the regulator will prevent this from occurring. It's certainly not a "sure way" to burn out an alternator becuse it's happened to me several times and never did I burn out an alternator! (a computer, but not an alternator ) Okay Mark, It seems that at this point, you agree on the fact that running your alternator without a battery will cause damage. When did I say otherwise? For someone such as yourself that has been here for a long while, you are fully aware that this news group is mostly for newbies to have a place to go to for advice. Why would you tell someone to run their alternator without a battery when you know that you can do serious damage by doing so? I didn't literally mean to go out and try it! a) Undervoltage condition is generally indetectable by the human ear. Undervoltage tends to overheat transistors, causing your amplifier to go in to thermal protection and shutting the amlifier off making this detectable by the human ear. Wrong. Which transistors are they overheating? It also creates distortion at lower power levels, How?? which may damage your speakers. How?? We've addressed the "distortion blows speakers" myth in here ad nauseum, and have demonstrated it to be total trash. Quite simply, lower voltage means less power which means you're less likely to blow your speaker. There's nothing more to it. http://www.polkaudio.com/car/faqad/a...le=hownottowax http://www.geocities.com/audiotechpa...ingframes.html In other words, voltage fluctuations don't matter, Are you totally sure? Totally. unless headlight dimming really bothers you. In that case, there are other more effective ways of dealing with the issue. Care to share? Anywhere from installing small capacitors near the headlights (I've installed 100,000 uF caps) to actual diode isolation in serious situations. If it gets too serious, you can start damaging things like computers and the like. In that case, no amount of capacitance will save you. |
#23
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Capacitors
I know of no practical applications where a capacitor is a more viable option, aside from trying to prevent dimming by putting them as close to the headlights as possible. Yet the reasons most often attributed to adding capacitance tend to be to improve sound in some fashion by mounting them as close to the amplifiers as possible - total bull. There are a lot of misconceptions about what capacitors are, what they do, and what to look for in one. A capacitor will not make your system suddenly sound much louder (although it can improve it slightly). It will not increase the voltage in your cars system (but it will help maintain it). A capacitor will not provide extra power for devices (but it will maintain it). A capacitor, however, will provide a benefit for most audiophiles in overall sound quality, and can benefit your cars electrical system. For starters, a capacitor has a specific construction. The most basic form of a capacitor is two metal plates, which are very close to each other, but do not touch. The plates are separated by some type of insulating material. Air, which does not conduct, can be used as an insulator, and on older AM/FM radios, the tuning capacitor uses air. Other materials can be used, like plastics, or electrolyte pastes. When power is applied to the capacitor, the charges flow from positive, to the positive plate of the capacitor. The charges stop at the one plate, because of the insulating material, but the electrostatic charge pushes against the charge of the other plate, and causes the current to flow on that side. This flow will happen as long as the charges are able to build up on the plates. The size of the plate, and the distance between the two plates will determine how much charge the plates can hold. When the power source is removed, the charges are still there, and they have no place to go. The charges would like to meet each other, to equalize the charges between the two plates, but the insulator between the plates prevent this. If the plates were allowed to touch, the charges would all flow to the other side at once (which could be very dangerous). If some device, such as a light bulb, speaker, or motor were used to bridge the two sides of the capacitor, the charges would power that device until both plates evened out their charges. In this manner, a capacitor stores electrical charge. When a capacitor charges, it does so at a certain rate. Normally, a capacitor will try to take as much charge as it possibly can, as quickly as it can. Like the shorting of a capacitor, this can be very dangerous. When installing a power supply capacitor (often called a stiffening cap) in a car, you should always charge it through a resistor. A resistor will slow down the rate at which the capacitor charges or discharges. This is known as an RC time constant. This is useful when a capacitor is used for audio. As I said earlier, current will flow through a capacitor until it is saturated. The speed at which a capacitor can take on a charge, and let it out is the frequency at which that capacitor prefers to work. Capacitors, to a certain degree, will resist lower frequencies than it can handle, but will present very little resistance at higher frequencies. This makes