[Rclark]

Then I was misinformed. I may give this a go some time down the line. Can't hurt anything and it's reversable.

[JLM]

In my experiences room size/shape is more important than treatments for getting the best sound and active design versus passive trumps the room (tiny lofts, desktops, or tiny cubic rooms aside).  In fact with my Cardas room/setup design and large single driver/transmission line speakers I find no advantage with the (6) GIK 244 panels, no matter how I move them around.  But note in my case that room/speaker design has already taken care to minimize room effects.

Regarding mix/match of amps.  Most DIY active designs do mix amps to optimize and maybe save some coin (smaller/tube for the treble, and big/solid state for the bass is a common recipe).  Its an easy matter for the crossover/software to take care of volume/efficiency differences.

[dm]

dm,
Nice work!  However, I also think if you would have chosen a higher quality inductor that your passive results would have been even better.

I don't have any lab worthy data to share but I understand how hard it is to justify spending more money on the inductor. No one wants to risk a major portion of their budget on one single part, and this sort of thinking requires a big leap of faith since the math works out almost the same for the cheaper, near-equivilent inductor. I really believe that the quality of the inductor is just as important as the woofer itself in a passive design, maybe even more. This is an expensive proposition to tinker with as a do-it-yourselfer.

thanks for the kind words.  I did not get a better inductor  because at the time I was considering upgrading it, the price of copper was high and a high guage with low DCR aircore or ribbon inductor would have cost more than the cost of the minidsp.  So I just went active.

[doug s.]

when i first saw this thread, rick craig and selah audio was an example i was going to use, showing a commercial mfr who knows that a properly executed active system will outperform a properly executed passive system.  but, he beat me to it.  brian cheney and vmps is another example of a mfr on a/c who knows this.

i certainly believe it, based on my experiences, even tho i have not actually taken an existing passively crossed over speaker and made it active.  it's yust based on the results i have had, when i have used an active system, used outboard subs w/active analog x-over, and used a deqx to set up passive speakers.  if i were ever to buy brand-new speakers that were passive, i would insist that the mfr build the x-over separately outside the speaker, so i could run them active if (when) i want to.

and, rclark, as has been mentioned by others, your amp choices are unlimited when going active.  only if you buy pro-audio-type speakers w/built-in amplification, are you pretty-much stuck w/using the amp the mfr chose.  a speaker like aj's sam-1 offers a nice compromise - a built-in amp for the woofer, and you choose the amplification for the coax driver...

doug s.

[rollo]

   Nelson Pass has had very good success using active crossovers in his DIY projects. He uses a [6] channel stereo amp. Complicated and hard to do.
    The Soundfield speakers use a plate amp for the woofer, allowing one to use any amp for mid and treble. Simple yet affective.
     We have heard some serious sounding active systems over the years and have concluded that it can be done right, just to complicated to get right. Not worth the effort for the average hobbyist. It will drive ya nuts getting it right.
     If one desires to go active good luck the results can be staggering just a tough act.


charles
   

[doug s.]

   Nelson Pass has had very good success using active crossovers in his DIY projects. He uses a [6] channel stereo amp. Complicated and hard to do.
    The Soundfield speakers use a plate amp for the woofer, allowing one to use any amp for mid and treble. Simple yet affective.
     We have heard some serious sounding active systems over the years and have concluded that it can be done right, just to complicated to get right. Not worth the effort for the average hobbyist. It will drive ya nuts getting it right.
     If one desires to go active good luck the results can be staggering just a tough act.

charles

charles, i must respectfully disagree that it is too complicated.  if i can do it, anyone can.   

doug s.

[Davey]

A line-level crossover system is actually LESS complicated than a traditional (conventional) system.  This might seem counter-intuitive to some of you folks, but it is true. 

Reactive components in speaker-level crossovers are removed.
Amplifiers are bandwidth-limited which eases their requirements.
Relative gain adjustments are easily accomplished.

The list goes on and on.

Cheers,

Dave.

[rajacat]

If you use the new Dayton Audio OmniMic Precision Measurement System and the miniDSP digital signal processor the learning curve is lower than in the past. It least it's supposed to be. I can't speak from personal experience yet but this is the direction I'm heading.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-790
http://www.minidsp.com/

[rollo]

  Doug what I meant was the extra cabling, power supplies for crossovers, component isolation, powercords, ICs, etc. All add to the mix. Just suggesting to keeping it simple. The Nervosa alone in synergizing all can drive ya nuts. However if one wishes to dive in and try, hey nothing to loose but your sanity. IMO just not easy peasy.


charles

[Quiet Earth]

People keep saying that all of the problems associated with passive crossovers are removed with active crossovers but they are not removed, they are just moved. As long as you believe that moving the problem is better or easier to deal with then I totally get it. But a free lunch? I don't think so.

I still don't see any proof one way or the other, just personal preferences which I take as sincere. I am neither for or against either method being superior, I am for final results, which is all that really matters. (except for the fact that we are discussing this in the lab which doesn't make sense.)

