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Product Review - M&K S-1C & MX-700 Satellite/Subwoofer Loudspeaker System - January, 2000

Colin Miller
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S-1C Satellite Speakers 
Drivers: (2) 1" dome. (2) 5.25" poly Recommended Power: 25 watts min., 400 watts max.
MFR: 77 Hz - 20 KHz ± 2dB
Finish: Glass Bead Black
Dimensions: 21" H x 7 3/4" W x 10.5" D
Weight: 20 lbs. each
MSRP: $995 each USA

MX-700 Powered Subwoofer
Drivers: (2) 8" long-throw MK700
Internal Amp Power: 200 watts RMS
Frequency Response: 20 - 125 Hz ± 3dB
Finish: Black or White Lacquer
Dimensions: 14 1/2" H x 17 1/2" W x 12 1/8" D
Weight: 41 lbs.
MSRP: Black Lacquer Bead Finish,$1395 each.  Glass Bead White Finish, $1450 each USA

 
Miller & Kreisel Sound Corporation, 10391 Jefferson Boulevard, Culver City, California 90232; E-Mail info@mksound.com; Web http://www.mksound.com.

Miracles are by design.  A week before this text hit my laptop’s LCD display, I cursed out an indignation at the audacity of a saber saw (commonly called a jig saw) that cut into my left index finger.  The whirring teeth left their mark, staring at me in embarrassed disbelief. I thought, quite annoyed at myself, "I need stitches."  Some tightly wrapped band-aids, bubbling antiseptic, antibiotic gel, and I was whole again, with a minor scar to scold future grandchildren.

I understand basic biological components, but nevertheless find it amazing that live tissue incorporates such an effective crew of repair technicians.  The wonder compels a target for credit.  Praise God, chalk it up to natural selection, or do both without any contradiction, but anyway the picture’s framed, it’s a freaking work of art.

Though I don’t know any human feat that approaches the engineering of life, many carefully thought-out designs deserve admiration, and when it comes to well designed and carefully constructed loudspeakers, I tend to admire away.

I must continually interject that I love Infinity's late but not forgotten Renaissance 90s.  I gravitated toward them originally for sonic reasons.  However, while learning more about loudspeaker design, I feel they’ve only become more beautiful.  There is no perfect loudspeaker, not even close, but Cary Christie and his crew covered so many bases with such an elegant, relatively cost-effective (just under $4,000 retail) home run a few years ago.

I’m happy to say that the same applies to the subjects of this article.  Same league, same deliberate breed of genius.  While coveting the sensual curves of the Ren 90s, one of those “what ifs,” began scratching the back of my head, working its way to my ear lobes.  What if one took on extremely high-performance, truly full-range 2-channel music reproduction, usually considered the domain of monolithic floor-standing loudspeakers, with a satellite/subwoofer approach, conventionally regarded as a tool of home theater?

That pursuit doesn't get very far with the stereotypical satellite/subwoofer combination.  Most products of this kind strive to fulfill aesthetic agendas first.  Quoth the salesman, “You can put the ‘bass module’ anywhere, these tiny cubes fit wonderfully behind your various knick-knacks, and it will sound better than anything else, regardless of price, because of patented technology.”  Yeah, and butter sinks in mercury!

To take on truly great audio reproduction, the speaker system must not only integrate the satellite and subwoofer components convincingly, but also offer a flat frequency response, have a dynamic range that can pick up a listener by their pants, and incorporate a total bandwidth to not only tickle the furthest regions of the cochlea’s basilar membrane, but pump the lungs and settle the large intestine as well.

As for satellites the size of a wine glass, and a subwoofer based on a 6” mid-bass in a poorly built band-pass box, well . . . let’s not even go there.  Unfortunately, not only do most consumers never experience real state of the art audio reproduction, but the heavily marketed epitome of an interior decorator’s farce has stigmatized the entire satellite/subwoofer genre.

Miller & Kreisel (M&K) doesn’t offer your typical satellite sissies.  Even their least expensive LCR-55s will put a heap of clean power to good use, exploring occasionally dangerous levels of SPL in smaller rooms.  And their subwoofers?  Their subs started the whole thing 25 years ago, augmenting high-end planar speakers.

In fact, M&K has possibly contributed more to the development of the satellite/subwoofer concept than any other entity in the industry.  Before DTS, THX, Dolby Digital, or even Dolby Surround, M&K began a continual refinement of their products in home audio, as well as Hollywood screening rooms, where home theater meant having the 35 mm print to watch!  After combining those years of manufacturing and design with extensive recording experience (via their own recording label), the résumé on the desk screams, “You’d be a complete idiot not to at least give me an interview.”

