< Picture: level & mode display on DCX2496 front panel
Current projects - the 6-channel volume control
[Construction Guide board rev 2]
[Construction Guide board rev 3d]
This is a project to graft level control for each channel and global balance control and a few other features to a Behringer Ultradrive Pro DCX2496 Loudspeaker Management System (who dreams up these names, anyway?) digital crossover.
My first mod to the DCX was a fully passive output board
replacing the stock active board. That stock board used
not-so-hot opamps.
This project was published by AudioXpress and you can
find it
here.
The stock DCX has limited level control facilities: each
channel (and there are 6 of those in a 3-way stereo
set-up) can be adjusted +/- 15dB. But as with all
digital level controls, the more you change the level,
the more resolution you loose. At +/- 15dB you loose one
or two bits of those 16 bits of the CD format.
I decided I needed a good old analog level control for my DCX. While I was at it, I thought it would be nice if I could also adjust the relative levels of the low, mid and high frequency bands to compensate for differences in speaker- and power amp sensitivities. Also, I would like to be able to adjust the balance for those 6 channels simultaneously, keeping the relative levels of the frequency bands intact.
This mod gives the DCX2496 full pre-amp capability
I quickly realized that the only viable solution to do this with any accuracy and user-friendliness would be an electronic volume control solution. With 6 channels, all possibly having different settings, and all having to change in synchronization, that means a micro-controller. That also opens up the use of an IR remote control!
The unit will have balanced XLR outputs but can be used with unbalanced inputs without change.
(You may need to use an XLR-to-RCA adapter). The difference between balanced/pro and home/hifi levels is easily taken care of with the level control, of course.
Lastly, I foresee to use this thing with different speakers or different speaker-amp combinations. It would be nice to be able to save a complete setup, relative levels, balance etc and being able to recall it later.
So, there you have it: the spec sheet for my 6-channel remote controlled level control.
The User Interface consists of two 4-character displays that live on the DCX front panel as shown in the picture.
Some sample displays from the prototype:
- Overall level +3dB, system muted (the 'X'),
X+03 +03
- Balance shifted 1.5dB to the Left
<< 01.5
![[XXL Stuffing Guide rev 2]](images/DCX%20XXL%20stuffing%20guide.bmp){kind=link}
![[XXL Stuffing Guide rev 3d]](images/3d%20overlay%20web.bmp){kind=link}