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Sundown Audio

High pitch sound from amp?


Backwoods

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Question. Went from sundown SFB2K to SFB3K. Same dual 1/0 ofc inputs for power/ground, same grounding location, same alternator, same RCAs and everything except the amp changed.

 

Now I have a high pitched whine sound coming from the amp. It doesn't get louder when I press the gas, the sound doesn't come from the speakers, the sound doesn't stop when RCAs are removed, sound doesn't stop when the volume is down, doesn't get louder with volume up. 

 

SOUND STOPS WHEN CAR IS TURNED OFF, EVEN WITH AMP STILL ON. If amp is running on the battery only, no whine sound. Crank it back up, whine starts again. How do I fix this?

Singer 250amp Alt, Singer PCM bypass harness

Titan8 Lithium Underhood safe BCI PWR-S5

Big 3 W/ dual runs of power/ground. All 1/0awg OFC

SounDigital EVO 5K amp, Two 15" Fi SSD subs

Next Level Fabrication @ 7 cubes net, tuned to 32HZ 

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Turning the gain all the way down doesnt stop the high pitch whine. Removing RCAs and disconnecting the subwoofers from the amp doesnt stop the whine. 

 

Normally id suspect grounding location or RCAs... But i have been using the same grounding location for all 4 amps i have used so far in this vehicle and no issues with the other 3. Same RCAs as well, which are high quality RCAs. 

 

Im stumped.  I will see if maybe the screws holding the amp down are possibly grounding the amps case out when i get time tomorrow. 

Singer 250amp Alt, Singer PCM bypass harness

Titan8 Lithium Underhood safe BCI PWR-S5

Big 3 W/ dual runs of power/ground. All 1/0awg OFC

SounDigital EVO 5K amp, Two 15" Fi SSD subs

Next Level Fabrication @ 7 cubes net, tuned to 32HZ 

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  • 3 weeks later...

 Hi,

 

What you describe is internal oscillation within the amplifier.  As described I would posit something else connected to your car battery is emitting noise being conducted in the power feeds to the amplifier.  The battery +12V  input and  "key on" (amp on) are both capable of allowing noise to enter and ultimately cause the problem you speak of.

 

It could be coming from something else connected to your car's battery and one quick way to test would be to remove fuses from the fuse box one by one until it stops.   Suspect anything connected to the battery. Even your car's engine and vehicle management computer however use caution when working with that particular box. 

 

What you could try is various means of suppression in filter capacitors rated 25 volts , 100 micro farads (uF) placed close to the amplifier on the key on and battery terminals.  Alternatively a "parasitic suppressor" , also called a "zobel network" consisting of a .1 uF capacitor in series with a ten ohm resistor may also work.  Connect the 10 ohm resistor to the positive connection and the capacitor to ground.   What you've made is an RC circuit that filters out high frequency oscillations.

 

  A very large "beer can" sized capacitor may solve the problem however I would advise not connecting it to the key on terminal as the current draw to charge such a capacitor would probably blow whatever fuse the key on wire ultimately is connected to.       

 

I'm inclined to believe it's not within the amplifier itself as if it was the amplifier would make the same noise even if connected to it's own battery and nothing else.  

 

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1 hour ago, JohnP said:

 Hi,

 

What you describe is internal oscillation within the amplifier.  As described I would posit something else connected to your car battery is emitting noise being conducted in the power feeds to the amplifier.  The battery +12V  input and  "key on" (amp on) are both capable of allowing noise to enter and ultimately cause the problem you speak of.

 

It could be coming from something else connected to your car's battery and one quick way to test would be to remove fuses from the fuse box one by one until it stops.   Suspect anything connected to the battery. Even your car's engine and vehicle management computer however use caution when working with that particular box. 

 

What you could try is various means of suppression in filter capacitors rated 25 volts , 100 micro farads (uF) placed close to the amplifier on the key on and battery terminals.  Alternatively a "parasitic suppressor" , also called a "zobel network" consisting of a .1 uF capacitor in series with a ten ohm resistor may also work.  Connect the 10 ohm resistor to the positive connection and the capacitor to ground.   What you've made is an RC circuit that filters out high frequency oscillations.

 

  A very large "beer can" sized capacitor may solve the problem however I would advise not connecting it to the key on terminal as the current draw to charge such a capacitor would probably blow whatever fuse the key on wire ultimately is connected to.       

 

I'm inclined to believe it's not within the amplifier itself as if it was the amplifier would make the same noise even if connected to it's own battery and nothing else.  

 

This is the 4th amp I've used in a couple months and the only one to have this issue...

 

1 hour ago, 1point21gigawatts said:

@Backwoods, what happened in regards to this “old” issue?

 

I disconnected the amp, tried another amp, no strange sounds... Reconnected and screwed down the new amp with shorter screws... And it was gone. The only noise is the fan running.

 

The only thing I can think of is the longer screws were grounding the amps case out... But in that case it seems it would do it even when the vehicle was off... So I really don't know. 

 

But now the issue is gone... It still louder than the other amps with the fan running, but it's a more powerful amp. And I can't hear it at all with music playing. So no biggie.

 

I do plan on connecting a toggle switch to the remote line so I can turn the amp off completely when I want to listen to audio books, stand up comedy, or ride in complete silence.... And I know... that makes me sound old... Oh well LOL... But sometimes I don't want to hear the amp's fan running

Singer 250amp Alt, Singer PCM bypass harness

Titan8 Lithium Underhood safe BCI PWR-S5

Big 3 W/ dual runs of power/ground. All 1/0awg OFC

SounDigital EVO 5K amp, Two 15" Fi SSD subs

Next Level Fabrication @ 7 cubes net, tuned to 32HZ 

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check your grounds for corrosion maybe not trying to grasp at straws but ya never know.

what style lugs for the power and ground wires did you use i noticed the set screw style are not very good and you should use a crimp or solder job.

skar sk2500.1
0 gauge power and ground kunukonceptz
alpine HU
vxi65 components on BA gt-275
new build log -> http://www.stevemeadedesigns.com/board/topic/150642-project-d-kon-deathcards-build-log/#entry2148821
2 x-15 sundowns

singer alt, odyssey bat, and maxwell ultra caps

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I've checked all grounds. No corrosion. But... This vehicle is a 2019. I just started adding music to it a few months ago. It would take driving it through the ocean to have enough corrosion already LoL

 

Lugs at the amp? They're the same as the last 3 amps... Allen set screws, with dual 0 awg input to single 0 awg output. But I've checked the power and ground at the amp with a DMM and the inputs are solid. 

Singer 250amp Alt, Singer PCM bypass harness

Titan8 Lithium Underhood safe BCI PWR-S5

Big 3 W/ dual runs of power/ground. All 1/0awg OFC

SounDigital EVO 5K amp, Two 15" Fi SSD subs

Next Level Fabrication @ 7 cubes net, tuned to 32HZ 

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Hi Backwoods,

 

Given what you write about using shorter screws to secure down the amplifier leads me to believe there may be some kind of mechanical issue within the amp possibly causing the heatsink to ground out something on the internals of the amplifier that should not ground out.   Alternatively it may be causing the circuit board to flex and a solder joint somewhere on the amp to open when it should not.

 

Soldering issues in mass produced consumer audio and video has been an issue especially when there was a movement to lead free solder in the whole RoHS  (reduction of hazardous substances) movement within the electronics industry.  

 

You would be surprised to know how many failed electronics I've ressurrected using not much more than a magnifying lamp and not even a pennies worth of solder.

 

Cheers ! 

 

 

 

 

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