Speaker Whine When Engine Is On

[JakeC 1]

As the title states after recently installing a new amp and set of Wetsound tower speakers on my boat I have an engine whine while the engine on. I installed the speakers in my garage and couldn't of been happier with performance, however after getting onto the lake it quickly became apparent that there was a very noticeable engine noise in the new set of speakers. Some info about the setup and what I have tried so far. There are now two amps in the boat each of which are a different brand and draw different amounts of power, both amps + and - wires are attached to the same terminals on the second battery. The amp driving the onboard speakers does not have any engine noise. The new amp has a different gauge wire powering it since it required more power than the already wire amp. I tried disconnecting the RCA cables (which run from the head unit and then split right before the two amps) from the new amp but the noise still persists, only disconnecting the speaker wires running to the tower speakers makes the noise go away. This noise also shows up even with a minimal amount of gain set on the new amp. I am out of ideas on what could be causing this since the other amp does not have this problem.

[Troy 234]

sounds like an amp issue.  If the amp + and - are ran directly to the battery (straight, no coils) and you unplugged the RCA's and the noise is still there, I would point at a bad amp.  

Back in the day I installed an amp temporarily and had my wires coiled because the permanent install was farther away,  and I had noise. I uncoiled the wire and the noise went away. For the temporary install I just ran the wires back and forth like an S instead of a coil. 

[JakeC 1]

1 hour ago, Troy said:

sounds like an amp issue.  If the amp + and - are ran directly to the battery (straight, no coils) and you unplugged the RCA's and the noise is still there, I would point at a bad amp.  

 

I was suspecting this might be the case but was really hoping it was some sort of ground loop or the fact that each amp is using different gauge wire that could cause something like this. Thanks for the response as always.

[Wylie_Tunes 146]

Different gauge is not an issue, but incorrect gauge, as in too small, can cause issue. Have you checked voltage at all the audio components, and compared them? I do suspect something wrong with the amp, if the noise is present with no audio cables connected to the amp inputs. Take a short RCA and connect both ends to any and all RCA inputs on the amp. This basically shorts the inputs, preventing noise from entering. If noise is present and the gains are not excessive, this pretty much points to the amp. 

[JakeC 1]

22 hours ago, Wylie_Tunes said:

Have you checked voltage at all the audio components, and compared them?

I will do this today, also would it still be an amp issue if the audio only has this whine when the engine is on but sounds clean when its off?

[JakeC 1]

On 7/15/2020 at 7:23 AM, Troy said:

Back in the day I installed an amp temporarily and had my wires coiled because the permanent install was farther away,  and I had noise. I uncoiled the wire and the noise went away.

Would it be an issue if my + and - wire as well as the speaker wires coming out of the amp are all zipped tied together? Should I try separating them so they don't run along each other?

[Wylie_Tunes 146]

Amplifier output is dependent upon voltage, so engine off v's engine on can make a difference. Gain level also. A larger factor is a difference in voltage at each amp. 

Its very rare to have the DC voltage input, bleed into the AC voltage audio output due to cable routing.