# How to add digital outs to HU for $6



## SQMaxima

Figured I would pass on what I have learned about adding a Toslink optic digital output to a HU and yes it really will cost you less then $7. I have done this twice now and it works like a charm. If you have queations or comments please feel free to post them. Sorry for the blurry pics, my cam. such for closeup pictures.

Here you go - My Website 

Also, dont anyone know a way to be able to select from more then just two sources using an AI-Net headunit using a 701. Let me know PLEASE.

Rick


----------



## geo1317

Great find and writeup.  

off to digikey to buy some parts and see if i can get this to work for on my 9833.

i got this fron another forum


> In europe, the PXA-H701 is identical to pxa-h700. If you have a AINET HU and you connect pxa in AINET mode (not stand alone mode), this is the behaviour:
> SOURCE: CD ->pxa chose input through ainet cable N°1 or optical input N°1. If pxa feels optical 1 input, automatically switch from AINET analog signal to optical signal.
> SOURCE: CHANGER (only if a AINET changer is connected) ->pxa chose input through ainet cable N°2 or optical input N°2. If pxa feels optical 2 input, automatically switch from AINET analog signal to optical signal.
> SOURCE: TUNER ->pxa chose input through ainet cable N°1 or optical input N°3. If pxa feels optical 3 input, automatically switch from AINET analog signal to optical signal.
> SOURCE: AUX (you need a HU with AUX mode option)->pxa chose analog input through RCA inputs.
> Volume, balance, fader, subw level are all controlled by HU. After installation you can disconnect RUX and use only HU+PXA
> 
> IN STAND ALONE MODE instead you choose every input manually and Volume, balance, fader, subw level are all controlled by RUX


----------



## chuyler1

Wow...I wonder if I could acomplish this with my stock head unit. 

I've got a question though, do you only get digital output only when listening to CDs or will the radio signal pass through the digital interface also? Or is that something that depends on the head unit and implimentation?


----------



## chad

Only with CD.


----------



## geo1317

chuyler1 said:


> Wow...I wonder if I could acomplish this with my stock head unit.
> 
> I've got a question though, do you only get digital output only when listening to CDs or will the radio signal pass through the digital interface also? Or is that something that depends on the head unit and implimentation?


i would think if the head unit has a ADC it would, but most dont, so you only get the CD to play over the digital output.

PS: the parts are on their way from digikey.


----------



## solacedagony

What exactly are the benefits/disadvantages to using a digital output?


----------



## MarkZ

solacedagony said:


> What exactly are the benefits/disadvantages to using a digital output?


Ground loops are often reduced. You bypass the DAC of the HU in favor of an outboard DAC, which some claim provide an audible improvement. You can use external digital processing equipment without the added analog->digital conversion.

Drawbacks are the FM radio thing. Also, optical cables can be fragile, so care must be used when running them through your car.


----------



## chuyler1

MarkZ hit the nail on the head. I'm actually using an optical connection in my car right now...but I'm not crazy about the look of the aftermarket head unit. I love the red-orange glow of the stock cd player but it's SQ ain't great even after I hacked it open to put RCA outputs on the main board before the amp chip. Perhaps when I get some more funding I'll find a processor that will accept analog and digital inputs and only requires a volume knob to be installed on the dash.

Hey, here's a thought. Could you do the reverse with a digital processor (for example the RF 360 or the AudioControl DQX) to create optical input where there wasn't one originally? That'd be sweet!


----------



## SQMaxima

> If you have a AINET HU and you connect pxa in AINET mode (not stand alone mode), this is the behaviour:
> SOURCE: CD ->pxa chose input through ainet cable N°1 or optical input N°1. If pxa feels optical 1 input, automatically switch from AINET analog signal to optical signal.


I sure wish that was true but from what I have found out its not. I have tried it with my modded Alpine with no luck. It will not switch to digital. Now in my girlfriends car she have the Alpine w200 running digital outs to a 701 and once you inable the digital out from the setup menu it works fine. But if you unplug the digital outs it does not switch back to anolog. I am about 95% sure the AI-Net coming from the HU tells the 701 weather our not the unit has a digital out.....in stock form anyways.



> Wow...I wonder if I could acomplish this with my stock head unit.


Sure it could. All audio CD and DVD transport have the right signal for the Toslink somewhere in there circuit. Its all a matter of finding it. That would be super stealth to be using a stock HU with digital outs to a nice pro. and equipment. As stated you would still need analog for radio.



