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Old     (Bumpass1)      Join Date: Oct 2010       04-21-2012, 5:31 PM Reply   
Let me start by saying I don't know much about stereo systems. My tower speakers are dropping out from time to time. I talked to a friend of mine (who knows just enough to be dangerous) and told me that the amp was clipping. What does that mean and how do I fix it?
Old     (Bumpass1)      Join Date: Oct 2010       04-21-2012, 5:34 PM Reply   
Let me add that it only does it when the volume is turned up about 3/4 of max so the rider can hear the music.
Old     (boarditup)      Join Date: Jan 2004       04-21-2012, 5:39 PM Reply   
Clipping: Your amp does not have sufficient power to get as loud as you want it to. Get bigger amps.

Alternatively, if the amp has enough power, but the power supply to the amp is too low, you can experience similar problems, depending upon the amp. That is why caps, large alternators, and multiple battery setups are important.

The best amps have dynamic headroom - where they can overshoot their rating for short periods of time (drumbeat) and not clip. Some amps have "soft clipping" designs so it does not sound so bad and harsh.

If the amp is just dropping out without sounding harsh, the amps may be overheating. In that case, add fans and ventilation.

Good luck.
Old     (Bumpass1)      Join Date: Oct 2010       04-21-2012, 5:49 PM Reply   
It just drops out for about a minute or two, come back for a couple of minutes then drops again. Normally when it drops out I turn down the volume and the problem goes away.
Old     (Jeff)      Join Date: May 2010       04-21-2012, 6:22 PM Reply   
Clipping is not the right term for what you're describing. It sounds like it's going I to thermal protection mode (could be due to clipping for extended periods though). Usually amps will have an LED that's lit when they're in thermal protection mode. Locate that LED, if equipped, and then see if it's lit when your speakers stop working. It likely will be.

This could be due to insufficient cooling but could also be due to low voltage. Your power cable could be insufficient or have a bad connection somewhere. Are you running the engine or sitting and running off battery when this occurs?
Old     (Jeff)      Join Date: May 2010       04-21-2012, 6:25 PM Reply   
Oh, also how are your speakers wired up? They could be providing too little impedence and overworking the amp. Is this a new problem and they were previously working ok?
Old     (Bumpass1)      Join Date: Oct 2010       04-21-2012, 6:42 PM Reply   
Happens when the motor is running. I never have the volume up loud when the boat is off. The problem has npbeen there since I bought the boat (used). I'm not sure how they are wired up. I can check in the morning.
Old     (Iceberg)      Join Date: Dec 2011       04-21-2012, 9:51 PM Reply   
The description sure sounds like a thermal shut-down. Usually 2 main causes, not enough power for the amps or too much draw from the speakers, which could include a short or very low impedance. Watch for how many speakers are ganged together to lower the circuit resistance. Extra batteries, large cables, good connections and large capacitors for the sub ensure a killer sound system. Of course, you need a large alternator to power them as well.

Most of the newer amps have some clipping protection to protect the speakers and the amp. If you set up the amp to push too hard, the distortion goes critical and this wreaks havoc on the speaker coils. Most people set up the amps with not enough headroom. As was mentioned above, the source or pre-amp signal should be set close to 80% then the amp is adjusted to the clip threshold. It is true that most amps can go past this level for greater dB, but the sound quality will suffer and the next failures will be speakers self-destructing and the amps over-heating. The same goes for too many speakers hooked up to the amps. Phasing is important to not create sound cancelling. One way to reduce the power draw is to use more efficient speakers, a higher SPL. For example, a speaker with a 97dB rating is twice as loud as one with a 93dB SPL. As everyone should know, it is typically the subs and lower frequency speakers that use 80% or more of the power.

I have 12 speakers (8 across the back) and one sub driven by 2 amps. Power to the amps is supplied by 3 gauge wire. The speakers are set up to fade between inside the boat and behind the boat. All amp outputs are set to nominal 4 ohm circuits, even though the amps can handle 2 ohm. I have not installed any capacitors since I seldom have the base in sonar mode! The sound is very natural at reasonable levels and can be easily heard behind the boat.

You could try to reduce the load on the amps to see if this solves your problem. As well, you could run heavier wire to some of your larger speakers. I run 12 ga to all speakers 8" or larger.
Old     (brianinpdx)      Join Date: Aug 2009       04-22-2012, 2:52 PM Reply   
jamie - I'd agree with the rest of these guys. This sounds like a themal issue. And that basically means that the temp on the heatsink of the amplifier your using has exceeded its ability to cool itself so the amp shuts its self down to regain control. That often is a min or two --- i.e. temp goes down.

but once you've gotten into the cycle, you're going to see the amp come back on, then turn off once it hits critical again. this usually is 5-10 mins depending on how hard your running your system. If this is happening without hard system run, then it could mean you have a shorted speaker somewhere that is shorting back to the amp and thus its protecting itself.

Best advice is to get some details on specific models and connections and the group can guide some trouble shooting. With a little effort you should be able to resolve this problem.

-Brian
Exile Audio
Old     (Bumpass1)      Join Date: Oct 2010       04-22-2012, 3:45 PM Reply   
Thanks for the help guys.

I have been stuck on call for work all weekend and haven't had a chance to get all of the specs off of the amps and speakers. I bought the boat used and have not done anything to the system other than turn it on. As soon as I have a chance I will get all of the info and post it for review.
Old     (fullspeed)      Join Date: Oct 2005       04-22-2012, 4:32 PM Reply   
Didn't read what every one wrote, but check the gauge of wire to your amps. Make sure the gauge is what the amp specs call for. It may help. The gauge of wire power and ground should be the same. My amps call for 4 gauge wiring. The awesome stereo place that my dealer sent my boat to get my stereo installed use 6 gauge wire to my amps and once I change it too the correct gauge is helped with some of my problems.
Old     (espritv8)      Join Date: Dec 2009       04-23-2012, 6:02 PM Reply   
How do you know when you are clipping your subs/amps? I have an dual coil 400Wrms 12inch sub wired in 2 ohms, hooked to an 400Wrms@2ohms amp. I wonder how to adjust my amp to avoid clipping?
Old    mojo            04-23-2012, 6:34 PM Reply   
A capacitor in a boat doesn't really do anything unless the boat is left on all the time. Secondly, you turn down the gain to adjust your output. General rule of themb is to set your frequency then slowly turn the gain up(head unit at 80% of max) and back off when you hear distortion. I'm going to have a little plate made for when I'm riding to let folks know not to go above a certain vol. level

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