Product Review (August 2002)
Miller & Kreisel
S-150THX Speaker System

Includes the SS-250 Tripole® Surrounds
and MX-350THX MkII Subwoofer

By Kevin Nakano

Home theater speaker systems have become so popular over the years that virtually all speaker manufacturers now offer 5.1 systems. High-end companies that once frowned upon the idea of having their audiophile speakers combined with televisions are now meeting the demands of those consumers willing to pay for them. Finding the best system for your dollar is a time consuming process and becomes very subjective to say the least. Many of us rely heavily on product reviews to steer us in the right direction or possibly even look to those who are part of the professional recording industry. After all, the media we listen to passes through the systems these professionals use in their day-to-day work. If the latter weighs on your decision, you may be interested to find that many of the audio professionals rely heavily on M&K speakers for their monitoring systems. Over the past few years I've had the opportunity to visit several commercial facilities involved with the production of A/V software content for consumers. Most of these locations have systems that for good reason would be considered reference quality for mixing and producing audio for multi-channel recordings. The interesting part is that the vast majority of these locations have M&K THX certified speakers installed for monitoring the audio. One should not be surprised given M&K's reputation in the industry. Companies such as Dolby Labs, Digital Theater Systems (dts), 20th Century Fox, Skywalker Sound, and THX Division - Lucas Film LTD are just a few of the names who benefit from M&K speaker systems.

The reference S-150THX speakers are the consumer version of the ones found in the professional studios around the country. Our setup consisted of a pair of S-150THX speakers and one S-150AC center channel. The "AC" designation for the center channel stands for "Angled Center". All front channel speakers as well as the subwoofers are THX Ultra certified. The rear SS-250 surround speakers are similar to the S-150THX design with four additional drivers (2 + 2) firing forward and backwards into the room. This design (called Tripole®) radiates sound timbre matched with the front channels, while providing the dipole effect with sound surrounding the listener. For the ultimate in bass reproduction, we used a pair of MX-350THX Mk II subwoofers each having a built-in 350 watt RMS amplifier.

The S-150THX
The S-150THX speakers are just over a foot tall and hold five drivers on the front baffle. Three stacked tweeters sit next to a pair of stacked 5-1/4 inch woofers. The pair of S-150THX speaker sat on top of the LDM-125 speaker stands and worked perfectly for our setup. M&K offers the S-150THX in a variety of different configurations to maximize installation options. As a result, the S-150THX is produced in four versions with three SKU numbers. The first SKU is the standard pair (order as the S-150 pair), which we received for this review. Each box contains one left and one right speaker, both of which are magnetically shielded and mirror-imaged with front baffles that have complementary angles directed inwards. This helps improve the speaker's imaging and response by focusing the front baffle towards the listener. As with any speaker pair, the angles of the left and right speakers need to be adjusted to optimize the soundstage.

The second version is the standard center channel (ordered as the S-150C), which has a squared front baffle, with no horizontal or vertical angle. This speaker has additional magnetic shielding through M&K's high-performance Ferromagnetic Shielding System.

The third version is a variation of the second with an Angled Center channel (ordered as the S-150AC). This speaker's front baffle is angled 7.5 degrees in the vertical plane to aim its high frequencies either up or down, depending on the cabinet's orientation. We used it on top of a rear-projection television pointing downward. This aims the high frequencies at the seated listeners even though we found that we had to use an additional wedge to get the angle just right. This speaker also uses M&K's Ferromagnetic Shielding System. Depending on your needs, you could actually use three Standard Centers or three Angled-Centers for all three front channels. For example, if a perforated screen is used in the front, one may prefer the Standard Centers for all three channels. However, if the speakers will be in a wall unit above listener's head, three S-150ACs pointing downward work out better. The point is M&K offers the user or installer many options to maximize audio performance.

We used the Sound Alignment - System from Checkpoint Laser Tools to help us take the guesswork out of setting up these speakers. The 770-laser alignment unit attaches to the front of the S-150 speaker pointing exactly 90 degrees from the front baffle. All one need to do is turn the laser on and you will see exactly where the speaker is pointing. We also used Checkpoint's Inclinometer to measure the angle of the rear surround channels. We'll talk more about these products in a separate review.

SS-250 Mk II Tripole®
We were fortunate that M&K supplied us with their new Prosumer SS-250 Tripole® surrounds to compliment the front S-150THX speakers. The front baffle of the SS-250 is identical to the S-150THX speakers, but they have additional drivers designed to fire forward and backwards for a dipole effect. A total of nine drivers is designed into this surround speaker in case you haven't been following along. When combined together with the front baffle, M&K refers to this as the Tripole® mode of operation. Having an identical front baffle of the S-150THX front speakers, the SS-250s are ideal for DVD-Audio and multi-channel SACD while still providing a spacious surround effect with the side firing drivers. In addition, depending on the way the speakers are connected on the rear panel, the speakers can be setup for Tripole®, dipole or direct radiator configurations.

We exercised both the dipole and tripole modes to hear the sonic differences. What we found was depending on the source material one configuration worked better than the other. When the rear material was more ambient in nature, we liked the dipole mode. Sound didn't appear to come directly from the surround speaker, but rather spread around and behind us. In contrast, DVD-Audio 5.1, DTS 5.1 and multi-channel SACD material sounded the best when we ran the SS-250s in the direct radiator mode. This gave us the best timbre match with the front speakers. Ideally we would like to have five identical channels for most of the DVD-Audio and DTS music we listened to. However, the third (Tripole®) mode radiates sound from the front as well as the sides for the best of both worlds. We currently have our surrounds setup in the tripole mode and it seems to be the best all-around configuration for most material. Since this speaker offers different configurations, the user has the option of changing modes with a simple switchbox. We plan to implement an external relay to switch modes for us based on source material.

Similar to other offerings in the M&K subwoofer line, the MX-350THX MkII houses two long-throw 12" woofers in a push-pull configuration. This particular subwoofer is magnetically shielded to prevent any video problems due to the large magnet structures. The design has one driver facing into the room while the second driver faces up into the bottom of the cabinet. Driven by a powerful 350 Watt RMS amplifier, both drivers are wired electrically out of phase, but acoustically in phase with one another, doubling the amount of acoustical power into the room. This approach, according to M&K, virtually eliminates even-harmonic distortion by canceling out driver non-linearities. The MX350THX delivers a maximum output close to the same levels as the highly regarded MX-5000THX, while the Headroom Maximizer IV circuit prevents amplifier clipping and still achieves fast and articulate bass response. The rear panel of the MX-350THX offers the user maximum flexibility. Several options are available to accommodate various configurations.

Low-pass Filter - The low-pass filter control can be set to one of three different settings. The first is the THX mode, which bypasses all low-pass filtering in the subwoofer and completely relies on the THX controller to provide the low-frequency signal to the subwoofer with the 80Hz and 24-dB/octave crossover characteristics. The variable mode allows the user select the best crossover frequency for his/her setup with a variable control. The third setting is a fixed 80Hz and 24-dB/octave low-pass filter built into the subwoofer.

Bass Level - The bass level can be set to two different settings depending on the type of processor used in the system. The THX mode is a fixed level of 90dB with a 100mV RMS input. When using a THX certified processor, the THX mode should be utilized. The variable mode allows the user to adjust the level of the subwoofer using the variable control. When using the variable mode, the setting marked Reference is the same level the THX mode uses.

Bass EQ - The Bass EQ switch has two settings, THX and Extended. The THX setting produces the flattest response and is recommended for most installations. The Extended setting produces a flat anechoic response, which results in an increase in level below 30Hz due to room gain. This increase is about 12 dB/octave. The Extended setting is provided for measurement purposes and for those who might want this sonic profile. However, this setting limits the subwoofer's output and dynamic range.

Phase - The phase switch is used to control the phase of the subwoofer output. There are two positions, "+" for in-phase and "-" for inverted-phase. The only way to know what the best setting should be is to try both and determine which position produces the highest level output. Positioning of the subwoofer as well as room dimensions affect the desired phase setting.