> Hey, here's a thought. Could you do the reverse with a digital processor (for example the RF 360 or the AudioControl DQX) to create optical input where there wasn't one originally? That'd be sweet!


I am sure you could. The Toslink RX is about as simple as the TX to hook up once you find the right signal path. My queation would be why when you have prossecors like Alpines 701 that has way more options and inout, both digital and analog.


----------



## chuyler1

Well doesn't the Alpine require a full din unit up front to control the volume? I'm really looking for a solution that will make everything look stock (except maybe a single volume knob that I could integrate into the cigarette lighter or something).


----------



## geo1317

well no luck finding the DOUT pin or any chip that has a CP-1201 signal. I do have a DSP chip but thats it. anything else i can look for?

http://www.ortodoxism.ro/datasheets2/c/0guli5r7d5r4xp7sh0u93pkkrhky.pdf

here is what the board looks like:


----------



## SQMaxima

Hmmm. not sure at first glance that is the chip you need. Whats the chip at the top right on the board? The top left looks like a servo driver that controls the motors for spinning the cd plater and the lazer adjustment. Is there anything on the other side of that board?

Let me know, its got to be there somewhere.

Rick


----------



## geo1317

SQMaxima said:


> Hmmm. not sure at first glance that is the chip you need. Whats the chip at the top right on the board? The top left looks like a servo driver that controls the motors for spinning the cd plater and the lazer adjustment. Is there anything on the other side of that board?
> 
> Let me know, its got to be there somewhere.
> 
> Rick


the top right i could not find info on and the the back there is one Panasonic chip and again there was no info on it. i dont have access to the chip numbers at work, I have them at home.

Also i think Alpine can plug into that black socket on the bottom left to test the unit, so there might be a way to get the signal from there. Is there any way i can test for it?


----------



## SQMaxima

OK, let see if we can work toegether to find the DOUT. If you would can you post the chip numbers/letters. I might have a datasheet for then around here somewhere on my computer. Also be sure to check around on both boards for a point labeled "DOUT". I have seen it both on the transport board and the main board so be sure to check on both.

Once I get the IC numbers hopefully we can find the right point for you.

We will beat this thing, LOL

Rick


----------



## chuyler1

(threadjack)
I was browsing the rest of your site Rick...Nice job by you and your girlfriend on the Mustang. I saw it at SBN and was very impressed with the attention to detail on the doors. I wouldn't have guessed that it was a one man / one woman job.
(/threadjack)


----------



## geo1317

SQMaxima said:


> OK, let see if we can work toegether to find the DOUT. If you would can you post the chip numbers/letters. I might have a datasheet for then around here somewhere on my computer. Also be sure to check around on both boards for a point labeled "DOUT". I have seen it both on the transport board and the main board so be sure to check on both.
> 
> Once I get the IC numbers hopefully we can find the right point for you.
> 
> We will beat this thing, LOL
> 
> Rick


Let see.

This is what i found on the Alpine CDA-9833.

These are all chips on the two boards:

Texas Intrusment
DSP
TMS	160A
320VC5416PGE
CC-39A4LLW

BA5984FP
404	T43

29DL800BA-90PFTN
0352	F76S

AN2200A

PANASONIC
MN---7482WB
(They used a marker and i can read the rest)

M16C
M30626FHPGP
348A1A1

BA6219BFP
351	H47

ALPINE
51T355S2Y03
350C89V

These are marked points on the transport board:
ROUT
LOUT
SGND
NRFDET
ARF
LD


----------



## notacop

I am wondering if this can work on the Sirius ALP1 tuner. I know the guys at mp3car have an addon board that gives Optical out as well as serial control, I do not need the serial control though. Here is the link to their page: http://www.mp3car.com/store/product_info.php?products_id=209

When you add optical outs to a 9835 do mp3 encoded cd's come out the optical or only analog cd's?

Also is there a way to add this to an ipod?


i am planning on getting an alpine h701 and the sources I use currently are:
CD through 9835
MP3 CD through 9835
Sirius Sat Radio through 9835 by way of SIR ALP1 tuner
Ipod throgh 9835 by way of KCA-420i


I am trying to find the best way to still have access to all these sources while using the h701.


----------



## illnastyimpreza

what are the benefits of using full digital fiber optic cables instead of RCA's??


----------



## chuyler1

First off, you do not get electromagnetic interference with an optical cable. But the real benefit is not having a D/A converter, followed by a A/D converter, followed by yet another D/A converter. So when you have a processor with optical input, it is best to make use of it.