small capacitors ideal for blocking low frequency bass from speakers which cannot handle them (you are probably familiar with these as "bass blockers"). The property where a capacitor has more resistance to lower frequencies is called Capacitive Reactance. There is a neat formula for it too, its like this: Xc=1/(2 PI FC) Where Xc is Capacitive reactance. PI is 22/7, or more commonly used 3.1415..... F is frequency, and C is the capacitance in farads, . Now since a farad of charge is highly impractical for audio uses, you will have to convert the rating on your capacitor (which is usually in microfarads, or "µf") to a decimal equivalent of a farad. The easiest way to do this, of course, is to move the decimal point to the left. Anyway.... When a resistor is placed in series with a capacitor, it will change the characteristics of the capacitor, with respect to its reactance. For most car applications, that resistance is the speaker it is used on. Knowing this, we want to look at the two applications of capacitors for car audio: Power Supply Stabilization Crossovers Very large capacitors are used for stabilizing the electrical system. As we have seen, a capacitor stores energy. In a system where several electrical devices are competing for power, when an amp starts using power at an inconstant rate (a little here, a little there), head and dash lights begin to dim. This can also affect other amps in the system. Amps have internal capacitors on the other side of their power supply which hold power for those times when it is really needed. However, the power to charge those capacitors has to come from somewhere, and during peak usage, the power is not always available. The result is that the distortion in the music increases slightly: Sound suffers. A capacitor will store the energy, and will give the energy up when it is needed by other components. Another benefit of the large capacitor, is that as we mentioned, it passes high frequencies. Any electrical noise will be filtered by a capacitor since the noise is AC. In addition, since the capacitor is a large one, then the "high" frequency can actually be pretty low. In this manner, a capacitor helps reduce power supply noise in your audio system. Unfortunately, the larger capacitors are usually polar, meaning that they have a + and - side, and do not work properly when working backwards. The saving grace here is that, even in reverse, there is some capacitance, just not as much as when polarity is respected. The second use of a capacitor in car audio, is as a crossover. As we've seen earlier, the capacitor (smaller, non polar ones) will pass AC of higher frequencies, and resist lower ones. Bass blockers are one example of this. When capacitors are used along with coils, they form crossover networks, which improve the sound going to a driver, and can make a speaker system sound a lot better. Many component sets have crossovers, which use a capacitor to carry the + signal* to the tweeter, and a coil would carry the + signal to the woofer. The negative signals do not need the components, because as long as the capacitor (or coil) are in the circuit somewhere, they will do their job. Without the coil and capacitors, the tweeter would distort badly, the woofer would usually do a really bad job of reproducing the highs, and there would be a nasty peak where the woofer and tweeter overlap. Finally, capacitors can serve several other functions. Getting back to the RC time constant, you could use a capacitor to do things such as allow lights to "fade out" when you turn them off, or to charge a relay for keeping power to your system until you arm the alarm/open the door. You can even make a buzzer from a small capacitor and a relay. The applications are endless if you use your imagination. |
#24
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Capacitors
I know of no practical applications where a capacitor is a more viable
option, aside from trying to prevent dimming by putting them as close to the headlights as possible. Yet the reasons most often attributed to adding capacitance tend to be to improve sound in some fashion by mounting them as close to the amplifiers as possible - total bull. There are a lot of misconceptions about what capacitors are, what they do, and what to look for in one. A capacitor will not make your system suddenly sound much louder (although it can improve it slightly). Slightly? Maybe. But not even close to being detectable by the ear. It will not increase the voltage in your cars system (but it will help maintain it). A capacitor will not provide extra power for devices (but it will maintain it). A capacitor, however, will provide a benefit for most audiophiles in overall sound quality, and can benefit your cars electrical system. How does it benefit sound quality? snip review, which is very well written and technically precise, by the way Very large capacitors are used for stabilizing the electrical system. As we have seen, a capacitor stores energy. In a system where several electrical devices are competing for power, when an amp starts using power at an inconstant rate (a little here, a little there), head and dash lights begin to dim. This can also affect other amps in the system. Amps have