Interesting tidbits about M&K . . . did you know . . . ?

Anyway, after searching http://www.mksound.com and pricking my neurons on the totally tricked-out S-1C top-o-dee-line monitor, I remembered a passing comment by a friend who has more often than not deemed subwoofers more obnoxious than helpful.  “That one (referring to the MX-700) is actually pretty good.”

The MX-700 is a small subwoofer, like many of these increasingly popular items.  Ever since Sunfire introduced their first True Subwoofer a few years ago, audiophiles have clamored for real bass in less space.  Many don’t realize that M&K beat Snow White to the dwarves with the MX-70, and the subsequent MX-70B.  Like the MX-700, they both utilized dual 8" drivers in a push-pull configuration.  The MX-700 is simply the next step: better drivers, more power, and an exclusively downward/rearward-firing arrangement to optimize room loading.

And so I came to a question, dare I ask for two MX-700s?  I did, and M&K graciously delivered.

A spousal selling point of satellite/subwoofer systems is the ability to remotely locate a single subwoofer out of the way.  However, two identical subs always beat out one (as long as you place them very carefully), if only for the sake of options.  Stack them and multiply dynamic range fourfold.  Strategically locate the pair to average out room modes to provide a flatter response.  And, if perchance you want to give it a go with the extreme, run them in stereo. Since the whole point of this excursion was to explore extremes, I did just that.

Background of the beasts

The MX-700, as stated, uses relatively small 8" drivers (Editor's note: in the US, 8" subs are considered small, but in some parts of Europe, consumers are a little less demanding of subs, and 8" is not so small) in a push-pull configuration, firing downward with an opening to the rear to maximize room coupling by loading off the rear wall.  For the sake of information, two drivers (in the same enclosure) doubles efficiency and doubles power handling, not only increasing possible output by a factor of four, but lowering distortion as well, since the drivers do less work at any given output level.  The push-pull arrangement further reduces distortion by putting even-ordered distortion products of each single driver out of phase with the other, canceling out the unwanted even-ordered harmonics.  

The drivers themselves look pretty hefty, with thick, steel-stamped baskets and seriously over-sized magnets, one of which cancels the magnetic field away from the gap, essentially "shielding" the woofer.  The stiff, treated paper cones, as well as the treated foam surrounds appear fit to outlast most pets, and will massage their stomachs along the way.

The extremely small cabinet of the MX-700, as well as the solid construction, moves the resonant frequency of the boxes far above the operating range of the drivers, making the enclosures impervious to panel resonance spawned by pounding out low frequencies.  The resulting small volume of air does make deep bass more difficult, as the air contributes to a stiffer total suspension that resists long excursions, but the MX-700 makes up for this with a hefty power amplifier and a set of heavy-duty dual voice coil drivers to boot.

An amplifier of considerably underestimated muscle, rated at 200 watts, can pull up to six amps from the wall plug before blowing its fuse.  To say the least, it’s got a little headroom.  And to maximize that headroom, M&K uses a “Headroom Maximizer” circuit (I hope they did not get charged very much for the marketing company to come up with this term).  Essentially, it’s a limiter that's smarter than the average bear.  According to Charles Back, who responded to numerous questions I fired at him, the circuit actually monitors the amplifier’s power supply, as well as the input signal, to allow uncompressed transient peaks, though guards against continuous overload which would result in audible distortion.  The result is a more transparent limiting circuit that still allows "maximum headroom."

The crossover, variable from 50 Hz -125 Hz, starts at 12 dB/octave, and then turns into a fixed 36 dB/octave slope at 125 Hz.  The gradual initial slope will allow an easier integration with a wider variety of loudspeaker at a broader variance of levels, as opposed to, for instance, the fixed 24dB/octave low-pass slope at 80 Hz of a THX crossover.  The extremely steep slope at 125 Hz, however, makes the subwoofer extremely difficult to localize, in a way taking the best from both worlds. A toggle switch right next to the variable crossover knob allows bypassing the crossover completely, should the user wish to implement the crossover found in the processor/preamp.

A phase +/- toggle switch allows optimizing summing with satellites at the crossover frequency without additional group delays, and the standard variable level control provides a means to match output should the preamp not have this feature. Inputs are entirely line-level.

The enclosures of both the MX-700s and S-1Cs I received sported a black bead lacquer, said to improve panel damping.  Whether due to this, the small panel dimensions, or extensive corner bracing and internal foam treatments, the knuckle rap test suggests that the enclosures of the S-1Cs are way DEAD.

The S-1Cs have their share of features as well.

