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The Benefits of an Active Speaker Lifestyle

December , 2002

Colin Miller

 

Introduction

This article compares passive loudspeaker systems which use a single power amplifier to drive an entire loudspeaker array through passive crossover components (capacitors, inductors, and resistors mostly) between the amplifier and actual drivers, and active loudspeaker systems, where the crossover components are placed between the preamplifier (processor) and power amplifiers, so that multiple amplifiers each reproduce a limited range specifically for a single driver type, such as just the tweeter(s) or woofer(s). In most cases, the active loudspeaker has the power amplifier built into the enclosure. You plug the line-level output of your preamp/processor into the RCA jack on the back of the active loudspeaker box.

To start with a sweeping generalization, I must say this . . .

In general, all other considerations being as equal as possible, assuming equal competency in all areas of design, manufacturing, and value, when it comes to the upper end of the loudspeaker market where budgets allow more extensive design and manufacturing, if comparing the hypothetical technical aspects between active and passive loudspeaker systems,

ACTIVE IS BETTER!!!

I can feel JJ, our Editor-In-Chief, saint of SETs and Behemoth FET-based amps alike wriggling in a tense grimace, his fingers itching at the editing keyboard, trying to resist the temptation to alter that statement.

Well, I can't blame him, or any of those who are immediately taking exception to that statement. Exception should be taken, because like any other generalization, while it may be true as a generalization, there are TONS of exceptions. Even so, that bold, underlined statement is one heck of a gauntlet to throw down among audiophiles and similar home theater enthusiasts, most of whom have passive loudspeaker systems into which they've sunk a fat piggy bank, and are probably very content having done so. Good for them. By all means, stay happy.

I would never hope to imply that any given active loudspeaker most likely outperforms any given passive loudspeaker. The most significant aspect of any loudspeaker is the sum of all components, from raw parts quality and manufacturing care, to perhaps most importantly the skill of integration, regardless of specific techniques utilized, be it an order of crossover slope, the use of particular materials over another, ported vs. sealed, or even active versus passive design. Get the best stuff on earth, put it together haphazardly with any methodology you choose, and you've got a mess. Flat frequency and power response, even dispersion, low distortion, good dynamic range and responsible transient response can all be achieved through passive design just as they can be screwed up in an active one.

However, if the active approach is taken, the most critical 'match' in the entire path of the audio system (the amplifier/crossover/loudspeaker chain) can be approached as a whole, far more efficiently, each component working in its most optimal scenario, yielding potentially superior results to a more "conventional" passive approach.

Why? I'm glad even if you didn't ask, because this is currently a monologue.

Efficiency and Output...

Instead of inserting lossy passive crossover components to filter frequency ranges and flatten driver response by altering the signal after the amplifier, an active system performs the same task prior to amplification. The result is a more efficient system, where everything put out by the power amplifier goes directly to the transducer, unhindered by resistors, capacitors, or inductors.

Keep in mind, though, that while the loudspeaker system itself is more efficient, if you try to express the efficiency and/or output capability difference in a fixed ratio, you'll fail. It gets a little tricky because the efficiency differences, and subsequently output differences, are dependent upon the efficiency of each driver in the passive design, the nature of compensation in the crossover, the individual drivers' response curves, the signal spectrum, the power supply configuration for the active speaker, the nature of the crossover division in the active system, plus a bunch of things that have skipped my mind right now.

If we were to make a blind, blanket statement about active vs. passive system efficiency differences, we could say that active systems are roughly twice as efficient with their amplifier power than passive ones. If you were to take the utmost extreme (and dishonest) scenario, you could set up a test case that would show an active system as four times as effective with a given amplifier rating as a passive loudspeaker system, based entirely on how loud you could play that particular signal before the amplifiers clipped. It's not really an accurate example outside of the lab, but some of that example would be applicable as a matter of illustration.

Independent Voltage Swings Over Multiple Bands

Consider a tone at 20 Hz, 20 volts RMS. Consider another tone at 200 Hz, 20 volts RMS. Let's consider a load that's 8 ohms, resistive to keep it simple. 20 volts RMS is 50 watts across 8 ohms.

