Active Speakers/Monitors: Dispelling the ignorance, confusion and myths

This thread is dedicated to dispelling the widespread ignorance, confusion and myths that surround active speakers/monitors.

Start by watching this video by Meridian's Bob Stuart.

The Case for Active Speakers

What are the fundamental differences between active and passive speakers?

The Crossover:  Active speaker crossovers are powered circuits consisting of transistors and modern, solid-state electronics.  A passive speaker crossover, on the other hand, consists of unpowered capacitors, inductors and resistors sans transistors and electronics.  An active crossover that utlizes electronic components can be designed to be significantly more accurate and neutral than a passive one.  An electronic crossover also allows for adjusting the signal in ways that are nearly impossible or impractical in passive crossovers.

The Amplifier:  Active systems have one amplifier for each driver.  Each amplifier is designed to match its associated driver, taking into account the driver's impedance characteristics, efficiency and frequency response.  Amps are optimized for their drivers.  A passive design consists of a single amplifier powering all drivers, designed for a wide range of impedances and frequencies, but optimized for none.  It is primarily for this reason--the need to be the Jack of All Trades, but Master of None--that outboard amplifiers need to be over-built.  Active designs, on the other hand, allow for the design of amps that deliver more precise power to its associated driver.  Intermodulation distortion--distortion created by the need to handle vastly different frequencies at the same time--is isolated and vastly reduced in passive designs.

The Sequence of System Stages:  In a passive system, the signal travels from the (outboard) amplifier to the crossover to the driver like so:

SIGNAL >>> Amplifier >> ||Crossover > Drivers||

In an active system, the sequence of system stages is different.  The signal travels from the crossover to the amplifier to the driver like so:

SIGNAL >>> || Crossover > Amplifier > Driver ||

In this sequence of stages the crossover acts on line-level signals which, coupled with the used of powered transistorized circuits, allows for a significantly more neutral and precise crossover.  An electronic crossover operating on line-level signal voltages allows for smaller, less expensive yet more precise and efficient splitting of the signal into its treble/mid-range/bass bands.

In addition, because there is nothing standing between the amp and the driver, the amplifier can more precisely control and damp the driver.  The amp is literally hard-wired to the driver, providing seamless integration and vastly improved transient and decay characteristics.  Nothing, including long runs of speaker cable, stand in the way between the amp and the driver.  Power delivery is immediate, precise and controlled.

Active systems allow for a significantly superior integration and optimization of system stages and components.  Many of those optimizations are simply impossible in a passive system.  Active speakers are not a fringe, esoteric technology for eccentrics with questionable technical merits or benefits.  Quite the opposite, active designs are squarely in the mainstream of professional music making.  Active speakers are what most professionals and semi-professionals purchase as a capital expenditure to be used as a tool for commercial, profit-making endeavors.  In comparison, passive speakers are largely the purview of hobbyists or "audiophiles" who purchase the speaker as entertainment based on discretionary surplus income.  In addition to technological superiority, these market forces are also aligned with active designs in producting high(er) quality equipment and sound.  Active monitors are designed to be operated round the clock, and therefore must be built to higher standards.

The Benefits of an Active Speaker

"ACTIVE IS BETTER!!!"

Active Versus Passive Loudspeakers

"The performance benefits of active over passive loudspeakers is substantial. Even a system, which incorporates the best available stand-alone power amplifier, will never achieve the performance of a similar active system…It is simply the fact that an active loudspeaker is an optimized coupling between amplifier and loudspeaker driver, and is the best solution, and an upgrade in the longer term is unlikely to be necessary. Thus an active system will always provide a superior result than its separate counterparts. Dollar for Dollar, in performance and value for money, there is no contest.

…

The demands of the recording industry were for highly accurate, ruggedly built speakers, capable of reproducing the dynamics and subtleties of the original performance, and frequently capable of being used on location as well as in the studio.  The only solution to meet this need was to design and build the amplifiers and drive units as a single close matching entity in one enclosure. Hence, Active loudspeakers are today used by virtually every recording company, every major recording studio, and every major film studio."

Sounding Passive?

"Conclusions

Apart from cost and the vested interest of manufacturers to keep persuading enthusiasts to buy a new amplifier then to buy a new pair of speakers, then to buy a new amplifier then to buy a new pair of speakers, then to buy a new amplifier then to buy a new pair of speakers... ad infinitum, I cannot think of any reason why domestic audio remains committed to this clumsy [passive] technology.

Even with modest sized speakers and modest amplifiers my experience has been that the same amount of money is better spent on an active set-up. As soon as a system reaches separate pre-amplifier and power-amplifier, whether it is solid-state, class D, push-pull valve or single-ended triode, the next step ought to be an active crossover to suit that technology and an extra stereo power amplifier."

Sounding Passive (part II)

"Conclusions

I cannot think of any reason why the upgrade path ever stops short of active loudspeaker operation, except for the vested interest of manufacturers in keeping all their components universal so that separates buyers remain on the upgrading treadmill at one-componant-at-a-time.  It may simply be a failure of imagination by manufacturers, or retailers, but it is just as likely to be the innate coinservatism of audio buyers.…It is very hard to accept any passive system as being any more than "good for a passive", once listenners have experienced an active system at a similar quality point."

FAQ:  Active Speakers

1.  How do you control volume with an active speaker?

The same way you control volume on a passive speaker:  With the volume knob in your pre-amp.

2.  How do you control signal equalization with an active speaker?

The same way you control equalization on a passive speaker:  With your signal processor or equalizer.