On a separate baffle, dual stacked soft-dome, ferro-fluid-filled tweeters (above, left) sit in stuffed transmission lines (above, right), eliminating the possibility of rear waves reflecting back into and interfering with the tweeter diaphragm.  Not only does this improve impulse response in the time domain, but allows smoother high frequency response from the tweeters themselves.  The foam, mounted above, below, and to the sides of the drivers, on the baffle, and the tweeter grille itself, creates a smoother dispersion and frequency response by minimizing undesired lobing and diffraction artifacts. (Lobing occurs when drivers interact with each other, combining unevenly off-axis due to different distances to the listener. For instance, if you stand up, you're closer to the top tweeter than the bottom one. The result can be VERY uneven frequency response that changes greatly with listening position. With more drastic lobing characteristics, the character of the sound will change dramatically as you move your head. The S-1Cs intentionally use lobing to limit the vertical dispersion, but they try to do so as evenly as possible. Diffraction occurs when a high-frequency waveform encounters sharp edges, such as the corners of the enclosure or the edges of a tweeter not mounted flush with the baffle, resulting in a secondary wave that emerges from those edges, causing a time distortion, as well as cancellations and reinforcements that cause comb filtering (peaks and dips) in the frequency response.)  Ferro-fluid simply clings to the magnet assembly of the tweeter, soaking the tweeters' voice coils and dissipating heat, increasing power handling, lowering power compression, and damping the suspension. All in all, pretty straightforward, and devilishly thorough.

The push-pull configuration (above, left) of the 5" drivers (they have cast aluminum baskets) lowers distortion up to a few hundred Hertz, allowing the same benefits derived by push-pull subwoofers.  Given that M&K recommends up to 400 watts for the S-1Cs, expect dramatic SPL output levels.  To most efficiently channel that power, M&K recommends the use of a high-pass filter (this eliminates really low frequencies, say, below 50 Hz), facilitating true active bi-amping when used with a powered subwoofer which, in turn, further lowers distortion and increases dynamic range.  Anyone besides me see a trend here?

In addition to two sets of gold-plated binding posts, and a switch that substitutes for traditional shorting straps, tonal controls provide three contours for both mid-range and treble (above, right).  These are not simply driver level adjustments, but rather separate crossovers that make broad adjustments without compromising the crossover blend.  Handy if you’ve got a sonically bright or dull room but not the freedom to acoustically treat it (e.g., foam tiles on the walls), or simply wish to tailor to your tastes in great detail.  

More unique, though, are the three selections of vertical directivity.  By varying the output levels between the tweeters, the network makes the vertical dispersion more or less controlled.  Prior to THX guidelines on vertical directivity, M&K utilized vertical arrays of multiple tweeters to control vertical dispersion, minimizing stray reflections from floors and ceilings.  Such reflections, arriving at the listener shortly after the initial launch, from slightly different directions, “blur” the sonic image (because the same sound is arriving from different parts of the room - having been reflected - and they overlap).  In short, sound reflected off the floor or ceiling not only creates tonal deviations resulting from comb filtering (caused by the phase shifted recombination of the sound, where some has been cancelled and some has been augmented), but also stretches the perceived image vertically, imparting an illusion of height, while compressing the sense of depth.  If the uncontrolled vertical dispersion is inconsistent in terms of frequency at the vertical angle which creates the strongest reflection at the listening position, it may even instill the notion that objects move up and down.  While this may benefit the listener in a recreational capacity, M&K satellites were developed first as studio monitors, requiring a more accurate portrayal of the sonic image.

A loudspeaker may increase the perceived depth of the soundstage by deliberately sending sound against a rear wall with either rear-firing drivers or dipolar radiators.  A distance of 5 feet or so from the wall will put a good 10 milliseconds onto the delay of the reflected sound, “improving” the depth perspective with added ambient information.  However, it will be consistent, regardless of listening material.  In terms of monitoring the facets of recording/mixing/mastering, that won’t do either.  Keep in mind that many aspects of loudspeaker design aren’t a matter of right or wrong, but rather design goals.  

Measurements

I did a variety of impedance sweeps with the S-1Cs to gauge how demanding these speakers really were with amplifiers.  Not surprisingly, the impedance above a couple hundred Hertz depended greatly on the contour settings.

As shown above, with "Normal" settings for both efficiency and treble levels, and a wide directivity control, the S-1C presented a nominal impedance of 6 Ohms, reaching a maximum of 12.33 Ohms slightly above 100 Hz, and a minimum of 3.11 Ohms at roughly 200 Hz, with another peak just over 1 kHz which then leveled out to about 6 Ohms all the way up.