If we want to put either of those signals into a system with a passive crossover with a crossover point between those two tones (anywhere really, it doesn't matter in passive systems as far as the amplifiers are concerned, but to keep it apples to apples, say 80 Hz, higher order for minimal overlap between drivers), we would need an output capability of 20 volts RMS, or in other words, something that could put out 50 watts continuously into 8 ohms.

In a bi-amplified active system, we would need two amplifiers, both equally powerful, one to run below 80 Hz for the Low Frequency section, and one to run above 80 Hz for the Higher Frequency section. To accommodate either of those tones, even one at a time, both must be capable of swinging voltage (and providing current) to put out 50 watts RMS into 8 ohms.

If we look at these tones, one at a time, both systems are equally efficient, but since the active system has an amplifier that isn't doing something in both scenarios, the passive system is more cost effective. The passive system requires a total of 50 watts of amplification hardware, the active system a total 100 watts of amplification hardware.

If, however, we try to play both tones at one time, the performance equality disappears, and the value of the active system skyrockets. Even if the passive crossover only engages in simple filtering with no loss in the crossover circuit, the passive system will suffer through this comparison. Considering that we must apply 20 volts at two different frequencies, because one tone must ride on top of the other at the output of the single amplifier with the passive system, when the peaks of each tone line up, that amplifier must output peak voltages twice that of either single tone, so that the peaks are equivalent to the peaks required by 40 volts RMS, or 200 watts @ 8 ohms, even if the RMS (Room Mean Squared, or the mathematical way of saying average) value is lower and the power output is half that. It's not really putting out 200 watts RMS, just 100 watts RMS. But, the nature of the complex signal requires extreme voltage swings at times, requiring very high power for short durations, so that if the amplifier can't source voltage swings like an amplifier that can source 200 watts RMS, it will most likely clip and distort.

The active system, on the other hand, will behave just the same as when it reproduces either single tone by itself, with two amps running just as if they were running alone. Not really more efficient, in terms of power drawn for power output acoustically, but able to do more work with less hardware. When you consider two 50 watt amplifiers next to one 200 watt amplifier, the economics of active systems become more attractive.

Coincidentally, audio signals usually contain multiple tones that straddle loudspeaker crossover frequencies. The latter example is the most extreme possible, but makes a very valid point.

Still, it's not really accurate to add the power output from each amplifier section in an active system and say you've got at X watts. This can be illustrated by looking at another extreme, energy focused instantaneously in a limited range. After all, even through the strength of the system may be the sum of all parts, the downfall may be that of the weakest link, i.e., a passive system operating with a single amplifier capable of 400 watts can put that power at any distribution within its bandwidth. An active system with four completely separate 100 watt amplifiers can only output 100 watts in a given frequency range at a time, with a 400 watts maximum total. If we were comparing a single 400-watt amp driving a passive system with four 100-watt amps in an active system running over separate bands, if the active system needed to reproduce a signal that only covered one band, all work falls on a single 100-watt amplifier. In this scenario with a narrow band signal appropriate for only one driver section, the active system with "400 total watts" would be no better off in terms of output than a single 100 watt amp in passive system.

The only exception where active systems win hands down under any circumstances in terms of power allocation is when the system's amplifiers share a single power supply, so that each amplifier draws what it needs dynamically. In such an instance, the active system has a total amplifier output capacity which can be assigned just as effectively as a single amplifier running by itself, in which case an active system's multiple amplifiers trounce the passive system's single amplifier when it comes to output capability of signals that spread at all across more than a single driver or driver complement.

Summing up the respective output advantages in these examples, they depend on signal distribution. When the signal is spread across bands of driver operation fairly evenly, all active systems have an inordinate advantage. When the signal is narrow in frequency content, the passive systems allocate amplifier resources more effectively than an active system with completely separate amplifiers for each driver section.  If the active system has a single common power supply feeding all the amplifier sections for the loudspeaker, it has all the potential advantages without any potential disadvantages of active signal dividing.

Some might be catching on that the scenarios of a perfectly divided workload, where active systems have an extreme advantage, and that of an extremely singular signal, where a single amplifier driving a passive speaker becomes more cost effective, are implausible during normal use. What we get with music or soundtracks are fickle variations that jump between the extremes, in other words, lots of various frequencies rather than just one or two.

