Hi 4pyros,
I have attached the pdf for the front panel deactivations..
There is quite a lot of good dialog on this topic in the yahoo users group, but in summary, this is the mod:
"..I choose to turn off/on in the same time both the LCD and the display LEDs, so I
used a double pole switch:
- One pole to invert RST on the display to RST from DSP or to GND. It deactivate
LEDs but not front panel buttons.
- Second pole to switch on/off backlight anode on the LCD
RST on LCD is still connected permanently to RST on DSP even if re-routed
through my new cables. So LCD is always active but dark!
Of course you can choose to have the LCD always on and use a single pole switch..."
Hope this helps!
View attachment DCX2496 Front Panel Deactivation.pdf
CM
Hmm, interesting.. Surprising, none of the DCX "big guns" have commented on this in all the mods mentioned?? Perhaps it's negligible??
front panel deactivations - photo anyone?
I looked at the pdf and (ahem) don't quite understand it - does anyone have a photo of a completed mod?
I looked at the pdf and (ahem) don't quite understand it - does anyone have a photo of a completed mod?
Don't think it's negligible, the RF will cause noise in opamps and required for EMI filtering and special layout (enough caps everywhere, close ground layer next to signal) to avoid emitting the RF noise. The DXC pcb is very bad design EMIwise. The guy who made these measurements is pro electronics designer and knows this stuff very well (actually he's happens to be also one of the guys behind the WinISD speaker box designer sw). I'd say 99% of all DIY digital stuff on this forum totally neglects EMI issues. One problem is that you need expensive measurement devices to measure RF upto 1 GHz.
Anyway, here are another two interesting plots on RF EMI nearfield measurements:
DCX off
DCX on
I think there are only two possible solutions, either redesign the PCB or build optical digital outputs for DCX. Well, some mods like new clock are good anyway (the less jitter the less noise there will be).
Electromagnetic interference - Wikipedia, the free encyclopedia
Yes, maybe you could build a new DAC board and put it into shielded case a little further from the DSP board. Like replace the analog board with a one properly designed digital+analog one, and a separate PSU of course. You could get the I2S signals quite easily from the DAC pins (the clock signals) and PCB nearby (from the three resistors next to DAC's). You might even use the same DAC chips as they are fine (if you can delsoder them, QuickChip makes good desoldering solder for that purpose).
Last edited:
it does seem that so much needs to be redone.
I may jump ship to minidsp myself, at some point. but the behringers seemed like quick easy jumps to at least get started with. at some point, it does not make sense to keep upgrading the unit IF there are other choices out there in the same price range and more diy friendly.
I may jump ship to minidsp myself, at some point. but the behringers seemed like quick easy jumps to at least get started with. at some point, it does not make sense to keep upgrading the unit IF there are other choices out there in the same price range and more diy friendly.
Here is the picture how to get the I2S signals from DCX:
Behringer DCX2496
See this thread:
http://www.diyaudio.com/forums/digital-line-level/36252-dcx2496-mod-digital-out-x-3-a.html
Unfortunately the original author hasn't shared his expericences (did he got it working). Another thing, I've read from somewhere that the DAC master clock is really 12.288 MHz even though the DCX master clock is 24.576 MHz, can anyone confirm this?
Behringer DCX2496
See this thread:
http://www.diyaudio.com/forums/digital-line-level/36252-dcx2496-mod-digital-out-x-3-a.html
Unfortunately the original author hasn't shared his expericences (did he got it working). Another thing, I've read from somewhere that the DAC master clock is really 12.288 MHz even though the DCX master clock is 24.576 MHz, can anyone confirm this?
Yes, I had known that, but I thought the issue was that noise from the DSP board was "polluting" the analog i/o board.. The issue then must be before that, to do with the DAC chips getting "polluted".. (?)
Thanks
CM
I’m not the youngest any more. So the frequency range of my ears ends at about 18 kHz. I already heard that some marketing guys of high end speakers could hear up to 40 kHz although I never met one of these guys. But it is completely new for me that somebody is able to hear frequencies above 1 MHz.
Sorry, but is there any audible reason to get rid of this HF noise which is more or less typical for all digital circuits?
RF EMI demodulates in analog circuits and increases audible noise level.
Yoy must have heard cell phone noises from analog amplifiers even though the carrier frequencies are hundreds of MHz's.
http://esken.net/ergo/blog/wp-conte...arta-48k-samplerate-yelloworig-greenergos.png
The noise level of the unmodified DCX is about -132dB (yellow) and -138dB for the modified (green) in the audible frequency range. To my ears that’s NO noise. I'm also not aware of any measuraments showing significant sonical improvement by reducing HF noise.
BTW: Adding this S/PDIF solution (instead of DACs) means reducing sonical quality significantly except you need digital output because of further digital processing.
opamps with Jan's analog board
I thought I would used different opamps for each pair of outputs so I could optimize the sound for each driver. I decided the easiest way to confirm which opamps output to which jacks was to just remove one. This where I got confused. With the opamp removed all channels still played fine. What??
I thought I would used different opamps for each pair of outputs so I could optimize the sound for each driver. I decided the easiest way to confirm which opamps output to which jacks was to just remove one. This where I got confused. With the opamp removed all channels still played fine. What??