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-   -   Behringer DCX 2496 to prototype active crossover (http://www.diyaudio.com/forums/digital-line-level/63433-behringer-dcx-2496-prototype-active-crossover.html)

akunec 30th August 2005 05:17 PM

Behringer DCX 2496 to prototype active crossover
 
I'm building a 3 way system (lambda TD12s, PHL 1120, morel supreme 110) and i'm hoping to prototype its response first with a DCX 2496. Once I have a response that I'm happy with, I will build an analog active crossover to replicate it.

Should I be expecting very much change in going from a DSP based system to an analog filter?

DIY_newbie 30th August 2005 05:22 PM

For what its worth,

I had the same plan but after hearing the DCX I ened up keeping it in my system.. The main thing to remember is that you'll need to atenuate the outputs of the DCX to get the full digital precision. I great way to do this is to use pro amps with gain controls instead of comercial amplifiers.

--Chris

ultrachrome 30th August 2005 08:36 PM

Yeah, what he said.

I bought the Behringer with the same notion but as I get into the passive design phase, I see that things are not going to translate perfectly. Maybe the only thing that translates is the crossover point and slope but you still need to measure your drivers, determine the correct passive component values, try to find the ideal passive component values, build, test, repeat.

First the Pros:
- added cost not that great compared to your driver costs
- immediate gratification (you can enjoy your system immediately)
- ability to immediately hear the difference between differend crossover points and slopes
- can be used with future projects.

Now the Cons:
- difficult to integrate in an unbalanced signal path.
- ideal sound quality config may not fit your needs
- does not measure your drivers or determine equivalent passive component values

Ideal config would be digital into the DCX with the DCX feeding its outputs into a 6 channel volume control before each amp. Pretty much eliminates the ability to use with home theater setups.

Less ideal config would be use a high-gain preamp feeding the DCX and then feed the DCX signal through an attenuation network before the amps. The idea is to increase the ratio between the input signal and the unit's inherrent hiss.

Read this thread to start and search on DCX2496 and read those as well: http://www.diyaudio.com/forums/showt...871&highlight=

That said, if you can deal with the hiss (eliminate or ignore) then I'd say go for it. It's fun to play with and educational to boot. But you'll need some sort of measurement software to get it to sound its best. I've used TrueRTA and that's been enough to get something enjoyable to listen to. But it's not the best type of tool to use for reasons I can't explain here...

DIY_newbie 30th August 2005 09:28 PM

LOL,

UltraChrome and I seem to post on all the same threads ;) That was a pretty good pros/cons argument above.

The only thing I would add is that if you use pro audio amplifiers you don't have to worry about the attenuation network after the DCX or the balanced to unbalanced coversion.

The best possible solution is to drive digital to the DCX and then analog to amplifiers which have adjustable gain. My personal setup looks like this :

CD-player -> SRC2496 (digital 16bit/44.1Khz)
** upsampled digitally with dithering in SRC **
SRC2496 -> DEQ2496 (digital 24bit/96khz)
** Digital Room Correction Applied in DEQ **
DEQ2496 -> DCX2496 (digital 24bit/96khz)
** DSP Crossover and D/A conversion **
DCX -> 3x A500 reference amplifier

This sort of configuration allows you to use the maximum digital dynamic range of the DEQ/DCX maintaining the highest signal to noise ratio

--Chris

akunec 30th August 2005 09:45 PM

I already bought an active filter board and have a power supply ready. The reason i don't want to use the DCX permanently is because I hear a lot of mixed reviews about it. I'm paying a fortune on my drivers so im not going to sacrifice anything on my xover. I also don't have a balanced source or balanced amplifier inputs. Will that be detrimental to the S/N?

DIY_newbie 30th August 2005 09:58 PM

Balanced interconnects are not essential, but they do help with noise rejection. The largest improvement you can make when using the DCX is keeping the signal levels on the inputs/outputs as close to clipping as possible.

As far as analog active/digital active crossover you'll see opinions on both sides saying which is superior. IMHO the DCX is so ridiculously better than any passive crossover I can't believe I've lived without one for so long ;)

Don't take my word for it though, listen to both see what you like better. In the end what really matters is what YOU like better not what anyone else does.

--Chris

ultrachrome 30th August 2005 10:22 PM

So your target is an active three-way? What active boards are you using?

Since you have them already, you might want to give it a go. It shouldn't be too hard picking crossover points from the datasheets of those woofers. The biggest difference in sound quality that I've uncovered with the DCX was with crossover slope. I tried LR48 last night after trying 12 and 24 and the difference was pretty obvious.

If I was building a fully active system from scratch, I'd likely build it around a DCX and then later upgrade to a higher resolution digital system that supported better filters and room correction features.

thylantyr 30th August 2005 10:42 PM

lambda TD12s, PHL 1120, morel supreme 110

This design will be very easy to tune as there is less problems
with integration than other common designs. It will be
an excellent system if you pay attention to fabrication details.

The reason i don't want to use the DCX permanently is because I hear a lot of mixed reviews about it.

People in cyberspace have a way to scare people away when
the pros outweigh any negatives by a HUGE margin.

Don't worry about the DCX sound quality, it's excellent without
mod, and excellent if you choose the analog pathway. The
feature rich DCX can only make your system more interesting
because you will be able to tune it for whatever listening mood
you are in vs. using passive crossovers which will only give you
one sound <-- that's ok too. :cool:

akunec 30th August 2005 10:46 PM

I'm using active filter one boards.

My plan was to:

1. Prototype with DCX. Find optimal filter slopes/notches/delay.
2. Implement equivalent filter using the active filter one boards.
3. Either sell the DCX or keep it to prototype future speakers.

I understand that active is better then passive, but I'm not convinced whether DSP is better than analog. Up to this point, I was convinced that the DCX is more convenient do to software implemented transfer functions, but analog has it beat in signal integrity. I guess the only way I can find out is if I do them both.

ultrachrome 30th August 2005 11:20 PM

That plan sounds pretty sound.

Behringer or not, you're going to need a measurement mic, mic pre, and measurement software.

Theoretically, feeding the Behringer an analog signal puts it at disadvantage. The Behringer's big advantage is its convenience.

I sound negative but I don't regret the purchase. Just annoyed by hassle of interfacing between pro with consumer gear. Essentially, getting it to work quietly with the amps I already had involved essentially another DIY project.


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