Fuse sizes question...

[Savant 10+ year member]

The fuses on the Vibe248 amplifiers I just got in are 2x15.. 30 amps of fuses per amplifier.. When I use the calculator I found online, it says for 1000 watts I need a 90 amp fuse in the distro block (and 4 AWG wire for amp power, but the manual says 8 AWG)..

I'm gonna go with a solid block and fuse holders inline after that, but need to have some idea what amp fuses to get..

Are the 30 amps of fuses in the amplifier different then what the amp would draw? or is it based on the efficiency so the amps only really draw 30 amperes.. seems a bit low for 1000 watts (500 x 2 at 2 ohm)....

So, for the inline fuses to the amps.. just over 30 amperes (around 40 - 50 amps maybe)? then for the 'main' fuse by the battery.. 80 - 100 instead of the calculated 225 amp fuse from the calculator? or since that run of wire is so long should that fuse be bigger.. maybe 200 amperes...

Any info would be GREAT.. as I'm trying to order stuff now //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

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[abcdefg 10+ year member]

well id do what the manual says

 

[Savant 10+ year member]

Originally posted by abcdefg well id do what the manual says

The manual doesn't specify anything before the amplifier.. but, if something shorts and isn't in the amplifier's fuse circuits, I don't want to blow anything (melt down my truck).. Trying to find out what I need as external fuses for each amp, and for the whole system..

Like I said, I'm showing a LOT more fuse at the battery than the combined rating of the amps.. not sure if I should go that high or not.. or how much to add to the battery fuse over the combined amplifier ratings to include the wire run... That make sense?

 

[Gauntlet 5,000+ posts]

The fuses on the Vibe248 amplifiers I just got in are 2x15.. 30 amps of fuses per amplifier.. When I use the calculator I found online, it says for 1000 watts I need a 90 amp fuse in the distro block (and 4 AWG wire for amp power, but the manual says 8 AWG)..

That would most likely be because the ratings on the Lanzar are the Max ratings and not the RMS. I wouldn't think that the amp would actually push more than 600 or 700 watts RMS. Although I'm not positive......that tends to be the case with most Lanzar amps (minus the OptiDrive)

Like I said, I'm showing a LOT more fuse at the battery than the combined rating of the amps.. not sure if I should go that high or not.. or how much to add to the battery fuse over the combined amplifier ratings to include the wire run... That make sense?

It's OK to go over the combined ratings, but not by that much. If the combined ratings of your amps are 60, I wouldnt go higher than 70

 

[Savant 10+ year member]

Originally posted by Jmac 14.4 volts x 30 amperes x 1 (100 % efficiency) = 432 watts

Then, should I take it that the fuses in the amp aren't the same as the external fuses (I would have to put in) as far as total power? The internal fuses are for something else (some part that won't be getting all power passed through)?

Like this.. the 15s handle rail voltage, maybe the bass boost circuit, crossovers, or something, but there are no fuses to handle if there is an internal short outside of those few circuits? Then I'd need a fuse before the amp, but one big enough to allow full pull but small enough to keep from melting the 8 AWG going to the amp... right?

Basically, the calculator shows ~250 amp fuse at the battery, 90 amp fuse on the amplifier for the 12"s (500x2 on the subs) and 75 amps on the amplifier for the 10"s (400x2 on those).. Does that sound right? And, is there an issue having fuses bigger than the device can use as long as the fuse is smaller than what the wire can use?.. Isn't the fuse at/after the distro to keep from melting the amp power wire, and the fuse at the battery to keep from melting the feed wire, all in case of a serious short?

Lemme know //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Thanks...

 

[Savant 10+ year member]

Actually, this is the claim..

* 2 x 300 Watts RMS at 4 Ohms

* 2 x 600 Watts Max at 4 Ohms

* 1 x 1200 Watts Max at 4 Ohms Bridged

* 2 x 500 Watts at 2 Ohms

I'm presuming the 2x500 @ 2 is RMS since it's not twice the RMS at 4 ohm and normally 1/2 the resistence doubles the power.. a normal guess would be 600 x 2 @ 2, but since they say 500.. *shrug*

I run the calculator based on 1000 total from one amp, 800 on the other (12"s run 500 RMS, 10"s 400).. I get 90 amp distro fuse for one, 75 for the other, ~225 at the battery.. Just not sure if I need that much.. But, it seems most AGU fuses are only up to ~60 amps.. not realy enough for the amps.. I have an ANL for the battery fuse, no biggy.. but would rather not spend all that cash for the amp fueses if it's not needed.. MAXI looks like it's only up to ~80 amps.. the only ones that get to 90 are ANL it seems.. The Phoenix Mini Wafer thingys have 80 and 100, but I hate getting into proprietary stuff...

Anyway, guess I'll just spend the extra bucks and go with what the calculator suggest.. the fuses it suggest seem to be rated for the wire more than anything, and since the only time that will be an issue is during a serious short, I guess I shouldn't be blowing fuses that often *crosses fingers*

 

[n2audio 5,000+ posts]

wow, 30A fuse for ratings like that? Guess I'll write off this series of Lanzar's. Just use 8 ga and nothing bigger than a 60A fuse, 40A would even be sufficient.

That thing is obviously WAY over-rated. We're talking pyramid league.