# Car PC SQ?



## HiloDB1

Looking at possibly doing a CarPC in my build. I was curious to know how the SQ is on a system like this is. Im not familiar with the types of DAC's (if any are built in) and types of outputs are possible besides the standard 3.5mm jack.

What about DSP would that be something that can be incorporated into the PC itself or would an external DSP a better option?

Thanks


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## Hdale85

You can do crossover and time alignment and stuff on the PC, there are some high end sound cards but they likely still won't be as nice as a outboard DAC.


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## HiloDB1

So what if I mated it with a nice DSP/DAC like a PXA-H800? Using the optical S/PDIF


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## Neil_J

The sky is the limit. You can truly do just about anything and approach the limit of perfection with a CarPC. However, the complexity and cost can be very prohibitive as you start chasing that last fractions of a percent of THD and jitter performance. I have gone down this road myself, and I will tell you, put your time and energy into acoustics, not processing, if you want to have a good sounding car. The DSP processing and DAC performance in my CarPC beats the specs of any commercial car audio processor. It took almost a year and a ton of money, and it still sounds like crap compared to simple installs I've heard. Processing is not a band aid for good acoustics, is what I'm basically trying to say.


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## MarkZ

Hdale85 said:


> You can do crossover and time alignment and stuff on the PC, there are some high end sound cards but they likely still won't be as nice as a outboard DAC.


What's the difference between a sound card and a DAC, aside from the value of the resistor in between the DAC and buffer?  

I don't know of very many things that an external processor can do that a PC can't. Except for certain proprietary algorithms. All the standard stuff -- channel mixing & level control, crossover, EQ, delay and phase, are all fairly easy and cheap to implement on a PC. 

Once you work out the bugs.


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## HiloDB1

Neil_J said:


> Processing is not a band aid for good acoustics, is what I'm basically trying to say.


This I know. My main concern was the built in sound card on the mobo. I have no idea what type of DAC is being used and therefore had no indication on the level of sound I would get out.


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## Neil_J

HiloDB1 said:


> This I know. My main concern was the built in sound card on the mobo. I have no idea what type of DAC is being used and therefore had no indication on the level of sound I would get out.


The sound card on the motherboard has a high chance of sounding like crap  To be specific, in my personal experience, they have very poor noise floor performance, if you turn the gain up while listening through a pair of headphones (you may need an external headphone amp if it's only a line-out), you will likely hear lots of stuff that's not supposed to be there. To what severity depends on the exact board and how the engineer routed the traces, and to a smaller aspect, which CODEC chips they chose. Use an external sound card if at all possible, but feel free to try it out first and see exactly how bad it is.


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## HiloDB1

Even with a good sound card it still seems I'd be limited with the number of analog outs I would have. Unless I want to use 3.5mm jacks to RCA. Is that my only option? I was hoping for a 5.1 style system or at least an active front w/ rear and sub.

*edit* think I found a sound card that will do what I want and has 8 sets of RCA outs.


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## MarkZ

Neil_J said:


> The sound card on the motherboard has a high chance of sounding like crap  To be specific, in my personal experience, they have very poor noise floor performance, if you turn the gain up while listening through a pair of headphones (you may need an external headphone amp if it's only a line-out), you will likely hear lots of stuff that's not supposed to be there. To what severity depends on the exact board and how the engineer routed the traces, and to a smaller aspect, which CODEC chips they chose. Use an external sound card if at all possible, but feel free to try it out first and see exactly how bad it is.


IME, it's more to do with the hash in the power supply. Usually laptops do a better job. 

But I've had muuuuuuuuch better luck with USB sound cards, but then you run into bandwidth issues unless you use one of the few 2.0's out there.

FWIW, my USB sound card that I'm using now has one of these as its DAC.

http://www.akm.com/datasheets/ak4358_f02e.pdf

Which I believe is just the multichannel version of the DAC in the M-Audio Transit, which is a pretty respectable unit according to most people.


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## Ultimateherts

#1) Set a budget as this will help narrow down your choices greatly.

#2) Decide on Tablet vs Motherboard and separate touchscreen.

#3) Decide on what OS you want to run as this will you narrow your choices even more.

#4) Decide on Front End software, but I feel most are inferior to just plain OS and separate programs.

