MTX ground issue

I have a MTX Thunder 421D mono block amplifier pushing one JL 10W6 V2 D4 wired in series presenting a 2 ohm load. I also half a one-half farad lightning audio cap. The problem I am having is with my amplifier and I think it may be due to the ground. Whenever I play music that has a sharp, fast, and not very deep beat the red power light on the amp flickers everytime the bass hits and when I turn it up loud when this is happening my system goes crazy. My sub just starts making all kinds of noise that isn't part of the music and sometimes the only way to get it to stop is to completely turn the entire system off. The amp is wired with 4 awg for the power/ground. I have played around with the ground a lot (moving it to various locations, making sure all the paint was removed from the metal, etc.) and I have had some success in reducing this problem, which is why I beleive that the ground may be the culprit. However, no matter what I do, I cannot seem to completely eliminate this issue. I am completely perplexed by it because I can play hip hop songs that have tons of bass with no problems, but when I try to play some techno, for instance, with a beat that doesn't even hit that hard everything goes to hell. If anyone could tell me some possible solutions to this problem, they would be greatly appreciated. Thanks.

Sorry, I meant to say that it is wired in parallel, not series.

did you try to bridge that amp?. Becuase thats a mono block amp with two output barriers and iff you try to hook it up like a bridgbed two channel you will get the results you are describing

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

No, the amplifier is not hooked up in a bridged configuration. The subwoofer is on the speaker 1 terminals.

What did you use for RCA wires ? Sounds like an inherent problem with noise coming through the RCA. Did you run the RCA along side any speaker wires or power wires ?

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

I have a triple shielded rca cable routed on the passenger side of the car and the power and remote wires are on the other side of the car. I used to have another 4 channel amp hooked up and the rca's were run right next to the speaker wires going the the amp from the receiver then, but this is no longer the case. However, the speaker wires are still in place even though they're not connected to anything. Is it possible that this could still be causing a problem?

Oh and when I said that the speaker wires were going from the amp to the receiver I didn't actually mean that they were connected to the receiver. I just spliced off the speaker wire there so I didn't have to pull the door panels again.

Darth_soul wrote:

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I have a triple shielded rca cable routed on the passenger side of the car and the power and remote wires are on the other side of the car. I used to have another 4 channel amp hooked up and the rca's were run right next to the speaker wires going the the amp from the receiver then, but this is no longer the case. However, the speaker wires are still in place even though they're not connected to anything. Is it possible that this could still be causing a problem?

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Not likely then. I'm just throwing out possibilities of what may be inducing the noise into your system. What is the output voltage of the RCA's on the deck in comparison to the input sensitivity of the amplifier ?

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

My head unit is a Pioneer DEH-P7600MP. From what I was able to find all three sets of the rca preouts are 2 volts. As far as the input sensitivity on the amp, I'm not sure. It is a MTX Thunder 421D. All I was able to find is that the maximum input is 8Vrms.

Another strike for me. If the output voltage for the RCA's are only 2 volts, then your fine. I can't think of anything right now.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

I suppose I should have also mentioned that back when I had the other 4 channel amplifier powering the other speakers, I, quite idiotically, touched the speaker wires from the 4 channel amp to the chassis of the vehicle when my system was on. This is when the problem started. Since then I have replaced the amp, installed a new higher quality amp kit, and had the preouts on my receiver replaced, but still the problem persists. Also, my car is a 2004 Oldsmobile Alero and when I had the 4-channel amp installed I had big alternator noise problems, which I think was due mostly to a ground loop. Does anyone have any idea if that particular car has inherent grounding problems and if so any remedies?

So I guess no has anymore ideas??

i have an mtx 8100d mono block amp and it had the same prob it is the groundin where are u currently groundin the amps, i suggest a seat belt bolt as a good point or otherwise sand back a little paint to ensure good contact, also make sure to run a large gauge wire for grounding as the mtx needs it

to Darth_Soul, try removing the cap, just bypass the cap and run the amp straight in and see if that changes the problem. Also if possible, try anoter head unit, just to remove the Pioneer as a possible, you said you had the pre-outs replaced in the Pioneer but I have found that most unit repairs are not completed very well...

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mrhifimrsound

Well, 30xbigboy, I currently have it grounded to a seat belt bolt and I did also remove the paint from the surface of the body. I am using 4awg power and ground wire, which should be plenty big enough because in the owner's manual it said that 8awg would be adequate. Regarding your post mrhifirmsound, I have already tried bypassing the capacitor with no luck. I'll admit that I didn't remove the cap ground (grounded at the same point as the amp) when I did this, but I don't know if this would have mattered or not. As far as trying another head unit, well, unfortunately that is not financially feasible for me at the time.
Thank you for the suggestions guys.