Installing Stereo Amplifiers

[Ingres]

Nicely done Steven, always like a neat looking boot... it is a clean install...

[legend_of_lazz]

Hi guys,

Rather than starting a new topic, I thought I'd ask here. I'm currently running an amplifier for my speakers and a monoblock amplifier for my sub. I am getting a little alternator whine coming from my speakers and I believe it may be due to my choice in ground, which is between the front seat bolt and the floor which has been sanded to expose more bare metal. What is the optimal place to ground an amp and is there anything else that could be causing the whine? It happens regardless of whether the inputs are plugged in.

Thanks.

[Steven]

Alternator whine can be caused by a whole lot of issues in a car. An earth is a good earth as long as it has a good contact (which by the sounds yours does).

First of all ensure your gains are set correctly. It is a common mistake to simply turn the gains up. The sad fact is that a small degree of alternator whine will normally always end up in the system, but by setting the gains properly it can be made inaudible.

I find the best way to set amplifier gains is:

1) Turn gains down completely

2) Set volume on source unit to 3/4 Max

3) Turn the gains up until you reach what you consider to be an ideal listening volume for driving

The resultant level of gain will depend on a few factors: for example the voltage of the RCA outputs from the headunit (most are between 1-2v, however some Eclipse units present up to 5v), as well as the RMS value of your amplifier (obviously a 75wrms amplifier will be louder at 3/4 gain then a 50wrms amplifier at 3/4 gain).

You can make some easy shorting plugs for testing where the engine noise is entering the system. A shorting plug is simply an RCA connector with both wires connected together. First of all try plugging it into the inputs of your amplifier - if the engine noise disappears, then in all likely-hood it's being introduced through your RCAs. No matter how good the RCAs, certain things will still induce alternator noise into the signal (ie proximity to power cabling or other devices in the car which may induce alot of interference like the body control module inside modern Commodores).

Hope this helps

[legend_of_lazz]

Alternator whine can be caused by a whole lot of issues in a car. An earth is a good earth as long as it has a good contact (which by the sounds yours does).

First of all ensure your gains are set correctly. It is a common mistake to simply turn the gains up. The sad fact is that a small degree of alternator whine will normally always end up in the system, but by setting the gains properly it can be made inaudible.

I find the best way to set amplifier gains is:

1) Turn gains down completely

2) Set volume on source unit to 3/4 Max

3) Turn the gains up until you reach what you consider to be an ideal listening volume for driving

The resultant level of gain will depend on a few factors: for example the voltage of the RCA outputs from the headunit (most are between 1-2v, however some Eclipse units present up to 5v), as well as the RMS value of your amplifier (obviously a 75wrms amplifier will be louder at 3/4 gain then a 50wrms amplifier at 3/4 gain).

You can make some easy shorting plugs for testing where the engine noise is entering the system. A shorting plug is simply an RCA connector with both wires connected together. First of all try plugging it into the inputs of your amplifier - if the engine noise disappears, then in all likely-hood it's being introduced through your RCAs. No matter how good the RCAs, certain things will still induce alternator noise into the signal (ie proximity to power cabling or other devices in the car which may induce alot of interference like the body control module inside modern Commodores).

Hope this helps

Thanks for the advice. I'll give it a go in the next few days.