audio over USB v. optical

**durwood** · 02-14-2007, 07:33 AM

Sorry haven't found any more info. I'm still researching some things. I'm still here in the background. Once I find something useful I'll post it up.

Don't worry you are not alone.

**durwood** · 02-14-2007, 07:41 AM

Here is a 8 Channel USB DAC chip by C-Media (CM106). Specs are not as promising though. The output would have to be run through a gain circuit to increase the output. That's to be expected though, there will not be a single chip to handle an large ouput voltage by itself.

http://www.cmedia.com.tw/?q=en/USB/CM106

**durwood** · 02-14-2007, 08:04 AM

Here is a crude block diagram for those who don't understand and need a picture

The USB interface has to be able to distinguish more than 2 channels, as many as 10 should show up in a routing program such as Console.

I think the bottom block diagram is what we are trying to do, unless someone can find a USB chip that can support more than 2 audio channels. The C-media chip I posted in the last post fits that bottom block diagram.

**RedGTiVR6** · 02-14-2007, 08:14 AM

that's pretty much it!

Again, once it's all figured out, we can go to other options, but for now, for an initial purpose, the simple start is needed.

**JasonWW** · 02-14-2007, 08:31 AM

Another slightly off topic question. What is the purpose of this, say over the H701?
Do you hope to extract a higher quality output to feed the amps or is it mainly more user control?
Do you hope to get a higher S/N ratio or more dynamics or do you think the H701 is lacking in certian areas?

You can PM me if you think it's too off topic. Then I'll delete this post.

**RedGTiVR6** · 02-14-2007, 08:36 AM

higher quality output
tuning via PC and not via an outboard processor
no need to mount a seperate controller

the 701 is not a bad piece, but it's not necessarially an option for everyone. in the future, it's not going to be a viable solution for CarPCs either as I feel it leaves a lot to be desired.

**JasonWW** · 02-14-2007, 08:39 AM

How much higher quality of output can you get? Enough to be noticable?

**durwood** · 02-14-2007, 09:17 AM

Yes. Most recordings are done via computer and high quality equipment. The less hardware in the loop and the more that is done via software, the better the signal is left intact. The less components the signal has to travel through, the less loss there is.

The H701 is a nice piece, more than most people would know what to do with. But then Alpine has the F1. Alpine wouldn't have made the F1 if they didn't feel the h701 was top notch. The H701 is VERY nice, easy to use, sounds great. But it can sound better. We have a computers in our cars, they can do unlimited signal processing combinations as long as the computer can keep up. If the software is programmed correcty, then it should be able to compensate for alterations to the signal.

Within the next few weeks my new PC with software processing is going into the car. The soundcard has upgraded opamps. I am going to put it head to head against the H701 and see what I come up with. I can't wait to see how a linear phase crossover sounds.

**RedGTiVR6** · 02-14-2007, 09:33 AM

Originally Posted by JasonWW

How much higher quality of output can you get? Enough to be noticable?

absolutely.

why would they have the F#1 processor if it's not any better?

**RedGTiVR6** · 02-14-2007, 09:35 AM

Originally Posted by durwood

Within the next few weeks my new PC with software processing is going into the car. The soundcard has upgraded opamps. I am going to put it head to head against the H701 and see what I come up with. I can't wait to see how a linear phase crossover sounds.

I'll be doing the exact same thing.

I've heard from others who have done something similar to this that have had the F#1 processors as well. They have said that the fidelity was way above and beyond the F#1 even.