The sonic benefits of an active crossover. A discussion.

[opus111]

Normally the crossover's part of the speaker system, no? So I can't see how its not adding another box, another set of ICs, another mains lead. When you add those things, you add more loop antennas to your system - resulting in a raise in the noisefloor. What am I missing?

I'm aware of the various documented issues with passive XOs. To my understanding the primary advantage of the active XO is making the amp's job much easier because the load gets split. This is a substantial positive but depends on what amps you start out with - if their power supplies are well engineered in the first place the gains are less (most aren't, they're substantially short on capacitance). There's also the gain resulting from reduced amplifier IMD, but this has to be offset by the increased IMD generated within the active XO box.

 

[LL21]

I was told in my case, Opus111, that by introducint the Active Crossover, we could bypass or remove the passive crossover in the X1...so we are adding one box and removing another. The question is which box is better as a crossover...the passive one or the active one. I am the least techie here, so apologies if i got this wrong.

 

[Keith_W]

Normally the crossover's part of the speaker system, no? So I can't see how its not adding another box, another set of ICs, another mains lead. When you add those things, you add more loop antennas to your system - resulting in a raise in the noisefloor. What am I missing?

You can have active crossovers which do not have IC's or op-amps. There are fully discrete circuits out there which are all-valve, some with a built-in preamp.

It is also false to think that adding another powered component will reduce performance. If you thought this way, then perhaps the converse is true - would subtracting powered components improve performance? Why not get rid of your preamp and power amp ... and buy an integrated amp instead?

Saying that a passive crossover is "part of the speaker" is an argument which is easily demolished. The Meridian DSP8000 contains a DAC and power amplifier. If I happened to own one of these, I could ask you why you think it is beneficial to add additional powered boxes to your system because it can never possibly be better and use your exact same arguments against you. Come to think of it, the humble Audioengine A5 has a built-in pre and power amp. Why do you see the need for separate preamps and power amps? They can never be better ... can they?

The reality is - the job HAS to be done SOMEWHERE along the chain. Whether it is powered or unpowered, or in the case of passive speakers - a bunch of electronics parasiting power off the power amps ... depends on your preference.

If you use a passive crossover, it simply wastes power from your power amp that you paid good money for. And remember - good quality power amps are expensive, particularly high quality with high power. If you have a Class A power amp, you have already wasted 90% of the input energy as heat. You waste even more in your passive crossover. Just as a passive preamp doesn't always improve performance, a passive crossover isn't necessarily superior to an active one. It all depends on implementation.

 

[Mike Lavigne]

Not quite what I was getting at, no

I'm saying the ideal solution, SQ-wise is a passive line-level XO, fitted inside your power amp or inside your preamp so no extra power supply and no extra ICs are required. Whether having a separate active XO box is an improvement is debatable. It could be, depending on the particular amps you use with it. Offloading the bass onto a separate amp can have a positive impact on the sound of your MF/HF amp for example if the amp in question has an underspecified PSU (most that I've seen do). So a lot depends on your particular set-up, no hard-and-fast rules here.

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.

the main towers are 3-ways and use a 1st order passive crossover. they themselves extend into the mid 20hz range; the bass towers crossover as high as 60hz but typically more in the 30hz range (mine currently are adjusted to come in at 34hz). there are adjustments on the active powered bass towers for crossover frequency, bass level, bass quality ('Q'), bass extension, and a rumble fliter. the main towers only have a tweeter level control where there is no boost, just attenuation.

the main towers are designed to fully intergate and don't have the fullness in the bass that a full range speaker would have......they are designed to integrate with the bass towers. to me this issue is the limitation to adding subwoofers to speakers designed to be full range. you are always fighting the crossover area to get the right amount of bass energy. and the reason to have the designed in active crossover in the bass for room integration.

i do think that an active DSP crossover speaker for full range can be justified at certain price points. but my opinion is that that price point is somewhere south of $10k.....as many speakers with passive crossovers even in that range would have fundamental advantages over anything applying DSP to the incoming signal. maybe for simplicity sake or packaging it could make sense. not likely ever my choice personally but i can see it.

