can a carputer compete with a head unit for sound quality? - Page 9

SickVette · 05-30-2005, 08:55 PM

Good explanation turbocad. I am trying to determine if I want to use head unit and computer or computer alone. I am still undecided but am getting close.

JasonWW · 11-24-2005, 01:10 PM

Good thread guys even if it did go off topic a few times.

Earlier in this thread it seemed there were some different ideas thrown around about how these PC systems can be used. Talk was made about using "enhancements" in the PC to improve sound quality.

I think we needed to seperate using a PC as a source and then using a PC to do "enhancements" like time alignment, cross overs, EQ, etc...

Some people don't have a high end sytem and want to use the PC for all of that. I don't think the hardware or software exists for that yet. In this instance a PC would not be equal to a head unit.

The Alpine processor that Red, and others, are using is basically a computer in itself. The PC and sound card are simply creating a digital sound output (optical or coaxial, doesn't matter) which can be of very high quality as there are no analog parts being used (basically). Even some mobo's have digital sound outputs built in.

The computer in the Alpine takes the digital signal and does all the processing, including EQ, time alignment, etc... and then uses it DAC's to output an analog signal that the amps will recognize. That's certainly a good way to do it, but requires all new equipment, usually. Now this setup can be better than a head unit as Red has shown in competition.

The non audiophiles get by on basic analog sound cards as the sound is pretty decent and they are not too picky. In this instance, a PC and basic sound card would not measure up to a head unit.

I seem to fall in a different category as I already have a complete high end sound system which has a digital pre-amp, digital 28 band EQ, and digital x-overs using the Rockford EPX2. What I want to do is use the computer to replace the traditional head unit as the music source. So I need just a pure, clean output with no added processing or sound enhancements at all. Pretty much a straight in and out source. I think a PC with a professional audio card will get the job done and this setup will equal or better a head unit.

So far what I have found is a cheap sound card, the Chaintech AV-710 for around $25-$30. It uses a mediocre 6 channel processor, but since it is a 7.1 card the 2 additional channels use a high quality Wolfson 2 channel DAC that can handle a high sample rate, capable of a much more robust 192KHz, and full 24 bit resolution. These 2 channels can be configured to act as the main outs and provide a very high quality stereo output for little money. If other people are looking for a cheap but fairly high quality sound card for their car PC, then this is worth taking a look at.
http://www.sudhian.com/showdocs.cfm?aid=654

http://www6.head-fi.org/forums/showt...ht=av710+setup

In a higher price range is the ESI Juli@ (julia). It runs about $140. You can read about it here:
http://www.digit-life.com/articles2/esi-julia/

From everything I've read, it surpases the M-Audio Revolution cards for sound quality and specs. This is the card I may go with to get the high quality sound that my CD player currently provides.

For those that don't understand bit rates and sampling rates here's a nice little explanation that makes a lot of sense:
http://www.neoseeker.com/Articles/Ha...echomia/2.html

jbors · 11-24-2005, 02:35 PM

Why don't you just use digital output from PC then ? Why do you need analog sound card ?

JasonWW · 11-24-2005, 03:21 PM

In my case I mentioned I use a regular CD player as a source, I need something to replace it. So the PC would need to have an analog output, just like a CD player would.

Back when the EPX2 was made in the mid 90's there were no head units that had digital outputs. There may have been one or two, but they were rare and very expensive. So it made no sense to have digital inputs.

It does have balanced inputs designed to work with Rockfords Balanced Line Transmiter, but you can't find those anymore. The Juli@ card I'm looking at has balanced outputs, so I contacted Rockford yesterday to see what type of voltages it accepts. The balanced outputs are like regular RCA analog but the signal is flipped 180* and the 2 signals travel together. At the other end they run through a differential filter which rejects any noise it has picked up and the 2 signals are rejoined. You get twice the voltage. Typically balanced outputs run 8-16 volts which means I'll have plenty of juice to run my gear as well as no induced noise getting into the signal cables. The regular RCA's are capable of tremendous sound quality, so they would be fine. If I could use the balance connectors, that would be even better.

You do bring up a good point. I wonder if I could bypass the ADC in the front of the EPX, but I don't know enough about it. It would be nice if I could avoid the digital/analog conversion at the audio card and then the analog/digital conversion at the EPX, but I don't know if it is possible. Probably the only guy to know would be Wayne Harris, who invented the EPX2.

