# Active crossover for main speakers



## adobo (Jun 18, 2008)

Over the years, I have explored the idea of using active crossovers and dedicated amplifiers for each driver on main speakers. I know that there are many discussions on this topic in other forums already but I wanted to get some opinions here..

There are certainly several ways that one could jerry rig a solution (using pro-audio gear or car stereo gear) but there seems to be a lack of a decent sounding/reasonably priced off the shelf solution. Obviously this is due to very low demand.

So my question is, why is there such low demand for something so seemingly beneficial?


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## dvenardos (Sep 27, 2008)

I have never tried so I can't say if it is something worth doing, but it certainly adds a lot of complexity.


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## adobo (Jun 18, 2008)

dvenardos said:


> I have never tried so I can't say if it is something worth doing, but it certainly adds a lot of complexity.


Well, it does add additional complexity. Currently, it is a lot more complex because of all the jerry rigging that is required to convert pro equipment for home use. Also, almost all home speakers, even high end ones, cannot be ordered without their passive crossovers as very few people even consider active systems in the home.

The pay off seems significant though. I mean, look at all the trouble people go through with their subwoofers. And subwoofers play only what, two octaves? Most of the action in music is happening in your main speakers.


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## dvenardos (Sep 27, 2008)

Why do you think an active system would necessarily sound better than a passive system? Is it that you want an infinitely variable crossover? It seems like room treatments are the biggest target for sound improvement, but at the lower octaves eq is necessary because room treatments aren't effective that low.


adobo said:


> The pay off seems significant though. I mean, look at all the trouble people go through with their subwoofers. And subwoofers play only what, two octaves? Most of the action in music is happening in your main speakers.


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## mojave (Dec 30, 2006)

I think the reason most don't do it is because it requires an understanding of the driver's parameters and speaker design. You also have to know how to take accurate measurements and interpret them. Putting all of these together is quite daunting for the average user. Even if one starts with speakers and removes the passive crossovers, getting it to measure as good with the active crossovers could be quite challenging. You have to adjust the gain for each driver and you need to select the best type of crossover and slope, etc. (I love using etc. It makes it sound like I know more than I do. )

I have a Behringer DCX2496 and enough amplifier channels to use active crossovers on my X-Omni speakers. For the reasons above I decided to just buy the Skiing Ninja upgraded crossovers.

An active crossover for the mains is difficult to integrate into a home theater system. Usually you have to convert to analog and then have the active system convert back to digital for the DSP and then convert back to analog for connection to the amplifier. This is because the decoded Dolby TrueHD or DTS-HD can't be sent out digitally once it is decoded (as its own channel). This results in a lot of wiring in addition to your satellite channels and subwoofer. This is how the Seaton Sound Catalysts work, but they are a little easier to integrate since the DSP and amplification is all one module. You still need power for each speaker, though.

John at Acoustic Elegance has said that he is working on an open baffle kit that uses the minidsp active crossover.


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## adobo (Jun 18, 2008)

To use your example... presumably, all X-omni's were built with xo's using the same xo frequency, using the same xo type, using the same slope. Example, 12/db oct, L-R at 2000HZ.

If swapping out the passive xo for an active xo, why would you not start with those same settings? Setting the gains would take some work but I trust my ears and I suspect you trust your ears too. BTW, if you think it's hard getting optimal balance between tweeter and woofer using an active xo, try it using passive xo components.

This question is related to tweaking speakers for more optimal performance in listening to music on a dedicated 2.1 channel system. I have a home theater system but I don't have any expectation of that system sounding very musical.




mojave said:


> I think the reason most don't do it is because it requires an understanding of the driver's parameters and speaker design. You also have to know how to take accurate measurements and interpret them. Putting all of these together is quite daunting for the average user. Even if one starts with speakers and removes the passive crossovers, getting it to measure as good with the active crossovers could be quite challenging. You have to adjust the gain for each driver and you need to select the best type of crossover and slope, etc. (I love using etc. It makes it sound like I know more than I do. )
> 
> I have a Behringer DCX2496 and enough amplifier channels to use active crossovers on my X-Omni speakers. For the reasons above I decided to just buy the Skiing Ninja upgraded crossovers.
> 
> ...


