Fuse rating vs. RMS question

[BamBam28 10+ year member]

Is it true that if a amp has two 30 amp fuses it can only put out 600 watts rms?

2x40 amp fuses = 800 wrms max ect ect...

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[skmfkr 5,000+ posts]

roughly. its about 10a per 100w

 

[thevic24 5,000+ posts]

that is just in general, for every 100 clean rms you need 10a of current.

some amps,as an example, are 80%efficent and some are 60%. so it will vary from amp to amp.

 

[BamBam28 10+ year member]

so 2x40 amp fuses can do 800wrms at 100% efficiency but it cant possibly do more right?

 

[thevic24 5,000+ posts]

so 2x40 amp fuses can do 800wrms at 100% efficiency but it cant possibly do more right?

at 100% yes but there arnt any 100%efficient amps that i know of. it wont do more than 800 clean rms though.

 

[azbass 5,000+ posts]

roughly. its about 10a per 100w

according to wat

 

[skmfkr 5,000+ posts]

the amps ive seen. my aq 2200d was 200a my 3250 is 300a. someone posted a jl 1000/1 and said the manual said 100a. so yeh its seems that its about 10a per 100w.

 

[azbass 5,000+ posts]

if you think so..

 

[Rashaddd 5,000+ posts]

at 12v, you can calculate the approximate max (clean) rms by multiplying 12*fuse rating. So an amp with a 10a fuse would give you 120 watts @ 12v. Now consider that it is likely 80% efficient or so depending on what kind of amp/quality/etc...and you end up with a little under 100 watts.

Yes, guessing that an amp will do 10 times it's fuse rating in power is generally a good estimate. You will not find an amp that needs a 50 amp fuse making 1000 watts at 12-14v without serious distortion and blowing that fuse if not damaging the amp

 

[Ferendon 10+ year member]

the amps ive seen. my aq 2200d was 200a my 3250 is 300a. someone posted a jl 1000/1 and said the manual said 100a. so yeh its seems that its about 10a per 100w.

If you are referring to the Slash series from JL Audio, then you are wrong. It doesn't have fuses.

 

[skmfkr 5,000+ posts]

If you are referring to the Slash series from JL Audio, then you are wrong. It doesn't have fuses.

no shit, he was asking what size inline fuse for it.

 

[SPLaudio 5,000+ posts]

totally wrong there is plenty of amps out there that have 2 40 amp fuses and are rated @1200rms and do 1400ish clamped. reason it takes 200% of fuse rating to blow over a 3sec period.

 

[jmanpc 5,000+ posts]

Thats my general rule of thumb. It's not accurate, but it's good enough for a guesstimate. There's usually a pretty good correlation.

 

[thevic24 5,000+ posts]

totally wrong there is plenty of amps out there that have 2 40 amp fuses and are rated @1200rms and do 1400ish clamped. reason it takes 200% of fuse rating to blow over a 3sec period.

true but i bet its not clean power.

and your saying that an 80a fuse will need to see 240a for 3 seconds to blow?//content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif

 

[gunz4me 10+ year member]

Fuse rating also depends on if your amp is High Voltage/High Impedance versus High Current/Low Impedance. I have an amp that does 400 watts RMS @ 8 ohms with a tiny *** 25 amp fuse! Of course the rail voltages inside of that amplifier are high enough to pack a serious wallop to them!