[Housteau]

As a note for those of you that had already read this shortly after I originally posted it, I have since noticed a few errors and have corrected them as well as explained some other areas a bit better.

There have been several people interested in going digitally active with the Behringer DCX 2496 for their speaker systems and I thought this post might help as a guide.  I have the RM-V60s with flanking VLA bass towers.  My system was originally set up for passive multi-amping using the included external analog xover.  Once making that change over to the DCX I could never imagine life once again without it.  I did have my concerns in the beginning though.  I mean how could such a cheap non-audiophile industrial unit possibly sound reasonable, let alone vastly improve anything?

What sold me was Brian's enthusiasm for this unit.  He did a lot of critical listening through it with the end results being that he found it extremely transparent when using the analog inputs.  He mentioned that whatever ill effects there may be they were greatly outweighed by all the positives that unit could provide.  There were discussions on this forum at the time about this, because how could it sound better for a digital source to be converted to analog first and then back to digital through the DCX, just to be converted back to analog once again for the output?  Wouldn't it be better to keep the signal digital going in to the DCX and just have one conversion to analog for it's output?  That does seem technically more logical. But, as with many things audio, listening tells us the true story and is the only one that has any real merit. 

Personally I go analog in as well and do not like the digital in, even though my unit has been highly modified with that digital section improved over the stock version.  Over the years just about everyone I talk to about this also uses the analog in.  There must be something very synergistic with this unit where the ADC and the DAC are able to work seamlessly together, but when that internal chain is broken by going digital in that synergistic magic is not allowed to happen.  Roger Sanders of Sanders Sound uses a stock DCX for the active crossover in his highly reviewed and highly resolving electrostats.  He uses them analog in and never considered modifying them.  He told me that was a good way to screw them up.

Brian wrote up a good tutorial on how to install the DCX:
 
http://www.audiocircle.com/index.php?PHPSESSID=8lt07tak95uq2k0ue69j05mae4&topic=63025.0 

This was written early on during what I would still call the discovery phase of all this unit was capable of doing.  In this tutorial he mentions using the set up of LH LH LH for the six output channels.  I don't do this.  My unit is set for LL MM HH which is a full three way design.  All this designates is that there are three stereo pairs being output from the DCX.  With the DCX you can make any pair anything you want and don't need to be concerned with the letter designations of low, midrange and high.  Since my unit is modified allowing full analog volume control of two of those three pairs (LL and HH only), I am using LL for the output to my V60 mid bass and HH for the mids and highs.  MM for me is the sub bass output to the VLAs.  My sub bass amps have volume controls of their own.

Here is a basic block drawing of how both the digital DCX and outboard analog crossovers are being used in my system.  Many ask if they can triamp a three-way speaker that does not use a separate subwoofer directly with the DCX, bypassing either an outboard analog crossover or a filter of some sort on the tweeter?  Technically I see no reason why not, but I know that Brian did not recommend doing that and instead recommended using the DCX as a two-way xover in that circumstance.  I know of several people that ended up blowing their tweeters even though they were being careful while triamping.  It may be that the DCX is not a good buffer for amp start-up for such a sensative component?

[John Casler]

Thanks Dave,

That is an awesome diagram and should maybe be included in Brian's thread as a reply. so that those reading the explanation will have your diagram to follow.

Also it will then be stickied.   

Recently we have been able to make great progress on building a "digilog bridge", for those who wish to take their VMPS speakers digital, and don't have an OXO.

It is actually a pretty simple project and involves simply wiring all the drivers "DIRECTLY" to a pair of binding posts.

This means you will have to add a pair of binding posts for the tweeter, and then use the remaining two pair for the Neos, and the Woofers.  You can even let the "old" internal XO to stay, but you have to desolder and disconnect it from the binding posts so you can "direct" wire to them.

It is a "weekend" project.

BUT. . . .As Dave mentions above.  TRI-AMPING has proven to be a hazardous approach, and having a naked tweeter wired directly to an amp without the "digilog bridge" is likely to end up trashing the ribbon portion, or worse. 

For those with an OXO, this is a walk in the park, and you follow Dave's diagram exactly.

Anyone with questions can post them here, or contact me directly.

