Will I lose sound quality going to a Carpc with my Quality System?

**ddotderek** · 07-26-2005, 12:14 AM

red gta vr6 lol yup, you are correct

..I guess i need two DAC converters..how much do those run??

**accentsound** · 07-26-2005, 03:30 AM

You do not need two dacs. As most have 5 channel line outs plus sub.

The one we use is made by Audiobahn

ADD51T
1/2 Din 5.1 Dolby® digital, DTS® surround sound decoder with remote
DSP — PCM, Dolby® Digital (AC-3, DTS®), Pro Logic® II, Pro Logic®, Movie, Music
Two Digital Inputs — Optical and Coaxial
Three Analog Inputs — RCA
Six 9v Audio Outputs (LF, RF, C, LR, RR, SUB)
Two composite video signal inputs
One 2.2 volt composite video signal output
Delay functions
Sound field effects
Dimensions: 7/8" (H) x 7" (W) x 5 1/8" (L)

So you see you just route the line outs from the dac to your amps just like from your HU. Car PC to Dac via coax or optical. Line outs from the dac to amps.

**accentsound** · 07-26-2005, 04:08 AM

On the other hand though you have to undrstand that PC's and their sound cards and drivers are not designed with audiophile functions in mind. They are designed mainly for the gamer and playing DVD's

Take for instance the pioneer 9600 HU it has built in crossovers for it's mids and highs channels as well as it's sub woofer outputs. It has equalization for it's independent channels and a host of other features. It uses a 24 bit burr-brown decoder.

It is in this area that PC fall way short. You have EQ built into the sound card driver and thats about it. You have to do 90% of your eq and sound processing outside of the PC. Things as simple as front rear fading or independent stereo balance adjustments can be a pain or just unavailable in the software drivers.

Most high HU's have saveable user presets for all of these settings. PC's so far are sketchy in this regars allowing to save some profiles but not others.

All in all it takes much more time fiddling and adjusting a Car PC system to sound as good as a head unit because they were not intended for that purpose. What is a fifteen minute operation on a high end head unit can be a 3 hour ordeal on a car PC. So you have to decide whether it is worth your time and effort. Once set up though a quality Car PC system will sound as good as a quality HU.

**RedGTiVR6** · 07-26-2005, 08:12 AM

to go out from your pc direct into yoru amps without boosting the signal voltage is asking for noise and low quality sound...

I'd recomend using an EQ or the like (I use the alpine processor for this) to boost your line level voltage to get a much more clean signal among other benefits

by using the alpine unit we were able to still function like a head unit but I was able to not have a head unit in my car...the alpine unit just takes care of all of the processing, etc

**Nic** · 08-31-2005, 12:51 AM

if computers are not yet fast enough to transcode an mp3 in real time then how can we listen to them?

additionally even if that was true you would have to have some super fantastic decoding program, one that decoded slower than realtime, and then you would have to recompress it again, which for lossless formats is never a good idea.

i have no idea about what you are on about being physically recorded, because analog recording is only going to furthur reduce quality

**ALonDonThinG** · 08-31-2005, 07:42 AM

i suggest reading up on the sound quality coming out of the new "pro" XFI cards by creative,
apparently playback of CD,s is especially good

**jmaclean** · 08-31-2005, 12:50 PM

Originally Posted by kdunn926

Thats actually not completely true. When you have an MP3 encoded at a lesser bit rate, all it means is it is compressed, via an encoding algorithm (typically lame). Since the way it is compressed is via a constant operation or algorithm, it is possible to decompress the MP3 some in order to gain some quality back, however typically you have to increase the bitrate 2x, so if you upconvert to 256 from 128 you should notice drastic improvements in your quality.

I'm afraid I have to disagree with this. While this works for many things, such as opening up an archive such as a zip, rar, lzh, this works because these compression methods are lossless.

While the nature of mp3 allows different vendors to compress using slightly different schemes, mp3 is not a lossless format. Most often, encoders use the way we hear to remove some of the content in order to achieve compression, then combine this with a lossless compression algorithm. Regardless, this removal of content is inherantly lossy. Often, if compression is set high (to say 128), some of the lower and higher end notes are removed. These cannot be brought back by re-encoding.

No matter what, when you attempt to re-encode, you're doing to have to decode the current signal. If it's poor quality (at 128k), then you're going to decode the poor quality signal (the same as if you were playing it), and then re-encode that.

