I got a Behringer DCX2496 crossover

timbley · « **on:** 27 Mar 2005, 06:52 am »

I'm using it wih my Panasonic SA-XR50 to bi-amp my Klipsch RF-7s, inspired by the folks at Newform, and it really is a huge upgrade over using passive crossovers. I'm also using the DEQ2496 with the calibrated microphone, which I found indispensable for getting the speakers EQ'd. The passive crossovers were doing a pretty impressive job at creating fairly flat response from drivers that aren't very flat.

"Caps coils and resistors, you did a fine job, but from now on you must stay away from my speakers!"

If any of you have been thinking of trying this setup, I heartily recommend that you do. Getting everyhing EQ'd correctly takes some patience. But once you get it set up right, the sound is improved in just about every way.

ryno · « **Reply #1 on:** 27 Mar 2005, 05:07 pm »

I've got a DEQ2496, EQ but no XO, but digital I/O. I found it hard to EQ with just the behringer, the resolutions not all that great. I just got hooked up with true rta, what a difference. 1/24 per octave resolution lets you use the parametric EQ rather than the graphic. Software $100, new soundcard $30, mic preamp $50, and a couple of cheap cables from the shack. If the DCX has parametric EQ's, it's worth it.
Ryan

timbley · « **Reply #2 on:** 27 Mar 2005, 09:25 pm »

True RTA sounds very interesting. The DCX does have parametric EQ. Strangely, I find it very difficult to get good result with the parametric unless I'm going after a spike. For general curve shaping, I have a much easier time with the 31 band graphic EQ on the DEQ.

ryno · « **Reply #3 on:** 27 Mar 2005, 10:59 pm »

I feel that spikes, or room nodes are the main reason for an eq, and are dealt with much better with a parametric. If you have the resolution to measure it. Your right about general curve shaping, a graphic is fine.
Ryan

KKM · « **Reply #4 on:** 28 Mar 2005, 01:20 am »

Is this thing a poor man's DEQX and Tact room correction thingy? Want to learn more about this thing. I thought equalizers are a no-no for audiophiles.

ryno · « **Reply #5 on:** 28 Mar 2005, 03:04 am »

In the behringers, all EQ and XO are done in the digital domain. You don't have the phase shifts and other nasties associated with analog EQ's. I know DEQX also has phase correction and I'm sure better DAC's. I used the DAC in my DEQ2496, no XO, and it sounded similar to the entry level denon DVD I was using as a transport. When I add a CIaudio DAC, there was a big improvement. Bigger soundstage, better imaging. I'd love to go with the DCX2496, includes XO, but it only has analog out. Still looking for a budget EQ/XO with digital I/O.
Ryan

timbley · « **Reply #6 on:** 28 Mar 2005, 03:58 am »

Quote from: ryno

I feel that spikes, or room nodes are the main reason for an eq, and are dealt with much better with a parametric. If you have the resolution to measure it. Your right about general curve shaping, a graphic is fine.
Ryan

I'd like to get some higher resolution RTA going and see what kinds of spikes are going on. I'm using the parametric to take care of a 42 hz room boom. Since I'm using the active crossover, I need some general curve shaping to get the drivers flat. The passive crossovers were doing a good job of that before I removed them.

JoshK · « **Reply #7 on:** 28 Mar 2005, 03:59 am »

Quote from: ryno

In the behringers, all EQ and XO are done in the digital domain. You don't have the phase shifts and other nasties associated with analog EQ's. I know DEQX also has phase correction and I'm sure better DAC's. I used the DAC in my DEQ2496, no XO, and it sounded similar to the entry level denon DVD I was using as a transport. When I add a CIaudio DAC, there was a big improvement. Bigger soundstage, better imaging. I'd love to go with the DCX2496, includes XO, but it only has analog out. Still looking for a budget EQ/XO with digital I/O.
Ryan

How is this so? I don't think Behringer claims this. FIR filters are ones that are suppose to be phase linear, not the IIRs done in Behringer. IIRs still do the same phase shifts as regular analog xos.

timbley · « **Reply #8 on:** 28 Mar 2005, 04:04 am »

Quote from: KKM

Is this thing a poor man's DEQX and Tact room correction thingy? Want to learn more about this thing. I thought equalizers are a no-no for audiophiles.