Fwiw (not much), I like the fact that my passive crossovers do not
- require a power supply
- require more line level circuitry, filters, and gain stages
- require an a/d converter, d/a converter
- require a dsp or algorithm that I don't understand
- use an op amp
- alter the basic character of the line level signal
- require more interconnects
- require more power amps
- complicate things further

Unscientific but whatever.

[Davey]

Who said anything about a "free lunch?"  The "concept" is simpler but, of course, there can be issues regardless of which way you go.  (The "full-range" guys would no doubt be snickering at this point, but that's another can of worms.)

Line-level crossovers do not

- necessarily require a power supply.
- necessarily require additional gain stages....but you do need filtering in one place or another.
- necessarily require an ADC or DAC.  (think analog.)
- necessarily require any sort of DSP-gadget or processing.  (think analog.)
- necessarily use op-amps.  (think discrete active components...or passive.)

They do

- alter the line-level signal via filtering action.....that should be obvious.
- require more interconnects.  However, if number of interconnects is a concern then I suggest system priorities are in need of rearranging.
- require more power amps.  Other than possible increased cost, this is an advantage.
- NOT complicate things.  (As I explained above.)

Line-level crossover systems have been around for decades.  I'm still puzzled by the (general) misunderstanding these have in the audiophile world.

Cheers,

Dave.

[brj]

I think that some folks might be talking past each other a bit when discussing active vs. passive simplicity, as people seem to be referencing two generalized categories of active systems without always stating it explicitly:

1) Systems where the manufacturer develops the crossover filters, and possibly supplies the physical crossover and even amps
2) Systems where the user develops the crossover filters

Option 1 should be not more complicated than a passive system for most users.  If not supplied by the manufacturer, one can choose the active crossover on which to run the filters just as one would choose the brand of parts to implement in a passive crossover.  Choosing amps is no different than in a passive system - you just have more of them to choose, although with far lower required power ratings.  If you choose a system such as PMC or many of the active studio monitors, you actually have fewer parts to worry about than in a passive system because the crossover and amps are fully integrated into the system already.  (Of course many audiophiles like to obsess...)

Option 2 will be appreciably more complicated for most users, as you're essentially climbing at least a large part of the same learning curve you'd need to design passive crossovers.

This same choice - manufacturer designed and possibly implemented network filter design - exists in the passive speaker world, but it isn't nearly as common.  There are certainly DIY types that design their own passive crossovers, but since each iteration of your network filter design involves soldering, parts swapping, etc., it is slow and costly.  Once you've purchased the measurement rig, crossover and software for an active system, however, you can change your active crossover filters in seconds without penalty or additional financial cost.  You have to know how to run software instead of solder.

[cheap-Jack]

Hi.

People keep saying that all of the problems associated with passive crossovers are removed with active crossovers but they are not removed, they are just moved.

I still don't see any proof one way or the other, just personal preferences which I take as sincere.

Fwiw (not much), I like the fact that my passive crossovers do not
- require a power supply
- require more line level circuitry, filters, and gain stages
- require an a/d converter, d/a converter
- require a dsp or algorithm that I don't understand
- use an op amp
- alter the basic character of the line level signal
- require more interconnects
- require more power amps
- complicate things further

Unscientific but whatever.

BINGO! That's exactly what I want to say about active X-overs. Far too complex, much more money to acquire extra equipment: electronic X-overs, extra power amps to drive the loudspeaker drivers,  etc etc etc. The bottom line is much much more money to spend, more tedeous to set up, & worst is to alight the whole thing sonically right.

Yes, softewares may help bigtime to set the "right" corner frequencies. BUT, but it'd not help one to set the music to sound right!

Why?? Too much active electronics for the complex music signals to pass thru could only ruin the music sonically. This will generate transient distortions & phase sifts onto the music signals. Things will get worse as most electronic X-overs employ digital devices which can make the music sound more electronical  than musical.

If we are dealing with existing loudspeakers with passive X-overs, the win-win way is to upgrade the X-over board , which will warrant better sound for the much much less cost & HEADACHE.

To get the claimed 'better' sound of electronic X-overs, one can modify the stock  X-over network to PASSIVE bi-wiring or multi-wiring like what I'v done many years back for my KEF 2-way bookselvers besides replacing all the caps to metallized PP film caps & thick thick AWG#12  oxygen-free pure copper internal wiring.

So by bi-wiring or muti-wiring the stock X-over networks, the loudspeakers will sound much much better MUSICALLY without going thru the nightmare of active X-over networking.

I have a few rich audiophile friends who could afford spending tons of time & money switching from passive to active loudspeaker X-over networking. After a few years of such 'merry-go-around', they finally get back to passive.

For those not ready for such bigtime sonic game, may I suggest to think twice before jumipng from the pan to the fire.

IMO, active X-over networking can be a huge can of worms for those less prepared.

c-J

PS: I am yet to be impressed MUSICALLY by brandname loudspekers with built-in electronic networking.