internal capacitors on the other side of their power supply which hold power for those times when it is really needed. However, the power to charge those capacitors has to come from somewhere, and during peak usage, the power is not always available. The result is that the distortion in the music increases slightly: Sound suffers. A capacitor will store the energy, and will give the energy up when it is needed by other components. Distortion increases *slightly*. Yeah, this is due to a slight sag in the rail voltage corresponding to the current draw. Yet the difference in rail voltage between the external cap case and the non-cap case is too small to cause a change in the output to make it detectable by humans. I can demonstrate this to you mathematically if you prefer. The proof is based on the assumption that detection threshold changes in the typical musical spectrum at typical SPL levels is at the very least 0.5 dB (that's a low estimate). Then you simply do the electrical analysis, taking amplifier output impedance, global NFB, and speaker impedance into account. I've done these calculations in here before. You can try to google them up if you'd like. The net result was that the difference between having a cap and not having one tended to be well below threshold. Another benefit of the large capacitor, is that as we mentioned, it passes high frequencies. Any electrical noise will be filtered by a capacitor since the noise is AC. Electrical noise is filtered "better" by the smaller capacitors inside the amplifier. Why? Lower net ESL. In addition, since the capacitor is a large one, then the "high" frequency can actually be pretty low. In this manner, a capacitor helps reduce power supply noise in your audio system. Very low frequency noise is never an issue. snip crossover stuff |
#25
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Capacitors
On Mon, 01 Dec 2003 13:25:53 GMT, Mark Zarella
wrote: Batteries do in fact supply current to the audio system. Try running a system with the car on and the battery disconnected. Oftentimes the amplifiers will shut off due to voltage below threshold. In addition, a poor battery will draw excess current from the alternator when charging. This also has a detrimental effect. I agree that the battery will provide current when the alternator cannot keep up with the load. Unfortuneately, the battery is a poor candidate for this job, since it has a relatively high internal resistance. This resistance, combined with a high current drain, will cause a significant voltage drop. This is why it's acceptable for even a "good" battery to drop from 12V all the way down to 9.6V while cranking over the engine. Capacitors have a MUCH small internal resistance, so they can provide a larger surge of current without a corresponding large voltage drop. Batteries are an integral part of the audio system. Certainly moreso than a capacitor. The benefits of added capacitance do not significantly contribute to the alternator's net output. The same cannot be said of batteries. Although the output impedance of a battery is greater than that of a capacitor, the amount of energy it stores and therefore can deliver is much greater. Capacitors are useless for trying to keep up with musical transients, which tend to last longer than the usable discharge time of a 1 to few farad capacitor. Let me start off by saying that Captain Howdy and I are approaching this from two different angles. All I am saying is that in the specific case where your alternator is keeping up with the *average* electrical requests from your car's accessories, but you're getting a little flickering of your lights during transients, a capacitor placed in parallel to the battery can eliminate that flickering. I'm making no claims as to whether it will make your system "louder", "cleaner", or anything of the sort. I'm not even saying there will be an audible difference at all. I've never heard one myself. The voltage drop is proportional to the time. That means that there's ALWAYS a voltage drop as the capacitor discharges, and it can become quite substantial for "typical" (whatever that is) transients. This can all be verified with mathematics also. Again, you're absolutely right. There is a voltage drop across the capacitor's terminals as a load is applied, but we can vary how quickly the voltage drops by varying the capacitance. Depending on our needs for a particular installation, we can make the discharge time constant equal to whatever we want by using smaller or larger capacitors. Yeah, and for practical applications, this requires a pretty huge amount of capacitance. And for what benefit? It's not a huge amount at all. I've eliminate flickering lights with as little as 1/4-Farad of added capacitance. As for the benefit, it's like I said above - I make no claims as to the usefulness of capacitors except that it can smooth out transients enough to help with flickering headlamps or dash lighting. As long as your alternator can handle your car's average current requirements, it's not a "band-aid" or bad engineering to use a capacitor to handle the transients. The engineers already put them inside the amp. Are you suggesting their engineering is inadequate? I think the engineers