Yes, I'd say that's about it. It's not as sophisticated as the more expensive systems, but what it does is very good in my estimation. Now that EQ and crossovers can be done in the digital domain, the idea that EQ's and active crossovers are bad needs to be rethought.
There are lots of posts on this forum and audioasylum about the Behringer units and how they compare to the more expensive stuff.

Davey · « **Reply #9 on:** 28 Mar 2005, 04:09 am »

Quote from: JoshK

How is this so? I don't think Behringer claims this. FIR filters are ones that are suppose to be phase linear, not the IIRs done in Behringer. IIRs still do the same phase shifts as regular analog xos.

Yep, that is true. The phase shifts associated with the crossovers and EQ's in the DCX2496 are exactly the same as analog equivalents.

Cheers,

Davey.

timbley · « **Reply #10 on:** 28 Mar 2005, 04:16 am »

Quote from: JoshK

How is this so? I don't think Behringer claims this. FIR filters are ones that are suppose to be phase linear, not the IIRs done in Behringer. IIRs still do the same phase shifts as regular analog xos.

I've been wondering about that. It makes me wonder what difference the perfect phase alignment through the spectrum would sound like. Unfortunately, I can't afford the DEQX.

A friend of mine was telling me that Klipsch had selected some people he called "golden ears" for audio testing. These folks had shown exemplary ability to hear subtle differences in blind tests, and could reliably EQ a system to within +/- 3 db by ear.

One thing he was testing was the importance of phase alignment between drivers. He found that in blind tests, his golden ears heard no discernable difference as drivers were moved closer and further to the listener.

I've played with changing the phase and delay on my tweeter, and I have to say, I can't hear it. Maybe I don't know what to listen for. OTH, I can definitely hear the difference when trying to blend a subwoofer.

ryno · « **Reply #11 on:** 28 Mar 2005, 05:04 am »

Quote from: JoshK

How is this so? I don't think Behringer claims this. FIR filters are ones that are suppose to be phase linear, not the IIRs done in Behringer. IIRs still do the same phase shifts as regular analog xos.

Are these the same types of filters that are used in the EQ part of the behringers? If so, then this will also introduce phase shifts. sorry for the wrong info. But for me, the problems the EQ fixes are bigger than those it creates. At least for my ears.
Ryan

Davey · « **Reply #12 on:** 28 Mar 2005, 05:35 am »

Quote from: ryno

Quote from: JoshK
How is this so? I don't think Behringer claims this. FIR filters are ones that are suppose to be phase linear, not the IIRs done in Behringer. IIRs still do the same phase shifts as regular analog xos.

Are these the same types of filters that are used in the EQ part of the behringers? If so, then this will also introduce phase shifts. sorry for the wrong info. But for me, the problems the EQ fixes are bigger than those it creates. At least for my ears.
Ryan

If you're worried about phase shifts the "EQ fixes" and crossover slopes create then products like the DCX2496 are not for you. In fact, your selection criteria eliminates most every kind of processor available.

Davey.

ryno · « **Reply #13 on:** 28 Mar 2005, 05:48 am »

Quote from: Davey

If you're worried about phase shifts the "EQ fixes" and crossover slopes create then products like the DCX2496 are not for you. In fact, your selection criteria eliminates most every kind of processor available.

Sorry about the confusion. What I ment was, the benifit of the EQ to tame peaks outweights the phase shifts introduced. This is for my system with the DEQ2496, I've never used the DCX2496 with the XO's
Ryan

JoshK · « **Reply #14 on:** 28 Mar 2005, 01:56 pm »

Just so that my position is clear, I have no position on whether FIR or IIR is better, whether phase matters or otherwise on these matters. I have had no experience in these matters and therfore don't have an opinion.