[Housteau]

For those with an OXO, this is a walk in the park, and you follow Dave's diagram exactly.

A good benefit of using an OXO is that you will have a rotary pot to help adjust the tweeter level relative to the other drivers.

[jwalker]

Housteau,

I'm a bit confused by the block diagram.  It looks like tweeter has a high pass function provided by the analog crossover, but the mid does not get a low pass function since it is split directly from the mid/tweeter output of the amplified DCX out.  Would it make more sense to just use the "mid" output of the high-level analog crossover and connect that to the mid?  Just wondering.

[Housteau]

Housteau,

I'm a bit confused by the block diagram.  It looks like tweeter has a high pass function provided by the analog crossover, but the mid does not get a low pass function since it is split directly from the mid/tweeter output of the amplified DCX out.  Would it make more sense to just use the "mid" output of the high-level analog crossover and connect that to the mid?  Just wondering.

One of the benefits of using the DCX is the removing of the midrange Neo panels from the analog xover.

[jwalker]

One of the benefits of using the DCX is the removing of the midrange Neo panels from the analog xover.

Yes. But the response of the midrange panel now fully overlaps the tweeter response in your configuration for better or for worse.   Is this how Brian Cheney designed the passive crossover for the tweeter/midrange for this speaker?     

[Housteau]

Yes. But the response of the midrange panel now fully overlaps the tweeter response in your configuration for better or for worse.   Is this how Brian Cheney designed the passive crossover for the tweeter/midrange for this speaker?   

I do not know the internal settings of the analog xover.  But, once the DCX came into use Brian was completely taken with it's capabilities and how he could set ideal slopes for a blending he could not achieve quite the same way in the analog domain.  That along with correcting room and driver issues with the parametic EQs made the DCX his new best friend.

The xover to the mid/highs is set by the DCX.  Brian has that roll-in set at 266 Hz for the V60 with a natural roll-off on the top end.  The midrange panels see that entire frequency range and roll off to their limit on the top end.  The passive xover also sees this same feed, but filters out the extreme highs to be sent to the tweeter, that of course will naturally roll off much higher.  This allows the proper blend Brian wanted.

The 6.5" mid-bass drivers of the V60 are set to take over from 233 Hz on down from the DCX where they roll off naturally.  Brian felt the gap between 233 and 266 Hz allows the best blend between the upper bass and midrange drivers.  They are both Butterworth with one at 18 and the other at 24.

[Doug Ravizza]

In his article Brian refers to a "Modded Behringer DCX2496". Questions that come to mind are:
- What are the modifications?
- Can the same benefits be realized with a "stock' unit?
- Is a DIY implementation of the mods possible?
- If not, how would one go about getting a modified one?

[Housteau]

In his article Brian refers to a "Modded Behringer DCX2496". Questions that come to mind are:
- What are the modifications?
- Can the same benefits be realized with a "stock' unit?
- Is a DIY implementation of the mods possible?
- If not, how would one go about getting a modified one?

Mine is a highly modded unit to a point where it acts as a full preamp with volume controls in the analog domain over the input, individual channel outputs and the overall gain all by remote control.  Brian had this same unit until it smoked during set-up at The SHOW in 2010.  We replaced it with a stock unit and all was well.  In fact the sound was wonderful without a hint of anything being out of place.  Ever since then I have no longer had a fear of something bad happening to mine.  All of Brian's thoughts and comments I have already mentioned that he had about the DCX were about the stock units.  The modified ones did not come about until later.  Did he feel they were better?  Yes, especially the fact that it could completely replace a preamp in a system.  Remember though that Roger Sanders feels the stock unit is perfectly fine exactly as it is and refuses to modify it.  Early on he used to place that unit into a custom case so it could not be identified as a Behringer DCX, but later just used it as is without feeling any need to apologise for it.

There are many mods available for this unit.  There is even a Yahoo Group set up for owners that often discuss these various mods.  Schematics are available as well as kits.  Depending upon your skill level they may not be too hard to implement.  There are individuals that will do mods for you, but I am not sure who is actively doing them today.

Ideally the digital nature of this unit wants to see an input close to full line level where the digital conversions have the best chance of taking advantage of their high resolution.  When driving a stock unit with a preamp that input is a good bit lower than full line level.  However, this is exactly how many use it including Roger Sanders.  Personally, I have not heard any ill effects when doing this.  I have heard it this way in quite a few systems and to me it remains transparent.