Here's a bit of info on the unit:
http://www.androselectronics.com.cy/...processors.php
I also have the 28 band EQ add in card.

For those interested, I believe this was one of the first all computerized sound systems in a car. Way back in 91 the original Symmetry came out:
http://www.termpro.com/articles/symmetry1.html
I remember it just blew everone away. Things sure have changed.

turbocad6 · 11-24-2005, 03:38 PM

I use m-audio transit w/ optical out, into the alpine pxa-h701...... sound quality is awsome.... sometimes I think I can discern a difference between a high quality cd in the head(alpine iva-d300, also optical to pxa-h701) compared to same ripped to pc.... other times I sware there is no difference....

bottom line is, if there is any difference it is negligable at best... & even side by side comparison is very hard to hear any difference at all.... unless you start ripping at like 128 or less that is.... from 192 up it gets real hard to tell a difference.....

turbocad6 · 11-24-2005, 03:48 PM

I had the rf symetry when it came out, swore by it for years.... then went to a audiocontrol digital.... forgot what it was called (dqx maybe?) it wasn't so hot..... Then the alpine 700..... the alpine is an amazing piece... it is comparable to the top of the line f1 status processor & a fraction of the cost.... anyone who is remotely serious about there sound should really consider this piece.... there is NOTHING on the market that comes close.....

JasonWW · 11-24-2005, 03:52 PM

It's bad enough I have to buy a whole new computer as well as a screen and PSU, so I definetely didn't want to replace my EPX2. I'm a poor boy.

Just out of curiousity, what would be the cheapest I could get that Alpine setup?
I saw some new ones for $300 on e-bay. The controller was another $200. I guess you have to have that, so maybe $500?

I might be able to sell my EPX2, save the expense of getting a $140 audio card (use the SPDIF out on the mobo) so maybe it wouldn't cost that much more.

Does it have any type of interface with the PC? For instance, it would be nice to adjust those EQ bands on the PC monitor instead of that little controller.

RedGTiVR6 · 11-27-2005, 08:43 AM

no way to controll it on the PC - honnestly - the contriller is pretty intuitive, using the touch screen isn't really all that easy for doing stuff much more than hitting play - I wouldn't want to control volume or the EQ settings on the touch screen. It's pretty difficult compared to the little knob on the controller for the alpine - sure, it may look cool to do eveything on the screen, but I can't imagine trying to mess with that stuff while on the road....

$500 sounds about right for the alpine piece.

when you say SPDIF from the mobo - are you meaning toslink or digital RCA?

because the alpine can ONLY take a tos-link in (as well as analog RCA) NOT digital RCA....

turbocad6 · 11-27-2005, 10:41 AM

when you consider all the alpine does, $500 seems like a steal.....

after all, it's the equeivelent of a dolby 5.1 processor AND 5 seperate eqt's.... one for each channel.... add to that 6 user defined pre-sets that are in non-volitle memory(the rf SUCKED BIG TIME THERE, disconnect the battery & hours of tuning down the drain!)... add to this another 1/3 octave eq for the subs in there usable bands.... add to that the time alignment features.... which are great to "center" the bass & align the phaze perfectly to the front stage.....

now add to that one of the best x-over setups out there... with full graphical control of x-over freq, as well as slope curves for EACH driver... the pxa-h700/701 replaces half a trunk of high end equiptment... it's a no brainer really..... BUT I also think it is absolutely necissary to have access to an RTA, at least for initial base line set-up to really take advantage of the 1/3 octave eq...

the alpine is an amazing piece.... to me it's worth at least 3-4 times what it costs .... & will make any system that much better for using it.....

the epx2 is still worth something on ebay.... & when you use the alpine to replace it, it's like going from pong to half life... I mean it's that dramatic of a difference.... the rf symetry was an amazing piece when it came out, but were talking over 10-15 years of evolution past it at this point... if you love music & love to tweek... & know how to use it, or even are willing to learn.... the alpine is a MUST HAVE!!! there is nothing else quite like it except for alpines pxa-h900(I think that's the model #?), which is over 3 grand... f1 status stuff..... belive it or not, the 700 is really close to it in function... but doesn't alow parametric & graphic at the same time, among a few other things...

RedGTiVR6 · 11-27-2005, 02:19 PM

tuning without an RTA is definately possible - just have to know what you're doing.....which is why I took my car to someone to have it tuned...because I couldn't come close to what this guy was able to do....lol

JasonWW · 11-27-2005, 03:58 PM

I was able to pick up the Chaintech AV710 that I mentioned locally. I'm going to try it out in the next few days and see how it compares.

