Behringer DCX2496 digital X-over - Page 327 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th April 2012, 06:23 AM   #3261
diyAudio Member
 
Join Date: Apr 2008
Default mic input question

I have removed the in / output completely and want to restore the mic input.

I have phantom power sorted out using the +15V lines on the flat-cable. Now I need to build a mic preamp or use a transformer to raise gain. It is unclear to me how much gain is needed (I will use a measuring mic similar to the Behringer)

So I would be much helped by answers to a couple of questions:

1. If using a transformer, what step-up range would work?
2. Suppose phantom power can be connected directly after the transformer without any extra components? Since the transformer isolates the DC from the DCX side.
3. If going with a clone of the original mic pre circuit from the DCX schematics, what opamp would you go for?

Thank you Peter
  Reply With Quote
Old 7th April 2012, 06:27 AM   #3262
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
The only thing the mic will do on the DCX is tell you polarity and delay. Handy, but you can do that with free computer programs, too.

I'll have a look at the mic preamp schematic, it should not be hard to imitate.
__________________
Take the Speaker Voltage Test!
  Reply With Quote
Old 7th April 2012, 09:03 AM   #3263
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by peterhenk View Post
I have removed the in / output completely and want to restore the mic input.

I have phantom power sorted out using the +15V lines on the flat-cable. Now I need to build a mic preamp or use a transformer to raise gain. It is unclear to me how much gain is needed (I will use a measuring mic similar to the Behringer)

So I would be much helped by answers to a couple of questions:

1. If using a transformer, what step-up range would work?
2. Suppose phantom power can be connected directly after the transformer without any extra components? Since the transformer isolates the DC from the DCX side.
3. If going with a clone of the original mic pre circuit from the DCX schematics, what opamp would you go for?

Thank you Peter
I have with Pilgham Audio developed exactly that. It's a stand-alone mic preamp on a little PCB and a connector that fits in the digital input hole on the back panel. The connector is a combined XLR (for digital in) with a 6.3mm jack for the mic input.
The board is build, I need to final check it.
Will try to do that next week and report here.
If it works as designed Pilgham will probably offer kits.
I developed this by request from people who build my active DCX mod.

Stay tuned!

jan
Attached Images
File Type: jpg micpre-2.JPG (216.1 KB, 441 views)
File Type: jpg micpre-1.JPG (150.9 KB, 437 views)
__________________
I won't make the tactical error to try to dislodge with rational arguments a conviction that is beyond reason - Daniel Dennett
Check out Linear Audio Vol 7!
  Reply With Quote
Old 7th April 2012, 10:51 AM   #3264
diyAudio Member
 
Join Date: Apr 2008
Default Guinea pig?

Hi Jan,

Glad to offer myself as Guinea pig ;-)

Peter
  Reply With Quote
Old 7th April 2012, 11:14 AM   #3265
diyAudio Member
 
Join Date: Apr 2008
Default Internals after 1st step

Just for info.

This is how I made space available to play around in the DCX.

Turned the output XLR connector 180 and soldered a prototyping board directly on to them. This gives space to play around with first order filters, buffers, volume control (ldr type?).

Since the proto-board sits quite high I can still put transformers under them if I like.
Attached Images
File Type: jpg dcx internals1.jpg (300.1 KB, 330 views)
File Type: jpg dcx inetrnals2.jpg (411.6 KB, 326 views)
File Type: jpg dcx internals3.jpg (463.5 KB, 321 views)
  Reply With Quote
Old 9th April 2012, 08:26 AM   #3266
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by peterhenk View Post
Hi Jan,

Glad to offer myself as Guinea pig ;-)

Peter
OK, sounds like a good plan!
I have the unit completed, need to do some basic measurements to make sure that there are no obvious mistake (like swapped supply lines ;-) and then I can send it to you for a user test.
The input is the same as the original DCX complete with 15V phantom power for the Behringer 8000 (?) mic.

jan
__________________
I won't make the tactical error to try to dislodge with rational arguments a conviction that is beyond reason - Daniel Dennett
Check out Linear Audio Vol 7!
  Reply With Quote
Old 9th April 2012, 08:41 AM   #3267
diyAudio Member
 
Join Date: Apr 2008
Hi Jan, Super!!

You have PM

Regards
Peter
  Reply With Quote
Old 5th May 2012, 03:29 PM   #3268
RevF is offline RevF  United Kingdom
diyAudio Member
 
Join Date: Oct 2003
Location: UK
Looking forward to the results of this!
I am having issues with my dcx currently - and have given up trying to fix it as the issue illudes me, and have ordered a new one... once I am up and running again and have the active mod installed in the new box, I would be interested in this mod though! )
  Reply With Quote
Old 11th May 2012, 05:46 AM   #3269
diyAudio Member
 
MurphyUHF10's Avatar
 
Join Date: Oct 2010
Location: Melbourne
Default Didden i/o Mod, Burson Discrete OPAs

Hello,

i Thought to post my "tweek" of the Didden active i/o..
Installtion of Burson Discrete OPA's!!

Firstly, +/-9v avaliable from the i/o board is too low for these power hungry modules,, the THD+N is too high (thanks to a thread on here).. Much better at +/-18v.

So I built an external power supply to power these modules, and modified the Burson IC socket adapter so not to get power from the existing i/o board.. Of course, the GND of this new power supply would need to be connected to the GND of the DCX power supply.. Which I did with a fly-lead coming from pin 4 of the power supply connector on the DSP board..
(my aplogies for such poor photos)

1.jpg

2.jpg

3.jpg

4.jpg

5.jpg

6.jpg


However,, I am getting very loud humming!! I measured this hum with TrueRTA and the analyser shows 2 big spikes at 50Hz and 100Hz.. (mains hum??)

When I use a non-modified discrete module and rely on i/o power, no humming..
Obviously to do with using 2 separate power supplies??

Any ideas??

Ta
CM

Last edited by MurphyUHF10; 11th May 2012 at 05:48 AM.
  Reply With Quote
Old 11th May 2012, 06:48 AM   #3270
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Looks nice!
The hum may have to do with the connection of the external power ground to the internal DCX ground. If it's only 50/100Hz it is probably not rectifier ground loops; in that case you'd have more harmonics.
Did you put in a direct connection between the external supply ground to the DCX?

jan
__________________
I won't make the tactical error to try to dislodge with rational arguments a conviction that is beyond reason - Daniel Dennett
Check out Linear Audio Vol 7!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 09:16 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2