 

[opus111]

You can have active crossovers which do not have IC's or op-amps. There are fully discrete circuits out there which are all-valve, some with a built-in preamp.

I'm aware of this. Just ruling out opamps isn't a guarantee of transparency. If you manage to combine an XO with a preamp that will remove my main objection to active XOs - the extra box, ICs and mains connection.

It is also false to think that adding another powered component will reduce performance.

Since I don't think this (assuming that 'performance' here means system performance), its a red herring and can be safely ignored.

If you thought this way, then perhaps the converse is true - would subtracting powered components improve performance? Why not get rid of your preamp and power amp ... and buy an integrated amp instead?

All other things being equal this would indeed be an improvement - one less set of ICs. But its hard to imagine any integrated which would satisfy the 'all things equal' criterion.

Saying that a passive crossover is "part of the speaker" is an argument which is easily demolished. The Meridian DSP8000 contains a DAC and power amplifier. If I happened to own one of these...

Then why would you be wanting to add in an external XO - they already contain a customized digital XO? I thought the context here was whether it was an improvement to upgrade a passive XO to an active one? Looks like another red herring as the Meridians contain no passive XO to my knowledge.

..., I could ask you why you think it is beneficial to add additional powered boxes to your system because it can never possibly be better and use your exact same arguments against you.

You lost me with your apparent sleight of hand here. How does this demolish my statement that a passive XO is normally part of the speaker (note passive speaker indicated from prior context) ?

Come to think of it, the humble Audioengine A5 has a built-in pre and power amp. Why do you see the need for separate preamps and power amps? They can never be better ... can they?

Where did I say that separates can never be better? Strawman from where I'm standing.

The reality is - the job HAS to be done SOMEWHERE along the chain.

Argument easily demolished - full range speaker

If you use a passive crossover, it simply wastes power from your power amp that you paid good money for.

Rather like saying if you bought a Ferrari and don't drive it at its top speed you're wasting mph (or kph) which you paid good money for. I agree that passive speakers waste more power than actives incidentally, but if you drive the actives with class A amps then the argument gets turned around pretty fast....

And remember - good quality power amps are expensive, particularly high quality with high power. If you have a Class A power amp, you have already wasted 90% of the input energy as heat.

You seem to be forgetting that in terms of overall acoustic efficiency, speakers turn about 99% of what's fed in into heat. Unless they're horns, which do a fair bit better like perhaps 98% or even 97%.

You waste even more in your passive crossover. Just as a passive preamp doesn't always improve performance, a passive crossover isn't necessarily superior to an active one. It all depends on implementation.

I haven't claimed that its necessarily superior, another red herring. There are some fairly crummy passive XOs out there with ferrite rods in the bass inductors which saturate a bit early with a 'cracking' sound. And others where the bass air-cored inductor's been wound with such thick wire to reduce the DCR that proximity effect hugely increases its losses at the turnover frequency. Just to give a couple of instances.

 

[opus111]

I was told in my case, Opus111, that by introducint the Active Crossover, we could bypass or remove the passive crossover in the X1...so we are adding one box and removing another.

If, as you say the passive XO is in the X1, how is that a loss of a box by taking out some components?

 

[LL21]

If, as you say the passive XO is in the X1, how is that a loss of a box by taking out some components?

Well, by removing the passive crossover or bypassing it, i presume that is eliminating a potential cause of distortion, no?

 

[opus111]

Yep, covered the issue of the extra distortion in an earlier post. It is almost certainly adding some more distortion but so are the speakers themselves and probably the speaker's contribution is up to an order of magnitude greater, especially at LF.

There's another interesting point about distortion introduced due to the DCR of the inductor which is that its debatable whether this actually appears as acoustic distortion. It almost certainly does when bi-wiring isn't used but if a speaker is wired with one cable per drive unit it may not matter at all. There are of course other factors like frequency dependent loss and loss of damping factor where inductors are concerned.