Good to know about the Alpine only accepting the optical inputs. BTW, the digital RCA connector is called digital coaxial. It looks like an RCA and uses the same 75ohm cable, but it's not called a digital RCA.

Does the pxa-h701 have an optional wireless infrared remote? I need one in order to control volume, etc... from the steering wheel. It would suck if I can't control the basics through the wheel.

Do you have the computer setup to have 2 channel digital sound sent out the optical line or do you have it send out all 6 channels and then have the Alpine convert it into 2 channel sound? I'm assuming all the people using the pxa-h701 run a basic stereo sytem (no surround sound) and have the 2 channels then run through the x-over and EQ circuits to provide the 6 RCA outs. You know, 2 channels (maybe summed to mono) for the sub, 2 channels for the mids and 2 channels for the tweets. Unless you are using a passive x-over for the mids and tweets in which case you would only be using 4 RCA outs.

Is the computer really reduced to a "play" button? That seems like a waste. I guess you still use the PC to store the MP3's and for video's and such, huh?

What program are you using to play the music, Winamp or something like Foobar2000?
As I've learned more it just gets more complicated. It seems like a lot of sound through XP or WN2K automatically gets resampled and you need to turn off Windows sound and to use a player like Foobar2000 along with some special drivers to bypass the resampling and send a higher quality output through the optical cable. It all seems pretty confusing. Any of you guys know anything about that? Cause if you are getting real high quality sound through Winamp for instance, it sure would be nice to know.

RedGTiVR6 · 11-27-2005, 04:27 PM

yes - the digital RCA is the same - but it's also called SPDIF - SPDIF can stand for Digital RCA as well as Tos-link - that's why I try to make sure what the individual is talking about when they mention SPDIF

i'm only running 2 channel period, nothing to do with 5.1, no point IMO

as for only being reduced to a play button - it's reduced to to just about everything a regular headunit does - track forward, back, pause, lay, stop, etc

in my specific situation - I wanted something that was seamlesly integrated, and having a computer that did too much stuff would impede on that

i'm using winamp, simply because it's simple, easy to use and, well, yeah...it worked for me at world finals, so I would think it should be fine

JasonWW · 11-27-2005, 04:58 PM

In case anyone wants to know:

S/PDIF (Sony/Philips Digital Interface) is a standard digital audio transfer file format. There are 2 ways to transfer that data. Digital coaxial and Toslink.

The coaxial is basically an RCA connector and the data is sent through it digitally.

The Toslink optical signals have exactly the same format as the electrical S/PDIF signals, they are just converted to light signals (light on/off).

So SPDIF is the digital format
Coaxial or Toslink is the transmission method

Hey Red, during the Iasca judging, you have to play their CD. Did you use a CD or DVD ROM that used a digital output or just a regular CD or DVD ROM and used the regular IDE cable? I'm guessing you used all regular parts, but I just wanted to make sure.

Also, in your case, did you know you might be able to get even better sound quality using a player like Foobar2000 and setting it up properly? You may be satisfied with using Winamp, but it doesn't have the best output. It's only software, couldn't hurt to try it out, huh?

Anyone know about a wireless infrared remote for the Alpine controller? I can't find any info. Reviews of the pxa-h701 are also hard to find as well. If anyone has any links saved on their computer, can you post them?

RedGTiVR6 · 11-27-2005, 05:40 PM

I don't compete in IASCA - but it's the same with USACi - you MUST listen to a CD - the CD/DVD-rom that I'm using goes through a USB cable - it's a regular laptop drive housed in an external USB case

the alpine doesn't have any kind of port for a remote to run it at all.....

it use to be called the PXA-H700, might have better luck finding reviews on that - this year it's the 701 and the display is sold seperately (before it was sold as a complete unit - some current radios have the ability to controll the processor is why they did this). There were a few changes made betweent he 700 and the 701, but not anything that I can think off of the top of my head that would make a difference....

I'm sure there are differnt players that will give me better results, but I'm of the mind right now that since it's working, I'm not going to mess with it....lol

btw - wilson adcock seemed to think that it was perfectly fine, and if he said it's fine....hehehe

JasonWW · 11-27-2005, 05:49 PM

I was thinking the controller may have an IR reciever on it.