amp keeps turning off, and sub gets trebble! - PeachParts Mercedes-Benz Forum

hedpe · #1 06-16-2002, 09:06 PM

Alright, so I got a JL 12W3, originally i had a 120watt rockford amp hooked up to it. Then my cousin gave me an $800 1100 watt max amp, it's an audio art 100HC amp. We hooked it up, and I can't figure out how to get it to cut out the treble. I have treble coming through my sub. I couldn't find how to wire everything and set up the amp to get about 300-400 watts from it. So it's kicking out about 900 watts at the moment on 1 ohm mono. I wired the sub for 1 ohm too.

So i couldn't get it to cut out the treble, we didn't get a manual with it because he got it for investing in to audio art $1000, and got about $4000 in audio equipment for it. I can't get through to them, they have a website audioart.net but the manual doesn't state how to cut out the treble or how to bridge it down or anything.

I keep the gain all the way down so i don't blow the sub until i figure out what it can take. But if i turn my head unit volume up past 14 the amp turns off. How could this be? It's a high current amp. Is it not getting enough power? It's running off of my battery with a Alpine V12 amp running off of the same battery. Can it not pull enough juice? Is that why it's shutting off? Any have any suggestions or ideas? I'd appreciate it, thanks guys.

G-Benz · #2 06-26-2002, 04:18 PM

Does the amp have a built-in crossover? There is really no such animal as a "sub" amp, just an amp with the crossover points optimized for bass frequencies and below.

Multi-channel amps usually have speaker outputs for a sub, but the built-in crossover filters out the upper frequencies, and there is usually a dial for additional tailoring of the frequency rolloff point for your sub(s).

Running the amp at low ohms to gain power is a pretty old trick (back in the CAN days when I competed, before IASCA was born). We used to do this so that we could compete in the 0-50 watt classes and really be pushing 300 watts!!! Needless to say, the amps had a short life!

Expensive well-designed amps can be designed to withstand 1-ohm loads and operate safely under those conditions. The tradeoff is heat and power. Your amp may be demanding an amp load (900 watts at 1-ohm) that your car's electronics cannot provide, so it shuts down in protection mode. It's no secret that competition vehicles usually come equipped with 200-amp alternators...I've even seen some with dual alternators!

Another solution is to use big storage capacitors...these are pretty mainstream now. Their job is to store up the unused voltage (which the way your amp probably operates 70-80% of the time) for the instance you have a demanding signal that requires more than usual power.

Check your power wires to the amp as well. If it's too warm after a lively stereo performance, then your wire gauge is too small. Think of wires as water pipes...you can't get Hoover Dam flow out of household pipes!

For 900 watts, I would go no smaller than 8-gauge. Many competitors use zero-gauge wire (which is used on professional welding equipment), but it takes Hercules to bend into desired positions.

Bottom line: if you are getting high frequencies in your sub, then you probably lack a crossover. That is your first necessary purchase.

I think 900 watts is a bit excessive for anything but dB competition vehicles (but I'm getting old).
You might have to drop down to the paltry 300-400 watts your amp is spec'ed to provide.

abew330 · #3 03-14-2005, 03:40 PM

i have a Pyramid 1600watt 4ch amp.. not that old. maybe a year or two... i have a new sony deck and a alpine g-180 eq and i have a 4ga. power wire hooked up to a 3farad voodoo capacitor then feeded to a fuse block then 8 ga. wire to the amp. i have two 15" mtx subs hooked up to the amp.. (briged)... i have the subs in parallel

note:
(i had a bazooka 600 or 700watt amp hooked up to these 15" mtx before and sound great never turned off .. the amp heated up but didnt turn off.. the only thing i changed was the amp to a pyramid...)

for some reason the amp turns off.. i tried hooking the subs to just one ch. but still turns off.. (amp turns off at high volumes).. i was thinking maybe its a overload protection? or maybe not enough curret goin to the amp? or maybe the way i have the subs hooked up.. (drive load) ohms?

i tired changing the levels and gain and bass boost all that and i got the amp to were it will play for a while then it turns off..
the amp never gets hot. and the fan is on all the time.. or i think it is...

any help would be great!!

donbryce · #4 03-17-2005, 10:58 AM

"i have two 15" mtx subs hooked up to the amp.. (briged)... i have the subs in parallel" Perhaps your amp isn't too happy with a 2ohm load, which I believe is what your 2 MTX subs @4ohms each in parallel will be?

Ashman · #5 03-18-2005, 08:08 PM

look on the amp for a switch that says high pass/full/low pass. Set it to low pass.

What headunit is this going through?

If the amp has no built in filter, you need something that is wired up between the speaker and the amp. a large coil type device that cuts the high frequencies.

Is the amp stable at 1 ohm?

Is the woofer dual voice coil and what ohms are each voice coil?

Alon

Ashman · #6 03-18-2005, 08:13 PM

I'm running a 12" JL Audio 12w3D4 off a fosgate 800.2 amp wired at 2 ohms on the speaker and the amp is brided mono. it's probably putting out around 1600 watts of power. It was hitting 2 15" fosgate dual voice coil subs before running each at 8 ohm but then run down to 4 ohm before getting to the amp.

The JL hits cleaner than the 2 15s and the bass is plenty. the amp's gain is not set very high, maybe halfway if that.

It has a 2.5 farad capacitor and 4 guage cable to the amp.

I alwasy run the thickest gauge cable I can.

As far as the amp shutting off, it is probably going into a protection mode. if you turn off the car and restart does the amp come back on and then play for a little while?

I would check the woofer wiring, and make sure you are not overloading the amp. if the ohms you have with the subs wiring is 1 ohm or 2 ohm, you need to try to wire them at 4 ohm and see if it makes a difference on the amp.

Not many amps are stable at 1 or 2 ohms.

Alon