3.  Can active speakers with their limited enclosure space really match the power levels of an outboard amplifier with a passive speaker?

At the outset, it is essential to understand that the primary, if not sole reason that outboard amplifiers are built with massive power supplies and heatsinks is that the amplifier has to be over-built in order to be able to tackle the different system design and inherent inefficiencies in a passive system.  Said another way, passive systems require large amplifiers and a lot of watts primarily due to the inherent inefficiency of passive system design.  Outboard amplifiers need to be huge and over-engineered so that they can power an unknown impedance range across the entire band of audible frequencies to all drivers.  It is a non-optimal, one-box-drives-all solution.  An amp in an passive system delivers its power to the crossover.

Active designs are not hobbled or constrained by the poor system design of passive speakers.  In an active speaker, each amplifier supplies power directly to its driver--and its driver only--without the crossover getting in the way, matched precisely to the driver's efficiency and impedance range.  This optimized approach unlocks a tremendous increase in efficiency.  Active designs require only a fraction of the power, typically one half of the power of passive designs in order to achieve comparable sound levels and quality.   An active speaker with, say, 100 watts of total amplification will be roughly as powerful as a passive speaker with 200 watts of outboard amplification.  Active designs dispense with the brutish, might-makes-right design philosophy of outboard amplifiers and passive speakers.  An amp in a active design delivers its power to the driver.

Ultimately what matters is not the nominal power delivered by the amp to the speaker terminals, but rather the dynamic power delivered by the amp to and at the driver.   Turning the question on its head, the more pertinent question is:  Can passive designs meet the power levels and power delivery quality to and at the driver possible with an active design?

4.  Don't active speakers require complex cabling and connections which make them unsuitable for home use?

Common perceptions about the complexity of the cabling and connections required by active speakers are largely informed by ignorance and resistance to change.  A passive speaker requires one input, the signal.  The active speaker requires two inputs, the signal and A/C power.  Nothing more than that is required.  In fact, active speakers have the advantage of allowing connection via balanced XLR inputs which provide increased resistance to noise and interference, making them more appropriate for long cable extensions.  Most active speakers come with both XLR and TRS line input.  A quality, gold-plated RCA-to-TRS adapter costs about $3.  What's the problem, really?  Why, in the electronics age, in the 21st century, do people living in a world of modern electronic convenience still resist the notion of providing electric power to their speakers as they do to the rest of their audio equipment?

5.  What other possibilities out of reach for passive designs do active designs offer?

An active design allows for the crossover to be implemented in the digital domain, with the advantages that that offers.  One day, hopefully not too long into the future when the masses discard the primitive notion of passive designs, the primary input to affordable, quality speakers will be a digital signal.  The speaker will split the signal into its driver frequency bands,and correct for phase and room-induced distortion both in the digital domain.  It will then perform the Digital-to-Analog conversion as the last stage before delivering the signal to the amplifier.   When that moment comes, the crude and archaic array of power capacitors and inductors that serves as the crossover in a passive design, as well as the active analog crossovers of active designs, will be replaced by a digital signal processor.  A continued fixation with passive designs only delays that moment.

6.  What is one to make of the claims that a well-designed passive system will sound better than a poorly-designed active design?

In the world of math, this statement would be akin to a trivial solution.  For example, the number 6 is divisible by one and by itself.  Yeah, tell me something I didn't know already.  Yes, it is true that a well-designed passive system can better reproduce sound than a poorly designed active design.  But then you can say that of most all types of competing systems and components in the world.  Yes, a well-designed carburated engine will run better than a badly-designed fuel injected engine.  Yes, a well-designed propeller engine is better than a poorly-designed jet engine.  Speakers are no different.

This type of statement also fails to take into account the information asymmetries and market incentives that distinguish the markets for passive and active systems.  Information symmetry and market incentives will conspire against a poorly designed active speaker aimed at the professional, for-profit sectors remaining in the market for too long.  Not so for the passive system aimed at the hobbyist or entertainment sector.  Between an equally well-designed active and passive system, at comparable price points, the active system will always reproduce sound more accurately and efficiently.

Quote:

Originally Posted by Hellbishop 

Thanks Maurico for the time and further info about the advantages of Actives vs Passives. Great links especially about taking apart a passive and turning it into an active. Best wishes on truth guiding you to your destination and us benefiting from it as well. Cheers

 

 

And yes its getting mighty tempting to purchase an active system just to hear the difference

"It is error only, and not truth, the shrinks from inquiry"

- Thomas Paine

Cheers!

Quote:

Originally Posted by ChiComm4 

Are not active speakers often prone to being overly active to a fault--over-active? But passive speakers tend to be more mellow, less aggressive?

The foregoing discussion has gone to show the myriad of ways in which active speakers can result in a more accurate reproduction of the sound signal.  You question is non-sensical.  "Active" describes a system design topology, not the timbre or dynamics of the sound.

I take no stand on that purely subjective issue.  You'll have to listen to them for yourself.

Mackie on Active vs. Passive

The criticism that active speakers cannot fit sufficient amplification in their enclosures (or, stating the criticism in another way, that their cabinets are not big enough) rests on a key, but flawed assumption.  That assumption is that an active design needs as big an amp as a passive design in order to achieve comparable sound levels and quality.  As I have explained, that assumption is simply flawed, and must be discarded when analyzing active designs.  An active design can achieve comparable sound levels and sound quality with typically one-fourth of the power required by an active design.  You think that a big amp is a good amp only because of the inherent inefficiency of passive system design.