Amplifier Enters Protection Mode When Volume Is Up

**Zshopa** · 04-13-2005, 10:34 AM

had the same problem, it wasnt grounded well enough

**skeeter007** · 04-13-2005, 10:43 AM

Originally Posted by dave2

No, the alpine will handle 2 ohms just fine. I'm guessing your voltage is dropping out, below 10.5 or so will send it into protect. Hook up that multimeter to the power leads and have a friend turn it up until the amp cuts, check what the voltage is when that happens. If your electrical system can't handle it, you might need a new battery or a cap to keep it alive. That's a relatively powerful amp, and they aren't too efficient, so they need lots of power. Since the amp turns back on, I'll almost guarantee that it's a voltage protection, not a heat protection. Thermal shutdowns require the amp to reset, by turning the remote lead off and back on, plus the heat needs to dissipate.

Only other idea is that the audiobomb sub might be shorting out a coil under high excursion, or touching the tinsel leads. Hook up your multimeter to the speaker leads, push the sub all the way in and all the way out, see if the coils ever short.

Boomin track, both the first ideas are not very good advice, getting a sub amp makes sense, since it will put out much more power to that sub. But all of them defeat the purpose of buying a 5 channel amp, which was to run everything off of one amp.

Dave

This sounds right on par with what I was thinking. I'm gonna get a meter and test it. I really want to use my 5-channel amp for all 5 channels, as I don't have much more room in the car for another amp. Thanks for the good ideas.

**skeeter007** · 04-13-2005, 10:45 AM

Originally Posted by WhiteRabbit

if you want to test what exactly is causing your problem, start disconnecting speakers one at a time, regardless of whether or not hte amp can handle the load. start by disconnecting the subwoofer fro the amp itself, leaving the sepakers hooked up. see if the amplifier goes into protect. you can work this way through until you have all your speakers disconnected. if it still goes into protect at a certain volume on the radio, then its time ot turn down the bass and treble boosts on the radio. If the amp still goes into protect, its time to test the am pon a bench, in someone elses car, anything to isolate the amp from your car and your charging system. And finally, if it still goes into protect after this, its time to get your amp repaired.

isolate and identify!

Thanks for the help...I've done this step and stopped at the subwoofer, because when I removed it the amp no longer went into protect even with the volume all the way up. So right now I'm pretty sure it has something to do with the subwoofer-amp combination.

**skeeter007** · 04-13-2005, 10:48 AM

Originally Posted by Zshopa

had the same problem, it wasnt grounded well enough

I was worried a bit about this, but I've tried multiple grounding spots with the same results. Where did you end up grounding to? I tried sanding the paint around a large bolt in the trunk and connecting to it with a ring connector. Then I tried (based on a friend's suggestion) connecting to one of the seatbelt mounts.

**SergeykoR** · 04-14-2005, 10:36 AM

then playing music, in some cases internal resistance of sub low down to 1 ohm and lower for a few milliseconds. So current (and heat on amp output transistors) increases too. Amplifier protection system recognizes this (and may NOT) and then immediately enters protection mode. It happens sometimes then concrete copy of power amplifier or concrete copy of sub are uncompatible with each other. Try other sub with more then 3ohm. In this situation no matter point of grounding or less voltage at inputs - they may call only loosing sound level at peaks for a very short time (good capacitor may fix it up). Also check the heat level from amp (it must not to be hot). It may helps subsonic filter to turn on (the amp has it), or low down boost regulator (the amp has it, calls Bass EQ). But on my opinion (we had the same situation a few times) you should try to change subwoofer itself.

**WhiteRabbit** · 04-14-2005, 11:55 AM

is that amplifier really 2 ohm stable on the 5th channel? I cant imagine a dual 6 ohm subwoofer dipping into the 1 ohm region....

but trying even the subwoofer you have wired at 12 ohms will give you some data, if you dont have access to another driver.

**skeeter007** · 04-16-2005, 05:57 AM

I went to RadioShack and bought myself a multimeter to measure the voltage on the amplifier. When the amplifier went into protection mode (music turned up) the voltage was still around 13 volts. Even with the subwoofer going in and out the voltage never dipped below 12.5 volts, not even for an instant. Therefore I am assuming my problem is not the ground connection. By process of elimination, the subwoofer must be the problem. I hooked the meter up to the woofer and pushed the cone in and out, but did not see much of a change in resistance in the process. However, I don't know how this resistance changes when the speaker is actually being driven by the amp at high power, so I would guess there is a possibility it dips just below 2 ohms and causes the amp to go into protection. I will try wiring the speaker in series and update you on the results....

Thanks for the help so far.

**SergeykoR** · 04-16-2005, 11:31 AM

to skeeter007: it is not guess about i said, this are rules of acoustics!
first - if you need to measure the voltage on the amplifier in action you should to buy oscilloscope. Second - you don't need to do that. Your problem for 80% is subwoofer, 20% - power amlifier. Try use 4ohm sub. And you can't measure internal sub resistance while it playing without special equipment. Physics are: on some frequenses induction in coin are more higher than on others, it increase current in wire and resistance become lower. Output schemes of amplifier can have influence on resistance too.
Like WhiteRabbit said you can find true by connecting 6+6, but it may change sound power.