Passive speakers, separate boxes...help me understand the appeal

[svart-hvitt]

It surprises me somewhat that people are so sceptical in terms of reliability when it comes to active speakers.

Reliability is king in the world of PA, and yet the vast majority of direct-radiating 2- and 3-way PA speakers are active.

The active speakers discussed here - e.g. D&D and Kii - use mostly off-the-shelf modules for DSP and amplification, most (admittedly not all) of which will be serviceable even if the speaker manufacturer itself goes out of business.

And those that use in-house designed electronic parts (e.g. Genelec, to my knowledge) tend to be larger, more established manufacturers that are less likely to go bust anyway.

That which is alien in the eye of the beholder...

This is where emotion comes before rational thought.

People still don’t take Aczel’s cartoon seriously, do they?

Hey, the blitz trading on Wall Street runs on this new technology, SMPS and all. Should we be surprised that all the world’s financial trading works, every day? Do the most successful trading firms run on linear power supplies to their computers? Do they heed the advice of audiophiles?

 

[Pluto]

Passive systems... offer simplicity, reduced phase shift and ringing, and better transient response

Without getting involved in the active vs. passive debate it is a fact that a given filter, whether implemented via active or passive technology, will have the same foibles. Active filters make up for the losses inherent in their passive implementations but are governed by (essentially) the same maths. Two notable points regarding the distinction –

• Actives seldom need to use inductors as the effect thereof can be synthesized by a circuit element called a gyrator. Most electronic designers dislike inductors for a number of reasons. Production departments dislike them even more as keeping a critical inductor stable and repeatable over a long run is expensive as there is a lot more involved than merely the value and the tolerance.
• Your assertion that...

  Passive systems... offer reduced phase shift... better transient response

  is incorrect. As I said, the maths state that an active implementation of a particular filter element will, by definition, behave identically to its passive counterpart (losses aside). But the active filter designer has a rather better-filled toolbox with which to work. A too-frequently ignored weapon is the all-pass filter which can correct many of the phase anomalies introduced, unavoidably, by the type of filtering necessary to implement a crossover network and it is the use of these that gives the active designer the edge, should he choose to take advantage of them. While all-pass filters can be implemented entirely within the passive domain, they seldom are these days as to do so is tricky and of doubtful advantage.

 

[svart-hvitt]

Without getting involved in the active vs. passive debate it is a fact that a given filter, whether implemented via active or passive technology, will have the same foibles. Active filters make up for the losses inherent in their passive implementations but are governed by (essentially) the same maths. Two notable points regarding the distinction –

• Actives seldom need to use inductors as the effect thereof can be synthesized by a circuit element called a gyrator. Most electronic designers dislike inductors for a number of reasons. Production departments dislike them even more as keeping a critical inductor stable and repeatable over a long run is expensive as there is a lot more involved than merely the value and the tolerance.
• Your assertion that... is incorrect. As I said, the maths state that an active implementation of a particular filter element will, by definition, behave identically to its passive counterpart (losses aside). But the active filter designer has a rather better-filled toolbox with which to work. A too-frequently ignored weapon is the all-pass filter which can correct many of the phase anomalies introduced, unavoidably, by the type of filtering necessary to implement a crossover network and it is the use of these that gives the active designer the edge, should he choose to take advantage of them. While all-pass filters can be implemented entirely within the passive domain, they seldom are these days as to do so is tricky and of doubtful advantage.

This quote from John Watkinson on the math of passive networks may be of interest?

«As sounds add linearly in the air in front of the drive units, it follows and indeed it is obvious, that one of the fundamental requirements of a crossover is that it should produce a pair of electrical signals that, if added, would reproduce the original audio waveform. A crossover that can do that is called a constant-voltage crossover.

It came as a surprise to me when I discovered, some time ago, that it is fundamentally impossible to obtain such a pair of signals from any passive crossover. In other words, passive crossovers cannot and do not work because they fail to provide the signals necessary for the drive units to linearly add together again. Passive crossovers will always be audible because in the vicinity of the crossover frequency the input waveform cannot be reproduced correctly. Passive crossovers have various other drawbacks including unwanted DC resistance that reduces the damping factor of the woofer and common impedances that reflect woofer distortion currents into the tweeter».
Source: https://www.thebroadcastbridge.com/...dspeaker-technology-part-8-crossover-networks

So he argues that passive networks behave in a way that yields a mathematically different result than a competently designed active network will.

