I have provided the pic coder with all my requirements, and have paid a deposit on the code. It will use a small lcd display as of now a 15x2 character green backlit display to match the face of the dcx. It will use twin rotary encoders, one for volume, one for source selection. The volume rotarty will be a dual function, so you can mute by pressing the decoder in like a button. Also, the microcontroller board will have and additional plug for you to run rocker switches for volume and source selection for custom steering wheel mounts, or external controls for competition. The unit will also be controllably via remote using the sony ir codes. The following buttons/functions will be enabled:
Channel up/down (next/previous source)
1,2,3,4,5,6,7 (source direct access)
Mute (unfortunately the micro we will be using for ir control does not natively support the sony mute code, so it will be assigned to button number "0")
The display will always show what input is selected in the top line of the display, and the volume level or mute status will be shown in the second line.
The rotary encoders, ir sensor, and/or rocker switches will all be remote mountable, and attaced to the micro board by cat 5 cable and rj45 connectors, so you can easily make cables as long as you want, for custom installations. A wiring diagram will be provided for maximum noise rejection.
Final details on the digital input section are as follows:
3 optical inputs
3 coaxial inputs
1 AES/EBU input
It will also still retain 3 analog-multipurpose inputs.
The volume control chip has been set in stone now, and it is the wolfson wm8816 chip being used in the new marantz reference gear. It is by far the most superior volume controller out there, and it has no internal opamps to color the sound. I have setup the board to use the burr brown op2227, but they will be socketed for use with any dip-8 dual opamp package.
The power supply has been the biggest challenge of this project. I simply have not found a cost effective isolated method. The only real answer is a SMPS similar to that of what behringer used in the firstplace. However, smps design is a long, difficult, and dangerous process that i honestly dont have the time or the skills to undertake at this time. I am going to recomend Rob's power supply. I have built one, and it functions flawlessly with this exception: garbage in = garbage out. If you have dirty power/ground in your car, it will show. To solve this problem, i suggest using an isolated 12v dc-dc converter, such as those offered by Cosel. I will be supplying an isolated upgraded power supply, but it will be expensive. It will be fully isolated, and the bipolar section will be seperated and adjustable so you can crank up the voltage to the opamps over 20v if you want higher voltage outputs. I know what my costs are on this piece, as i have already built 2, and this "premium" supply will be over $150, but less than $200. I havent decided what to charger for it to help cover the development costs. The "Rob M" supply, can be built DIY for under $60, and with his permission, i will be offering bare boards, and assmebled units.
As far as the physical form factors of the board, all the upgrade boards stack ontop of the DSP board inside. There will be a total of 3 boards: 2 full size that will stack, and a thin board that will hold all the digital inputs, and interface ports. All the outputs will be left bare on the board. The board will have a phoenex style screw terminal, so you can install any pannel mount connectors you want. I will have a good supply of neutrik connectors here, and will install or supply them with the unit. If you want a different connector, you can send them to me and i will install them, or it will be an very simple installation for you to do at home. Using the onboard screw terminals will let you change out your jacks at anytime you want. This will also let people using balanced amps to install the correct connector for that amp, so no adapter cable is necesary, or mix and match outputs for different amps/processors.
I have not started on the custom cases yet. I need to get all the boards back from the board house, put them through some rigorous testing, and make sure there will be no changes needed. Then i will need to measure all the common jacks that people may want to use, and design the case around them. As it is now, the foot print will be VERY small, probably 7"X4" with a height around 4", or i may lay the boards out horizontaly instead of verticaly, and have a 14"x4" chassis, about 2" tall.
I will post when i have the first version of the micro code back.