So, as you can see, while the basic active system will most likely hold a substantial advantage with anything with more than a few harmonics, when it comes to output potential, it's not a simple comparison, and when looking at the previous examples, not truly a matter of efficiency, but of signal-dependant output limits.

"Lossless" Crossovers...

Where real issues of efficiency come in is the nature of passive crossover design. While there are resistive losses in passive crossover components, these are relatively minor.

"Lossless" Response Tailoring

What is more relevant is that each driver's raw frequency response is rarely what a particular designer has in mind for the particular task, unless the designer has the luxury of actually designing their own drivers. Even with in-house driver engineering, further tailoring may be desirable just to make it a better product. Tailoring networks that flatten or curve a driver's response need not involve "extra" crossover components, but may be as simple as altering the crossover curves of the "ideal" filter network to incorporate the driver response and compensate. Response tailoring, though beneficial to sound quality, must selectively attenuate frequencies beyond the simple filter function, so that a given amount of power in at some frequencies results in less total acoustic output than without the response tailoring.

Whether the losses are inserted in the passive crossover, or in the driver design through additional electrical or mechanical damping, the effect is the same, namely an additional loss of acoustic output from the driver. In contrast, an active system performs crossover filtering and response tailoring prior to amplification, so that the power amplifier couples directly to a driver that works as efficiently as it can, without the detriment of insertion losses or less efficient driver design. Maximum efficiency is reached for each driver. In essence, the active system can achieve flat frequency response without imposing losses of power to achieve that flat response, allowing the driver to work as efficiently as possible.

"Lossless" Driver Level Matching

Most importantly for the sake of discussing efficiency losses in a passive system, is that like the active system, the passive system must integrate all drivers to operate as a single loudspeaker, not only in the gradual transition between drivers, but to behave as one in relative output for a given input level. This means that output level from each driver must be matched to the output of every other driver across the board. In an active system, we can simply alter the gain of the input on each amplifier to compensate for sensitivity differences between drivers. In a passive system, we have to lower the output of all but the least efficient driver by sticking in resistor networks to soak up power. In other words, you make the most efficient drivers less efficient so that they match the sensitivity of the least sensitive (roughly least efficient) driver. In even more words, in terms of voltage sensitivity, all drivers must cater to the lowest common denominator. For any speaker that is trying to reproduce bass in an enclosure short of a Volkswagen, this usually means that all drivers operate at the approximate efficiency level of the typically inefficient woofer by receiving signals through resistor networks that intentionally turn the speaker level audio signal into heat. This typically means that a tweeter or midrange operates 3-6 dB less efficiently than it could.

One of the beautiful aspects of the "hybrid" speakers with "powered" woofers is that even though the speaker requires a "full-range" signal from the power amplifier to pass signal to the woofers, they still inadvertently reap efficiency benefits. While such a setup isn't as elegant as an active division of labor through a subwoofer/satellite system (all speakers set to "small" in the receiver/surround processor with bass redirected to the subwoofer), the midrange and tweeter can run with the lowest common denominator between themselves, far more efficiently, because the woofer operates from a completely different power amplifier. As a consequence, while a hybrid system with "powered" woofers still requires the power amplifier feeding it to output the entire signal, the speaker looks more efficient to the amplifier, asking for less power at a given SPL. Though I think of built-in powered woofers as a somewhat half-baked solution, I have to admit that there are advantages over a conventional, entirely passive "full-range" loudspeaker.

Are the Output Advantages Relevant?

To be fair, any efficiency advantage of an active design can be countered easily with a bigger amp behind a passive design. While a passive design fed by a mongo amplifier may be "wasting" power, most audiophiles or AV enthusiasts don't really care about efficiency so long as the dynamic range is maintained. If that requires a hulking outboard amplifier fed by a dedicated 20 amp line, and the spouse and budget concede, most consumers don't mind another bigger box, or multiple bigger boxes. If anything, there seems to be some kind of bragging rights that come with the extensive use of resources, particularly among the "high-end" connoisseurs. I wanted to address the efficiency/output argument because it has been raised in the past, but I personally consider it a dead issue for most, beyond the scope of a technical discussion. In either a passive or active loudspeaker scenario, the available amplifier power should remain higher than the required amplifier power. If that's not the case, we need to reevaluate the entire system, or maybe our listening habits.

