active crossovers : off the shelf & DSP views/experiences

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active crossovers : off the shelf & DSP views/experiences

What do people think of off the shelf active crossovers such as those from Behringer and Rane (in a bi/tri amping setup) as a means to avoid the complexity of designing/implementing one ?

Also, I read in an article that crossover designs don't just determine the frequency of the crossovers but are also designed to correct for other aspects of the drivers such as resonance ; is this true ? And if so, presumably the Rane and Behringer units are of no relevance in a hi-fi context ?

Views and experiences ?
 
Rane

hello,

Behringer make cheap products with minimum-cost parts but have a decent engineering team, and so the products (especially in the digital realm, ie: DCX2496, DEQ2496) sound VERY good IF and only if fed a digital signal.

Rane make top-quality crossovers using the best components. I have a Rane AC23B and it's a fantastic unit. Build quality is impeccable, the layout is beautiful, the specifications are fantastic and the sound is transparent. It also has a delay on all non-tweeter channels, which is awesome as you can compensate for different acoustic centers. Rane is also a great company to work with, their "Tech Notes" on their website are very well written, informative, and useful.

Behringer also make decent equipment, but they're built to a completely different price-point, and they steal the majority of their designs from other companies like Mackie, Alesis, etc. They've been sued for this, and have lost several times in the past. Nonetheless the DCX2496 is an incredible product, you just need a 6-channel volume control. Pansonic digital receivers are very good for this, as they have a discrete 6-channel input, and have fantastic amplifiers. For $250 each for the DCX2496 and the Panasonic XR50, you can have a actively tri-amplified system with all the bells and whistles, with EQ for each channel, etc...

cheers,

-tal
 

thylantyr

Member
2001-02-19 10:38 pm
Mars
Re: Rane

Behringer make cheap products with minimum-cost parts but have a decent engineering team, and so the products (especially in the digital realm, ie: DCX2496, DEQ2496) sound VERY good IF and only if fed a digital signal.

I'm using the DCX with analog inputs and the sound is great.

Rane make top-quality crossovers using the best components.

I can show you schematics where they use 'cheap parts' too.

Lets look at this in detail. The DCX uses 4580 opamps.
The Rane AC24 uses ............. 4580 opamps. /// rofl ///
Rane also uses the archaic TL072 opamp in some designs...

Nonetheless the DCX2496 is an incredible product

yes it is.

you just need a 6-channel volume control.

no you don't, use analog input :cool:
 
Most "fixed" crossovers -like the analog Behringers- don't provide a good way to compensate for driver flaws (and real-world drivers have flaws). So, you would likely need to add passive components to bridge the gaps between real-world drivers and textbook crossovers...a good active analog/passive hybrid can be as much work as a well designed passive crossover.

On the other hand, DSP based crossovers -like the DCX2496- can EQ individual driver response, delay, phase, as well as several other very useful functions...highly recommended.

"Wings" WTW project
 
I can'y say about their XO but I use the Behringer Ultra-Curve Pro for room EQ and am impressed by the results. Getting it set up right is an adventure just because it has so many capabilities beyond what I actually need. I opened it up some time back to upgrade the firmware and couldn't see any grounds to fault the manufacturing quality. Sometimes I think the "build quality" issue confuses expense and flash for substance.

I recall somone writing about B. Carver that only he could find a way to substitute cheap components and improve reliability at the same time. This was not meant as a compliment which struck me a peculiar thinking.
 
Thylander and RobWells:

Do you use RCA adapters for your inputs and outputs or do you actually used the balanced XLR inputs and outputs? Please give details about how you use your DCX's and what kind of systems you have. I'm in the process of testing an active 3-way with the Behringer CX3400 and am seriously considering the DCX.


RobWells:
What benefits does the DEQ add in conjunction with the DCX? Doesn't the DCX already have EQ functions?
 
For analog crossovers I have not been able to get a good sound without using custom RC combinations between the buffer stages. No combination of the standard slopes could build the required transfer function. If you have read linkwitzlab.com notes on active crossovers you understand how powerful active crossovers can be.

I have a Krell Xover that supports plug-in modules, and a DIY Xover with Borbley JFET buffers. The JFET articles on the Borbley website are excellent.

Longer term I keep watching for a complete digital solution..digital from the DVD/CD, through a digital cable or fiber to the speaker, to a digital Xover with room equalization driving the bit stream to digital amps.
 

thylantyr

Member
2001-02-19 10:38 pm
Mars
m0tion said:
Thylander and RobWells:

Do you use RCA adapters for your inputs and outputs or do you actually used the balanced XLR inputs and outputs? Please give details about how you use your DCX's and what kind of systems you have. I'm in the process of testing an active 3-way with the Behringer CX3400 and am seriously considering the DCX.


RobWells:
What benefits does the DEQ add in conjunction with the DCX? Doesn't the DCX already have EQ functions?

My sound system is never permanent, actually it's setup more as
a development tool. I'ts a simple setup.

