That is the question.
This topic is going to take a little explaining; but I know how much everyone loves my story telling, just kick back relax and sit a spell; Im gonna take you on a journey!
6 months and $600.00 ago
I found this darling little mp3 player on sale at Parts Express. Nifty used thumb drive/ SD memory and had a remote. Works off 5v. and a line level stereo ouput. Now how was I gonna get that in my car. They were only $8 or somthing, so I bought 2 of them. They are fantastic; except for a couple tiny manufacture flaws (no support what so ever, and a remote that has more functions than it says it does. Including a software library that I have yet to figure out. , amazing none the less.
So, coincedentally iSimple makes a aux input for my car, and the OEM radio I have has a premium CD changer you can get, yet I dont. The iSimple device lies (more like teases) the radio and computer to think that it has a compliant OEM CD changer on board, and i just turn on the mp3 player now installed on my dash. Perfect. Especilly the remote feature. I dont even have to lift my arm to change songs. And I hve a ton f old SD memory cards from cameras. and a new 32 gb that has all my mp3's and i can jam out for....like .....forever man!
I built a harness that converts the 3 wire output to dual RCA using a wiring i borrowed from the equipment I use at the studio. Ballanced TRS. You have a hot and ground, and a 3rd wire that surrounds and shields the two active wires from noise. I did not borrow the imnpediance leveling however as that would require a transformer a couple caps and stuff that really? i dont need that. The isimple isnt even a low level input. and neither is the radio. But the technique just the same was easy enough, maybe i could prevent any hum or signal decay. well it sounds great. no problems except one. This device was not made for a car. and when i use a thumb drive, it makes some nasty noise and clearly not the way to go. The SD memory cards are pin drop silent, and i have no problem just stickin with that.
The mp3 palyer dosnt have a case, open PCB and open microprocessors, usb plug/ memory slots bare, and the back is a haven for anything to get in there and cause mischief.
So how can I shield this accessory that does contribute to the sound sytem, yet it donent actually eat much of any resources. I dant have it fused yet, i need to do that. I have it hooked up to a switch, but it makes a hell of a pop when i turn it on, so i turn it on before i turn on the car, then its allready made its pop, and i dont have to endure it through my system.
On my guitars if I experience noise depending on the guitar itself i may go as far as to add foil shielding and a ground plate this seems to help when dealing with passive magnetic humbuckers. But may have no effect on this player. I could use a little magnet that is wound around a inch or so of USB cable. I used a USB cabel because coincedentially its 5volts. and the USB cabel was for a video camera that had one on it, so i left it. when i hook it up to the input uf the computer, no noise what so ever, frigin genius.
So anyways thats ther story of the little MP3 player that just wants to be part of the cool gang down at the playground.
Somewhere i heard there is no such thing as sheilding. what you are really expperiencing is a complex filter. The interference is still there, and still penetrates the device, its just masked by a series of filters, so you dont hear it. Kinda like that not - so - fresh feeling that everyone else notices; but you just seem to be amune to the noise.
Thanks for any assistance or guidentce, i know this is a unique idea, so maybe this will also inspire others to seek. I want to make a old school VU meter for my sub box. and a volt meter alarm for the battery and system load. And strategic areas of lighting where comon mainainence points are. How are these non sound devices worked into the design of a system, and how do I manage resouces and prevent system failure.
Be not guided by morality, but rather, integrity.