DCX 2496 for dummies

Hey

Wasn't quite sure where to make this thread.. if this isn't the right place I hope a mod will just move it.

I just got a Behringer DCX 2496 - and I want to connect two subwoofers to it.

I have OUTPUT 1 (Left subwoofer) & OUTPUT 2 (Right subwoofer). They are connected to the EP2500 which is powering them. Then I have a cable from "INPUT A" to my surround receiver "SUB PRE-OUT".

All I want to do, is to just set it up correct - so that I can play music and watch movies etc. And I need to know how I set the subsonic filter to 15hz on OUTPUT1 and 23hz on OUTPUT2. I have also boosted the signal with +3dB on both OUTPUTS and the INPUT (so that I don't have to turn the gain so much up on the EP2500).

I must have done something obviously wrong, because when I turn the gain just a tad up on the EP2500, the subwoofers are just humming.

PS: I do have the manual... and I might figure it out sooner or later.. It's just that I want to set this thing up RIGHT NOW..

Also: Is there a way to delete all the old settings on the DCX ?

I've never used the DCX 2496 myself, but from reading, to reset the unit you press both "page" keys during power-on to do a factory reset.

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We're all in this together!

I'd be inclined to find out why you now have a hum. There aren't many settings that would result in a hum. Likely a ground loop that these devices are notorious for creating. Use a cheater to prove it's a loop, then see what you can do about it...

brucek

I connected OUTPUT 1 & 2 to INPUT C.. And now the subs work (no hum).

There is no info about SS-filter in the manual though. And I don't know what the difference between High Pass and Low Pass is.

Also... adjusting DELAY , ain't that the same as adjusing the phase?

A high pass filter will block frequencies below it's set point. Example, if the filter is set at 20hz, it will allow the frequencies above 20hz and block the frequencies below 20hz. A high pass filter is a subsonic filter.
Low pass is the opposite. It allows the frequencies below the set point and blocks the frequencies above.

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We're all in this together!

Go to http://www.behringer.com/DCX2496/index.cfm and click on software updates on the right and get the new OS and remote control software.

If you can connect a PC to the DCX setup is pretty quick and easy.

Setting up a subsonic filter (high pass) at 23 hz. is not hard, but you will have an issue setting one at 15. The minimum center frequency for filters is 20 hz, although the filter effects go lower.

As for the other filters, keep in mind the DCX can apply filters to the inputs and the outputs. If you want a filter to apply to both outputs, put it on the input to save work and CPU capacity.

The delay setting adds an equal amount of time lag to all frequencies. Phase affects each frequency differently. For example a 180 degree phase delay will shift a 1 hz signal half a second, a 10 hz signal 1/20th of a second a 10khz signal 1/20000th of a second and so forth.

Indeed, but phase adjustments are normally second order all pass filters with a low Q to give a fairly linear phase response over their range, and as such are a reasonable approximation to a time delay for the range that they're intended. That is the goal of an all pass design.

brucek

I am honestly not sure exactly how they have implemented phase on the DCX since I avoid using it, but according to my version of the manual (older code release) the phase adjustment is tied to the upper crossover frequency which would imply it is indeed a delay calculated off a phase input. In general, if using the DCX for subwoofer EQ you will want to disable the low pass crossover filters since this should be handled upstream and turning them off saves a lot of CPU. That means for our purposes you will want to use the delay (long delay tab) rather than the phase option, and therefore I have never played with it. The "long" delay is in 5 cm increments (about .15 ms) which is a super fine adjustment relative to the frequencies we are dealing with. Most revceivers have delay trims in 1 ms or 1 foot (30 cm) increments for comparison.

With the above said, my advice to a new DCX owner is to go through it and delete all filters and crossovers as a start to minimize CPU waste. The next step would be to adjust the routing and to mute any inputs and outputs you will not use. I also connect all of the unused outputs to an unused input to avoid confusion down the road. For multiple subs I would generally say to put your filters on the input and send the same signal to each sub and only adjust the delay and possibly level at the output. That said the OP seems to want different SS filters which implies the subs are quite different. I would still try to do as much as possible on the input but that is a much more complex setup and integration problem than identical subs with identical signals.

One more thing I forgot. To set that SS filter at 23 hz, you will want to use a high pass crossover on the crossover tab. That is not a "filter" in DCX lingo, but you will see you have a number of options in part because the primary function of a DCX is as a crossover. Keep in mind the 23 hz is a center frequency to a DCX so frquencies above will be reduced. You will probably want a Butterworth 24 or even a but 48 to minimize that and you my want to set the frequency at 20 rather than 23. Look at the graphical representation in the remote software to see what I mean.

Thanks for great replies!


What I'll do is basically this:

1) Delete all old settings
2) Disable all INPUTS & OUTPUTS I don't use.
3) Boost the gain on the INPUT with 8dB (The Ep2500 doesn't clip as often then)
4) Disable SS-filter on SUB1 (Which is tuned to 14.5hz)
5) Enable a BUTTWORTH Filter (24 or 48.. I assume this is a High Pass filter?) on SUB 2 (which is tuned to 23hz) - and I'll set it to 20hz instead of 23hz because of the upper end.
6) I will only adjust delay (not phase) on SUB2 (Which is at the back of the room... as opposed to SUB1, which is at the front of the room). Im not certain if I should measure the distance from the DCX/SUB1 or from my front speakers?