#5) Make sure to have more time available than a typical CD player install due to problems such as Software issues, Driver Issues, Compatability Issues ETC.


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## HiloDB1

Ultimateherts said:


> #1) Set a budget as this will help narrow down your choices greatly.
> 
> #2) Decide on Tablet vs Motherboard and separate touchscreen.
> 
> #3) Decide on what OS you want to run as this will you narrow your choices even more.
> 
> #4) Decide on Front End software, but I feel most are inferior to just plain OS and separate programs.
> 
> #5) Make sure to have more time available than a typical CD player install due to problems such as Software issues, Driver Issues, Compatability Issues ETC.


1) Budget is unlimited as long as I end up with what I want. But I wont spend money just to spend money.
2) I am going to do a mobo with touchscreen.
3) OS is one thing I havent looked much into yet. Either Win 8 or 7
4) I a very well aware of install time and possible issues. The interior is pretty much stripped as is.


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## Ultimateherts

Well considering whether or not you will go (4) way, you will need a minimum of (6) channels (8 if you go 4 way). Neil_J has gone extreme with his diy dac/processor, but not everyone can do that. As for soundcards/dac look into prosound firewire/usb audio interfaces as they will have all the inputs/outputs you will. Some even offer balanced output solutions so you can get even higher voltage. Motu, RME, and Apogee are brands I would look into first. Focusrite is the brand I will be using in my install and they offer the best bang for the buck. However, I listed the other higher end brands first since money is no object for you!


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## chad1376

Maybe something to consider when weighing internal sound card -vs- external DSP is signal runs. Right now I'm laying out my system, and everything stays in the digital realm from the PC, to DSP to DACs. I'll only have 3" of analog line level from each DAC to each amp.

A rats nest of analog outputs from a soundcard to wherever the amps are located sounds like it could be more prone to noise.


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## MarkZ

Shouldn't be any more of an issue than any HU driving an amp in the trunk.


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## chad1376

MarkZ said:


> Shouldn't be any more of an issue than any HU driving an amp in the trunk.


True, if carefully routed.

I plan on routing my single optic S/PDIF from my computer, into the engine compartment, wrap it a couple times around the alternator, spiral wrap it around a a spark plug wire, and then back to the DSP...OK, not really, just being snide


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## Hdale85

My current plans are to use a tablet or some form of android device going USB to I2S through an Xmos board, then into a SHARC DSP board (Xover, PEQ, Time alignment so on) then into a Buffalo III 8 channel dac, then into my amps and so on. I've gone the PC route once before and was never happy enough to actually put it in my car. I use my tablet with a windshield mount all the time though and am relatively happy with and I believe can be even more happy with it when I tweak the UI for car use.


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## HiloDB1

What I would like is to have full T/A, Phase, XO, and full EQ control without the need for an external processor like a Bit.10, PXA-H800, PS8, MS-8. If possible I was hoping I would be able to use some sort of software to control this and some DAC down the line to so I could run analog to my amps. Also would be nice to have 8 outputs.


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## MarkZ

Search around the forum a bit. There are a number of ways to achieve what you're trying to do. Basically, you need a VST host, a set of VST plugins, and an 8ch sound card. You had mentioned that you were concerned about the DACs that those sound cards use, so my best suggestion would be to contact the manufacturers of a few candidate sound cards, find out the DACs used, look up the data sheets, and determine whether or not they meet whatever your requirements are.


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## HiloDB1

MarkZ said:


> Search around the forum a bit. There are a number of ways to achieve what you're trying to do. Basically, you need a VST host, a set of VST plugins, and an 8ch sound card. You had mentioned that you were concerned about the DACs that those sound cards use, so my best suggestion would be to contact the manufacturers of a few candidate sound cards, find out the DACs used, look up the data sheets, and determine whether or not they meet whatever your requirements are.


Thanks Mark. I have come across a couple of cards that look good. Like the HT Omega Claro Halo XT and Asus Xonar HDAV1.3. Now just to figure out the software portion.


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## MarkZ

Also consider the 1010lt which is fairly popular for this application.

M-AUDIO - Delta 1010LT - 10-In/10-Out PCI Virtual Studio

A lot of people use either Console or Audiomulch as VST hosts (Windows). VST plugins can be found fairly easily, and that's the easy part anyway.