More substantially on the topic of comparison, active systems tend to have . . .

More Stable Crossovers

Passive crossover components rely on the complex reactive (and changing) impedance of drivers, in addition to the impedance of each other, to perform their filtering. As a consequence, passive crossovers can be far more difficult to implement precisely, and more limiting in the filter's precision, than their active counterparts. Unlike passive crossovers, active crossover components are completely isolated from the fickle impedances of loudspeaker drivers, "buffered" not only by the power amplifier, but in active active (vs. passive filter "active") crossovers, by their own amplifiers. Designers of passive systems can apply impedance compensation components to counter the reactive properties of the drivers themselves, should they wish to incur the cost, making the filter design easier, but they're still not out of the woods, even with today's fantastic computer modeling. Huh? Consider.

At high output levels, drivers heat up. The hottest part is where the heat begins, at the voice coil. As the voice coil heats up, the coil resistance increases, and maybe the suspension compliance changes (they can temporarily become looser, which in turn affects the resonant frequency and damping.) The point is that the passive components are no longer dealing with the same scenario they started with, and the driver impedance changes. The filtering characteristics of the passive crossover begin to shift, and so by definition either work less optimally at low output levels, or work less optimally at high output levels. The same applies to the loading of bass-reflex systems, which is why good sound reinforcement gear is designed so that it doesn't actually sound right until it's obnoxiously loud, but we're getting off track.

Active systems, because they're buffered from the changing impedance of the drivers, are completely immune to this behavior. It is true that passive systems with high power handling through and through will have less of a problem with this, as the coils heat up less to begin with, but that's nowhere near as nice as the complete immunity offered by the active system.

But wait, there's more, such as . . .

Loudspeaker/Amplifier Matching

There is one more point on behalf of active systems that I'd like to make. The active loudspeaker system has a practical performance advantage that one should point out to those who could consider multiple dedicated amplifiers an extravagance or even hindrance when one would do, particularly if that one could be more expensive per channel. This point is the relationship of the loudspeaker to the amplifier, and it's got nothing to do with passive crossover components. When a manufacturer builds a high-performance outboard amplifier, the amplifier MUST accommodate a wide range of loudspeaker impedances, some of which may be very unusual. In order to do this, the manufacturer needs not only good design, but to massively overbuild for extreme variances in loudspeaker loads. This usually translates into big, heavy, and expensive. Unfortunately, this overbuilding usually yields benefits not in proportion to the effort.

For example, my own big, outboard, muscled-up, stereo amp of choice and budget can source 20 amps continuously into each channel, or in other words, cruise into 2 ohms at 800 watts, twice, for 1600 watts of continuous output, assuming my wall socket can hang in there. If we tie that kind of output with premium sound quality, that ability costs mucho dollars.

My particular amp is from a no-frills manufacturer, so it's still relatively cost-effective for what it is, but not so cheap as I'd like so that I could buy a few more. The extreme low impedance output capability is nice to talk about, and handy when in use as a reference amp so that it's ready to drive any review sample that comes in the door, but until I actually use a loudspeaker that gets to 2 ohms over any substantial part of the higher energy portion of the audio spectrum, i.e., mid-bass, low bass, maybe midrange, I can't get the full output potential out of that amplifier in terms of milking the power supply for everything it's got, even if I can drive it into clipping distortion by exceeding it's substantial voltage swing capacity. It was 'optimized' for the most strenuous current delivery scenarios possible.

If the designer of my particular beast of an amp had a specific loudspeaker in mind, he could have designed the amplifier to deliver that full 800 watt capability for real, without worrying whether something stranger might happen along. However, what I'm actually getting with most speakers is an amplifier capable of an easy and stable 400-500 watts/channel, because that's what the impedance of most loudspeakers allows the voltage swing to push through. I may be better off than an amp that was 'optimized' for power delivery of 400-500 watts into that load since the power supply remains more stable when it never goes beyond 60% of its real capacity, but that's only because it can't.