So I take it by your omission of response on the box question that's a 'no loss of box' answer?

 

[LL21]

Yep, covered the issue of the extra distortion in an earlier post. It is almost certainly adding some more distortion but so are the speakers themselves and probably the speaker's contribution is up to an order of magnitude greater, especially at LF.

There's another interesting point about distortion introduced due to the DCR of the inductor which is that its debatable whether this actually appears as acoustic distortion. It almost certainly does when bi-wiring isn't used but if a speaker is wired with one cable per drive unit it may not matter at all. There are of course other factors like frequency dependent loss and loss of damping factor where inductors are concerned.

So I take it by your omission of response on the box question that's a 'no loss of box' answer?

I guess I really am a non-techie...i consider removing a crossover from inside the speaker as removing a 'box'...because literally i always thought since they're these boxy things in epoxy, they are essentially another box inside the speaker which, by removing, means removing a possible element of distortion. Thus, replacing this box with the Active crossover box, at least i am not increasing the net number of boxes in the system.

 

[andromedaaudio]

You mean physically removing lloyd , why would you do that , it would make the X1 virtually unsellable afterwards , by passing if possible okay
On crossovers : (passive) crossovers are the glue which hold the units together and make them be able to sound as one , nothing bad about them if done right off course , its all in the execution .
People who hate X overs usually own bad designed ones and think anything whats in between the amp and the LS unit degrades the sound

In your case first the problem should be understood / adressed
What do you dont like in the sound , can we see it in measurements and act from there , put in a adjustable (passive ? ) X over and start fiddling/adjusting wont get you very far i reckon

 

[Groucho]

Has any active speaker owner here demonstrated their system to a person who has only ever heard passives before? My experience has been that at about 3 seconds in, they turn to you, and their eyes say "Ah. I now see what the fuss is all about." - I enjoy demonstrating my system. It's not that you can always put your finger on the limitations of the passive system when you listen to that, but you can recognise the absence of those limitations in the active system when you compare them.

 

[JonFo]

^^^ While I'm proud of my active system, and demonstrate it regularly with positive comments every time, I'm afraid I can't just attribute that to the active nature alone, as for most listeners, they've rarely heard: A large electrostatic speaker, a truly clean and powerful sub (an IB) and a custom-designed and acoustically treated room, much less the combo of all of the above.

I think a good comparison would be to have all else be equal, and then show the A/B of passive vs active. I was able to do that while I still had possession of the original passive for my Monoliths (about 5 years), but then sold-off the passives. So I can no longer A/B that aspect.

 

[JonFo]

Meridian just updated their 7200 active speakers, and in the videos embedded in the linked page, Bob Stuart clearly explains many of the benefits of a DSP-based active speaker system. Specifically, the time alignment of the impulse responses (although they use the marketing term "Enhanced Bass Alignment")

http://www.meridian-audio.com/en/me..._of_the_DSP7200_Digital_ActiveLoudspeaker/41/

 

[microstrip]

Well, by removing the passive crossover or bypassing it, i presume that is eliminating a potential cause of distortion, no?

Lloyd,

You asked for advice in a thread where most people are more interested in getting ammunition for their theoretical battles on the ultimate performance of imaginary speakers than debating implementations. Sorry to say, this type of analysis on your distortion is worst than mine is of little help in your case.

As far as I know the information about the crossover and each speaker response on your speaker (X1 series 5) is not public domain. Admitting it is similar to that of the X series 1 measured by Martin Colloms in 1994 the woofer is crossed around 150 Hz with 6dB/slope. This could in principle be easily implemented in the Krell active crossover. But your passive crossover is implemented with an inductor in series with a quasi-resistor (the coil resistance) and the active crossover will be probably implemented with a capacitor, perhaps in the feedback network of the active circuit. This means that the phase response of the active and the passive system can be quite different. Is it relevant to speaker performance? Did Wilson change the crossover in subsequent versions with the same speakers?

