The sonic benefits of an active crossover. A discussion.

Papa smurf and the baby smurfs sound very good to these ears. I just can't help but feel like Tinkerbell will jump out from behind them any second. I much prefer the Nautilus shape, alas that is B&Ws IP. I do believe the form follows function in the case of Giya loudspeakers and isn't just an attempt to look different.

Groucho said:

Is it just me, or is the Giya G2 absolutely hideous to look at? I've seen them and their ilk at shows, and they never cease to surprise me in their ugliness. They look like the sort of thing that only an engineer would imagine was stylish or iconoclastic.

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+1 and this is my reaction to them .. I don;t see myself having any of those in my listening room ... I was told they sound great still ... they are to me almost repulsive ...

FrantzM said:

+1 and this is my reaction to them .. I don;t see myself having any of those in my listening room ... I was told they sound great still ... they are to me almost repulsive ...

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They remind me of "the Diva"in the movie "The Fifth Element" but in spite of being butt ugly they sound incredible

Steve Williams said:

They remind me of "the Diva"in the movie "The Fifth Element" but in spite of being butt ugly they sound incredible

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Point taken. They should be listened only in blind test conditions.

Keith W. said:

would subtracting powered components improve performance?

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Theoretically, yes...

Why not get rid of your preamp and power amp ... and buy an integrated amp instead?

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Less wire, fewer jacks and plugs, fewer noise-generating component parts...why not indeed?

Mike Lavigne said:

my Evolution Acoustics MM7's are an example of how and where to use an active crossover in a high resolution speaker; fully integrated for deep bass only.

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Why stop at deep bass? Why not fully integrated active crossovers for each stage? Is there something about deep bass that benefits from active crossovers but is a detriment to mids and highs?

Tim

Phelonious Ponk said:

Would subtracting powered components improve performance

Theoretically, yes...

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Sorry Tim, I don't think the answer is a theoretical "yes" Audiophiles are really inconsistent when it comes to whether something is a component or not. For example, a passive crossover built into a speaker is not considered a component, but an active crossover outside the speaker is considered a component, even if there is no passive XO in the speaker. So, what makes it a component? It is because it is powered, that makes it a component.

Okay then. Are passive preamps components, because they are not powered? What about a passive preamp which is built into a power amp - are those components?

If your power amp has individual power supplies for each channel (instead of one power supply for both), do you now have two components instead of one, and have you reduced sound quality because you have introduced more components into your system? Or do they only become components when you remove them from the same chassis and turn your dual power supply stereo amp into monoblocks?

As I have pointed out ... if fewer components are better, then why not forget about preamps and power amps ... and just use an integrated amp? (Ignoring the fact that the integrated amp has all these components built into one chassis and using the same power supply).

My question to people who say that active crossovers are separate components is: what is your definition of a "component"?

Phelonious Ponk said:

Mike Lavigne said:

"...my Evolution Acoustics MM7's are an example of how and where to use an active crossover in a high resolution speaker; fully integrated for deep bass only."

Why stop at deep bass? Why not fully integrated active crossovers for each stage? Is there something about deep bass that benefits from active crossovers but is a detriment to mids and highs?

Tim

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Hi Tim,

I am only just learning about this and am interested in learning more. The article interviewing Andy Payor, Laurence Dickie of Vivid and Richard Vandersteen definitely espoused the beneficts of active crossovers.

"Dickie: Assuming that filtering at the signal level and connecting the low-frequency drivers directly to the amplifier output offers the ideal approach, perhaps it’s better to ask, What are the downsides of LF passive filtering? Clearly, the size of the components involved in the passive low-pass filter cause much concern; with inductors in the range of 5 to 10mH and capacitors of a few hundred microfarads, the temptation is to go for cored inductors and electrolytic capacitors, both of which are frowned upon in high-end designs because of their very real shortcomings. The alternative use of air-cored inductors employing kilos of copper, and polypropylene capacitors occupying a liter of space, causes sharp intakes of breath when considering the cost. Furthermore, the LF driver is the one that experiences the greatest excursion and hence risks the greatest modulation of its impedance. This modulation, in turn, causes the passive filter response to vary with the voice-coil position, giving rise to a whole gamut of distortion mechanisms. Of course, this variation of impedance with position is one of the effects we try to minimize through careful design of the magnetic circuit of our bass drivers."