**3onDubs** · 08-31-2005, 06:55 PM

Originally Posted by Red GTi VR6

to go out from your pc direct into yoru amps without boosting the signal voltage is asking for noise and low quality sound...

I'd recomend using an EQ or the like (I use the alpine processor for this) to boost your line level voltage to get a much more clean signal among other benefits

by using the alpine unit we were able to still function like a head unit but I was able to not have a head unit in my car...the alpine unit just takes care of all of the processing, etc

Hey Red...you always have good advice, I was wondering what Alpine processor you used in your setup...is it just called an Alpine "processor" or is it a crossover? Also, does the processor automatically boost your line level voltage, or do you have to adjust certain settings?

**RedGTiVR6** · 08-31-2005, 07:30 PM

http://iweb.alpine-usa.com/pls/admn/...ory=&p_main=10

that's what I'm using.

it's more than just an EQ, it's a full processor, surround sound decoder (though I'm not using that part of it), etc.

it boots line voltage to 4v max....no adjustments needed

**00christian00** · 09-01-2005, 04:34 AM

Hey Red,i just changed my sound card with a professional sound card as i couldn't find an alpine h700 for less than 500 euro in italy(i paid my card 350 euro) and at least i don't have to recable for just a controller,and i can use the awesome dac of the card.

The card is that :

http://www.esi-pro.com/viewProduct.php?pid=2&page=1

Specifications
<WaMi Rack 192X>
1. Analog Input Specification
1) Type : 4 channel analog line input - 1/4" TRS Phone jack (X4)
- Balanced XLR Connector (X4)
2) Level : +4dBu balanced, +4dBu Nominal, +22.5dBu Max (Gain +0dB)
3) Gain Adjustment : +0dB ~ +20dB
4) Impedance : 10K ohm
2. Analog Output Specification
1) Type : 8 Channel analog line output - 1/4" TRS Phone jack (X8)
- Balanced XLR Connector (X2)
2) Level : +4dBu balanced, +4dBu Nominal, +22.5dBu Max
3) Attenuation : Digital -127dB ~ 0dB, 0.5dB Step Size (with Mute)
4) Impedance : 100 ohm
3. Mic preamplifier Specification
1) Sensitive : 66.5mV max (Gain +0dB)
2) Gain Adjustment : +20dB ~ +40dB
3) Impedance : 1.5K ohm
4) +48V Pantom power
4. Headphone Amplifier Specification
1) Output Power : 60mW Max
2) Dynamic Range : 110dB (Typical)
3) S/(N+D) Ratio : 101dB, 0.03% (Typical)
5. Sample rate : 16, 22, 24, 32, 44.1, 48, 88.2, 96, 176.4, 192 KHz
6. A/D Convertor Specification
1) Type : 24bit, 192KHz, 128X Oversampling (Full Differential Input)
2) Dynamic Range : 123dB (@ -60dBFS with A-Weighted)
3) S/(N+D) Ratio : 105dB (@ -1dBFS, measurement method)
4) Frequency Response : 6.5 ~ 21.768KHz, +/- 0.001dB (@ fs=48KHz)
6.5 ~ 43.536KHz, +/- 0.003dB (@ fs=96KHz)
6.5 ~ 87.072KHz, +/- 0.007dB (@ fs=192KHz)
5) Interchannel Isolation : 120dB
6) Interchannel Gain Mismatch : 0.1dB
7. D/A Convertor Specification
1) Type : 24bit, 192KHz, 128X Oversampling, 8times Digital filter
2) Dynamic Range : 106dB (@ -60dBFS with A-Weighted)
3) S/(N+D) Ratio : 90dB (@ -1dBFS, measurement method)
4) Frequency Respons : 0 ~ 21.768KHz, +/- 0.05dB (@ fs=48KHz)
0 ~ 43.536KHz, +/- 0.05dB (@ fs=96KHz)
0 ~ 87.072KHz, +/- 0.05dB (@ fs=192KHz)
5) Interchannel Isolation : 100dB
6) Interchannel Gain Mismatch : 0.2dB
8. Digital I/O Specification
1) Type : Coaxial I/O Connector
2) Format : IEC-958 Consumer(S/PDIF),IEC-958 Professional(AES/EBU)
3) Sample Rate : 32,44.1,48,88.2,96,176.4,192 KHz
4) Resolution : 24 Bits

I calculated with a program and and it came out that the output voltage are 1,2 v nominal(4dbu) and 10v max(22,5 dbu) so the voltage should be enought.
Have i understood well?Or will the card have pre-out always lower than a h700?