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## mojave (Dec 30, 2006)

adobo said:


> To use your example... presumably, all X-omni's were built with xo's using the same xo frequency, using the same xo type, using the same slope. Example, 12/db oct, L-R at 2000HZ.
> 
> If swapping out the passive xo for an active xo, why would you not start with those same settings? Setting the gains would take some work but I trust my ears and I suspect you trust your ears too. BTW, if you think it's hard getting optimal balance between tweeter and woofer using an active xo, try it using passive xo components.
> 
> This question is related to tweaking speakers for more optimal performance in listening to music on a dedicated 2.1 channel system. I have a home theater system but I don't have any expectation of that system sounding very musical.


The low pass and high pass might have a L-R crossover, but the high pass might be 12 dB/octave and the low pass might be 24 dB/octave. Also, the tweeter might have an efficiency of 92 db and the woofer 88 dB. With the room interactions, it would be hard to get a flat frequency response without measuring and using a gated response. You can't just "do it by ear." Because the driver in the X-Omni is listened to at a 90 degree angle to the axis, you might have to use a different slope than the tweeter.

It is easy enough to run through a bunch of settings and you might get close and even do better. Maybe I'll try it with a pair of my speakers some day.


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## django1 (Jan 28, 2009)

mojave said:


> (I love using etc. It makes it sound like I know more than I do. )


Lol. I don't know if you know a lot but that is smart!


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## lennon_68 (Jan 27, 2008)

If you're going to go with an active setup you should skip the commercial side of things altogether. The most difficult and crucial aspect in designing a loudspeaker is the crossover. It makes very little sense to pay $ for a commercial loudspeaker and then ask them to leave out the XO - leaving you with a very nice looking enclosure (probably) and some very cheap drivers. You'd be much better off going the full DIY route if you want to tackle such a project. Pick up some nice drivers, a Behringer DCX2496, and some amps and go to town. Hooking up the Pro Audio gear to consumer level electronics isn't difficult either - yes they do take XLR or 1/4" TRS connections but one can easily build/buy an RCA to XLR (or RCA to 1/4 TRS) cable. Also some of the high end Onkyo/Integra preamps have XLR outputs.

Honestly though I don't get the impression that you have a firm grasp on what you'd be getting yourself into. You seem to be under the impression that creating an XO is as simple as choosing a slope and a frequency... and being able to tweak those will result in a better sounding speaker than what the MFG chose... If only it were that easy. Before you buy any gear do some reading - something like the Loudspeaker Design Cookbook - just to get an idea of what you're in for


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## tesseract (Aug 9, 2010)

django1 said:


> Lol. I don't know if you know a lot but that is smart!


Nebraskans are eminently practical. :smoke1:


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## mojave (Dec 30, 2006)

tesseract said:


> Nebraskans are eminently practical. :smoke1:


Nebraskans are eminently practical, etc.


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## tesseract (Aug 9, 2010)

*Consider this*

http://www.rane.com/pdf/pi14dat.pdf :dancer:


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## mojave (Dec 30, 2006)

That needs its own thread. It is hilarious. Did you notice the fine details like the smiley face XLR connectors and the warning statement:

WARNING - TO PREVENT
THE POSSIBILITY OF
BEING VAPORIZED, DO
NOT ATTEMPT TO OPERATE
THIS UNIT IN THE
PRESENCE OF AUDIOPHILES.

Even the references are funny:

3. T. Pennington, and D. Bohn, “Adaptive This and That for Stereophonic Sweeping From Here to There: presented at the 163rd


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## adobo (Jun 18, 2008)

lennon_68 said:


> If you're going to go with an active setup you should skip the commercial side of things altogether. The most difficult and crucial aspect in designing a loudspeaker is the crossover. It makes very little sense to pay $ for a commercial loudspeaker and then ask them to leave out the XO - leaving you with a very nice looking enclosure (probably) and some very cheap drivers. You'd be much better off going the full DIY route if you want to tackle such a project. Pick up some nice drivers, a Behringer DCX2496, and some amps and go to town. Hooking up the Pro Audio gear to consumer level electronics isn't difficult either - yes they do take XLR or 1/4" TRS connections but one can easily build/buy an RCA to XLR (or RCA to 1/4 TRS) cable. Also some of the high end Onkyo/Integra preamps have XLR outputs.
> 
> Honestly though I don't get the impression that you have a firm grasp on what you'd be getting yourself into. You seem to be under the impression that creating an XO is as simple as choosing a slope and a frequency... and being able to tweak those will result in a better sounding speaker than what the MFG chose... If only it were that easy. Before you buy any gear do some reading - something like the Loudspeaker Design Cookbook - just to get an idea of what you're in for


Skipping consumer level speakers altogether assumes that you don't already own speakers. And to me, the one of the best/least expensive ways to get first hand knowledge of the real differences between a passive and an active network is to use have both in hand. I suppose I could ask the internets for their others' experience on this but I prefer to have first hand knowledge.

