Boss Amplifier Turns Off With High Volume?

[hop1308]

Hi guys, i've got a R34 gtt and ive got all 4 speakers connected to my boss 1200 watt ba-4500 amplifier. ( i know its not the best brand). anyways, the whole amp set up worked well for about 6 months and now all of a sudden if i put my volume past half way the amp just turns off with the protection LED light turning on.

im wondering what's going on?

[Bitsushiti]

I'd check to see if the amp still has a solid earth and that it hasn't come loose from vibration and do the same for the fuse and all connections on the power line, then try setting all gain settings on the amp back to 0 and give it another go. If this fails or gain is already set to 0, pull the amp out, remove the cover & inspect the PCB and around the terminals for burnt mosfets/capacitors etc.

If you can't remove the cover, try giving the amp a light shake to listen for loose rattly bits and also use your nose and have a sniff around, capacitors have a really distinctive smell when they get fried.

If there's nothing visibly wrong with the PCB, take it to a TV sparky to get them to check over it (if it's worth salvaging), or... use this as an excuse to upgrade

[GTR.jono]

try replacing its fuses

[Carbon 34]

I'd check to see if the amp still has a solid earth and that it hasn't come loose from vibration and do the same for the fuse and all connections on the power line, then try setting all gain settings on the amp back to 0 and give it another go. If this fails or gain is already set to 0, pull the amp out, remove the cover & inspect the PCB and around the terminals for burnt mosfets/capacitors etc.

If you can't remove the cover, try giving the amp a light shake to listen for loose rattly bits and also use your nose and have a sniff around, capacitors have a really distinctive smell when they get fried.

If there's nothing visibly wrong with the PCB, take it to a TV sparky to get them to check over it (if it's worth salvaging), or... use this as an excuse to upgrade

Dont bother removing the cover or a sparky

You can replace it for cheap ,bad advice !!

But check the amp with no speakers on it

Does it shut down?

Yes , check voltage , grounds and 12turn on wires

Stray wire strands on block or loose battery connection ( it better be on the battery not car wiring !! And fused at battery !!)

Rca's grounded out on bolts or pinched

No - which is likely , the voice coil or speaker wires on one of the speakers is grounding out

Hitting the speaker frame or door skin

A voice coil that leaves the gap of the magnet creates problems because it starts to melt and drag , shorting out the load = 0 ohm load dead short protection light comes on

A overdrive gain can do it , overheats the amp

Too low ohm load as well not likely if its just 4 coax or splits

If you run splits it can be a short in xover block or stray wire strands

anything below a good12v will shut it down

Overheating as well

[Carbon 34]

try replacing its fuses

Why one fuse works now ,so another wont matter

The protection light comes on

[hop1308]

thanks for all the help guys. it was a mad help. i thought i'd have to replace the entire amp, i ended up re doing my power cables and turns out it was a bad ground. tightened everything and put it back together.

a quick question though, my amp is 4 channel and i decided to change its set up. i connected the two front speakers to 2 channels on the amp. and where the two rear speakers were connected, i connected a subwoofer with a bridged connection, making it 3 a 3 channel amp sorta.

will this end up frying it?

its pretty much running -- Two 6 inch speakers and 1 subwoofer

[Carbon 34]

thanks for all the help guys. it was a mad help. i thought i'd have to replace the entire amp, i ended up re doing my power cables and turns out it was a bad ground. tightened everything and put it back together.

a quick question though, my amp is 4 channel and i decided to change its set up. i connected the two front speakers to 2 channels on the amp. and where the two rear speakers were connected, i connected a subwoofer with a bridged connection, making it 3 a 3 channel amp sorta.

will this end up frying it?

its pretty much running -- Two 6 inch speakers and 1 subwoofer

No as long as the sub is 4ohms or more its fine

Normally You can run all 4 speakers on front and sub on rear and still be safe , creates a 2ohm load to front and 4ohm bridged load to rear ( or 2ohm load shown to amp in bridge mode)

But some people dont like the rears on

use 120hz or less xover on sub ( 75-80hz best)

120-150hz high pass xover for the fronts so bass is blocked out saving them from destruction

[hop1308]

oh wow never thought about that. hmm maybe i should connect by rears to my front ports, currently they're not even on. im really not sure with the ohms its capable of running. its a 1200w boss ba-4500. i dont have the box and couldn't find any information on it on the internet.

so with your knowledge, do you think it would be safe to have all 4 of my speakers connected to the two front ports, with just the sub running off the rear?

[Carbon 34]

oh wow never thought about that. hmm maybe i should connect by rears to my front ports, currently they're not even on. im really not sure with the ohms its capable of running. its a 1200w boss ba-4500. i dont have the box and couldn't find any information on it on the internet.

so with your knowledge, do you think it would be safe to have all 4 of my speakers connected to the two front ports, with just the sub running off the rear?

2 ohm per channel stable amp but will run hotter and draw more current

It will handle it fine if air can get to the amp ok

And wire gauge is big enough / voltage is stable

If the sub is below 4ohm or dual voice coils you could have a problem if wires wrong

any idea what model or specs ?

Two 4 ohm speakers run in parallel is 2ohms nominal per channel ( focal can be 2 ohms so watch out for those) fine for that amp

Another option depending on the deck

Hook the rears to back channels of deck power so you can fade them out

Edited February 5, 2013 by Carbon 34

[hop1308]

yeah i ended up connecting them to the back. the only problem i have now is to do with the bass. I've asked around and noone i know, knows how to fix it. going with the set up mentioned before, how to i avoid bass coming through my speakers. its like my front 6 inch speakers try to keep up with the sub woofer in the song. and everytime the bass hits the speakers sound so bad trying to make some bass also.

is there anyway to avoid this? so the bass is left for the subwoofer and vocals for the speakers? ive got 6 inch fusion speakers. i understand they can handle a small amount of bass but they keep making an ugly pop sound while trying to make bass

[Carbon 34]

yeah i ended up connecting them to the back. the only problem i have now is to do with the bass. I've asked around and noone i know, knows how to fix it. going with the set up mentioned before, how to i avoid bass coming through my speakers. its like my front 6 inch speakers try to keep up with the sub woofer in the song. and everytime the bass hits the speakers sound so bad trying to make some bass also.

is there anyway to avoid this? so the bass is left for the subwoofer and vocals for the speakers? ive got 6 inch fusion speakers. i understand they can handle a small amount of bass but they keep making an ugly pop sound while trying to make bass

If your amp is crossed over right they wont make bass ( only midbass) turn on the xover on the front channels to highpass and set to 120-150hz

then set the sub back channels to 80hz low pass

Turn off all bass boost you dont need it if setup right , turn down the bass to flat on the deck

If your crossover is on the deck as well you need to use one or the other both will just confuse things

And surround sound will make distortion if your blasting tunes like techno, dub step , slam rock

If you have done that and still cant get it to work

You can put a capacitor inline with + of the 6" fusions to block the bass below a freq ? let me know if thats the case so i can review the specs on the fusions and recommend a xover cap for your ohm load and roll off freq.

check your gain on the amp it should never be higher then a hair over 3/4 in most cases

[hop1308]

thanks a heap for that, i followed your instructions with the xover on the amp, and it works a beaut. theres barely any bass coming out of the speakers now with no distortion. my gain is set at 1/2 way for both front and rear. and my head deck has the bass set to like -4 i think. the minimum is -12.