do the best they can within the constraints of packaging size, cost, and the fact that they can't predict how exactly the amp will be used. They don't know how much capacity your car's alternator has, or what other loads are sharing that capacity. My guidance is that unless you know for certain that your stock alternator isn't up to the task (like trying to put 3000 watts of amplification in a stock Civic), give it a try without upgrading the alternator or adding a capacitor. If you can drive around all day playing music at your normal levels without discharging the battery, then your alternator is obviously capable of handling the *average* load you're putting on it. If your battery is discharging, there's no amount of capacitance that will help. That's exactly what I said. If your battery is discharging over a long period of time, the solution is not a capacitor - it's a higher-capacity alternator. At this point, either everything's good, or you're getting some dimming of lights during large transients. Now, I would try a capacitor. Start off with the 1 Farad/kW estimate and go from there. If that still doesn't solve the problem, you have to find out which is cheaper - more capacitance, or a higher-capacity alternator. Some applications are cheap - you can get 150A alternators for Hondas for less than $250. For older or more offbeat cars, the choices are slimmer. I'm not saying that every installation needs a capacitor, and I'll admit that beyond a certain point, it becomes more cost-effective to put in a higher-capacity alternator. I'm just responding to the people that make blanket statements like "capacitors suck", or blindly follow rules-of-thumb like "one Farad per 1,000 watts amplifier power". I know of no practical applications where a capacitor is a more viable option, aside from trying to prevent dimming by putting them as close to the headlights as possible. Yet the reasons most often attributed to adding capacitance tend to be to improve sound in some fashion by mounting them as close to the amplifiers as possible - total bull. I've never made such claims about the audio benefits of capacitors - you must have me confused with someone else. All I've been saying from the beginning is that in cases where your alternator can handle the *average* load presented to it, but you're getting some flickering of your lights during transients, a capacitor is an acceptable solution vice upgrading to a higher-capacity alternator. Scott Gardner |
#26
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Capacitors
Batteries are an integral part of the audio system. Certainly moreso
than a capacitor. The benefits of added capacitance do not significantly contribute to the alternator's net output. The same cannot be said of batteries. Although the output impedance of a battery is greater than that of a capacitor, the amount of energy it stores and therefore can deliver is much greater. Capacitors are useless for trying to keep up with musical transients, which tend to last longer than the usable discharge time of a 1 to few farad capacitor. Let me start off by saying that Captain Howdy and I are approaching this from two different angles. All I am saying is that in the specific case where your alternator is keeping up with the *average* electrical requests from your car's accessories, but you're getting a little flickering of your lights during transients, a capacitor placed in parallel to the battery can eliminate that flickering. I'm making no claims as to whether it will make your system "louder", "cleaner", or anything of the sort. I'm not even saying there will be an audible difference at all. I've never heard one myself. Then we're in agreement. I know of no practical applications where a capacitor is a more viable option, aside from trying to prevent dimming by putting them as close to the headlights as possible. Yet the reasons most often attributed to adding capacitance tend to be to improve sound in some fashion by mounting them as close to the amplifiers as possible - total bull. I've never made such claims about the audio benefits of capacitors - you must have me confused with someone else. Sorry. I wasn't referring to you specifically. |
#27
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Capacitors
much louder (although it can improve it slightly).
Slightly? Maybe. But not even close to being detectable by the ear. Not really, I didn't expect any volume increase when I installed my caps. How does it benefit sound quality? By smoothing out the voltage in the car, the caps ensure the head unit, as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. Personally I use caps because I don't want to burn out my alt. If you expect your alternator to give you 100 amp power spikes reliably, you gotta check out the small leads connected to the brushes. I want my alternator running as constantly as possible. If I can make it so that it runs at a constant 40 amps, and the caps handle the 100 amp spikes and 10 amp lows, then my alt is going to be a lot happier. Anyway I don't want to beat an old horse here, just adding my educated $.02 to the mix Cheers, Aaron |
#28
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Capacitors
How does it benefit sound quality?