I've been down this DIY road before and intend to go there again. This is really the motivation for this question. I had a Focal MTM kit with a custom built network. (I did not personally design or build the network. The vendor put that together for me.) To me, the inherit flaw of this approach (using a DIY kit without an active crossover) is that though drivers and cabinet are equal to or better than what I could purchase on the consumer side of things, you will likely not have not heard the speaker until after the purchase. Once the speakers are up and running, regardless of how "good" the drivers are, you still have a reasonably good chance of not having an appreciation for how the speakers sound. Without an active crossover and dedicated amps, what options do you have to tweak the way the speakers sound?

I realize that for mainstream companies, it does not make any sense to offer active crossovers as a separate component. But I am asking this question on a niche product vendor's forum. It strikes me as odd that I cannot find one consumer level active crossover network that is sold by even a niche vendor. 

Thanks for the suggestion regarding the the Loudspeaker Design Cookbook. It's been over 15 years since I lost my second copy of it so I should probably pick up another.


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## lennon_68 (Jan 27, 2008)

adobo said:


> Skipping consumer level speakers altogether assumes that you don't already own speakers. And to me, the one of the best/least expensive ways to get first hand knowledge of the real differences between a passive and an active network is to use have both in hand. I suppose I could ask the internets for their others' experience on this but I prefer to have first hand knowledge.
> 
> I've been down this DIY road before and intend to go there again. This is really the motivation for this question. I had a Focal MTM kit with a custom built network. (I did not personally design or build the network. The vendor put that together for me.) To me, the inherit flaw of this approach (using a DIY kit without an active crossover) is that though drivers and cabinet are equal to or better than what I could purchase on the consumer side of things, you will likely not have not heard the speaker until after the purchase. Once the speakers are up and running, regardless of how "good" the drivers are, you still have a reasonably good chance of not having an appreciation for how the speakers sound. Without an active crossover and dedicated amps, what options do you have to tweak the way the speakers sound?
> 
> ...


Converting a speaker you already have to active bi-amp does make sense for the reasons you stated - also you could convert only one and compare them against eachother. I was referring more to your comment that even high end speakers do not offer an active version.

Setting something like this up is not that difficult from a hardware perspective. It can get expensive to buy all of the components but once you have them you'll likely get years of use out of them. The Behringer DCX2496 is a very capable active crossover - it's got 3 inputs and 6 outputs. Although intimidating to look at it's actually quite intuitive to use (that's what I'm currently using). Like I said in the last post you'll need some RCA to XLR cables - you can buy these or just make them (wire the ground of the XLR to the negative of the RCA). The DCX will do pretty much anything you can imagine for an XO. From the DCX you'll probably be going back to RCA which is why I prefer to build my own cables - buy 6 RCA cables and 6 XLR cables and make yourself 6 RCA -> XLR male and 6 RCA -> XLR female. Alternatively you could keep with the PA gear and buy some PA amps to push your speakers (which is what I'm running right now although I've got some X-amps I'm going to try out in their place).

It sounds like you're pretty serious about giving it a try - I say go for it, as long as you have an appreciation for what you're getting yourself into :yes:. Keep an eye on eBay and you should be able to pick up a DCX for around $200 shipped - maybe even as low as $175 if you're lucky (there's one on there right now for $215 shipped). The resale value on them is good since they're so versatile. If you find it's not for you just sell off the DCX, you're probably out $35 bucks or less.


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## madpoet (Jul 26, 2010)

Not advocating this, but the Loudspeaker Design Cookbook can be found online


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## keenween (Feb 12, 2008)

These are reportedly of good quality:
http://www.marchandelec.com/xovers.html

I like the idea of active speakers! Not sure I could afford what I would want at this point though.


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