On also doing an active crossover one driver up from the bass driver, Laurence Dickie said:

"Whether the high-pass filtering of the next driver up is accomplished at signal level or left to the passive filter is another question. The simplest thing is to keep the passive filter unchanged and drive it with a full-bandwidth signal, but this wastes amplifier-voltage headroom. Removing the high-pass components, unfortunately, cannot be done without redesigning the whole of the circuit for that band, so it’s a nontrivial operation and of course requires that the whole signal go through an active high-pass filter, which some may find ideologically challenging simply because they feel every stage of electronics has to be messing the signal up in some way."

What do you think of this point? Is there a point where the problems identified above in the bass driver (large inductors and capacitors) is diminished with smaller drivers such that passive crossovers either are no better/worse than active or that other complexities in active crossovers make passives a better way to design? thanks for your thoughts. I know you've been a big proponent of actives for a long time, and certainly if you read this article...these three big designers are moving your way.

BTW, Rasmussen of Gryphon has also said the best is to design the crossover, amp and bass driver together...because designing an amp to deliver bass to an unknown driver with unknown varities of characteristics is never going to be quite as good.

Keith_W said:

My question to people who say that active crossovers are separate components is: what is your definition of a "component"?

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It looks to me as if you're getting hung up over categories here, rather than examining attributes of a complete system. For myself (though I don't self-identify as an audiophile particularly) I haven't been arguing about 'components' rather boxes - an additional box can't improve the signal because it can only add noise and distortion to the signal, it can never take them out. Having the same parts (transistors, passive components etc.) in the same box with the same mains power source is a step forward because then there's no additional noise-inducing loop of the additional mains supply lead and also no interconnects. A passive preamp is an additional box without the mains supply - hence only suffers the degradation (additional noise) of interconnects.

So its not necessary to talk about definitions of components, that's a distraction. Everything should be as simple as possible, but no simpler.

lloydelee21 said:

On also doing an active crossover one driver up from the bass driver, Laurence Dickie said:

"Whether the high-pass filtering of the next driver up is accomplished at signal level or left to the passive filter is another question. The simplest thing is to keep the passive filter unchanged and drive it with a full-bandwidth signal, but this wastes amplifier-voltage headroom. Removing the high-pass components, unfortunately, cannot be done without redesigning the whole of the circuit for that band, so it’s a nontrivial operation and of course requires that the whole signal go through an active high-pass filter, which some may find ideologically challenging simply because they feel every stage of electronics has to be messing the signal up in some way."

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Is it just me, or does mixing passive and active seem like a very limp thing to do? It's muddled and confused, and I would think not a great concept to sell to your customers. It's not exactly the Big Idea that you could state in a sentence in your brochure.

Is it just me, or does mixing passive and active seem like a very limp thing to do? It's muddled and confused, and I would think not a great concept to sell to your customers. It's not exactly the Big Idea that you could state in a sentence in your brochure.

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Hello Groucho

It's done all the time. I don't see an issue with it at all. There are plenty or systems with powered subwoofers and passive tops. Any 3 way system that is biamped is a mixed system. Anyone who uses a preamp with analog bass management ends up with a biamped and mixed system. I think every one is getting too hung up on this. All Passive, All Active or a mix of both can give excellect results. It's all in the implimentation.

Rob

opus111 said:

It looks to me as if you're getting hung up over categories here, rather than examining attributes of a complete system.

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This is why I get exasperated - I am arguing that it does not matter whether you call it a component or not, or whether it has a power supply or not, or whether it is hooked up with an interconnect or not - because what matters is that the job is done in the context of the complete system! What you fail to see is that just as an additional box may not change the signal, subtracting the same box will not degrade the signal. You are, in fact, arguing that having all the components in the same box with the same power supply will improve the sound. Well in that case, why not buy one of these which has a CD player, DVD player, preamp, and 5.1 power amp built into the same box?

