Subwoofer Squaling/High Pitch Sound

[tluft912]

Back in July 2017, I installed an Alpine PDX-M6 amp and two Pioneer TS-SWX2502 subwoofers with 4 gauge wiring. They worked great for about 5 months. I unplugged the power connector from the amp and then replugged the amp back in a couple days later. As soon as I plugged in the amp, both of my subs started making a squealing/high pitch noise. This sound eventually stopped, but only because this caused both of the subs to be blown. I never abuse my equipment, so I know that it was not due to neglect. I just got two new subs today, same ones that I had before. Come to find out, the same problem that I was having is still present. No fuses are blown, getting the full 12v to the amp from the battery, and the ground should be good (see below). If the speakers are plugged into the amp when my key is in the accessory potion, no sound comes from the subs but my amp turns on. Not in protection mode, normal blue light is on and solid. After I start my engine, the new subs start to make the same squealing/high pitch noise and the cone pushes outwards. I made sure I unplugged them before they had the chance to burn up this time. This problem occurs regardless if the RCA cable is plugged in or not. Linked below is a video of the noise of what is happening. I opened up the amp and nothing seems to be out of the ordinary, no busted capacitors. Thank you in advance for all of the help.

View attachment 26557328

Click to read more...

 

[Louisiana_CRX 5,000+ posts]

Back in July 2017, I installed an Alpine PDX-M6 amp and two Pioneer TS-SWX2502 subwoofers with 4 gauge wiring. They worked great for about 5 months. I unplugged the power connector from the amp and then replugged the amp back in a couple days later. As soon as I plugged in the amp, both of my subs started making a squealing/high pitch noise. This sound eventually stopped, but only because this caused both of the subs to be blown. I never abuse my equipment, so I know that it was not due to neglect. I just got two new subs today, same ones that I had before. Come to find out, the same problem that I was having is still present. No fuses are blown, getting the full 12v to the amp from the battery, and the ground should be good (see below). If the speakers are plugged into the amp when my key is in the accessory potion, no sound comes from the subs but my amp turns on. Not in protection mode, normal blue light is on and solid. After I start my engine, the new subs start to make the same squealing/high pitch noise and the cone pushes outwards. I made sure I unplugged them before they had the chance to burn up this time. This problem occurs regardless if the RCA cable is plugged in or not. Linked below is a video of the noise of what is happening. I opened up the amp and nothing seems to be out of the ordinary, no busted capacitors. Thank you in advance for all of the help.
View attachment 26557328

Ground loop

 

[tluft912]

Ground loop

What would you recommend doing to fix the ground loop?

 

[Louisiana_CRX 5,000+ posts]

What would you recommend doing to fix the ground loop?

Is it a Pioneer Deck ? If so you most likely blown the Pico fuse in the deck on the rcas..

 

[tluft912]

Is it a Pioneer Deck ? If so you most likely blown the Pico fuse in the deck on the rcas..

Yes, I have a Pioneer MVH-X380BT.

 

[Louisiana_CRX 5,000+ posts]

Yes, I have a Pioneer MVH-X380BT.

The pico fuse is blown ..they blow due to what’s called hot swapping ..that’s plugging the RCAs in while the amp and radio are powered ..it is a safety fuse Pioneer puts on the rcas inside the radio a simple test it may go away or get quieter is touching a small ground wire to the edge of the rcas ..if you are good with a soldering iron you can fix the issue yourself by going inside the deck

 

[THATpurpleKUSH 5,000+ posts]

Almost sounds like the amp is putting out dc current.

 

[Louisiana_CRX 5,000+ posts]

Almost sounds like the amp is putting out dc current.

That would fry his speakers

 

[THATpurpleKUSH 5,000+ posts]

That would fry his speakers

Well he did mention the first pair of subs blew

 

[Louisiana_CRX 5,000+ posts]

Well he did mention the first pair of subs blew

I missed that part ..you may be right on that then ..he will need a dmm to test and see if the amp is producing dc voltage if so a bad power supply in the amp ..sometimes a winding can wear and touch inside the torrid choke and you’ll never see it visually

 

[tluft912]

Well he did mention the first pair of subs blew

Correct. And the new set of subs make that noise that's in the video, regardless if it's connected to the head unit or not. If I start the engine and leave the subs connected to the amp, it will make that sound continuously until they burnt out again.

 

[tluft912]

I missed that part ..you may be right on that then ..he will need a dmm to test and see if the amp is producing dc voltage if so a bad power supply in the amp ..sometimes a winding can wear and touch inside the torrid choke and you’ll never see it visually

I do have a multimeter. How would I go about testing to see if the amp is producing dc voltage?

 

[Louisiana_CRX 5,000+ posts]

I do have a multimeter. How would I go about testing to see if the amp is producing dc voltage?

The output from the amp is ac voltage input DC of course 12vs ..unhook your subs and put the leads from the meter on the speaker outputs and see if it’s reading AC or DC voltage on your dmm ..if it’s reading dc voltage it’s a bad power supply ..I have a competition Kicker XS100 that’s doing that that came from eBay ..guaranteed to work and blew a $600 set of speakers as soon as I hooked it up ..cone shot out then smoked

 

[MasterJones93]

Yeah that looks and sounds like dc current.

 

[tluft912]

The output from the amp is ac voltage input DC of course 12vs ..unhook your subs and put the leads from the meter on the speaker outputs and see if it’s reading AC or DC voltage on your dmm ..if it’s reading dc voltage it’s a bad power supply ..I have a competition Kicker XS100 that’s doing that that came from eBay ..guaranteed to work and blew a $600 set of speakers as soon as I hooked it up ..cone shot out then smoked

I will be sure to try that tomorrow after work and I will report back! I did hook up the multimeter to the speaker outputs earlier today and it fluctated between about 2.15-2.4 V, but I can't remember if it was AC or DC... I greatly appreciate the help. And that stinks man! Another reason why I have a hard time trusting people on eBay....