While I consider it better to err on the side of clipping the voltage rail a little sooner (only a problem for the duration of clipping) by under-winding the secondary of the power transformer for greater current capability vs. exhausting the power reserves (a problem until the transformer can refill the capacitors) by over-winding the secondary of the transformer for excessive voltage capability and impressive "peak" output levels, a "perfect" match is more ideal than either situation.

In real world scenarios, outboard amplifiers themselves are often an inefficient allocation of manufacturing resources, and therefore money, when it comes to cost/performance gains. Surely we're better off than using an under-powered receiver, but by using massively overbuilt products, we often use and pay for more than we need for a given application, and get less from what we put in than if the same amplifier were designed as a dedicated unit for a particular loudspeaker, be it passive or active. I'm not saying that big outboard amplifiers don't reap substantial rewards compared to using the onboard amplifiers found in typical receivers. In many cases, particularly at higher output levels, the extra juice pays off big time, not only in sheer volume, but clarity.

What I'm trying to say is that even if the active system uses smaller power supplies and less output devices, etc., because amplifiers in a fully active system are truly part of a known whole, they can offer the same raw performance as big, huge outboard amplifiers when used in that specific scenario for which they were intended, or for that matter, even possibly perform better than the 'bigger' outboard counterpart. Does that mean that a dedicated amplifier in an active system necessarily performs better than another amplifier with its own chassis? Of course not. If there ever were a universal truth in audio, it would be, "It depends."

Not Necessarily Sunny

Most of this has been pretty one-sided, in favor of the active systems. However, there are some myths about the superiority of active loudspeakers, as well as some potential downfalls.

Myth- Active Loudspeaker Systems Have Better Damping of the Woofer, due to a direct electrical connection between the amplifier and the driver, as opposed to Passive Loudspeaker Systems, which require an inductor or two in series, adding electrical resistance.

Well, sort of, but it's misleading to imply that an active system will necessarily have tighter bass because of "better" damping from the power amplifier.

First, more damping is not necessarily better. Rather, there is an amount of total damping in the system that is considered the target area to maintain flat frequency response, good transient response, and healthy output levels at the lowest range of the woofer. Too much damping, and the frequency response will prematurely decline, leaving the sound thin and anemic. Too little damping causes a peak right before the low frequency limit, causing the bass to sound fat, "slow", and muddy. In sealed systems, the "ideal" target range of the system "Q", a number that describes a system's resonance, and inversely damping, is usually considered between 0.5 (critically damped for fastest settling time) and 1.0 (most extension for a particular box size.) In that range, the optimal target depends on the design goals. With ported or passive radiator bass-reflex systems, there are multiple resonant devices that are all combined, so it gets more complicated, but the basic principles are the same.

Placing a passive component, such as an inductor, between the amplifier and the driver doesn't mean worse damping, and so far as the inductor is linear, requiring that it's air-core versus an inductor that uses a metal slug inside it to increase inductance for a given loop, doesn't create more distortion. It simply means less electrical damping by the power amplifier, which can easily be compensated for by the designer via more mechanical damping of the driver suspension, or within the enclosure. Less electrical damping itself may even be beneficial in particular contexts if it serves the total design.

What is relevant is that the damping in a passive system creates another variable, which is not only by definition variable (the resistance of the coil can change a little with current) but provides a factor by which the variation of a more variable factor (the resistance of the voice coil) will translate into more dramatic changes in system damping. Is it a big deal? If the inductor has a reasonably low resistive component, probably not a whole lot. But, if the inductor is of the air-core variety, the low frequency nature of the crossover for a woofer will require the inductors to be quite large, and because of the length of wire needed, even if it's of relatively heavy wire gage, the resistance will be more significant, and the inductor will be more expensive. Big deal? I don't know. As I said, probably not a whole lot.

However, few manufacturers use air-core inductors exclusively, particularly with woofers, due to the aforementioned size and cost required, in which case you're now dealing with the non-linearity of an inductor of an iron-core or similar variety, which can become detrimental beyond the extent of changing system damping, but can saturate, and dynamically change their inductance value, screwing with the crossover in a transient manner.