Ah, forget it. I get the feeling that i'm talking to walls.

Keith_W said:

You are, in fact, arguing that having all the components in the same box with the same power supply will improve the sound.

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Yes, all other things being equal that is so. The best cable is no cable at all.

Well in that case, why not buy one of these which has a CD player, DVD player, preamp, and 5.1 power amp built into the same box?

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Oh did you notice what you did there? You suddenly changed from a discussion about a hypothetical high-end audio setup to a specific integrated unit which emphatically does not keep all the other things equal. Easy to see the flaw in your logic there but odd that you haven't noticed.

opus111 said:

Yes, all other things being equal that is so. The best cable is no cable at all.

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Vague, dubious and dangerous statement IMHO. As no cable does not exist it can not be verified. Second, as the components being connected are not ideal, it is not sure than the real cable does not have a specific purpose improving sound quality-

A cable can improve the quality of the signal its carrying can it?

opus111 said:

A cable can improve the quality of the signal its carrying can it?

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A cable transfers the signal between two units - its function is much more complex than you seem to think. BTW my sentence addressed sound quality - what are calling the "quality of the signal"?

microstrip said:

A cable transfers the signal between two units - its function is much more complex than you seem to think.

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How I seem to think is a function of your own perception.

BTW my sentence addressed sound quality - what are calling the "quality of the signal"?

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How close to the originating end signal the far end's signal is. Will that do for a start?

Incidentally you said my statement was 'dangerous' (in your opinion). Dangerous for whom?

opus111 said:

How I seem to think is a function of your own perception.

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Yes, my perception tells me that when you refer to "signal quality in a cable" ignoring the whole context you are oversimplifying and the conclusion will not be correct.

opus111 said:

How close to the originating end signal the far end's signal is. Will that do for a start?

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No. The originating signal is affected by the cable and the charge. I hope you are not referring to the famous null test next.

opus111 said:

Incidentally you said my statement was 'dangerous' (in your opinion). Dangerous for whom?

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Dangerous because it suggests the old wire with gain methods and analogies. Take it as an humorous statement.

BTW, my opinion is that none of the typical and widely accepted known electrical measurement will correlate with the cable sound. So we must currently debate cable sound using listening tests, not measurements. And the reference is not a minimal cable, approaching null cable. Others will think differently.

Keith_W said:

Sorry Tim, I don't think the answer is a theoretical "yes" Audiophiles are really inconsistent when it comes to whether something is a component or not. For example, a passive crossover built into a speaker is not considered a component, but an active crossover outside the speaker is considered a component, even if there is no passive XO in the speaker. So, what makes it a component? It is because it is powered, that makes it a component.

Okay then. Are passive preamps components, because they are not powered? What about a passive preamp which is built into a power amp - are those components?

If your power amp has individual power supplies for each channel (instead of one power supply for both), do you now have two components instead of one, and have you reduced sound quality because you have introduced more components into your system? Or do they only become components when you remove them from the same chassis and turn your dual power supply stereo amp into monoblocks?

As I have pointed out ... if fewer components are better, then why not forget about preamps and power amps ... and just use an integrated amp? (Ignoring the fact that the integrated amp has all these components built into one chassis and using the same power supply).

My question to people who say that active crossovers are separate components is: what is your definition of a "component"?

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Regardless of the semantics of "component," whether that is something complex, contained in a box or a single capacitor inside a "component," the answer is still "theoretically yes." Theoretically, removing an inch of wire would be an improvement. An audible improvement? Let's not go there. There are many, many things that audiophiles obsess over which are not demonstrably audible. While were on theory, though, theoretically the most transparent active crossover should be as simple as possilbe, and analog. But, while those are what is in my system, that is not my experience. I've heard digital crossovers that demonstrated remarkable transparency to my ears.