In order to send this unit a line level signal the preamp needs to be between the DCX and the amplifiers.  The analog modded units are set up for this to happen internally.  A very simple do-it-yourself fix is to place an inline pot on the inputs to your amplifiers.  These pots can reduce the output of the DCX allowing you to increase the gain from your preamp feeding the DCX with a higher signal level.  These pots will also allow you to balance your muli-amp system in the analog domain. 

[John Casler]

A good benefit of using an OXO is that you will have a rotary pot to help adjust the tweeter level relative to the other drivers.

We can build the L-Pad into the Digilog box. 

[John Casler]

In his article Brian refers to a "Modded Behringer DCX2496". Questions that come to mind are:
- What are the modifications?
- Can the same benefits be realized with a "stock' unit?
- Is a DIY implementation of the mods possible?
- If not, how would one go about getting a modified one?

1) Brian didn't specify what the mods were and they were different from different modders. 

2) As Dave mentioned, one might be hard pressed to easily notice the differences without an A/B comparison.  Obviously the mods were checked by Brian, to make sure he liked them, but as Saunders and Brian both discovered the stock units perform beyond their expectations.

3) There is a DIY Kit from a German Comapny, whose name escapes me at the moment, but you might do a search on DCX-2496 mods and find it.  It is well beyond my pay grade, but many DIY's use it and I think Mike Galusha used it as a foundation for his mod.

4) You could also contact Clint at Wyred4Sound and ask  if they could give you a price on a mod.  Ric Cullen used to do it for Brian, and may still be offering such a mod.

[Hipper]

I have RM30Ms with internal crossovers (bought 2006), don't use a sub and I like the idea of going active.  I use a digital equaliser, a Behringer DEQ2496. The set up is CD Transport/Behringer/DAC/Power Amp. The DAC has a volume control.

I am intending to use two amps. My understanding is therefore that I can stick the DCX after the DAC. From what Housteau says, it is suggested that the DCX sets the crossover low-mid whilst the existing passive crossover mid-high remains in place, the two signals being sent two seperate amps, the DCX also doing volume equalisation. It is too risky to the tweeter to consider an active mid-high crossover. Is that correct?

I've no experience of doing any of this, or soldering, but am willing to give it a go. I have time! I do though need information - what bits to cut out etc.. What crossovers to set. Does that info exist somewhere?

[Housteau]

Does that info exist somewhere?

The best place to find out is right here on this forum from other RM-30 owners.  There is a good chance that someone here has either done this already, or has at least been into the xover and is able to describe those inner workings.

I think you have the right idea of what needs to happen here to actively biamp.

[Housteau]

Here is a link to one of the mods to my unit.  I have several, but this is the most valuable one to me:

http://www.linearaudio.nl/linearaudio.nl/index.php/my-projects/dcx2496-6-channel-vol-control

[Housteau]

Here is another link for some inline attenuators that can be used between the DCX and your amps.  He also has mods for the DCX.

http://mysite.verizon.net/vze4c5pt/id2.html

[Hipper]

Many thanks.

Looking back through these pages it seems I asked this question three or four years ago, but got no exact response.

Mind you I still love listening to the music through Brian's speakers.

[GeorgeAb]

I am setting up my digital crossover for my V60s and I need a clarification on slopes of the crossovers points.
 
Is the low pass going to the bass 233 Hz with 18dB slope and high pass going to mid/tweet 266 Hz with 24dB slopes or vice a versa (233 Hz with 24dB slope and 266Hz with 18dB slope)?

From the above post, “The 6.5" mid-bass drivers of the V60 are set to take over from 233 Hz on down from the DCX where they roll off naturally.  Brian felt the gap between 233 and 266 Hz allows the best blend between the upper bass and midrange drivers.  They are both Butterworth with one at 18 and the other at 24.”   

[Housteau]

The bass moduleof the V60 has a high pass filter of 233 Hz (Butterworth 24db)  The wing section has a low pass filter of 266 Hz (Butterworth 6db)

[Housteau]

In my room the 6db slope works best.