< Picture: display pcb with microcontroller and IR remote receiver (Yes dear, it will be mounted upside down...). The bezel for the memory card slot on the DCX front panel is removed. A red Plexiglass window is glued in and the display is mounted behind that window.
System architecture
The heart of the system is an multi-channel level control chip, the CS3318. This is a truly remarkable chip. Designed for automating studio consoles, it has 8 analog channels, each of which can be controlled in 0.25dB steps from +22dB to -96dB, with -112dB THD.
As you see below, the CS3318 actually has 8 channels (all things digital come in powers of two). For the DCX2496 6 channels are needed to control the output to the stereo 3-way system. The two remaining channels are used to set the level for the A and B analog inputs. That means that if you use analog rather than digital inputs, you can leave the DCX input level control at 0dB and set the input level with my unit to just below clipping.
[Shortcut to the Construction Guide]
[Shortcut to the User Guide] [XXL Stuffing Guide]
Technology glimpse: Jeff Rowland Design Group have been using the predecessor of the CS3318 (the CS3310) in some of their products. They offer some background on the technology that allows these chips to reach the -120dB THD level. Interesting (technical) read.
The CS3318 is a single ended unit. The DCX2496 however puts out 6 balanced signals from three balanced stereo DACs. I convert each balanced signal to single ended before going into the CS3318. That cancels some of the remaining differential distortion and also gets rid of the +2.5VDC the outputs of the DACs are riding on. The output XLR is connected in such a way that the unit can be used either as a balanced output or an unbalanced output.
The whole system is controlled from a standard IR remote control. You can use the control to set all channel levels, balance, save/restore sets of settings (what I call 'profiles'), as well as MUTE and On/Off. In addition, you can use it to set the levels of the analog inputs A and B if you are using those. I have tried to organize the control functions and buttons software as logical as possible.
Want to build one yourself?
A complete kit is available from Pilgham Audio, see the order page.
PCB Rev 2: On the PCB Rev 2, the routing of the flat cables has been improved. There was an additional picture of the new routing in the Construction Guide, but this picture was not correct. The corrected picture is now in the Construction Guide.
![[XXL Stuffing Guide]](images/DCX%20XXL%20stuffing%20guide.bmp){kind=link}