By smoothing out the voltage in the car, the caps ensure the head unit, as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. A cap will not take a system running 11.5 volts and smooth it out to 14. Are you sure you even know what a cap is and does? Personally I use caps because I don't want to burn out my alt. If you expect your alternator to give you 100 amp power spikes reliably, you gotta check out the small leads connected to the brushes. I want my alternator running as constantly as possible. A cap is not going to help your alt. IF your alt is burning out then capacitance is not the issue. If I can make it so that it runs at a constant 40 amps, and the caps handle the 100 amp spikes and 10 amp lows, then my alt is going to be a lot happier. WTF?? What are you talking about? Anyway I don't want to beat an old horse here, just adding my educated $.02 to the mix No offense Aaron but you educated 2 cents needs to get its ass back into school and learn what a cap is and does. It is not a wonder fix it all make a system sound better as you imply. In most cases it is at BEST a bandaid and at worse a detriment to the system. Les |
#29
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Capacitors
How does it benefit sound quality?
By smoothing out the voltage in the car, the caps ensure the head unit, as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. How?? |
#30
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Capacitors
By smoothing out the voltage in the car, the caps ensure the head unit,
as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. How?? The same reason as the amps do, higher voltage to the head unit will ensure it doesn't have to work as hard to make the same sound, and it will reduce distortion near the limit. If you guys disagree with this I really should just leave this NG... Aaron |
#31
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Capacitors
By smoothing out the voltage in the car, the caps ensure the head unit,
as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. How?? The same reason as the amps do, higher voltage to the head unit will ensure it doesn't have to work as hard to make the same sound, and it will reduce distortion near the limit. If your not running into clipping it will sound the same. Regardless of the voltage. Assuming reasonable levels. If you guys disagree with this I really should just leave this NG... Aaron Well bye. I see your logic but it has an inherent flaw. It will only be able to get louder without distortion, which is not better sound, just louder without distortion. Les |
#32
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Capacitors
If your not running into clipping it will sound the same. Regardless of the
voltage. Assuming reasonable levels. True. But at reasonable listening levels I'm not getting voltage drop either. The only time I'll get voltage drop is at 10/10ths, and that's when my head unit might run into clipping. |
#33
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Capacitors
If your not running into clipping it will sound the same. Regardless of the
voltage. Assuming reasonable levels. True. But at reasonable listening levels I'm not getting voltage drop either. The only time I'll get voltage drop is at 10/10ths, and that's when my head unit might run into clipping. Nontheless your SQ will not change up to the point of clipping. The unit may be able to play LOUDER, but that is not the same thing as it sounding better. It will have the same SQ but just get louder. Make sense? Les |
#34
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Capacitors
In article , Aaron wrote:
much louder (although it can improve it slightly). Slightly? Maybe. But not even close to being detectable by the ear. Not really, I didn't expect any volume increase when I installed my caps. How does it benefit sound quality? By smoothing out the voltage in the car, the caps ensure the head unit, as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. Personally I use caps because I don't want to burn out my alt. If you I don't think caps help an alternator last longer. But I have not tested that really. But a cap does help an alternator and the wiring losses. An alternator must be running at high RPM to come close to its rated capacity. Even if your driving down the road it may not be running fast enough to put out 100% capacity. A cap does help maintain a voltage closer to the alternator rather than the battery. greg |
#35
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Capacitors
"Aaron" wrote in message
... By smoothing out the voltage in the car, the caps ensure the head unit, as well as the rest of the car, has proper voltage more often. A head unit will sound a lot better running at 14 v than 11.5 volts. How?? The same reason as the amps do, higher voltage to the head unit will ensure it doesn't have to work as hard to make the same sound, and it will reduce distortion near the limit. If you guys disagree with this I really should just leave this NG... Aaron your speaking of if you have more input voltage you need less current which puts less stress on the HU/amp components |
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