Overheating/Power Loss?

[thakidd420 10+ year member]

I installed 2 Infinity 120.9W's into my '93 Chevy Caprice last week. They sounded great for a week. They still sound ok but now they do not get as loud as they used to. It's like they are not handling enough power to be loud as they should anymore. It's also as if they don't hit all the notes to the fullest because of it.

The amp is getting really hot, but so are the subs. It's like the subs are not handling the power well anymore and are overheating, causing the sound output to become restricted.

Any help on what I should check to get this fixed is greatly appreciated.

The subs I have: Infinity 120.9w Kappa Series 12" subwoofer with selectable 2- or 4-ohm impedance at Crutchfield Signature

The amp I have is an audioque AQ1200D: AQ1200D Amplifier

I have 4 gauge wiring, new speaker wire to the subs, and my head unit is an Alpine CDE series with a selectable sub output setting(0-15).

Thanks!

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[audioholic 5,000+ posts]

This is possibly caused by a couple things. One, its extremely common that a person's hearing becomes accustomed to the output levels in the first few weeks of listening to a new system, giving the perception that the stereo is not quite as loud as it once was.

The other possible reason is system voltage. If your charging system is not sufficient, system voltage will continue to drop over time until it fails completely (car wont start etc). Im not familiar with your amp, but if it has an unregulated power supply, and your alt is stock, this is a likely cause of your issue. It would also explain why your equipment seems to be getting hotter, as low system voltage often makes an amplifier clip, causing increased heat levels which could damage your equipment if the issue is not addressed. Check your voltage levels regularly, have an on-board gauge if possible, and consider how likely your alt is at handling the power draw your system is capable of.

 

[dipitydoo 10+ year member]

may also want to check both subs to make sure one of them is not blown

 

[thakidd420 10+ year member]

Thanks for the replies guys. I definitely thought that I was just getting accustomed to the volume at first. Now I can tell it is significantly lower and it's not just my hearing. I really think that your second guess about system voltage is the issue. I have a new battery, recommended one for my car model, the alternator is stock and probably has not been replaced since the car was made in '93.

How can I resolve this issue? Should I replace my alternator? Buy a capacitor? Get a new amp? Would a bigger battery help?

My cars lights flicker when the subs are turned up, sometimes my car has difficulty starting on the first few times turning over. I was already considering I may need to address this with one of the above mentioned remedies.

Also I checked the subs, not blown, just getting hot when I listen to them for even 5-10 min.

 

[LosIsATool 5,000+ posts]

autozone will test the alternator for you. It might be time for a upgrade

 

[dipitydoo 10+ year member]

your subs are rated for 350w each. are they wired for 2 or 4 ohm? what's final impedance to the amp? 1 ohm? 2 ohm? at 1 ohm, that's 1200w, almost double the rating of the subs. if you are having trouble starting your car, it could be a dying battery, alternator, starter, or a combination of these. have them tested at autozone. also, you may want to check the dc resistance of the subs coils and make sure each are reading properly, if you haven't done so already.

 

[THATpurpleKUSH 5,000+ posts]

I wouldnt run over 500w to those, they only have a 2in voice coil. If you wired them to 1 ohm, they are getting 600 and it could be a clipped signal which would make it even worse.

 

[thakidd420 10+ year member]

I'm not sure about how many ohms they are wired to. I have them wired with a separate set of speaker wire to each sub. The amp has 4 spots, 2 negative 2 positive for speaker output. Each sub is wired to one of each.

I am also unsure of what checking the dc resistance of the subs is. Sorry guys I'm new to this. Thanks for all the help.

So far I know I'm going to test my alternator and probably replace it.

 

[THATpurpleKUSH 5,000+ posts]

Sell those have the selectable impedance so pull one out of the box and look at what the switch is placed on. My guess is they are set for 2ohms each which gives you a final load of 1ohm to the amp. If you dont wanna keep having to buy new stuff every month, I suggest learning ohms law and as much as you can about everything else involving electricity, 12v/dc power systems and car audio in general or else you will be frying your equipment on a regular basis.

 

[dipitydoo 10+ year member]

I'm not sure about how many ohms they are wired to. I have them wired with a separate set of speaker wire to each sub. The amp has 4 spots, 2 negative 2 positive for speaker output. Each sub is wired to one of each.
I am also unsure of what checking the dc resistance of the subs is. Sorry guys I'm new to this. Thanks for all the help.

So far I know I'm going to test my alternator and probably replace it.

to check subs' resistance, get a voltmeter, touch the leads to the terminals on the voice coil. typically, dc resistance should read a little lower than the coil's impedance.

 

[>>SQL<< 10+ year member]

I'm not sure about how many ohms they are wired to. I have them wired with a separate set of speaker wire to each sub. The amp has 4 spots, 2 negative 2 positive for speaker output. Each sub is wired to one of each.
I am also unsure of what checking the dc resistance of the subs is. Sorry guys I'm new to this. Thanks for all the help.

So far I know I'm going to test my alternator and probably replace it.

Can you explain this further, at each sub woofer would be 2 positive and 2 negitive wires.

How are those wired to your amp?

 

[Haunz 10+ year member]

Most people do not realize there is more then one way for an amplifier to 'clip'. In any case limiting the power going into an amp is not going to make it produce more power to the subwoofers, whether or not the output stage is overloading.

I am not familiar with the subs but it seems to me they probably have a 2ohm coil wound along with a 4ohm coil and you can select one or the other.. kind of a stupid design IMO but whatever sells product.. In any case if the switches are shorting out at all you are going to get less power to the voice coils & less musical output, along with more power from the amp and more heat all around...

My advice would be to try different subs...

 

[thakidd420 10+ year member]

Can you explain this further, at each sub woofer would be 2 positive and 2 negitive wires.
How are those wired to your amp?

Each sub has 1 positive and 1 negative wire going from the terminal its connected to into the amp. The amp of course has 4 spots, so each wire from the sub has its own spot.

Trying new subs is not a good idea as I just got these ones. If that was a feasible option I'd be trying a new 2011 Camaro an 6 JL Audio w7's as well.

 

[LosIsATool 5,000+ posts]

The 2 + and 2 - on the amp is the same thing. They are just there for convinance. it is really 1 and 1

 

[thakidd420 10+ year member]

I figured that was the case since the amp is mono. Should I have the subs on 2 ohm or 4 ohm? I would guess 2 but I may be wrong.

With the way I have them wired how many amps are they getting?

If my alternator is good when I get it tested tomorrow what else should I try?