Question about Phase Linear UPA424CS Car Audio Amplifier

1 Answer

Humming noise thru my speakers

I bought the amp and installed it a couple of weeks ago and since then i always get this humming noise and when i step on the gas to my jeep is gets louder and louder

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has answered 1,000 questions.

  • Master
  • 1,139 Answers

You are getting engine noise through your amplifier. To solve this problem you will need to install a filter in-line with the DC path, or install a voltage regulator in-line with the DC path.

Posted on Sep 08, 2007

  • Henry McKelvey
    Henry McKelvey Sep 12, 2007

    Hello Big tony ,

    I usually don't reply to the double red squares, but in this case I am kind of perplexed, short of me telling you how to change out your alternator to a new one with clean brushes (the cause of the voltage spikes) and getting a new voltage regulator. That's about all that can fix this problem. However that solution does not make any sense. You have voltage spikes on the line and the only way to remove them is with an LC (inductor/capacitor) filter in-line with the DC path. Your problem is that the amplifier is amplifing these voltage spikes or your amplifier is not properly filtering out the incoming spikes. But the fact is your dc voltage has spikes on it and a way of removing those spikes is with a LC filter. Or on the off chance that it is the power supply in the amplifier, take of the cover off and find the main voltage input and use an oscilloscope to see if the DC voltage is clean (free of voltage variation) This may mean that you have to replace a filter capacitor in the amplifier. Other then this your options are all spent.

    I am sorry I did not give you the answer you were looking for but, I have always felt that being honest makes one a good technician, and non-complicated problems deserve non-complicated answers.

    Thank you and I hope that you find what you are looking for.



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Why do my desktop computer speakers have a humming noise all of a sudden? They were turned off for a couple of days .

Check the speaker cables for connectivity. Be sure to securely plug in the stereo jack/s at the back of your pc

Jul 21, 2014 | Logitech Audio Players & Recorders

1 Answer

2006 lincoln ls, noise comming from speakers when the radio is off

My wife had that issue with her 2004 a week ago

The radio quite working for a couple hours,but as
you said, had sound from rear speakers,then came
back to normal

We have lost the radio about 4 times since Nov of
2003, but not in a couple of years

If I have a solution I will let you know.

I have all the service manuals, but would be here for
days looking thru trouble charts on that issue

Jun 08, 2011 | 2006 Lincoln LS

1 Answer

I have a pair of JM lab Electra 905 speakers, running through a DNM amp and power amps. When powered up, the left speaker makes a very loud humming noise. This has happened recently. I haven't changed...

Switch on your amp, keep its volue down to extreme low, and listen if there is still hum through the left channel or not. If still there is hum, the left side power amplifier section inside the amp;ifier is faulty. If htere is no hum at this state, hum enters thorugh the audio input terminal, and the input wires must be checked for open sheild connection. OK.

Apr 10, 2011 | Jmlab Electra 905 Speaker

1 Answer

I have a set of subwoofers in my car powered by an amp with capacitor all 3 years old. A couple weeks ago I encountered a problem where my system will suddenly emit a weird loud humming noise (similar to...

try taking out the capacitor and wire the amp up with out it. it sounds like the cap is back feeding or discharging voltage when it should not be . if you reinstall the amp with out the cap and noise goes away buy a new cap or do away with it .

Oct 29, 2010 | Rockford Fosgate T600-2 Car Audio...

1 Answer

Speakers dont work

if the pc runs windows vista they won't work in less they have a power but if the pc runs windows xp try to install the drivers for the speakers here is the download link

May 29, 2010 | Dell A215 Computer Speakers

1 Answer

Planer Rattle

If it is belt driven then maby replace the belt. That may be the problem.

Jun 14, 2009 | Tools & Hardware - Others

1 Answer

Left rear speaker noise

The internal amp for the left rear speaker has a faulty transistor or IC chip this would need to be replaced.

Aug 21, 2007 | Creative Labs Gigaworks S750 Computer...

1 Answer

Humming from speakers when CD player running

Yes, The humming is always there you just can hear it better when the cd is playing. The humming is caused by the electrical system in your car. There is an inline filter you can buy and insert it between the car's power source and the head unit. I had a head unit I bought that was absolutly terrible until I installed that filter. Also if you did a do it yourself job on your amp wiring it is usually best practice to run your RCA cables on the opposite side of the car as your power cable. You can also purchase shielded spark plug wires which is a source of noise usually of a different kind tho. First make sure you have a good ground. This means that you have grounded your amp to bare metal not painted metal. If that didn't work put in the inline filter on the head deck as they are only $20 available at radioshack. If that doesn't work, go back an wire your car right this time and put the power and RCA on opposite sides of the car. If you still have that hum it may be the spark plug wires but that sounds more like static than hum. You have a text book case of alternator hum... Hack

Jul 11, 2007 | Xtreme Sound WMS336 CD Player

Not finding what you are looking for?
Phase Linear UPA424CS Car Audio Amplifier Logo

Related Topics:

1,780 people viewed this question

Ask a Question

Usually answered in minutes!

Top Phase Linear Car Audio & Video Experts

Lyle Siemens
Lyle Siemens

Level 2 Expert

328 Answers

Jaime Hernandez

Level 3 Expert

2326 Answers

The Audio Lab

Level 2 Expert

82 Answers

Are you a Phase Linear Car Audio and Video Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides