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Bronze Member Username: JmillerPost Number: 25 Registered: Nov-04 | I just installed a MTX thunder 404 to run 4 Polk DB650. I'm using speaker level input to connect it to the HU. Both crossover front and rear are set to hi pass. I'm getting at lot of noise specialy when I step on the gas. I'm also getting two pops when I turn off the radio. I only get the noise when the car is on, it sound very nice when the car is off. Oh I always get the two pops when I shut down the radio. |
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Silver Member Username: James1115Ct Post Number: 323 Registered: Dec-04 | thats engine noise. Most likely you have either a bad ground or you are picking engine noise up through your RCA cables which should be wired on the opposite side of the car as your power wire just to make that clear. I would recheck your ground and see what happens. |
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Bronze Member Username: JmillerPost Number: 26 Registered: Nov-04 | Thanks James. I'm not using RCA cables, I'm using speaker level input. I will check the ground and take it from there. |
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Gold Member Username: CarguyPost Number: 1283 Registered: Nov-04 | Speaker level inputs are the worst way of using an amp. They can easily pick up noise and produce distortion. You'll notice that as you increase the volume, distortion increases, highs no longer will sound clear, and the bass will be almost gone. RCA is the way to go. |
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Bronze Member Username: JmillerPost Number: 27 Registered: Nov-04 | What line converter do you sugest ? under $30. |
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Gold Member Username: CarguyPost Number: 1287 Registered: Nov-04 | That's the problem, there are no good line converter you could buy to get quality sound. RCA is the only way. |
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Bronze Member Username: JmillerPost Number: 28 Registered: Nov-04 | Are you saying that I should change the HU? There is no other way to solve the problem? |
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Gold Member Username: CarguyPost Number: 1291 Registered: Nov-04 | If all you want is just a louder sound from your speakers then speaker level input is okay. To get rid of the alternator noise, you could try and run the wires away from all power wires and get a better ground for the amp. Don't expect high quality sounds, especially the lows and highs. You'll get plenty of mids. The only way to get quality is via rca connectors on your HU. If that's not available on your current HU, then yes, you will need a new one. |
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Bronze Member Username: JmillerPost Number: 29 Registered: Nov-04 | I got an 04 Accord so changing the HU is out of the question for now, the adapter plate is $150 plus another $3 or $400 for a good HU; I can't affort it right now. I noticed that the bulk of the engine noise is on the rear speakers. I also niticed that the wires for those speakers happens to be on the same side as the power cable. I'll run a new line on the other side and connect the harness for SLI closer to the radio. |
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Bronze Member Username: JmillerPost Number: 30 Registered: Nov-04 | I ran new line away fron the power cable and fixed the ground, but I'm still getting noise on the rear speakers. I'm also getting two pops on all 4 speakers when I turn off the radio. Any Ideas? Do you think that using an external line converter close to the radio and running RCA cable to the AMP will make things better? |
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Gold Member Username: CarguyPost Number: 1322 Registered: Nov-04 | I'll give you a tip. Cheap 4 channel amps have noise problem. They tend to pick up engine/alternator noises. You can try getting a better ground, but I doubt it'll help much. This is why I always recommend people to buy good amps when it comes to 4 channels. You might either have to get HU upgrade or sell your 4 channel amp and get 2 2 channels. If you separate your front and rears, you'll have less noise pickup. You can test this theory yourself. Take your 4 channel amp and unhook your rears. You'll probably notice that the engine/alternator noise is gone. Repeat the same procedure with the rears, unhook the front. A great 4 channel amp will have built in circuits that deal with ground loop and noise pickups. Check out Xtant/Zapco/PPI/Orion specs. |
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Bronze Member Username: JmillerPost Number: 31 Registered: Nov-04 | Thanks for the feedback Isaac. I didn't know I have a cheap AMP, on the contrary I thought I had a very good one. I bought this MTX Thunder 404 based on Glasswolf recomendation, he said it was a very good AMP. From your note I gather that an external line converter will not inprove things. |
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Gold Member Username: CarguyPost Number: 1327 Registered: Nov-04 | Actually that is a good amp but to me a good amp is PPI PCX/PC series, Diamond Audio, Xtant etc. A great amp is Orion HCCA, Zapco, Arc audio, Mcintosh etc. Who knows, maybe your amp with rca wires, could be a different story. From my testing, speaker level inputs aren't for good audio sounds. For your reference, check out Xtant's 4 channel amp. Are you sure Glasswolf said that amp was "very good"? Normally he reserves that for Zapco/Arc Audio etc.. brands. |
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Bronze Member Username: JmillerPost Number: 32 Registered: Nov-04 | Isaac, here is the link, he actually said that "it'a a great AMP" so I got it. https://www.ecoustics.com/electronics/forum/car-audio/114438.html |
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Gold Member Username: CarguyPost Number: 1366 Registered: Nov-04 | J. Miller, I checked out that amp. It's a good - great amp. I wouldn't say it's "great", but close enough. What I couldn't find were the real specs of that amp. I know it's 50w x 4 of underrated power. But I've no idea what the SN Ratio, slew rate, damping factor, stereo separation, THD etc. From my experience, companies tend to hide such information cause then it'll be easier to compare amps and judge quality. |
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Bronze Member Username: JmillerPost Number: 33 Registered: Nov-04 | Isaac, I installed a pair of external line filters (Tsunami 9.99 each at Circuit city) close to the radio and ran RCA cables to the AMP and everything is well now. the noise is gone so are the pops at shot down. I had to cut the lines, the rear channel was still picking up noise from the power cable. Thanks for the help. |