I have been reading up about this topic for a little over a year and came to no definitive conclusions, since the arena seems to be divided on this topic. Until I test it for myself I will not know.

csero · « **Reply #15 on:** 28 Mar 2005, 03:31 pm »

Quote from: timbley

One thing he was testing was the importance of phase alignment between drivers. He found that in blind tests, his golden ears heard no discernable difference as drivers were moved closer and further to the listener.

This is called Blauert and Laws criteria
Approximately for audibility the thresholds are the following:

Frequency Group delay
8 kHz 2 msec
4 kHz 1.5 msec
2 kHz 1 msec
1 kHz 2 msec
500 Hz 3.2 msec

Note: 1 ms is about 1 feet difference in the distance of the acoustic centers of the drivers

csero · « **Reply #16 on:** 28 Mar 2005, 03:59 pm »

Just very briefly:

In a typical audio system there are so many many components that alter phase and introduce frequency-dependant delays, that it really does not matter if some IIR filter adds some more.

No natural phenomenon causes significant pre-ringing - they all behave like IIR filters with little or no pre-ringing, and much post ringing.
Linear phase FIR filters have symmetrical -and usually long - pre and post ringing. Asymmetrical FIR filters have very little pre-ringing but they are minimum phase, not linear phase.

It can sometimes make sense to use a linear-phase (zero-phase) FIR filter, but most of the times the pre-ringing produced by such a filter is more disturbing that the frequency-dependant delay of a linear-phase filter.

Most DSP studio-monitors that feature FIR filters to compensate the drivers and use them as crossovers have a recommended minimum-phase crossover setting, because the spot where the different pre-ringing artifacts played by the different drivers cancel each other out would be very small in linear-phase mode.

IMHO the downside with IIR filters is that they need high floating-point precision to calculate precisely - but you can always use a minimum-phase FIR filter to get (nearly) the same result.

konut · « **Reply #17 on:** 29 Mar 2005, 01:17 am »

I was introduced to electronic crossovers about 1973. I heard a Altec Lansing VOT with one, and having used the passive version for PA purposes, I noticed immediately that the improvement was not subtle. The reduction in distortion when implemented in the voltage domain rather than the power domain, is dramatic. Although passive crossovers have gotten better, they still cant hold a candle to a correctly implemented active, either analogue or digital. Digital offers a futher reduction in the potential for distortion. As far as phase is concerned the drivers themsevles usually are, until recently, more prone to phase meandering than electronic crossovers. I think it was Audio magazine that used to print a graph of the phase plot of reviewed speakers and they usually looked like fly circling a plate of food. Having said all that, I've found, and this is purely anecdotal, speakers that are implemented with the acoustic centers in the same plane have better imagining and less wander than any other designs. If the speaker is made where the centers are not in the same plane, some form of correction is needed. The correction often adds something in addition to the planed correction that does nothing good to the sound. This is truley a case where less is more. Of course there are exceptions, I'm just giving you my general personal experience.

timbley · « **Reply #18 on:** 31 Mar 2005, 10:29 pm »

Thanks for all the input guys.

I'm feeling pretty relaxed about the phase issue now. That'll save me some dough. I can hear something happen when listening to pink noise if I reverse the phase of the tweeter. I can't see it on the RTA though, so it must be some sort of very narrow band interefernce thing. Listening to music, I can't tell if the tweeter has it's phase reversed or not. My method of blind testing is to turn the dial real fast without looking, and then sit back and see if I can guess if it's reversed or not.

timbley · « **Reply #19 on:** 26 Apr 2006, 07:42 am »

I've been using a couple of these Behringer crossovers for a while now to run my 5 way speakers. Over the last few months they developed a lot of strange noise and were sounding bad all around. I was ready to give up on them, but decided to do a little research and see what people might know.

I found the solution to the problem on this forum:
http://srforums.prosoundweb.com/index.php

The fix is simply to put waxed paper under the XLR boards. As I sat at the dining room table and tediously removed screws to get the XLR boards up, I was pretty much expecting that this wasn't going to work. It sounded too simple, too good to be true.

I'll be darned to heck! They sound great again! Apparently the boards sag a little over time and touch the bottom of the steel casing, creating all sorts of havoc.