 

[Pluto]

Watkinson is entirely correct, largely because of the many phase correction techniques available to designers of (both analogue and digital) active filters that, although theoretically possible in the passive domain, are not practical to implement. If the active designer does his job well, he is far more likely to arrive at a mathematically correct outcome than his passive colleague.

 

[svart-hvitt]

Watkinson is entirely correct, largely because of the many phase correction techniques available to designers of (both analogue and digital) active filters that, although theoretically possible in the passive domain, are not practical to implement.

Well, he writes «fundamentally impossible» on passive networks. I took that as «a mathematically closed door»?

We’re discussing 1/64 of a cent here...so hardly interesting outside of a theoretical discussion...

 

[Pluto]

To be frank, I have no idea just where on the scale of “Too Easy <–> Impossibly Hard” the implementation of passive all-pass filters (at low-to-mid audio frequencies) really lies. But it's too close to the right hand side for my taste!

Most filters suffer from phase shifting within the transition band. It's a lot easier to correct in the active domain, should the designer care to do so.

 

[bravomail]

Long thread. I thought somebody would delve into Edifier active speakers with their built-in equalizer, which gives them unfair advantage over other such systems. Anyone has those Edifiers? Are they really that good?
Another active pair being actively marketed are Mackie CR3 . Anyone has those? Are they any good?

 

[JanRSmit]

Having worked as a loudspeaker designer, i trend to disagree with mr Watkinson. My perception is that hè is downplaying passive cross-over concept. Hardly a convinging argument for actieve cross-overs. The endgoal is to have a audible sound that closeley resembles the electical “sound”. The key problem here is that we do not know the sound as presented i an electical signal. Basically because they are fundamentally different in format of appearence.

Whatever the cross-over concept chosen it has to take into account the inherent non-linerarities of the loudspeaker units, which is in essence an electro-acoustical converter. Digital techniques are far from ideal or neutral or perfect.

 

[Pluto]

We’re discussing 1/64 of a cent here...so hardly interesting outside of a theoretical discussion...

I wouldn't be so certain... the problem with x-overs in the transition band is that the phase relationship between the signals feeding, say, the LF unit and the tweeter is changing* throughout the transition band and this can be audible and unpleasant. Assuming the listener's head is not clamped in a vice and moves around a bit, the effect can be resemblant of the “phasing” effect so beloved of music from the psychedelic era. If the phase relationship is not well managed, this can result in comb-filtering, a trait clearly unhelpful to the speakers designer's aims.

* to quote you, we're not talking about a linear and consistent 1/64 cent but something that is changing from 1/10 to 1/100 with changing frequency and that is far more harmful than an unchanging, static error.

 

[JanRSmit]

I wouldn't be so certain... the problem with x-overs in the transition band is that the phase relationship between the signals feeding, say, the LF unit and the tweeter is changing* throughout the transition band and this can be audible and unpleasant. Assuming the listener's head is not clamped in a vice and moves around a bit, the effect can be resemblant of the “phasing” effect so beloved of music from the psychedelic era. If the phase relationship is not well managed, this can result in comb-filtering, a trait clearly unhelpful to the speakers designer's aims.

* to quote you, we're not talking about a linear and consistent 1/64 cent but something that is changing from 1/10 to 1/100 with changing frequency and that is far more harmful than an unchanging, static error.

This can occur, and is true regardless of active or passive filtering.

 

[Pluto]

But in my view, the problem is somewhat easier to manage if the phase variance between the two signals is static – a state far easier achieved in the active domain.

 

[levimax]

Without getting involved in the active vs. passive debate it is a fact that a given filter, whether implemented via active or passive technology, will have the same foibles. Active filters make up for the losses inherent in their passive implementations but are governed by (essentially) the same maths. Two notable points regarding the distinction –

• Actives seldom need to use inductors as the effect thereof can be synthesized by a circuit element called a gyrator. Most electronic designers dislike inductors for a number of reasons. Production departments dislike them even more as keeping a critical inductor stable and repeatable over a long run is expensive as there is a lot more involved than merely the value and the tolerance.
• Your assertion that... is incorrect. As I said, the maths state that an active implementation of a particular filter element will, by definition, behave identically to its passive counterpart (losses aside). But the active filter designer has a rather better-filled toolbox with which to work. A too-frequently ignored weapon is the all-pass filter which can correct many of the phase anomalies introduced, unavoidably, by the type of filtering necessary to implement a crossover network and it is the use of these that gives the active designer the edge, should he choose to take advantage of them. While all-pass filters can be implemented entirely within the passive domain, they seldom are these days as to do so is tricky and of doubtful advantage.

