Active crossovers and speakers - amplification? - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 41 Old 11-03-10, 11:45 AM Thread Starter
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Active crossovers and speakers - amplification?

I've seen some interesting plans for 2-3 way speakers that use active crossovers.. By active crossovers, I mean Behringer DCX2496 or some of the cheaper models.

However, with active crossovers and separate line level outputs - with a pair of 3 way speakers, you're looking at having 6 sources to amplify. What do most DIY builders do - when they need to amplify 4-6 channels for a pair of speakers?

Multiple pairs of amps? Or a multichannel HT amp?

Or...... are active crossover arrangements that uncommon because of the issues with number of amp channels needed.
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post #2 of 41 Old 11-03-10, 12:11 PM
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Re: Active crossovers and speakers - amplification?

Zeitgeist,

This method, called bi-amping (or tri-amping for three ways) has been around for a long time in commercial sound reinforement. It separates the frequency ranges prior to final amplification. This is different than a passive crossover in a cabinet, which takes a full-range signal and attempts to deal out frequencies to different drivers, and hopefully presents a relatively flat frequency response output.

Although it does add quite a bit of complexity, it has a few advantages....

1. You are not locked in to a fixed crossover and can change the frequency response of the signal driving each of the cabinets (you can't really change the response of a driver in a particular cabinet, just compensate for it)

2. You can use higher power amps for the low frequency stuff, and less powerful and perhaps better sounding ones for the mid to high frequency parts.

3. You don't lose power in passive crossovers


Does it sound better? If you are going for LOUD it might be the way to go. Personally, I have let this particular technique go, in favor of reduced complexity.

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post #3 of 41 Old 11-03-10, 12:25 PM Thread Starter
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Re: Active crossovers and speakers - amplification?

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torceador wrote: View Post
Zeitgeist,

This method, called bi-amping (or tri-amping for three ways) has been around for a long time in commercial sound reinforement. It separates the frequency ranges prior to final amplification. This is different than a passive crossover in a cabinet, which takes a full-range signal and attempts to deal out frequencies to different drivers, and hopefully presents a relatively flat frequency response output.
torceador
Hi Torceador,

I've read about the advantages - and personally I like to tweak and play with things - so being able to change the crossover points and gains of each driver had some appeal to me..

I have an Onkyo PRSC886 - which supports biamping (which I'd like to do.....) - but I 'd lose 2 of the surround channels by biamping. It uses 2 of the surround channels for it. But I don't own bi-ampable speakers anyway.

I was just curious if the practicality of needing to power 4-6 channels makes biamping/triamping unpopular.
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post #4 of 41 Old 11-03-10, 01:28 PM
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Re: Active crossovers and speakers - amplification?

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Zeitgeist wrote: View Post
I've seen some interesting plans for 2-3 way speakers that use active crossovers.. By active crossovers, I mean Behringer DCX2496 or some of the cheaper models.

However, with active crossovers and separate line level outputs - with a pair of 3 way speakers, you're looking at having 6 sources to amplify. What do most DIY builders do - when they need to amplify 4-6 channels for a pair of speakers?

Multiple pairs of amps? Or a multichannel HT amp?
I use multiple amps.

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Or...... are active crossover arrangements that uncommon because of the issues with number of amp channels needed.
In terms of commercial designs, I feel active designs are less common for the simple reasons of most philes are used to passive designs plus it's much harder to mix and match amps and speakers, and in DIY for the added cost and/or complexity. DIYers seem to come in two basic performance flavours, bang for $ and push the performance envelope. The former will tend to go for passive, though for a 2 way, once a few xover components are purchased you aren't all that far from the cost of the active if you hunt around and buy secondhand amps at good prices.

I had my first active system 20 years ago and whilst I've built some passive designs since, the advantages of active, especially with the digital designs on offer are so great that I don't bother with passives at all, and can never see me going that way again. Designing passive xovers is a massive pain, even with xover software such as PCD and they don't have other features such as EQ and delay, let alone the ability to instantly change a setting to see how that sounds.

I don't understand the complexity argument at all. Once in situ and dialled in there is no need to touch anything except source selection and volume control, ie exactly the same as a passive system, The only time I could see it being a real issue is if you were extremely tight for space and even then there are work arounds.
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post #5 of 41 Old 11-03-10, 01:34 PM Thread Starter
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Re: Active crossovers and speakers - amplification?

Hi A9X- Thanks for your comments...

I've seen a number of commercial arrangements that rely on active crossovers (most?) -- so interesting to see that it's so much less common in non-commercial environments.

But no doubt - there are a lot of reasons why commercial use active - from flexibility to high power..

Active crossovers and multiple amps has some appeal to me - in part because of passive crossover design. Seems like designing a good crossover is much harder than other aspects of speaker design.
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post #6 of 41 Old 11-03-10, 01:45 PM
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Re: Active crossovers and speakers - amplification?

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Hi A9X- Thanks for your comments...

I've seen a number of commercial arrangements that rely on active crossovers (most?) -- so interesting to see that it's so much less common in non-commercial environments.

But no doubt - there are a lot of reasons why commercial use active - from flexibility to high power..
Cheers. Undoubtedly the performance factors of flexibility and no power loss and stable performance with temperature (ambient and heated with use) of active over passive makes obvious engineering and commercial sense for large PA systems. Why apart from the reasons I mentioned this hasn't translated to home systems baffles me to some extent at least in the more expensive end of the scale. A set of Meridian or ATC speakers would only need a source and preamp to make a complete 2ch system of very high quality and WAF as it would have a low aesthetic footprint.

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Active crossovers and multiple amps has some appeal to me - in part because of passive crossover design. Seems like designing a good crossover is much harder than other aspects of speaker design.
Passive xovers are difficult to do and get right, plus can consume a lot of excess cost in redesign if parts are changed out. Plus no passive could ever begin to come close to what something like a DEQX could achieve.
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post #7 of 41 Old 11-03-10, 01:48 PM Thread Starter
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Re: Active crossovers and speakers - amplification?

What are losses like.... % wise in terms of total power for a driver in passive crossovers?

10%? 30%?
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post #8 of 41 Old 11-03-10, 01:55 PM
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Re: Active crossovers and speakers - amplification?

In domestic use, except for LF xovers to subs or extremely inefficient speakers, not much. I doubt more than 1/2 dB, worst case outside of the exceptions.
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post #9 of 41 Old 11-05-10, 01:06 PM
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Re: Active crossovers and speakers - amplification?

If you are interested in active crossovesr check out minidsp prossesers very slick units.
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post #10 of 41 Old 12-13-10, 09:55 AM
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Re: Active crossovers and speakers - amplification?

I'm using some active EQ and use an old Yamaha receiver as a multichannel power amp, in addition to an Emotiva XPA5 that powers the main speakers. I use a new Yamaha receiver as if it were a pre pro, not using its power section at all. For a middling diy er like me, active EQ is just easier to get right, and that makes home building speakers practical for me.
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