Why is my amp off my sub at high volume?

[alexdbest2000 10+ year member]

Why does my amp cut off my sub at high volume?**

went full retard on the title...

this is my setup:

Kenwood bt852hd (2.5V pre-outs)

Alpine MRV-M500 amp (500 rms at 2 ohm)

Sundown SA-12 D4 sub

1 gauge wiring

To adjust gains I:

1) unplugged all speakers and sub

2) set all eq, bass boost, gain etc to 0

3) set LP filter to 80

4) played an 50 HZ track on repeat

5) connected DMM to sub +/- terminal on amp

5) turned gain up to meet voltage requirement (31.6)

6) had to turn gain almost to max...

Every time the sub hits hard at around 3/4 the volume the amp turns the sub off, while the amp stays on. The sub will only work after i shut the car off and then turn it back on, the amp is brand new. I dont think its a grounding problem, i drilled a hole in the chassis and grinded away any paint. Is it normal for the gain to be set that high? Is the amp going into protect mode? Why is it doing this? Am i missing something with tuning the amp?

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[caterham09]

Your amp is most likely going into protect mode. You probably set the gains wrong and your amp is trying to draw more current than your car can manage.



use this video

 

[alexdbest2000 10+ year member]

Your amp is most likely going into protect mode. You probably set the gains wrong and your amp is trying to draw more current than your car can manage.

wouldnt using a DDM be more accurate?

 

[caterham09]

yeah it would be but something might be wrong if youre having to turn it all the way up

 

[alexdbest2000 10+ year member]

yeah it would be but something might be wrong if youre having to turn it all the way up

where approx should it be?

this is mine looks like

 

[caterham09]

it all depends. Just use that test tone and find the sweet spot. If thats where its supposed to be then thats where it needs to be. Unfortunately it still doesn't adress your cutout problem. Are you running a stock battery? have you done the big 3?

 

[alexdbest2000 10+ year member]

it all depends. Just use that test tone and find the sweet spot. If thats where its supposed to be then thats where it needs to be. Unfortunately it still doesn't adress your cutout problem. Are you running a stock battery? have you done the big 3?

yes stock, and i have the wire to do it. just waiting on the terminals

im only doing it because i planned on upgrading though, shouldn't 500rms be ok for a stock alt/battery?

 

[caterham09]

it should in theory but batteries do wear out every 5 years or so and depending on your car you could have a hilariously small stock alternator. Like some civics had some 60 amp ones I think also what gauge wire are you running to your amp could affect it as well.

 

[alexdbest2000 10+ year member]

it should in theory but batteries do wear out every 5 years or so and depending on your car you could have a hilariously small stock alternator. Like some civics had some 60 amp ones I think also what gauge wire are you running to your amp could affect it as well.

its a 2004 civic, 70 amp alt, 1 guage wiring

 

[caterham09]

yeah that alternator is pretty small in theory 500w rms draws around 72 amps of power. I'm not saying you absolutely need a new alternator but i would recommend a new battery

 

[Jeffdachef 5,000+ posts]

Why does my amp cut off my sub at high volume?**went full retard on the title...

this is my setup:

Kenwood bt852hd (2.5V pre-outs)

Alpine MRV-M500 amp (500 rms at 2 ohm)

Sundown SA-12 D4 sub

1 gauge wiring

To adjust gains I:

1) unplugged all speakers and sub

2) set all eq, bass boost, gain etc to 0

3) set LP filter to 80

4) played an 50 HZ track on repeat

5) connected DMM to sub +/- terminal on amp

5) turned gain up to meet voltage requirement (31.6)

6) had to turn gain almost to max...

Every time the sub hits hard at around 3/4 the volume the amp turns the sub off, while the amp stays on. The sub will only work after i shut the car off and then turn it back on, the amp is brand new. I dont think its a grounding problem, i drilled a hole in the chassis and grinded away any paint. Is it normal for the gain to be set that high? Is the amp going into protect mode? Why is it doing this? Am i missing something with tuning the amp?

Turn your head unit 90 to 95% of the way up, Turn subwoofer level to the max. Hook up the subwoofer then set your gains again. Even by ear you can hear when the subwoofer starts changing tone and thats the point of massive clipping. With an actual load on the amp, it will behave differently.

 

[alexdbest2000 10+ year member]

Turn your head unit 90 to 95% of the way up, Turn subwoofer level to the max. Hook up the subwoofer then set your gains again. Even by ear you can hear when the subwoofer starts changing tone and thats the point of massive clipping. With an actual load on the amp, it will behave differently.

Ok i set the gains by ear, at 75% volume distortion occurred a few clicks after the halfway gain mark, so i dialed the gain back from there and tested the voltage and it came to 10.8V. I tested it with music and it seemed fine, subs stayed on at high volume... but is it ok to have the subs running at such low voltage when they should be at around 32?

 

[gstokes]

yes stock, and i have the wire to do it. just waiting on the terminals
im only doing it because i planned on upgrading though, shouldn't 500rms be ok for a stock alt/battery?

yes, 500 watts is only a 36 amp load, with a 75 amp alternator you can dedicate 50 amps to the sound system, that's 690 watts of power at 13.8 volts

 

[Jeffdachef 5,000+ posts]

Ok i set the gains by ear, at 75% volume distortion occurred a few clicks after the halfway gain mark, so i dialed the gain back from there and tested the voltage and it came to 10.8V. I tested it with music and it seemed fine, subs stayed on at high volume... but is it ok to have the subs running at such low voltage when they should be at around 32?

your fine, sometimes the DMM method is not always the best method most likely your were having a heavy clip before. Make sure you check your sub's temperature periodically