You are correct, a filter is a filter active or passive. What I was trying to get at was that high end passive speakers tend to be very well engineered mechanically so they can use lower order filters. The advantage of lower order filters is better transient response. While other issues caused by filters such as phase shift and group delay can be "corrected" reduced transient response can never be recovered.

 

[Dogen]

This is a fascinating conversation! I’ll just add that, to me, achieving rationality and perfection (almost certainly one box for everything and active speakers) in my system would take some of the fun out of the hobby. Tinkering and swapping things out is a part of the enjoyment, and the endorphins produced by placebo effects have the same effect as honest endorphins. I’ve never spent stupid money on gear, and i don’t believe in audio magic, but building and changing a system is a pleasure distinct from listening to music.

The pursuit of happiness is often more engaging than happiness itself.

 

[svart-hvitt]

You are correct, a filter is a filter active or passive. What I was trying to get at was that high end passive speakers tend to be very well engineered mechanically so they can use lower order filters. The advantage of lower order filters is better transient response. While other issues caused by filters such as phase shift and group delay can be "corrected" reduced transient response can never be recovered.

What do you think about the 1971 article by Smith on transients?

 

[PierreV]

Hey, the blitz trading on Wall Street runs on this new technology, SMPS and all. Should we be surprised that all the world’s financial trading works, every day? Do the most successful trading firms run on linear power supplies to their computers? Do they heed the advice of audiophiles?

Not a surprise given that they use redundant power supplies (if the design is the old blade). FWIW, if one excludes hard drives (by very far the main trouble spot) and undetermined failures ("did you try switching it off and back on ?"), power supply failure comes second after RAM issues.

That being said, I would assume most people use power shelves these days. Redundancy and hot swap included. In fact, most data centers now have migrated from stacks of complete boxes (stack of old complete "blades") to separate devices: power shelves/compute shelves/storage shelves etc for... efficiency and reliability reasons...

 

[levimax]

What do you think about the 1971 article by Smith on transients?

I think I wish I could read it ..... not a subscriber...

 

[svart-hvitt]

I think I wish I could read it ..... not a subscriber...

A subscription is recommended if one wants to get an idea on how audio ideas have been discussed previously.

«Transients» is one of those words often dropped by audiophiles in search of superb audio. But it seems like transients have been under scrutiny by audio engineers long before any of us got into audio.

 

[levimax]

A subscription is recommended if one wants to get an idea on how audio ideas have been discussed previously.

«Transients» is one of those words often dropped by audiophiles in search of superb audio. But it seems like transients have been under scrutiny by audio engineers long before any of us got into audio.

My understanding (from reading free articles ) is that the technical definition of "transient response" is the "settling time" of a filter i.e. how long does the filter "ring / oscillate" after it receives an input before returning to "steady state". The higher the filter order the longer it "rings". It looks nasty to me on graphs and unlike phase it can't be compensated for. What I don't know is how audible it is.... it seems things go from science to opinion at this point.... some swear by first order filters, other say up to 4th order is fine while other say the benefits of 8th out weight the disadvantages and some even swear by "brick wall" filters.

 

[levimax]

Here is a link to a study that says "stay under 600th order for high frequency and 1000th order for low frequencies"..... I guess I am safe with my 4th order filters.
http://lib.tkk.fi/Dipl/2008/urn011933.pdf

 

[Old Listener]

Sure, but as I said, that's a lifestyle (ease of use) solution.
Same can be said for a modern receiver or integrated vs DAC>Tuner>Phonoamp>Preamp>Power Amp
Your choice.

When you label something "a lifestyle (ease of use) solution" in an audiophile forum, it is usually a dismissal. I think that misses the point about modern active speakers.

I would not have selected the active speakers I use now if I had not thought that they would deliver good sound in my context. They are also quite cost effective compared to a traditional system. (I paid $ 7000 for the Waveform speakers and crossover ~20 years. The last multi-channel amp I used with them was ~ $ 2000. The Dynaudio LYD48 speakers I use now cost # 2300 in 2018. I don't feel that I'm missing anything with the Dynaudio speakers.) I suppose you could say that it was a lifestyle choice; I've got more money for the rest of my lifestyle than I would have I gone with an active system with an external crossover and amp.

In the $ 1000 to $ 2500 range active speakers with crossover and amps inside seem very cost effective for my needs. Below $ 1000, active speakers and powered speakers may be very good choices, especially for near field listening.

My context is probably different from yours. Your choices are probably different than mine.