Consider that the non-linearity of metal-core inductors is worse at high current levels, that most woofer's impedances are lowest right above and below their low-frequency limits and so draw more current at those frequency ranges, and that the spectral distribution of energy peaks are often heavily weighted in the mid-bass on down, and you've got a very difficult situation. You can minimize this problem with higher capacity metal-core inductors, though it starts becoming an increasingly expensive band-aid, as they get heavier and larger, which only minimizes the problem instead of solving it.

This is starting to sound like another benefit of active design. Well, it is, and it's most substantial in the ranges prime for woofer crossover frequencies. However, we don't have to go completely active to completely avoid this pitfall of saturating inductors, as we can use a typical subwoofer/satellite combination, where the subwoofer/satellite filter uses an active crossover (provided with every unit that offers bass management,) and the higher crossover frequencies used with mid-bass/mid-range drivers and tweeters make air-core inductors extremely plausible and cost-effective. Vance Dickason, author of the wonderful "Loudspeaker Design Cookbook," goes into inductor saturation much more thoroughly, and actually recommends this type of "hybrid" approach, as an easy method of side-stepping inductor non-linearity in DIY loudspeaker design.

Hmm . . . . I think I remember at least one manufacturer out there advocating just that approach before receivers even had bass management, so much that they provided the line-level low-cut filters to make it happen. HP-80 anyone?

Despite the seemingly overwhelming advantages of a fully active system, there is a serious potential pitfall . . .

Whatever You've Got, You're Stuck With It.

Even if the manufacturer can either design or OEM active electronics that more or less work, with an active loudspeaker system that uses dedicated, on-board electronics, from input to the electronic crossover to the output stages of the power amplifier feeding the driver(s), be it a fully active system, or a hybrid job with "powered" woofers, there is no upgrade path. Not enough power, low parts quality, or just poor circuit design, what's there is all we'll ever have. Sorry, go to jail, and don't pass go.

Stacey reminded me that there is an exception when the manufacturer offers an upgrade to a newer revision, but that's their choice, not yours.

While I think that the typical audiophile or AV enthusiasts takes mixing and matching, from speakers and amplifiers to cables and shoelaces to an extreme, the convenience and advantage of having a completely integrated package that comes with a self-contained active system can be a hindrance, in two scenarios.

The first example of where the complete system approach of a fully active loudspeaker system can be a disservice is where the manufacturer may have gotten some parts right, but fell short in other areas. In the audio industry, it's unfortunately common.

The typical example is a loudspeaker designer who really doesn't have a clue about amplifier design, or simply underestimates the value of putting resources into high quality electronics, and as a result ends up with a product that performs more poorly than passive equivalents mated to a higher quality front end.

Some "high-end" loudspeaker manufacturers, particularly the small boutique companies, don't have engineering resources much beyond a few texts documenting generic projects, a few guys handy with a soldering iron when they're not engaged in terrific carpentry or lacquering work, and a lot of time to listen. These people, though perhaps fantastic "artists" when it comes to designing and customizing the sonic colorations of loudspeakers through trial and error of swapping passive crossover components, aren't comfortable or even competent with electronics design. If you screw up a passive loudspeaker, it sounds screwy. If you screw up an active one, things could blow up. These manufacturers should absolutely stay out of the active market.

Just like other audio components, fully active systems aren't created equal. Way back when I tagged along with my friend Andor at an AES show, where active monitors aren't such a rarity, although the Genelec demonstration did well in the dynamic race on the showroom floor, nothing I ran across at the time (KRK, Tannoy, Alesis, etc.) convinced me that active loudspeakers were appropriate for high fidelity reproduction. They seemed more just like a vehicle to get small speakers to play really loud with lots of bass. In fact, with some of the blatant response peaks so obvious even with passing listening, it made me wonder if they actually made their speakers less accurate so as to make them sound more superficially detailed.  That's not to say that the real quality stuff wasn't there, but I just didn't find it.  It was also a few years ago, and maybe all of the problems I perceived were acoustic issues, so all of those companies may actually offer truly good products now.