DVD player -> Preamp -> DCX2496 -> Amps -> Line array

The DVD and preamp is RCA output. One of my amplifiers is
RCA input, the others are XLR input.

I made my own RCA to XLR cables, but you can buy them too.
For XLR to RCA on the Behringer output, I made a special cable to reduce
the gain 6dB to reduce hiss. This was suggested on the Behringer
thread, it works good when mating to a home amplifier using RCA
input.
 

SpeakerBob

Member
2002-08-15 6:21 pm
UK
Pretty similar here. Use the lexicon dc-2 into the DEQ, then to dcx, then to amps. My power amps have gain controls which helps.

The deq accepts 'home level' signals as well as pro level signals whereas the dcx only works at pro (I believe - its been a long time since I've been round the back of my rack. )

I made all my own leads aswell.

The deq is not really needed here as I'm only using 1 band of parametric eq at the moment. Could easily do without it at the moment. (the dcx has enough processing to do this)

Maybe when I do my 2-way subs the deq will become more important - I use a feedback destroyer on my subs at the moment but am intending to get rid of it in favour of the deq.

If I was digital only, and stereo only I'd be looking at a used meridian 518 as a preamp. Unfortunately I have a lot of vinyl..

http://www.stereophile.com/digitalsourcereviews/367/index3.html

Cheers,

Rob
 
I took an XLR cable from Radio Shack, cut it in half and terminated it with RCA per the methods decribed here:

http://www.rane.com/note151.html

http://home.comcast.net/~marcwhitney/public/grounding_whitlock.pdf

Note the later claims there can be some improvement over standard unbalanced RCA-to-RCA when you lett the shield run the length of the cabling. You might not get this benefit if you use an adaptor that lets you use and unbalanced RCA type interconnect cable and just transition at the balanced input.
 
thylantyr said:


My sound system is never permanent, actually it's setup more as
a development tool. I'ts a simple setup.

DVD player -> Preamp -> DCX2496 -> Amps -> Line array

The DVD and preamp is RCA output. One of my amplifiers is
RCA input, the others are XLR input.

I made my own RCA to XLR cables, but you can buy them too.
For XLR to RCA on the Behringer output, I made a special cable to reduce
the gain 6dB to reduce hiss. This was suggested on the Behringer
thread, it works good when mating to a home amplifier using RCA
input.


Could you state again for me exactly how you would terminate the unbalanced cable into a balanced connector in order to get the -6dB gain?
 
From the Behringer DCX outputs connect Pin 1 to the RCA shield and Pin 2 to the RCA center pin. Leave Pin 3 unconnected. This will "program" the output amplifier inside the DCX to 6db less gain than it would be if you jumpered Pin 1 to 3 as would be done inside a commercial XLR/RCA adaptor.

This forces you to increase the signal level coming from your source by 6db (times 2) to compensate. That's what you want because it increases the internal levels inside the DCX.

Make sense?

Cheers,

Davey.
 

george a

Member
2002-05-06 1:12 pm
oz
Hi All

I too have a DCX2496 and am very happy with it using it as a 3 way controller. In terms of volume control this is done at the analog input end with 6 (1 per channel ) attenuators at the output end.

The change my sytem experienced by going triamped with the DCX was very worthwhile, to illustrate the next most dramatic increase in sound quality (with changes in electronics as opposed to speakers) was regulating power supply to front end of (hafler ) power amp.(very dramatic)

The DCX in my system provides 3 stereo bands at 48db/octave+ time delay + some eq on each driver before it runs out of processing power.

Current setup uses 2 hafler dh-200 clones + 1 aleph 5 clone on mid).
Waiting to get time to build another Aleph to power the tweet - or even a Pass F1.

All my system is at this time unbalanced with connectors all done as per Rane's excelent documentation.

However the temptation to go to digital input is very great but it raises the problem of the 6 channel variable attentuator.
If I understood or could find a layman's guide to building a relay based attenuator I would do so - programming PIC or whatever that is starts to make my eyes glaze over.
The pricing of a dact attenuator is prohibitive...around here the DACt is not much less than buying a DEQ....tempting.

If I had the money would probably go for a better built unit than the DCX in the hope of better performance- but I suspect in my case it would be mostly on ego grounds- I'm really that happy with it.
Some of the mods on this forum look great but again cost (if going to use transformers for output stage for example ) is too me excessive.-but is most likely still cheaper than buying another brand with same capabilities I'm sure.

I'm not sure if it is a original Behringer design or as has been implied a design taken from elsewhere..

cheers
 

SpeakerBob

Member
2002-08-15 6:21 pm
UK
Hi Rick,

I use the DEQ with the DCX, so cannot really listen to the DEQ in isolation (would still need the DCX in the chain to evaluate the DEQ.)

That said I cannot hear a quality drop putting the DEQ into the chain.

This is the DEQ2496 btw - the older DSP8024 ultracurve had a noticable effect on the signal. (I used to own one of them)

Cheers,

Rob.
 
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