With both efficiency and treble levels set to low with wide directivity (graph shown above), the impedance averaged 8 Ohms, hitting 13 Ohms at both 100 Hz and 1 kHz, falling to a minimum of 3.39 Ohms at 200 Hz still, but staying close to 10 Ohms 2 kHz and above, making the impedance just slightly easier on amplifiers even though the minimum impedance still dipped below 4 Ohms.

Contrasting both the normal and low efficiency, settings, the impedance plot averaged 4.4 Ohms with the high efficiency, high treble, and wide directivity (chart shown above).  Interestingly enough, changing the directivity setting to narrow had almost no effect on the impedance.

There are more permutations than I'd care to get into, but the bottom line is that the S-1C will dip to near 3 Ohms in the mid-bass, an area where much musical and/or theatrical content lies, and depending on the contour settings, may draw more or less current in higher ranges as well.  It's not an incredibly difficult speaker under any circumstances, but it may pose a problem for less robust receivers, especially in high efficiency mode.  Heavy-duty outboard power amps, in my opinion, are always a nice option. That is why we always recommend checking for pre-out jacks on receivers when you are shopping. It pays off in spades down the road.

The peak just above 100 Hz (103 Hz to be exact) indicates the woofer's low-end resonance, which had a Qtc of 0.94 in the high efficiency setting.  A Qtc of 0.94 is slightly in the higher side, but it does have practical benefits.  For one, the very small box size for the woofer enclosure requires a relatively high Qtc to reach the lower end cutoff limit of the design without compromising efficiency.  To maintain the same -3dB cutoff point with a lower Qtc would require either a far larger cabinet, or a heavier cone which would, in turn, lower the efficiency of the speaker.  The only real drawback to the higher than average Qtc in the mid-bass is a slightly elevated response in this region, and hence, a marginally warm character.

Here is a short explanation of what the Qtc specification means. Q is the degree to which the electrical, mechanical, and pneumatic characteristics of the driver/enclosure interact to affect resonance. High Q values (near 1.0) in speakers tend to imply a warm sound, while low Q values (near 0.8) represent tightness. A Q value near 0.5, chosen by a few manufacturers, would be extremely tight, to the point that many listeners would find the bass thin and anemic. The general consumer market tends to prefer speakers with a value near 1. The Qts is the total Q of the driver at its resonance frequency fs (the resonance frequency of just the driver itself, out of the enclosure in free air). Qtc is the total Q of the speaker system (driver and enclosure with everything assembled) at its resonance frequency. It should be noted that a single Qtc does not apply to bass-reflex speakers of any kind, as they are comprised of two resonant devices which interact to sum to a total response, and cannot be considered by themselves.

I played around with test tones for the MX-700s.  The specified 20 Hz lower-end limit is based on an in-room response such as required by the THX Select spec of 2,000 cubic feet.  Bass response depends heavily on placement and room characteristics, but in my room, which has large doorways into other rooms for two of the four corners, extension went into the low twenties, still strong at 25 Hz, before rolling off despite substantial cone excursion.  It is interesting, or perhaps simply appropriate, that M&K chose to configure the roll-off for in-room response, as opposed to many subwoofers which seek to achieve their specified extension limit under anechoic conditions.  Subs which have a flat anechoic response almost certainly will not have a flat response with normal listening conditions, but rather a response that rises as frequency falls due to room loading characteristics.  Such responses may be impressive at first, and perhaps even suitable for very large rooms, but may also detract from ultimate realism with a "theatrical" bottom octave, as well as increasing demands on the driver and amplifier at any given volume level.  The MX-700 did not take this route, but remained rather composed all the way to the bottom.

Listening . . . listening . . . and more listening

Deep, solid, but never over-bearing, the MX-700 doesn’t espouse the exaggerated grandeur of many subs, but may be that much better off for it in the real world.  I very much appreciated the MX-700's ability to deliver shuddering realism without the extra fat.  Kick drum, kettle drum, or the slap of a string bass, the pair of MX-700s proved adept at each and all, displaying a dexterity and prowess to envy.  Certainly, larger beefier subwoofers may better fit extremely large rooms that require more low frequency energy and higher output levels. But, for rooms (like mine) meeting the THX Select specification of 2,000 cubic feet, even a single MX-700 should be plenty, let alone a pair.  Don’t misunderstand, these little kiddies can crank.  With electronic bass provided by a friend's Techno selection at his preferred listening levels, the pressure changes in the room fell just short of cracking plaster.  The MX-700 can smack, it's just not an MX-5000THX or FSR-1800 is all.  In terms of quality of the bass, however, I’d venture to offer up the MX-700 as one of the best-sounding, most invisible subwoofers I’ve had the pleasure to mingle with.  Combining a remarkable level of control with formidable extension, the MX-700 sounds invisible as components go, rather unlike a speaker.

