Fuse Size

[grtn316 10+ year member]

I have a hifonics bx1800d amp thats 3000 watts peak and 1800 watts rms. I am trying to run 1800 @ 1ohm. I have 4 gauge wire with a 60 amp fuse. I keep blowing my fuse. How big of a fuse do I need for this?

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[PhatTonyDeMarco 5,000+ posts]

Go for a ~120A ANL fuse.

 

[grtn316 10+ year member]

I used these calculations to figure out the size of fuse I needed, but it still blew.

Gain Setting:

Sqrt(1800 watts *1 ohm) = 42.3 volts

Fuse Size:

1800 watts/ 42.3 volts = 42.3 amps

I set my gain around 40-50 volts (The knob was maybe turned up a quarter). I then hooked up the speakers and played it for about 15 minutes and blew a 60amp fuse. Did I do something wrong? How come i hit 42.3 volts at a quarter of the way up on my amp? Shouldn't this be a little over 50% turned on a 3000 watt amp?

I went to a local store and found a 100 amp fuse. I am going to try this tonight. It would be a bad idea to raise the gain any higher than 42.3 volts right? My two subs are 900 watts rms, so 1800 watts should be perfect. Just a little confused on why the gain is so low but my volts are so high...

Can anyone clear this up for me?

Thanks

 

[n2audio 5,000+ posts]

Gain is dependent on the voltage of the signal coming from the HU. 1/4 gain would be about as expected if you're using a fairly high voltage source.

What HU are you using?

To approximate fuse size you want to use the voltage of the power supply (12-14) not the voltage out of the amp's speaker output.

1800w/14v = 128A.

That would be test tone power requirements. 100A should work well for you.

 

[djman37 5,000+ posts]

I have a hifonics bx1800d amp thats 3000 watts peak and 1800 watts rms. I am trying to run 1800 @ 1ohm. I have 4 gauge wire with a 60 amp fuse. I keep blowing my fuse. How big of a fuse do I need for this?

how much protection is on the AMP!? it's probably around 180 amps

the amp has protection from over powering it, fuses.

YOU fuse the WIRE rating. there's a chart on a few places including http://www.bcae1.com

btw, the AGC glass tube fuses only go to 80 amps.

 

[n2audio 5,000+ posts]

100A agu's are out there. Just hard to find.

http://www.marineworksaudio.com/marineconnects.html

 

[grtn316 10+ year member]

Gain is dependent on the voltage of the signal coming from the HU. 1/4 gain would be about as expected if you're using a fairly high voltage source.What HU are you using?

To approximate fuse size you want to use the voltage of the power supply (12-14) not the voltage out of the amp's speaker output.

1800w/14v = 128A.

That would be test tone power requirements. 100A should work well for you.

I have the kenwood kdc-mp828 HU with 5.0V preout. Should I take my 100a fuse back and get the 150a fuse?

I bought a different fuse holder so I can fit big fuses.

Now that I think about it, I had the 0-18db knob turned to 0 on the amp, but had a remote knob that was turned up to 18db. When I turned it down to 0db the fuse popped. I should leave the db level on my amp at 0 right?

 

[grtn316 10+ year member]

The latest...

Last night I hooked up my 150A fuse. Then I played a 50hz test tone and tried set the gain on my amp. I turned the gain all the way up and the highest reading I got was like 20.1 volts. I was looking for 42.3 volts. I then decided to put in a music CD and set the gain this way. After this, everything is working great. Something I noticed was that my lows are lower than i desire (sounds like the lows stretch out longer than they should in the song) or used to. I have my Low pass(35hz-250hz) turned up a quarter of the way and I am guessing I have this set to low for the sound I am looking for. I also think that my Low pass was too high/too low (not sure) and my 50hz freq was being ignored by the amp. Does this sound right? Was my Low pass to high or to low? If I want a more dominant bass sound instead of a low long lasting bass sound, what do I need to adjust?

Thanks

 

[djman37 5,000+ posts]

100A agu's are out there. Just hard to find.
http://www.marineworksaudio.com/marineconnects.html

good find!