----------



## hc_TK

Is it possible to put optical out on my Alpine 9853? It took such a long time to load the How to page, so i didnt read it all..


----------



## crabbdaddy

SQMaxima said:


> Figured I would pass on what I have learned about adding a Toslink optic digital output to a HU and yes it really will cost you less then $7. I have done this twice now and it works like a charm. If you have queations or comments please feel free to post them. Sorry for the blurry pics, my cam. such for closeup pictures.
> 
> Here you go - My Website
> 
> Also, dont anyone know a way to be able to select from more then just two sources using an AI-Net headunit using a 701. Let me know PLEASE.
> 
> Rick



great install on the mustang convert on your website!! good info all the way around in this thread.. .cant wait to see the finished product on the mustang.


----------



## didlybopper

You wouldn't happen to know if there is an equally easy way to add a coax digital out would you?


----------



## GlasSman

Coax is a better choice even if you just look at the durability factor when running a cable through a car. The problem is finding processors that have coax inputs. But if you could add an input to a processor then I guess that wouldn't be a problem. It always baffled me why Toslink was chosen for car audio equipment while both Toslink and Coax are offered for home audio.


----------



## chad

GlasSman said:


> It always baffled me why Toslink was chosen for car audio equipment while both Toslink and Coax are offered for home audio.



Because glass does not conduct electricity and eliminates grounding issues. Coax does not offer this.

Chad


----------



## didlybopper

I have the processor. It is a DEQX. I need the input to it. I am thinking of just getting a HU with a coax out.


----------



## ATB

If you use an alpine unit with a digital out and AI-net (W200, 9861), can you select one of the other digtial inputs? If somehad wanted to use a carputer as an additional input, for exmple?

Have you attempted a digital out mod on your riocar?



SQMaxima said:


> I sure wish that was true but from what I have found out its not. I have tried it with my modded Alpine with no luck. It will not switch to digital. Now in my girlfriends car she have the Alpine w200 running digital outs to a 701 and once you inable the digital out from the setup menu it works fine. But if you unplug the digital outs it does not switch back to anolog. I am about 95% sure the AI-Net coming from the HU tells the 701 weather our not the unit has a digital out.....in stock form anyways.


----------



## nubz69

I know I am bringing this back from the dead but has anyone else done this mod and made it work? If so could you give us some details?


----------



## JayinMI

OK...another long lost bump.

When I originally read the "How_to" it called for parts that are now obsolete.
I have some points on the board of my radio that I can grab digital signal at, and from what I have been reading, should work when used with a Toslink Transmitter...but they are available with different speed ratings (12.9mbps and 16mpbs for instance)....Will the 12.9 be fast enough or is the faster part required?

Jay


----------



## TheBlindMan

I plan to install the factory head unit back on the 2001 GM truck. I also plan to get iSimple iPod integration unit which plugs into the head units CD changer port, so if I were to do this mod on the head unit, would digital out work for the iPod aswell? Processor in mind is the PS8 or 3Sixty.3, but leaning more towards the PS8.

So if I were to do this mod, would I be able to use the volume control on the factory head unit, that's what I would prefer...


----------



## andre#4

Did anyone have the foresight to save the info that is now unavailable due to the original site being dead? (referring to the link in the first post of this thread which used to have a wonderful instructions for making digital out on a head unit)

I thought I had saved it, but I can't find it now. I was gonna save $700 by putting optical out in my new alpine nav unit. Now I have to buy a 2 year old unit to get the optical out and ainet. I would have sent my unit back, except that I had found this article. Now, I can't send it back cause it's too late, and I cant do the optical out now because the article is gone.

Thanks a lot if any one has it.


----------



## tx4wl

bump im curios as well


----------



## tijuana_no

x3 here also


----------



## Mrimstad

x4 Someone must still sit on this info?


----------



## thehatedguy

Internet Archive?


----------



## Thumper26

thehatedguy said:


> Internet Archive?


that was my first thought too. I checked, and while his site has a few entries logged around the time of the initial post, all I can get to pull up is the quick links he had at the top of his page. From the way it's laid out, I think he used host provided creator, and all of the content was wiped when he stopped paying for the domain.

Sucks too, because I remember reading this back in the day and never got around to trying it.


----------



## Mrimstad

How to add digital output to any headunit for $6 [Archive] - Hybrid Audio Technologies Forum

Found this after some searching, doesnt have any pics but the process is preaty easy if you follow trough.


----------