One could say the same for the S-1Cs.  For the heck of it, Maggie (my daughter)  and I started listening to the S-1Cs in the most anechoic environment available to us, our front yard.  While certainly not perfect, it eliminated any possible ceiling reflections, and reduced room interaction.  The “Normal” settings for both the midrange and treble switches proved most appropriate for our tastes.  Inside our living room, due possibly to the small dimensions (providing bass gain) and damped character, I eventually settled on the high-efficiency contour which de-emphasized the mid-bass region, with a "normal" treble setting.  I can imagine that in a highly reflective room with hard-wood floors and large glass doors, low efficiency and low treble contours could prove more enjoyable.

Which vertical directivity setting best met my needs depended on the situation.  For everyday, casual operation, I liked the wide setting, as it allowed me to walk around and perform my chores without a dramatic change in character.  However, if sitting in just the right place, at the right height, the more controlled vertical dispersion of the narrow mode created a slightly more focused stage with greater depth rendition. The beauty here, is that you can change the acoustics to suit your mood. Removing acoustic wall and ceiling tile for an afternoon on the ironing board would be a little more effort, don't you think?  Regardless of the settings, the imaging capabilities never dropped below superb, painting landscape to fall into.

Before beginning the demise of self-respect, I must qualify the following commentary with a few notations.  The S-1Cs do little to modify the experience of the original recording.  In accordance, the S-1Cs neither high-light nor notch narrow regions, regardless of the selected broad band contour.  Add low distortion characteristics that do not smear energy up the frequency spectrum, and you have a speaker with minimal coloration.  Homogenize the sound, it certainly does not.  While that may seem like a unilaterally desirable feature, it also differentiates qualities of recorded material almost to a fault, perhaps suggesting that recreational use of DSP and/or EQ for much of popular music may be a better idea than many involved in high-end audio would like to admit.  Speakers with such resolving abilities may even justify re-mastering CDs on the PC (like refrying beans) to burn a CDR to taste.  “We have the technology.”  I’ve just got to get my lazy rear end over to get a CD burner and digital sound card.

And so comes the gushing.

Sure, the MX-700s are incredible, absolutely saucy, but the S-1Cs ROCK!  Oh, I know, for two grand a pair, they should have something shiny, curvy, leather stitching, or at least something exotic to set them apart.  They don't need it.  From Mars Lasar's "The Eleventh Hour," to Fiona Apples latest dalliance with the drum kit amidst 'Limp,' Chris Issac’s 'Blue Spanish Sky,' Dire Straights’ 'Fade to Black,' Metallica's 'Of Wolf and Man,' a sweeping piece of Wagner, or a stab of Tchaikovsky, these little devils had me glued. Great depth, great lateral imaging, amazing ambience portrayal, astounding detail.  An utterly unframed window.  Coincidentally, they sound very similar to M&K's own  relatively economical LCR-750THX satellites, but going just a delectable bit farther towards nirvana on a sled of bliss.

Aaron Hodges (a Secrets newly acquired writer) said recently that I have become a poster boy for M&K advertising.  Given that he himself owns M&K speakers, I took it as a joke.  There are many speakers in the world that I enjoy.  It's just that I adore these.  My absolutely favorite speaker?  I haven't decided yet, but it's made the short list.  And, even if I am partial to these speakers, well, each of our more than two dozen writers has favorites.

Call it what you like, but see it for what it is.  Picture, if you will, a lunatic curling some serious rug under clenched toes, sweat beading on his temples as the auditory centers of his brain approach a complete melt-down.  Teeth clamped on the sides and tip of a flattened tongue, he stifles a scream of delightful delirium so that he might simply . . . hear more.

If you come across the chance, I highly recommend the experience.

- Colin Miller -

components used during this review

Aragon 8008BB Stereo Power Amplifier
Aragon 8008x3 Three-Channel Power Amplifier
Sunfire Stereo Power Amplifier
Yamaha RX-V995 Receiver
Infinity Renaissance 90 Loudspeakers
JVC XL-Z1050 CD player
Toshiba 2109 DVD Player
Bybee/Curl Prototype AC Purifiers & Power Cords
M'Dor Power Cord
DH Labs Silver Sonic Interconnects, WBT RCA connectors
AudioQuest Diamond Interconnects
Liberty Emerald 14-4 Speaker cable, custom-terminated.


© Copyright 2000 Secrets of Home Theater & High Fidelity
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