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Bronze Member Username: Malby7Post Number: 90 Registered: May-04 | Hi, I have a 2 ga wire coming off of my battery running into an ANL fuse holder with a 125A fuse in it. Then the 2 ga splits into two 4ga via simple dist. block. These two 4ga power my 2 amps (JL Audio 300/4 and 500/1). I would like to know what the amperage draws are for each of these amps so that I don't accidentally run too much power to these things a screw them up. Am I safe with leaving the 125A fuse at the battery or should I fuse each of the 4ga lines going to the amps? help me out Guru's please! - Mike |
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Anonymous | i'd go ahead and fuse each of the 4ga wires, just to be safe. something like a 60A for the 500/1 and a 40A for the 300/4. |
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Bronze Member Username: Malby7Post Number: 91 Registered: May-04 | ok Thanks! |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4543 Registered: Dec-03 | go to jlaudio.com and get the PDF manuals for the amps. they list peak current draw. otherwise, figure the 500/1 is a class D, and 300/4 is a class AB. take the total power output of the amps, and divide by 12. then for the 500.1 multiply that total by 1.2, and that's your current draw at peak. for the 300/4 take total power, divide by 12, then multiply total by 1.4 to get your current draw. the multipliers factor in average efficiency for a class D and AB amplifier. that'll give you an idea for each one. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 514 Registered: Sep-04 | I wouldn't think you would need to fuse each individual run of 4 gauge as long as that 125 amp fuse is close to your battery. Its not there to protect your amps but more to protect your car from catching on fire if your power wire(s) accidentally grounds to the chassis somewhere. -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2250 Registered: May-04 | Wouldn't hurt anything, JL amps don't have internal fuses. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 519 Registered: Sep-04 | Wow, I thought everyone had internal fuses these days. http://www.jlaudio.com/amps/pdfs/500_1.pdf You're right. I don't see one there at all. Wonder why they did that? -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2252 Registered: May-04 | They put it like this: As long as the amp is properly fused at the battery, then there will be no problem with the amps as the fuse will stop those as well. In a distribution block, if one amp is overdriven and the other isn't, then the fuse may not blow since the current drawn may not exceed the fuse at the battery. They do have a slew of protection circuitry, though. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 528 Registered: Sep-04 | So they're not worried about their amps drawing a lot more current than what their rated output power would suggest, say like 125 amps in this case. What do they have an internal circuit breaker(s) that automatically resets or somethin? or do they figure if their amps are drawing that much current something is seriously fubar'd as it is. My lil Class A Soundstream has an internal 15 amp blade type automotive fuse thats not mentioned at all in the owner's manual and can't be accessed unless you crack open the thing. They recommend an external 20 amp fuse however. -Fishy |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4553 Registered: Dec-03 | funny this came up now. I just went to town yesterday to grab four extra 5AG-40A fuses. my three Orion 2250SX amps each take two of them in parallel internally for protection. one nice thing about using a distribution block that's fused for each output of the block is you can disable each amp by pulling a fuse. makes messing with the system really easy when you're trying out ideas and such.. |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4554 Registered: Dec-03 | funny this came up now. I just went to town yesterday to grab four extra 5AG-40A fuses. my three Orion 2250SX amps each take two of them in parallel internally for protection. one nice thing about using a distribution block that's fused for each output of the block is you can disable each amp by pulling a fuse. makes messing with the system really easy when you're trying out ideas and such.. I tend to use a thermal ckt breaker at the battery and fused distro blocks at the amplifiers. |
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New member Username: Krazy_karlKansas City, USA Post Number: 6 Registered: Oct-04 | To be safe, since a 4ga or 8ga will burn at a lower voltage than the 2ga, I would put a smaller fuse in the Dist Block for each of the 4ga wires and then the 125 at the battery for the 2ga. A dead short will pop all the fuses immediately so no bother there but in theory, if something strange happened at the amp and voltage between say 60ish and 125 were going through, your 4ga would cook and the 125A fuse at the battery would never blow. If you are hanging crossovers/EQs/Fans/Neon/whatever off the block with like 18ga or 16 ga, I would make sure each of those had it's own in-line fuse as well. Actually 2ga should be good up to a max of 200A and 4ga up to around 125A. Like I said, probably no big deal but since you asked... |
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New member Username: Krazy_karlKansas City, USA Post Number: 7 Registered: Oct-04 | I should clarify. I believe that we put in fuses to keep the wire from catching on fire in case of a short or over-voltage. So I'm not sure that the current draw from the Amps are a concern (except that the fuse needs to be higher obviously) as long as your fuse is the right size to let the amp do it's thing and still protect the wire from burning. I guess if you knew the amps absolute top potential current draw, you could do the math and grab a fuse that was slightly higher and not worry but if you get a fuse that matches the wire, you will be fine. As always, somebody please correct me if you disagree. |
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Bronze Member Username: Malby7Post Number: 92 Registered: May-04 | I'm just trying to protect my amps from being damaged what do you guys think is the best way to do this; leave the setup I have right now or modify it? If you say modify it please tell me how! - Mike |
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Bronze Member Username: Malby7Post Number: 93 Registered: May-04 | Anyone? |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4662 Registered: Dec-03 | use a fused distribution block. on each branch (to each amp) use a fuse rated for the peak RMS current draw of that amp at the load you'll be presenting to the amp. if you have an amp that'll be giving you 1200 watts, and it's class D, and draws 115A, then fuse it with a 115A fuse. If you have that same amp, but it runs a 4 ohm load and only 600 watts, then fuse it with a 60A fuse. this way the amp will get all the current it needs to operate, but if there is a short due to a blown speaker, or a loose connection, or what have you, the amp won't get any more current across it than it would under normal use before the fuse blows. then use a fuse or circuit breaker at the battery equal to the total current draw of the combined amplifiers. that's your failsafe for a dead short to prevent a fire in the car. |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4663 Registered: Dec-03 | btw, you can also fuse your speaker wiring if you wish. they make smaller glass fuse blocks for speaker wires. this allows you to protect the amplifier and speakers from shorts post-amplification. It's not required but folks do it now and then. remember speakers get high voltage AC signals.. possibly equal to or greater than that of a wall outlet in some cases. |
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Bronze Member Username: Malby7Post Number: 94 Registered: May-04 | Thanks Glass!!! |