[Tyson]

Active crossovers also give you the ability to tune the speaker to your own preferences.  Want a bit more high end?  Just boost it a bit.  Got a bad room resonance in the bass?  Cut it.  Just as long as you save your original settings, you can always go back, and experiment to your heart's content. 

[cheap-Jack]

HI.

Active crossovers also give you the ability to tune the speaker to your own preferences.  Want a bit more high end?  Just boost it a bit.  Got a bad room resonance in the bass?  Cut it.  Just as long as you save your original settings, you can always go back, and experiment to your heart's content.

So why don't we go for a much simpler, less costly & straight-foward solution:- using an audio spectrum equalizer. Any room acoustical problems, e.g. resonances can be taken care of neatly.

c-J

[Tyson]

Also, if you really want to get good results with active, you'll need a good calibrated mic (I like Earthworks), and measuring program (I like HOLM Impulse).  As you manipulate the signal and adjust crossover settings, you start to get a feel for how different changes affect the sound of your speakers, in your room.  Very useful.  And more powerful/effective than cable swapping or amp/preamp/dac swapping.

But, the learning curve is pretty steep. 

[Pez]

HI.
So why don't we go for a much simpler, less costly & straight-foward solution:- using an audio spectrum equalizer. Any room acoustical problems, e.g. resonances can be taken care of neatly.

c-J

You can and people do this. But you are A. adding extra crap in the signal path and B. Failing to get rid of the lossy passive crossover components.

[Tyson]

HI.
So why don't we go for a much simpler, less costly & straight-foward solution:- using an audio spectrum equalizer. Any room acoustical problems, e.g. resonances can be taken care of neatly.

c-J

Because IMO, the biggest benefit of going active is being able to send your amps a bandwidth limited signal (very useful with tube amps), and getting large inductors and caps out of the signal path, allowing your amps a direct interface with your drivers (hello micro and macro dynamics!)

Does active sound better?  IMO, yes.  Is it more costly and more complex?  Oh yes.  But if we are after the best sound, it's a pretty large improvement that you can't really get in any other way.

[brj]

Why?? Too much active electronics for the complex music signals to pass thru could only ruin the music sonically. This will generate transient distortions & phase sifts onto the music signals. Things will get worse as most electronic X-overs employ digital devices which can make the music sound more electronical  than musical.

If we are dealing with existing loudspeakers with passive X-overs, the win-win way is to upgrade the X-over board , which will warrant better sound for the much much less cost & HEADACHE.

Like everything else in audio, I wouldn't say that this decision is quite that cut-and-dried.

The components in a passive crossover certainly impact distortion and phase shift, and I could buy a lot of gear for what someone might decide to spend upgrading their passive crossovers with Dueland caps...

Also, your reference to "digital devices" makes me think you're assuming that all active crossovers employ DSP.  You can certainly use active analog crossovers populated by passive devices if you choose.  You still enjoy the benefit (chiefly to dynamics) that you get by coupling the amps directly to the speaker drivers.  This benefit chiefly stems from the fact that in an active setup, your tweeter amp, for example, no longer has to damp the back-EMF generated by the other drivers.  (That said, giving up DSP also gives up the potential benefits of using phase-linear FIR filters.)

I'm not saying that anyone is right, because much of this remains subjective.  Your decisions should reflect your own audio preferences.  In general, people that highly value dynamics are the ones more likely to benefit most from active setups.  And one can simplify the pursuit of an active configuration by making just the lowest driver(s) active, and leaving the tweeter/mid crossover passive, as the woofers with their relatively massive motor structures are the biggest source of back-EMF.

(And if those lowest frequencies are below the localization threshold of roughly 80 Hz and generated from a separate enclosure, you have the option of positioning them separately to better mitigate bass frequency room modes.)

[Tyson]

The full range guys are right.  The best crossover is no crossover.  The 2nd best crossover is active, and the 3rd best is passive, all other things being equal.

Same goes for rooms - a well treated, acoustically ideal room is best.  2nd best is a well treated, non-ideal room, and worst is a non-ideal room with no treatment.

Doesn't mean a system in an untreated room can't sound good, but it will never sound as good as it possibly could in a better room.  Same with crossovers - lots of good speakers out there with passive crossovers, but they would probably sound even better still if active.

I mean, think about it - a single amp driving a full range speaker with a passive crossover is seeing a very complex load with very large demands on it to do bass, mids, and treble simultaneously.  Now imagine that same amp only having to drive a tweeter.  Much easier load.  Do you think the highs will sound better?  Oh yeah.  Same applies for the mids and bass, only more so IMO.

With a passive setup, you need a single amp that has both delicate highs and an iron grip on the bass.  That's a tall order, and it's expensive to get one that can do it.  On the other hand, with active, you can use a bass amp that's a monster, and you don't have to worry how it sounds on the mids or the highs, and that's a lot cheaper/easier to do.  Same with the mids and highs - you can use amps that have delicate highs and that "midrange magic" without having to worry about either of them having an iron grip on the bass.