When step 1-6 is complete.. I think my next steps will be to measure frequency response on each subwoofer, flatten them out, then try to integrate them.

Did I miss something now ?



Btw. Sometimes I hear this "knock" every 20-30 minutes or so. It sounds like someone stands outside the room, and give a slight knock on the door. But it comes from the subwoofers. It's not a big problem though, as it's not that loud. But if someone knows what might be the cause of that, please enlighten me

5) To set you subsonic filter, go to the crossover setting tab (or menu on the front panel) and create a high pass filter. You will then be able to select butterworth (but) fron the list of available filter types. The number after the type is the db/octave drop, so 48 is twice as steep as 24.

6) The delay setting will be the most difficult. I think my approach would be to measure the distance from each sub to the listening possition and put the delay setting on the output of the one that is further away. If the subs are 4 meters and 6 meters from the seats, but a 2 meter delay or 5.82 ms delay on the further one and leave the closer one at 0. You can than use the input delay or the distance/delay settings on your receiver when you integrate the subs to the front speakers. In this case, as a starting point, I would use the actual distance to the main speakers and the distance to the closer sub minus 1 foot as a starting point. The reason for the minus 1 foot is the processing in the DCX takes some time and introduces a bit of delay. From that point run some sweeps or better yet use the RTA feature of the new REW to fine tune the sub delay to minimize any cancelations at the crossover frequency range.

7) I would strongly recomend you not try to EQ each sub individually. My first crack at it would be to EQ them as one sub by measuring the combined response and trying to flatten it first by moving the subs if possible (a foot or two matters) and then finally adding a few PEQ filters to the input. If that does not work, or the capabilities of the subs are drastically different, you can make individual adjustments, but any change to 1 sub will affect the room response of the other when played together and will also influence the integration with the mains. In otherwords it gets very complicated.

My best gues is there is a small stray signal that is turning your sub amp on and off. The DCX does not draw much power so I have mine connected to the power outlet on the back of my receiver. That way when the receiver is off the DCX is off, and there is no signal path to the sub amp. It also keeps the LCD panel and all those LED's off.

It seems I have been doing the HP/LP the wrong place, all this time. I've been in the EQ and DYNAMIC EQ Menu and done things there (They are not enabled atm).

What confuses me, though.. is when I go into the Crossover setting menu - there aren't just ONE Xover frequency / filter types. It's like there is for 2 channels... when I set both to But48 / 20hz - there is basically no sound from the subwoofer. Sorry for being so anal about this.. but how should I set it?

If you have DCX-Remote version 16a, the options under the EQ and dynamic EQ tab are only Parametric EQ and high and low shelves. A low shelf will raise or lower the signal level for all freq below the shelf point (with a several octave transition above and below the center freq.) which is a useful way to impact freq below 20 hz, but not whatyou are after.

To do SS with the software, got to the x-over tab (4th one in 2/3 of the way down the display). Select the output you want along the top right edge. For HP filter select But 48, frequency 20. For LP filter select Off. The settings will be the same on the LCD display but navigation is a bit clunkier.

There are not 2 channels BTW, just entries for High Pass and Low Pass. Ignore the top box for now which is just a name, or select Subwoofer. The next two down are for the High pass (what you want) and the bottom 2 are the Low Pass. If you have a LP at the same freq as your HP you are basically telling it to filter out everything above and below that frequency! Remember HP means let anything above this freq pass and filter out what is below, and LP means let anything below this pass and anything above gets filtered out.

I don't know what version it is. I just found a RS232 cable - so I'll hook it up to my computer tomorrow and configure everything there (and upgrade if I need to). I'll come back with some feedback then

I'm currently in the process of setting up a DCX, replacing my BFD. I've actually had to set a low pass setting, (above the high pass) due to way too much full range signal being passed by the LFE output of my HT receiver. My original HSU sub amp must have had low pass filtering in it, now I'm using a Mackie pro amp.

Most all receivers have selectable crossover frequencies with standard slopes. Why would your receiver pass too much full range signal? Have you tested the crossover in the receiver with REW to determine if it's defective?

brucek

Well, that's my next step The receiver, a Rotel RSX1055, has all the speakers set @small, with an 80HZ. crossover setting. When I had a stock HSU sub and amp (with that amp's crossover turned off) hooked up to a BFD, from the Rotel, I didn’t hear this problem. I upgraded to a Rythmik driver (using the same enclosure), DCX and Mackie pro amp, right off the bat I could hear more of the higher signals passing though. Setting the low pass for 100 HZ made the sub sound like it did before. I'll probable go a little higher, once I can spend some time using REW.

I wouldn't be surprised if the Rotel has a problem, it's been in the shop once already, and has always had a few quirks since I bought it brand new, even after a firmware upgrade. Not sure I would buy Rotel again.

I've hooked the DCX2496 up to my computer now, upgraded it, and set SS filters right.

It will be hard to integrate the 2 subwoofers with eachother.. The RLp18" is like 10cm away from the listening positions (I use it as a corner table). The hardest part is next (measure freq.responses / integrate). Perhaps I'll ~stack the two subs to ease things up a bit.