fuses in parallel
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=24938
Printed Date: September 11, 2025 at 3:01 AM
Topic: fuses in parallel
Posted By: satchmoe27
Subject: fuses in parallel
Date Posted: January 20, 2004 at 2:39 PM
I need some help with finding the right fuse value. First of all I am trying to connect a fuse inline with my sub so that I wont blow it. I found out what amperage i needed by taking the square root of continuous power (375) and dividing that by 4 (ohms) I got 4.841. The problem is that there is no fuse of that size, so I thought about putting (3) 1.5A fuses in parallel. I wanted to know would that work.
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screamon deamon
Replies:
Posted By: DYohn
Date Posted: January 20, 2004 at 2:44 PM
No, putting thee 1.5A fuses in parallel will result in a 1.5 amp circuit. Just use a single 5 amp fuse and you will be fine. Make sure the continuous power rating your used in your calculation is the rating of the speaker, not of the amplifier, and that you install your fuse between your passive crossover output and your loudspeaker.
Posted By: satchmoe27
Date Posted: January 20, 2004 at 5:48 PM
Thank you for your help  ------------- screamon deamon
Posted By: HamiltonAudio
Date Posted: January 23, 2004 at 2:56 PM
what about this....have the sub in the PROPER box, make sure the amp is delivering CLEAN power, and that the crossover and gain are setup PROPERLY. you can then beat the hell out of the subs all day long, without fuses...a blown sub is far more often the result of clipping and/or distortion at high power levels, not all-out thermal power failure... b
Posted By: geepherder
Date Posted: January 23, 2004 at 8:25 PM
satchmoe, you are very close, but your formula is flawed. Fuse rating = square root of (rms rating of speaker/ohm of speaker). So, twice the fuse rating you originally calculated, or roughly 10 amps. Putting fuses in parallel does increase the overall current handling (I think DYohn was thinking series), but is not the best way to do this. I agree it's better to use 1 fuse. I also agree with HamiltonAudio that subs usually do not have problems unless the signal is distorted. ------------- My ex once told me I have a perfect face for radio.
Posted By: DYohn
Date Posted: January 23, 2004 at 11:49 PM
YIKES! A Kirchoff's law error! :) Yes, I read parallel and thought series, my mistake. Still, one fuse would be the way to go, and yes, a properly designed system will always be better than worrying about fusing your loudspeakers.
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