IMHO, if you want to try this approach you need some type of measuring equipment or an expert you can trust blind - otherwise you risk an endless task because the initial settings are wrong. Only afterwards you should start the fine tuning by listening. Remember it is very easy to ruin the performance of an excellent system and it is not an easy task to significantly improve it.

 

[Groucho]

Meridian just updated their 7200 active speakers, and in the videos embedded in the linked page, Bob Stuart clearly explains many of the benefits of a DSP-based active speaker system. Specifically, the time alignment of the impulse responses (although they use the marketing term "Enhanced Bass Alignment")

http://www.meridian-audio.com/en/me..._of_the_DSP7200_Digital_ActiveLoudspeaker/41/

Thanks for that. They're very desirable speakers.

Yes, it's interesting that there are some people who still like the idea of active speakers but who trade off the time alignment (and all the other interesting DSP tricks) against having a stripped down analogue system to lessen perceived distortions within each active component or connection. Which is more important? The absolute timimg accuracy of Meridian's style of speaker or the perceived distortions caused by extra op amps and DSP processing? As I say, my attitude is one of simply having to have the timing accuracy once I know it's possible. I can hear the difference if I turn it on and off, while I can't say I could ever hear a problem with active electronics and DSP per se.

 

[LL21]

Thanks everyone who has participated. This began when my local dealer suggested I try this. He is happy to bring over the latest active crossover from Wilson along with an amp to try. The audio engineer he would come with, is very knowledgeable on Wilsons.

Before doing so, I wanted to get an idea of whether this is something worth trying...I am perfectly happy and was not looking for further changes. My dealer has looked after me long enough, this is not a big sale for him...so he genuinely seems to think it will be better.

Based on everyone's feedback, sounds like it has the potential to be better, but I am not getting the sense this a a transformational change about to happen...and poor implementation will of course make things worse.

One to consider...does not jump out at me as a must-do.

 

[DonH50]

A few random thoughts FWIWFM... Changes I have observed and measured over the years switching from passive to active crossovers were system-dependent. With drivers in isolated boxes, meaning no or little pressure coupling in the enclosure, you can increase the crossover slopes significantly so each driver is better confined to the frequency range over which it provides lowest distortion and other parameters for optimal performance. This not always the right thing; some designs depend upon driver overlap for power handling and dispersion, for example. You can also use the crossover filters (with digital, much easier, or analog all-pass if you must) to time-align the signals and improve the impulse response. I spent much time going after the perfect impulse response, only to discover that in many cases it was unheard except under stringent test conditions (that is, other things mattered more). The benefit of driver control, letting the amplifier better control the speaker, is almost always a benefit, except in those cases where the crossover's higher impedance was used to provide a particular sound character. Two examples I have in mind are to roll off the HF response with a series resistor to the tweeter, and a network that raised the impedance to the mid-bass driver. The latter provided a "boomier" sound (and much poorer impulse response) that was less clean but many people preferred; it sounded like "more bass".

One benefit for some that may be less obvious (pun intended) is the amps can now be hidden on the floor behind the speakers instead of dominating the rack. Less weight and heat in the rack, and short speaker cables. For Mac's and other amps with big meters or fancy front panels, "hidden" may be a drawback...

 

[LL21]

I just re-read this article from Soundstage interviewing Andy Payor of Rockport, Richard Vandersteen and Laurence Dickie, the designer of Vivid...specifically about active crossovers. http://www.ultraaudio.com/index.php...payor-laurence-dickie-and-richard-vandersteen

Good read for non-techies like me.

 

[Groucho]

I just re-read this article from Soundstage interviewing Andy Payor of Rockport, Richard Vandersteen and Laurence Dickie, the designer of Vivid...specifically about active crossovers. http://www.ultraaudio.com/index.php...payor-laurence-dickie-and-richard-vandersteen

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.

 

[mep]

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.

Oh, they are funky looking alright. But do they sound good? I think so.