One alternative is to use foobar2000 as the player and processor. But it's a bit of a pain in the ass. I wrote a tutorial here a few years ago, but I don't remember where it is.


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## HiloDB1

Thanks for the heads up on the M-Audio sound card.


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## Ultimateherts

MarkZ said:


> Also consider the 1010lt which is fairly popular for this application.
> 
> M-AUDIO - Delta 1010LT - 10-In/10-Out PCI Virtual Studio
> 
> A lot of people use either Console or Audiomulch as VST hosts (Windows). VST plugins can be found fairly easily, and that's the easy part anyway.
> 
> One alternative is to use foobar2000 as the player and processor. But it's a bit of a pain in the ass. I wrote a tutorial here a few years ago, but I don't remember where it is.


Here ya go:

http://www.diymobileaudio.com/forum/how-articles-provided-our-members/82600-how-set-up-your-carpc-sound-processing-using-foobar2000.html


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## Wy2quiet

MarkZ said:


> Also consider the 1010lt which is fairly popular for this application.
> 
> M-AUDIO - Delta 1010LT - 10-In/10-Out PCI Virtual Studio
> 
> A lot of people use either Console or Audiomulch as VST hosts (Windows). VST plugins can be found fairly easily, and that's the easy part anyway.
> 
> One alternative is to use foobar2000 as the player and processor. But it's a bit of a pain in the ass. I wrote a tutorial here a few years ago, but I don't remember where it is.


This is what I run and it does the job. It stopped me from going to an ITX board though since it needs a PCI slot, NOT PCIe! take that into consideration. Was kind of annoying.


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## glack

also if you're using the 1010LT, make sure you're getting a motherboard that has *native* PCI support. this isn't always the case with newer mobos, and there are documented glitch issues. as i recall, for socket 1155 the B75 chipset mobos are the most recent of the pack to still support PCI natively. i've got a build on the bench with two 1010LT's in an asrock b75 pro3-m and they both seem happy so far.

the 1010LT (and lots of other soundcards, for that matter) also can protest with sleep/hibernate, so plan for that accordingly. i haven't had problems yet, but i haven't really tried to shake the beehive in testing yet either. with an ssd and windows 8, you should have no complaints with boot time and disabling sleep states.


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## req

i have not read this whole thread - but this rings true;



neil said:


> *once you work out the bugs*


USB stuff is a pain in the ass.
1. how it gets power? (if it does not run of the built in 5v)
2. how does it turn on? is there a physical button on it?
3. does it play nice with hibernate\sleep? (in my expierence - USB stuff almost never does)

i am using toslink digital straight out of the motherboard into my helix P-DSP and it is great, but whenever windows starts (read: windows loading screen -> desktop) windows decides to output a fullrange full amplitude signal for like 100ms over the toslink output (does not happen with analog i do not think). so i have a timer that delays the amplifier turn on until after the pc boots - its annoying, but it works. i can not find out why windows is doing this (im thinking of trying windows 8 tbh). 

also, the resolution of most "car friendly" LCD's will usually not work with;
A. most outboard DSP software (helix, rockford, alpine, arc, mosconi) - they USUALLY dont fit on the screens properly (netbooks included)
B. the interfaces were NOT MEANT FOR CHUBBY FINGERS! as far as i have used, there arent any touch screen based DSP thingies anywhere. so you better have some kind of hand held keyboard (somone linked to one once, i dont remeber where)

carPC's are a pain in the ass.


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## MarkZ

req said:


> USB stuff is a pain in the ass.
> 1. how it gets power? (if it does not run of the built in 5v)
> 2. how does it turn on? is there a physical button on it?
> 3. does it play nice with hibernate\sleep? (in my expierence - USB stuff almost never does)


All valid concerns. But FWIW, it's not uncommon to see multichannel bus-powered USB sound devices... that satisfies #1 and #2. And I agree with glack that sleep/hibernate isn't really necessary for most car PC builds, especially if you use a stripped OS or an SSD. If your boot time is under ~15-20s, it's hard to justify screwing around with sleep IMO.



> B. the interfaces were NOT MEANT FOR CHUBBY FINGERS! as far as i have used, there arent any touch screen based DSP thingies anywhere. so you better have some kind of hand held keyboard (somone linked to one once, i dont remeber where)
> 
> carPC's are a pain in the ass.


