Amplifier fuse ?

[chezwez123]

Hey guys, got a 250W amp/sub combo today and on the drive home it cut out, when i went to the boot the amp was quite warm and smelled of electrical burning. I have now discovered it was simply the fuse had blown, but my question is whether or not I can put a 20A fuse in instead of the 15A that was in there. The fuse on the power lead is 30A.


Thanks.

-C

 

[MT AUDIO]

No and your power lead fuse should also be 15

 

[Dink]

if the fuse has fused then i'm 99% sure your amp is dead

 

[chezwez123]

I am about to head out and try it so I will find out, how come the power cable should only be 15 aswell? Surely the 30A is more a precaution than actually to serve a function?

 

[Dink]

i wouldn't worry too much about the one for your power cable (as long as it is sized right for the cable)

but don't put anything bigger than 15A in your amp

 

[chezwez123]

everything still works fine but i have a 20A fuse just now til i can pick up a 15A one

 

[MT AUDIO]

seriously why bother asking if you want to let your amp go up in flames, it has a specified fuse rating for a reason

 

[Dan@M.A.D]

^^^ listen to this guy, He fixed my mates sub & amp in about 10 minutes, We had spent 2 days trying to get it to work! :clown:

 

[chezwez123]

I "bothered asking" cause I wasn't sure as I said it was only temporary and I have put it right now, as for the power lead I have heard different opinions on the size of the fuse, some saying its better to have a bigger fuse, even a few saying they use a smaller fuse for the power cable than they do for their amp :S Anybody have a solid answer for me so I can rest easy knowing my fuses are all correct?
Thanks .

 

[Dink]

the fuse on the power cable is there to protect the cable itself.

so should be sized accordingly

 

[1clio6]

if the amp is a true 250wrms amp then it will pull more than 15A
250/14.4=17.36amps

it will be safe to stick with the 20A fuse, this will not make any difference. if something seriously fails on the amp, this fuse will blow just as easy at the 15A fuse

 

[john182rs]

from what i k now of, the car will not always pull 14.4. Ive got TB3 done on my car with 2awg cable and it still only gets 13.8.

If the manual for the amp says a 15a fuse, then use a 15a fuse. Using anything bigger is stupid.

Fuses on the power cable are rated to stop your power cable going up in flames and taking the car with it.

 

[1clio6]

the voltage depends on alot of factors. temperature, load, engine speed. etc

most cars produce 14.4v , because this is what the regulator in the alternator is telling the alternator to produce.

your alternator will more than likely produce 14.4v when cold and around 2000rpm engine speed but will settle off as the engine gets warmer.


this dip in voltage will cause the current to increase, if you kno work out the same calculation but with 13.8 volt instead,

250/13.8=18.1A this is the max current that amp will pull under correct working conditions and at 100% efficiency,(most class a/b amps are around 60-70% efficient. Class d amps are around 80-90% efficient) this is possibly the reason why you fuse blew in the first place.

so a 20A fuse will be fine.

my 2 amps are externally fused at 300A each and this is recommended by manufacturer. but when at full load using all 3200wrms will still only pull around 270A and this including inefficiencies.

 

[chezwez123]

Very useful thanks very much, and also to everyone else who has helped out I shall go back to the 20A fuse now that I now it should be fine.. Thanks again to everyone for the help!

 

[Dink]

don't bother with a fuse just use a nail instead

the 15A they stuck in when it was made was just lying around so that's probably why it was used

 

[john182rs]

don't bother with a fuse just use a nail instead

the 15A they stuck in when it was made was just lying around so that's probably why it was used

Like me, I think we will both await the subject of 'car set on fire from amp burning up' what car, amp and fuse should i get?

Not every amp is made solid, some will take a larger fuse as the components inside are alot more sturdy.
Even though your chucking a larger fuse on to your amp are you 100% sure that the internals can take the higher power rating?

IF you put the allowed size fuse in which is 15a, when some thing goes wrong with it, the fuse will break. Now your chucking another 5a fuse on to make it 20a, what will blow next time? Will it be the 20a fuse or the internals? bearing in mind, if that 20a fuse does break, you could still have fried all your internals of the amp, if the fuse does not break THEN you could end up with the fried internals of your car.

Loosing your car for a 20a fuse instead of 15a fuse = FAIL.

 

[1clio6]

we arnt all perfect and neither are machines. both can make mistakes and it could be that the wrong sized fuse has been put in the amp from start. ive had this myself. at such low voltage as in a car, going up 5 amp isnt going to make an ounce of difference, check your manual mate and see what size fuse is recommended in there.

 

[Dink]

we arnt all perfect and neither are machines. both can make mistakes and it could be that the wrong sized fuse has been put in the amp from start. ive had this myself. at such low voltage as in a car, going up 5 amp isnt going to make an ounce of difference, check your manual mate and see what size fuse is recommended in there.

yeah 60w lamps don't get hot at all do they.

what you need to relise is the fusing current of the fuse.

i suspect a 15A fuse wont open till about 25A