Tim

lloydelee21 said:

Hi Tim,

I am only just learning about this and am interested in learning more. The article interviewing Andy Payor, Laurence Dickie of Vivid and Richard Vandersteen definitely espoused the beneficts of active crossovers.

"Dickie: Assuming that filtering at the signal level and connecting the low-frequency drivers directly to the amplifier output offers the ideal approach, perhaps it’s better to ask, What are the downsides of LF passive filtering? Clearly, the size of the components involved in the passive low-pass filter cause much concern; with inductors in the range of 5 to 10mH and capacitors of a few hundred microfarads, the temptation is to go for cored inductors and electrolytic capacitors, both of which are frowned upon in high-end designs because of their very real shortcomings. The alternative use of air-cored inductors employing kilos of copper, and polypropylene capacitors occupying a liter of space, causes sharp intakes of breath when considering the cost. Furthermore, the LF driver is the one that experiences the greatest excursion and hence risks the greatest modulation of its impedance. This modulation, in turn, causes the passive filter response to vary with the voice-coil position, giving rise to a whole gamut of distortion mechanisms. Of course, this variation of impedance with position is one of the effects we try to minimize through careful design of the magnetic circuit of our bass drivers."


On also doing an active crossover one driver up from the bass driver, Laurence Dickie said:

"Whether the high-pass filtering of the next driver up is accomplished at signal level or left to the passive filter is another question. The simplest thing is to keep the passive filter unchanged and drive it with a full-bandwidth signal, but this wastes amplifier-voltage headroom. Removing the high-pass components, unfortunately, cannot be done without redesigning the whole of the circuit for that band, so it’s a nontrivial operation and of course requires that the whole signal go through an active high-pass filter, which some may find ideologically challenging simply because they feel every stage of electronics has to be messing the signal up in some way."

What do you think of this point? Is there a point where the problems identified above in the bass driver (large inductors and capacitors) is diminished with smaller drivers such that passive crossovers either are no better/worse than active or that other complexities in active crossovers make passives a better way to design? thanks for your thoughts. I know you've been a big proponent of actives for a long time, and certainly if you read this article...these three big designers are moving your way.

BTW, Rasmussen of Gryphon has also said the best is to design the crossover, amp and bass driver together...because designing an amp to deliver bass to an unknown driver with unknown varities of characteristics is never going to be quite as good.

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I honestly don't know, Lloyd. There are very few listening test that have compared active and passive crossovers in the same speaker design with the same drivers, but I can tell you that there is a characteristic sound I hear in active speaker systems, I consider it an improvement, an enhancement of clarity and transient response that is a definite positive. And I hear it in small active monitor systems that have no deep bass at all.

Tim

Phelonious Ponk said:

I honestly don't know, Lloyd. There are very few listening test that have compared active and passive crossovers in the same speaker design with the same drivers, but I can tell you that there is a characteristic sound I hear in active speaker systems, I consider it an improvement, an enhancement of clarity and transient response that is a definite positive. And I hear it in small active monitor systems that have no deep bass at all.

Tim

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Tim,

I fail to understand what you learn from comparing "active and passive crossovers with the same speaker design". Such thinks are very different in response, safe for a few designs that have very simple passive crossovers and can not be considered representative of high-end loudspeakers. And sometimes the enhancement in clarity and transient response is carried at the expense of other aspects of the speaker sound quality.

I firmly believe that good designers can idesign great active speakers f they are allocated resources and time - I have listened to examples of them, such as the original B&W Nautilus four way snails twenty years ago. But it needs great expertise. It is not just an affair of picking some amplifiers and tweaking a digital crossover during the weekend.

My reserves come from the hype of the active sector - I own and have played in the past with a Behringer DCX 2496, that most active speaker proponents consider a great crossover. IMHO when it is used as a high pass crossover it sounds poor and clearly compromises my system. My experience was carried with SoundLab A1PXs, bypassing the existing passive crossover (6dB low pass, 12 dB high pass). YMMV, as you often say.