Some ideas to a 12v custom noice filter.


Hi Forum.

I hope that some of you guys can give me some inspiration to a high-end noice filter that operates in 12v DC.

This project of mine, is making a true HIGH-END automitve audio system, so i use some parts i know sounds grate, from our home systems.

Ive made a drawing, which you can take a look on - it isn't with the right symbols, but i can read diagrams, so if any of you has an idea, to a filter / Ground Loop ect. then you will be a fantastic help.

www.lydprofilen.dk/ippec/projekt.jpg

as you can see from the drawing, the DAC has to be switched on with the engine from the car, it shall not have power directly from the acc. The Transport and the Router, gets power directly from the acc, and one thing to be aware of, is that the Transport needs 12v aswell as 5v.

Best Regards.

Jesper, Denmark.
fluffyman

Showing 1 response by casouza

Jesper, DC noise filters can be implemented passively with shielding, more capacitance or inductance (a choke).

I do not recommend any form of voltage regulation, because a car batery is nominally rated for 12 V, but in reality most batteries operate around 14 Volts. Regulating to 12 Volts will reduce the power output of your power amps.

So, if you hear engine noise through the system, you need suppressor spark plug cables and a choke inline with the 12V DC feed to your DAC and head unit.
Most car audio stores sell the chokes (even Radio Schack sells a nice one).

Capacitance provides additonal filtering and also serves as a very stable power supply. Several vendors make 1 Farad capacitors for powerful car audio systems. These are usually needed for Nascar SPL contests and extremely powerful amps, anyway, a large cap makes an excellent noise filter, even if you listen at low volumes.

Lastly, make sure your interconects and the digital cable between head unit and DAC are double-shielded and do not run speaker cables near any IC.

I hope this helps