Voxengo's VST plugins FTW!


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## Neil_J

req said:


> USB stuff is a pain in the ass.
> 1. how it gets power? (if it does not run of the built in 5v)
> 2. how does it turn on? is there a physical button on it?
> 3. does it play nice with hibernate\sleep? (in my expierence - USB stuff almost never does)


So true. Those are exactly the same problems I've ran into. I've almost got them mitigated, but my god have they been annoying. I'd also add, if the USB device gets unplugged, it might reset the sample rate to something crazy.



> also, the resolution of most "car friendly" LCD's will usually not work with;
> A. most outboard DSP software (helix, rockford, alpine, arc, mosconi) - they USUALLY dont fit on the screens properly (netbooks included)
> B. the interfaces were NOT MEANT FOR CHUBBY FINGERS! as far as i have used, there arent any touch screen based DSP thingies anywhere. so you better have some kind of hand held keyboard (somone linked to one once, i dont remeber where)


Luckily, Room Eq Wizard looks alright on my touchscreen. Im using the apple bluetooth trackpad for tuning as the touchscreen obviously is useless. It does have great hotkey support though so certain things could be scripted. They do have a few supported DSPs that will automatically upload the eq curves and such to the device. I really wish they would add more devices like the 6to8 and others.


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## MCiN7

HiloDB1 said:


> What I would like is to have full T/A, Phase, XO, and full EQ control without the need for an external processor like a Bit.10, PXA-H800, PS8, MS-8. If possible I was hoping I would be able to use some sort of software to control this and some DAC down the line to so I could run analog to my amps. Also would be nice to have 8 outputs.


Hey mate,

I use Audiomulch (it is pricey but you are getting a 'processor') along with 2x Asus Xonar D1's (the reason for 2x is because when using some decent stereo - rca cables you can only fit 1 cable per 2 outputs).

If you decide to use Audiomulch - Google "How To: Basic setup in AudioMulch"

I use these VST's;
RS-MET CrossOver - self explanatory
RS-MET EasyQ - perfect for tuning peaks after an RTA
KarmaFX Filter - setting cutoffs (KarmaFX also have a 31 band EQ that you can change between full, high, mid or low ranges)
SDelay (comes with Audiomulch) - setting delays

Hope this helps!


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## Ultimateherts

Neil_J said:


> I'd also add, if the USB device gets unplugged, it might reset the sample rate to something crazy.


Then you need a USB lock:

LUSBA11100 Amphenol Commercial Products | Mouser


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## audioperv

another option is equalizer apo very nice hacks your soundcard

Equalizer APO | Free software downloads at SourceForge.net


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## ZeblodS

Neil_J said:


> The sky is the limit. You can truly do just about anything and approach the limit of perfection with a CarPC. However, the complexity and cost can be very prohibitive as you start chasing that last fractions of a percent of THD and jitter performance. I have gone down this road myself, and I will tell you, put your time and energy into acoustics, not processing, if you want to have a good sounding car. The DSP processing and DAC performance in my CarPC beats the specs of any commercial car audio processor. It took almost a year and a ton of money, and it still sounds like crap compared to simple installs I've heard. Processing is not a band aid for good acoustics, is what I'm basically trying to say.


I think acoustics (mounting?) and processing are both equally important.
The processing isn't about "percent of THD and jitter performance", but correcting material and placement limitation, in order to have the smoothest gain response and no phase (with group delay) issues at the listening point, usually the driver seat.

For my setup, I chose to use an external DSP, based on a miniDSP 2x8 card with an isolated power supply and optical input, in order to avoid all interferences and noises I couldn't get rid of with the use of internal or USB sound cards.
So I use this DSP to manage each speaker with biquad corrections (crossover and EQ, simulated with REW and mic measures of each speaker), delay and level.
And I use FIR convolutions on the computer to deal with phase corrections (global left vs. global right) and phase linearization (getting rid of all group delay induce by IIR corrections of the DSP ).

If "it still sounds like crap compared to simple installs", you probably did wrong somewhere on the tuning and/or the mounting. If the speakers are mounted on solid bracket without acoutics interference and with enought rattle damping of the door, your problem is the tuning.


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