FPeter

Hi All!

I started my CarPC project 3 years ago, and I met with the biggest problem at the first time when I turned on the new system in my car. Groundloop, generator noise, clacks at HDD, USB communication, and other annoying voices. I started with an old SoundBlaster PCI card, so I replaced it with an SoundBlaster MP3+ USB „card”. That was a bit better, but far from the heaven. I tried it at several place: under and in the dashboard, half way to back and in the trunk next to the audio amplifiers. One time there was less generator noise, but I experienced others. Other time generator noise disappeared, but I got another constant noise. I heard about ground loop isolators, but I think its only a „slap to the crap”... So I decided to solve this problem, by total isolation of the amps from the computer...

The solution is the S/PDIF. I have never used before, and I had no experience with it, but I knew that this is the key. I searched the net for articles, and after a few week, I finished my first receiver:


click to enlarge

Based on Cirrus Logic CL8416 receiver and Texas Instruments PCM1754 DAC, with an Toshiba TORX173 optical receiver. I connected it to my MP3+ USB adapter, and I used it for month. After it, I built my other circuit with TI DIR9001 and the same TI DAC:


click to enlarge

Now I’m working on a C-Media CM108 chipset based USB audio adapter with some CarPC-related functions: rotary encoder knob for volume control, power on/off logic for amplifiers, and of coure the S/PDIF...

Is here anybody, who has the same problems, and would like to solve it?

MP3Car.com

 

galvitron

Nice. I'll have to give this a shot...

__________________
2006 Lancer Evolution IX MR In-Dash PC Project - WIP

Planning:
[----------] 100%
Purchasing:
[----------] 90%
Installation/Fab/Assembly (Revised v2):
[----------] 90%

galvitron

Any way you could post some detailed part numbers for what you used?

__________________
2006 Lancer Evolution IX MR In-Dash PC Project - WIP

Planning:
[----------] 100%
Purchasing:
[----------] 90%
Installation/Fab/Assembly (Revised v2):
[----------] 90%

bes51659

I want one FPeter, please.

I have just installed (today) my PC in my car and had audio for the first time. Even though my RCA cable is only one feet long I had very much noise! I did expect total silence because of the PC and poweramp standing right next to eachother.

As you I am bored with solving ground problems and prefer a final solution.

I have Spdif out, so I only need your receiver... Any plans on selling it?

As for the USB project; no, not interested. Sorry.

eric_barcus

how much where are the parts? do you have a parts list?

__________________
MY build...a walk thru, finally getting to it

FPeter

there are several part that can be used, like CS8412,CS8414,CS8416,DIR1703,DIR9001 as receiver, and many many DAC ICs from different suppliers like Texas Instruments, Cirrus Logic, Analog Devices and others...

i choosed the CS8416 (up to 192KHz 24bit, it was 1700Ft - ~10.3$ at local store) and TI PCM1754 (up to 192KHz 24bit SNR 106dB, i got it earlier from somewhere...), but I2S receivers and DACs are compatible in most cases, other types can be ok too, like CS4334 (up to 96KHz 24bit SNR 96dB)

i used this guide to make my own circuit: DAC Final test and the DAC's reference pdf from the TI's website

if you plan to use 192KHz, you need a high speed optical cable and receiver, like the TORX141P. i used TORX173 that can handle only the 96KHz, but i think resampling the 44.1KHz CD/Flac/Ape/MP3 source to higher level is a dummy thing, so i use 44.1KHz 16bit - like the source files...

__________________
Intel D201GLY, 512MB DDR2, Samsung SP1213N 3.5" 120/7200/8M HDD, audio through digital line
bye bye noise - the DIY S/PDIF DAC

FPeter

i have the plan to make a real product, but now its only a DIY thing... i write a pm to you...

__________________
Intel D201GLY, 512MB DDR2, Samsung SP1213N 3.5" 120/7200/8M HDD, audio through digital line
bye bye noise - the DIY S/PDIF DAC

greatwhite

Guys, I'm not saying this solution doesn't work, I'm sure it does. But most noises in the audio is a result of the install being, well............shall we say "less than professional"

My amp and puter are mounted back to back in the same cavity with the HDradio tuner and it's dead silent with the music paused and no interference problems. There's not even a layer of 3/4 MDF between them as the amp is in a hole and the puter is metal-to-metal with it.

Like so:





(Shameless plug for finished project)



If this little gadget cures your noise woes, then great! Install and be happy!
But it's not the only way.

Just sayin'.........................

__________________

MP3Car.com

 

galvitron

Actually I want to use it to maintain a digital connection all the way back to the trunk.

__________________
2006 Lancer Evolution IX MR In-Dash PC Project - WIP

Planning:
[----------] 100%
Purchasing:
[----------] 90%
Installation/Fab/Assembly (Revised v2):
[----------] 90%

FPeter

metal to metal? the case of the amp should not be grounded! this is a very base thing in car hifi topics! in rare cases this can destroy the amp, loudspeakers and the source too! and make fire in the car...

__________________
Intel D201GLY, 512MB DDR2, Samsung SP1213N 3.5" 120/7200/8M HDD, audio through digital line
bye bye noise - the DIY S/PDIF DAC

greatwhite

Ah, no. I think you misunderstood.

Niether is case grounded.........

__________________

FPeter

oh ok...

but the generator, groundloop noise is one, but several people has others, like HDD,ODD,USB,PS/2,etc I/O-related noise...

__________________
Intel D201GLY, 512MB DDR2, Samsung SP1213N 3.5" 120/7200/8M HDD, audio through digital line
bye bye noise - the DIY S/PDIF DAC

greatwhite

Yup, had that stuff too, until I cleaned up my install to it's final form. HDD accessing noise was the worst, thought I'd go nuts chasing it down.

As I said, I'm not saying your hardware won't work, I'm sure it does by going spidf. And, as also mentioned, staying digital as far as possible is another good reason.

I'm just saying it's not the only way to deal with "noise".............

Cheers

__________________

eric_barcus

id agree with great white on the "less" than professinal install, do some further isolation to figure out where your sould issues are comming from, use a differnt audio source, mp3player cd ect, use a dif amp use "straight runs" from the amp to a speaker to see if you have an exposed wire somewhere, when you isolate smartly by taking out one piece at a time you can usually figure it out
BTW CLEAN install great white

still a great product thou, small too

__________________
MY build...a walk thru, finally getting to it

audiology

Heres a good example of how wires should be installed.

http://forum.sounddomain.com/ubbthre.../1#Post1368137

__________________
[98%]

MP3Car.com