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Question for car audio bubbies


Gixxus Christ!

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Ok. I have a mild system in my car, design acoustic Gothic series 600 watt amp bridged to a single  kicker comp 2 600 watt 12" woofer. Damn amp will not quit going into protection mode if I'm listening to something with a lot of bass for more than say, 15 min. Any suggestions?

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21 minutes ago, zx3vfr said:

people still put aftermarket stereos in their cars?

 

I didn't realize it was 2001 and Paul Walker was still alive....

Subaru base model stereos are junk. I'm gonna have this car a long time and I spend about an hour and a half per day commuting so I want a quality sound system. I also wanted Bluetooth and a backup camera and navigation, so I put in a Kenwood touchscreen that did all that stuff, replaced the junk door speakers with some decent infinity units and put a single sub in the trunk for low end. 

 

I like to enjoy my music. So now that you understand all this, fuck the fuck off out of my fucking thread you fuck.

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55 minutes ago, TheBrown57 said:

Did you set the gain properly? Sounds like amp is getting over loaded due to high demand. I'm no expert though but that is something I think might be contributing.

Could be but I've had amps in the past that went into that mode, but it was right when they turned on before music even kicked on. (I ended up buying another amp.)

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2 minutes ago, jporter12 said:

What's the impedance of the speaker?  What is the amp rated for impedance wise?  If the amp is only stable at 2 ohms bridged, and the load it sees from the speaker is 1 ohm, that would be the problem.  

Good question, I have no idea what the impedance of the speaker is, I've never taken it out of the enclosure. Pretty sure the amp bridges at 2 ohm stable. 

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Correct, if you were closer I have a tool that is more precise you could use but that is how I used to tune my amp before I got it. I normally get it to match the meter then back it down just a tad to be safe. Same with the volume of the head unit, as an example my previous head unit went to 35 but I never went over 30.

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Hell Back when my buddys ran bump in the trunk we ran a ground wire no longer than 12 inches and cranked the gain far as it would go. Usally ran a 4 channel briged down to 2 channels to who knows what kinda ohms. Wonder what damage we did?..lol

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Could just be the amp doesn't have enough heat sinks built into its design.  I have an older Orion amp from when I had the stereo in my VW.  It would overheat in 15-20 minutes of full power.  I had it fully tuned with an oscilloscope to be sure it didn't distort.  The amp just ran really hot.  I ended up putting fans on it to try and keep it cooler.

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I'm not up to par with todays tech, and far from educated in car audio....but years ago my old Rockford Punch100 would do this running 2x12 Audiophiles  2 ohms.   Even with 2 huge heatsinks it got hot as hades.  Only at night though, and only when it was wound out pretty loud.  Figured out it was starving for juice, and crashed my alternator a couple times.  A 2 farad capacitor cured my issue, kept plenty stored up for the amp to draw on.  Not sure if your issue could be similar or not, but caps used to be fairly cheap ( $60ish for good ones )

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Is the sub dual or single voice coil? What ohms are the voice coil(s)? If dual VC how do you have them wired, series or parallel? What load is the amp stable to when ran mono? You need this info to see if the amp is seeing load it can't handle. Also check your ground and power connection. Are you running sufficient gauge wire for the amp?

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Yeah it sounds like you are pulling too much of a load on the amplifier, and the cheaper the amp the quicker it will go into protection when it doesn't like the impedance mismatch. I'd look into the sub impedance and voice coil setup as stated above and compare it to what the amp can handle. Anything out of spec and all you will get is protection mode.

I bought myself a nice Alpine headunit a few years back, with the imprint calibration hardware, and shelled out a few bucks for one of the Alpine monoblock PDX amps...... Man, talk about sound quality. Paired up with one of the 12" Dayton Audio Reference subs. I'll never need to buy car audio equipment again.

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I'd happily trade the comp 2 in a truck box (used to have a truck) for something that doesnt take up so much space in my trunk. The impreza trunk is shaped funny with a step in the floor of it and the only place the box fits is dead in the middle.

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Ok. Pulled the speaker out of the box and it's a single vc 4 ohm. So I did the calculation (square root of ohms times rms watts) and got ~62. Hooked my meter up, downloaded a 50 htz sine wave  and couldn't get anything higher than 45 out of it! Wtf?

 

Ready to dump this setup and go to two tens and a much better amp. 

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What numbers are you using, what is the amp model number?  Assuming the 600W@4ohm the square root is 48.9V not 62V.   If your amp is 600 Watts peak output you need to figure out the RMS output (lower) and use that number.  Assuming the magic interwebs formulas hold true and your amp is 600 peak, it should be roughly 425 RMS, using the same math (sqrt of 425*4) it would put your Gain setting at 41.2V which falls inside the max output you could get from your amp.

I have never used that method to set an amps output gain and the whole process is something I find interesting.  When I figured it out using the numbers from my old system I should have set mine at 34.6V;  1200W@1ohm.  I would not have figured a high output 1200W amp driving a 1ohm speaker load would use a lower output voltage than a lower power system but I guess it's possible.

 

The method I always used and it is only because I had access to the equipment was to hook an oscilloscope to the head unit output, crank the head unit volume until the peaks in the waveform start to flatten out (IE clipping) and back it down a small amount.  Then while the head unit was on max clean output I hook the oscilloscope up to the amps outputs and slowly increase the gain on the amp until the output from the amp started to clip also, same deal to just back it down a little bit to get it clean again.  Take note of the max number on the head unit volume control at this point and don't go past it unless you wanted huge distortion. 

Edited by vf1000ride
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You use rms watts, not peak. 

Square root of (240x4) 

 

Just realized my cell phone calculator fucked me. Forgot to put in parentheses, target voltage was actually 30 vac. 

 

I have an oscope I built over the winter, will hook it up when it's not hot as balls. Til then I found the 10" sealed setup I want. 

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