Behringer DCX2496 digital X-over

[EC8010]

I suspect what's being asked is whether the phase control adjusts driver delay by a very fine amount expressed as phase at the crossover frequency, or does it adjust phase at the crossover frequency but have little effect at other frequencies (ie not pure delay). I'd be interested to know the answer to that question too.

[Davey]

The phase control is frequency dependent delay just like a second-order all-pass function. The high-pass xover frequency set in the appropriate channel (whether it's activated or not) defines the point where the phase response rotates through 180 degrees.

The delay control implements a pure delay.

I have a SoundEasy screen capture of a test I did quite awhile back that illustrates how it operates. I used 1khz for the turnover frequency. I hope this link works.

http://f4.grp.yahoofs.com/v1/8AodQkO...ersusdelay.JPG

Cheers,

Davey.

[tiroth]

Thanks Davey. I can't see the image, but I know exactly what you mean. I'm impressed that they actually implemented this correctly; that's another tool in the arsenal.

My second question wasn't related to delay, I just wanted to confirm that you can have both digital and analog inputs active at the same time. (A+B digital, C analog) The software lets me do it, but I couldn't find anywhere in the manual that explicitly said it was kosher.

[Davey]

I haven't actually tried that, but I think it should work fine. On the routing tab you steer the "C" input where you want. I think the "B" input would probably not be usable however. I'm not sure.

I'll check it and report back.

Davey.

[EC8010]

Originally posted by Davey
The phase control is frequency dependent delay just like a second-order all-pass function. The high-pass xover frequency set in the appropriate channel (whether it's activated or not) defines the point where the phase response rotates through 180 degrees.

Thanks for that. Now all I have to do is to knock up a microphone amplifier so that I have a loudspeaker measurement system and I can play and see what I'm doing...

[petervv]

hi guys,

Just finished major surgery to my DCX, I removed the I/O pcb and
mounted input and out transformers. The transformers are microphone input transformers of good quality but of unknown origin, ratio is 1:3.16.

The '1' winding has a centertap that I use to supply a 2.5V offset
voltage (from two TL431's) to the ADC's.

Result is a lot more 'air', space and detail. The sonic impact of
this modification is about the same as mounting the Tentlabs XO2.
I mostly listen to CD through the digital input, but the analog
inputs improved quite a lot also.

kind regards, Peter

[mige0]

hello

for those who want to mod less radicale i can recommend to bypass the 100nf condensators for ps decoupling for the 4680 opamps (c1-4, 69, 70, 92-97) beside the mods on the analogue i/o suggested in this thread earlier.

i used 10uf smd tantal (c - footprint) and it really is surprising what a big improvement this is. especially on low and very low levels. which means first input led flashing or below you gain great in tonal smothness and soundstage.

one would think that at such very low levels the imperfections of digital converters would dominate the sound but as far as i can hear, there is still a lot of improvement that can be done at the analog side.

http://www.kinotechnik.edis.at/pages...6/DCP02068.jpg

http://www.kinotechnik.edis.at/pages...6/DCP02067.jpg

for peter
from your picture i would guess that your bypass condensators for the ad/da converters are still original. try to replace them with 10u tantal - if you dont have anything better in mind

http://www.kinotechnik.edis.at/pages...6/DCP02031.jpg

its a very cheap mod easy to do and gives very good results as well

[petervv]

hi mige0,

Thanks for the tip about bypassing the supplies, I must say I don't really like tantal caps, I'll think about it, maybe BG's?

The new clock is a quick and relative cheap mod, description can be found on Ergo's website.

regards, Peter

[mige0]

hello

tantalum condensators seem to have bad reputation among audophils, though they are industry recommended even for very high speed opamps.


http://www.linear.com/pc/downloadDoc...6xQCZLfcHCpxia!-1570396240?navId=H0,C1,C1154,C1009,C1022,P1109,D13 67
(linear technology lt1361)

but i have to admit that i havn't compared against BG's for example. i am just saisfied with the tantals until now.

the clock upgrade you recommend is something i will keep in mind, thanks. i probably will give it a try with the cheap xo clock module only.
http://www.tentlabs.com/

greetings michael

[AR2]

Our member Bill Dipoala has constructed volume control board, and op-amp replacement board that all fits in Behringer unit. I got from him these boards and the quality is outstanding. Not just that but he also supplies parts list, big schematics printout and parts placement map. Here is the link.
DCX2496 DAC volume control PCB
The boards are allowing you to use optical in instead of AES/EBU if you need, remote control, your choice of any popular dual op-amps, separate board for single ended output, or balanced board...
Circuit boards are in Bill's own words "All PCB’s are constructed using double sided FR4 laminate with plated through holes, solder mask and silk screen (better quality than what is in the DCX). "
If you do not need volume control, op amp board is stand alone and you could just order that. In my mind any modding on existing output stage is just a waist of time and money. In original construction analog stage first converts balanced signal to unbalanced, than it goes to servo balanced output circuit and all that makes up 24 op amp stages.
The fact that I like the most, with Bill's boards you do not need to destroy original Behringer. Everything is connected between boards by ribbon cables, and if you change your mind all that you have to do is unplug. Even more, the power is coming from original Behringer power supply so you do not need to worry about separate case, because everything fits within original housing.
I have built volume control and tested it. The sound is great with minimal influence. I am still to build and test op-amp board, and I will report on it. I am also testing Lundahl 1674 transformers as output instead of op-amps. It is much costlier solution, but the sound is awesome.
I am not associated with Bill at all, just a happy user. I think that Bill did such a great job that anyone wanting to modd Behringer should look into it.
Good luck with your modding
AR2