Alright guys. I need your help.

I started by installing an alpine hu to the stock speakers. Every works great. I know by installing the hu my factory sub won't work. I was ok with that since I knew I will be installing aftermarket amp and sub.

Well, I finally got around to getting an amp and a 10" sub. Installed it this weekend but a little disappointed. The amp powers up. Power and ground returns 12.5v, remote wire is turning the amp on/off. RCA is plug behind the hu and ran to the amp. The problem is very low output ftom the subs.

Any suggestions? The amp is set to 50% gain. Hpf and LPF is set on amp. HU subwoofer is set to on. What's the problem? Am I missing something?

 

You shouldn't get lower than 14v when checking across the amp's power and ground inputs... You've got some electrical problems in the alt or battery...

 

Really? Will this cause the the low output from the subs? I thought I should be good as long as get more than 11v.

 

Yes really. Yes it will cause low output of the subs. Some people don't mind their voltage dropping below 14, but if mine goes below that mark, I generally shut it off, unless I'm competing, and I know what's going to happen.

The lower your input voltage, the less power you're going to get out of your amps. This is because it takes power to make power.

 

thanks. The 12.5v I tested was with the engine off. Should I be testing my subs with the engine on? Will that result in higher voltage?

 

It should. I never play setup (once amped) with the car off. The amp draws too much current to even consider it. They will drain your battery in no time.

That voltage sounds better, now that you say it was car off. Most batteries rest in the 13v range, and with the added current draw of the amp, 12.5v makes sense...

 

I thought my problems had to do with the stock bose setup. I have my alpine volume at around 7 and the speakers are pretty loud but not much output from the sub. Do the Bose speakers have there own internal amplifier?

 

what amp and sub..? maybe a single 10/inefficient 10" isn't enough for a trunk setup?

 

Mbquart 750w rms at 2 ohm and single 10" xtant dvc 4 ohm. It should be enough. When I had my legend I had a 10" and it sounded better with only 250w.

 

^ Thats a nice 10.

 

That should be a very nice setup. Did you double check you're at 2 ohms and not 8? Not doubting you, but it's happened to all of us at least once...

 

This really sucks! When the engine is on I am getting 14.5v so I am good there. I checked my sub and I am running in Parallel at 2 ohms. The sub is barely moving. I am at 50% gain, Phase at 0, bass boost at 0, HPF at 25hz, and LPF at 100hz. The amp turns on but the sub is hardly moving. On my Alpine HU I am at Volume level 6, is that enough to do anything?

 

What Alpine hu?

I had a 9884, and I know it had 2 separate "Sub Systems". Sub System 1 had the sub level output very proportional to the out of the rest of the channels. Sub System 2 allows the user to control the sub output. This may be something to check in your menus if you're using a 9884, 9886, etc.. This would explain the low output with the lower volume. as Sub System 1 is the setting from the factory. This option is in the menus, in the same place as the Sub Level adjustment. If you go to the same menu where you can turn the sub level on/off, the next menu is the one where you determine the Sub System.

 

YES. I have the 9884 too!!! Should I use the SUBW SYS 2?

 

Ok. I just tested it with SUBW SYS 2. It made a little bit of a difference. I bumped the volume up to 10 which you know is pretty loud. I am expecting to see the sub get some excursion but it just vibrates a little. I am testing my system with a rap CD so I know there has got to be more bass than what I see.

 

Here's an idea. Grab a DMM, and check the AC voltage output on the amp's output terminals.

 

I am not following. You mean check the voltage of the speaker terminals? What kind of numbers should I be seeing?

 

Power = Voltage x Current.

That's the formula to determine how much power you should be seeing. Or at least this is the one that we use to determine actual power output of an amp, when we clamp them.

When you're looking at Power and Resistance, use:

Power = (Current)^2 x Resistance.

Since you said your resistance was 2 ohms, you can measure your current output (AC current) with a DMM and check your power output theoretically. You'll want to unhook your sub to do this.