This predicament of lop-sided system design need not be a substantial problem in practice IF the manufacturer takes care to address ALL aspects of the product, from electrical signal input to acoustic output, with equal attention. Even for the consumer who'll always want "better" electronics than the "standard" design, if the original electronics are really good, but he or she wants really, really good, the consumer is still better off with really good electronics in an active system than really, really good electronics in a passive scenario. If the product is really good due to careful deliberate design from the ground up, just leave it alone. If a person really needs to fiddle, then the problem is of the second variety.

Limited Tinkering Capacity

The second, and more relevant disadvantage of active loudspeaker systems has nothing to do with objective performance advantages or disadvantages, but rather the need of many consumers to twiddle with their systems to make it more theirs, more to taste, to wiz on it, so to speak. A fully active system takes away choices. If we want to soften the sound with a more mellow, warmer amp, or crisp it up with a slightly spicier alternative, we're out of luck. If we want to put some fat, fancy, after market speaker wires to roll off the top end for extra "refinement," too bad dude. From the hobbyist perspective, a comprehensively designed, all-inclusive system is a nightmare. If you sweat about after market power cords, "premium" digital cables, or Mping-pong discs more than the furniture and acoustics of your listening room, a completely integrated system probably isn't your bucket of tea.

Most high-end enthusiasts crave gizmos, more boxes, and a long chain of purist components, rationalizing performance advantages through specialization and isolation. For those who can remember a few years back, consider the fancy CD transport/premium digital cable/fancy anti-jitter device/premium digital cable/fancy upsampling device/premium digital cable/fancy outboard DAC/premium analog interconnects/fancy analog preamp combination that was touted as the ultimate in CD playback to precede the power amplifier.

In truth, a simple CD player with a volume control is the most ideal for such a task, and anyone who had a clue about how a CD player actually worked knew it. ALL CD players incorporate a FIFO buffer following reading the transport, as required by the jumbling done by Sony's error correction on the disc. In fact, a single box CD player slaves the servo of the transport motor to pick up data at the speed appropriate for the master clock that feeds the onboard DAC conversion, making jitter levels dependent ONLY on the quality of the master clock, without any need for jitter reduction. Actually, single box CD players have an architecture with lower inherent jitter than any multi-box solution.

While much fuss was made recently about "upsampling" and sample rate conversion accessories so that we could feed either a 88.2 kHz sample rate or 96 kHz sample rate to our new outboard DAC units with a full 24 bits from the "inadequate" 16 bit information sampled at 44.1 kHz gleaned from the CD, the truth is that every modern DAC, including the cheapest units sold in CD players ten years ago, "upsampled" to a minimum of 176.4 kHz, and usually 352.8 kHz sample rates, with more than 16 bits of data, not to increase resolution, because such is mathematically impossible, but to apply the digital reconstruction filter. Back then they called it "oversampling." Let's not even mention the shorter signal path possible within a single chassis, and just consider how much those premium digital cables and extra boxes added to the end price while degrading the ultimate performance potential.  I'm sure that somebody out there is going to hold up a truly poor single-box CD player as proof of the opposite, and to that, I've only got a few numbers to counter it, 508.24.

Summary

I don't want to put the vibe out there that people really need an active loudspeaker system, or that passive loudspeakers are substandard, because there are so many truly terrific passive alternatives.

What I do want to emphasize is that if you don't at least seriously consider an active alternative when it comes your way, and follow the typical bias of conventional "wisdom," you might be doing yourself an incredible disservice. While it would be nice to win over the market and the industry to buy and produce more active loudspeaker products, as I do consider it the most sensible solution to high-performance design dilemmas, I must be realistic. Most truly great loudspeaker designers I've talked to know the benefits of active systems and refrain from supplying such products. Why? The bulk of the high-end consumer market isn't ready.  But, when it gets ready, manufacturers will begin to supply more, and better options.  I'm just asking consumers to be ready by the time they get their next itch, because it is likely to be very good stuff.

I just wanted to share. Thank you.

 

- Colin Miller -

Copyright 2002 Secrets of Home Theater & High Fidelity
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