As with several of M&K subwoofers, the MX-350THX MKII includes the Active Headroom Maximizer circuit that prevents the all too common clipping associated with overdriving. We didn't use the internal low-pass filter because our THX processor took care of this for us. As a result of using the 80Hz crossover frequency built into the THX processor, the subwoofer blended seamlessly with the main S-150 front channels.

System Performance
Our evaluation of this speaker system started with the Parasound AVC-2500u THX preamp/processor and Parasound HCA-2205AT five-channel amplifier. The 4-ohm nominal impedance of the speakers requires an amplifier capable of delivering high current. The HCA-2205AT worked well in this setup. Sony's DVP-NS900V was used for both two channel as well as multi-channel SACD recordings. We also used it as a CD transport for our listening tests. The new Kenwood Sovereign DV-5900M 400 disc changer was used for all DVD-Audio and DVD-Video material. The six channel analog outputs were sent through an M&K BMC 5.1 mini bass management controller to properly crossover the frequencies for the main channels and subwoofers. Ultralink's Platinum Series Ultima Mk II cables were used between components

One of the advantages of these THX-Ultra certified speakers is the narrow vertical dispersion, which helps prevent floor and ceiling reflections. Reflective surfaces introduce secondary arrivals of sound that, when combined with the direct sound from the speaker, blur and defocus the image. To help dampen our listening room we have the walls treated with Echo Buster sound absorption panels. In addition, we have a pair of Echo Buster bass absorbers in the front corners of the room. Fortunately, our acoustically treated vaulted ceiling further reduces unwanted reflections. The narrow vertical dispersion of the S-150THX speakers works well in rooms that have reflective surfaces. We could hear significant differences in the upper frequencies if we moved outside this vertical window. Due to the driver arrangement on the front baffle along with the crossover design, we found the S-150s very consistent at all seating positions (horizontally) within the optimal vertical window. This uniformity provided us with excellent response in our home theater environment.

What sets this M&K system apart from so many speaker systems I've listened to is the ability to play them at high volume levels without the fatigue often encountered with lower priced speakers. While less expensive speakers can sound wonderful, they usually lack the ability to play at high volumes and still sound good. The overall performance of the S-150THX proved to be reference quality for home theater applications as long as time was spent to properly set up the system. These THX Ultra certified speakers are not forgiving if the alignment is not directed straight at the listener. This is why both THX and M&K endorse the Sound Alignment - System from Checkpoint Laser Tools as mentioned earlier. These tools help pinpoint the alignment of the front baffle to ensure the best high frequency response from the highly directional loudspeakers. A significant amount of time was spent setting up the speakers and the laser alignment tools took out much of the guesswork for us. Once the system was properly aligned, the results were spectacular.

We ran through the paces with scenes from Pearl Harbor in DTS. The attack scene on the harbor has been one of the industry's favorite surround demonstrations this year and we can see why. Planes moving through all corners of the room gave us a sense of reality few systems are capable of. The dialog was crystal clear with perfect intelligibility, never sounding overly bright. Sounds panned seamlessly throughout the room without any distractions. The Tripole rear channels were highly effective in providing a timbre matched to the fronts channels while spreading the sound around the back and sides. The low-end impact from the explosions was handled with ease by the MX-350THX subs. The two 12 inch drivers per cabinet moves an enormous amount of air and still has the ability not to sound muddy. The bass reproduction was tight and articulate as we have heard in the past with this push-pull design. Our Sencore SP295 Audio Analyzer confirmed the low frequencies we heard/felt showing substantial levels of bass in the 20Hz region.

While movies are a large part of how we use our speakers, music is equally important in any practical environment. The S-150THX speakers certainly hold their own against any home theater system we've heard. Certainly there are tradeoffs with any speaker system and if we were to buy speakers solely for listening to music, there would be many to choose from. However, the results of listening to several multi-channel DVD-Audio and SACD recordings with this system proved to be very satisfying. The new high-resolution 5.1 discs really push the edge when it comes to multi-channel high-resolution recordings and with these speakers we heard subtle details that overwhelmingly impressed us. In our opinion, the new DVD-Audio and multi-channel SACD recordings offer consumers a whole new level in audio performance. Since Warner Music has aggressively introduced remixes of some of the best groups of the 70's, much of our listening was based on this material. Fleetwood Mac's Rumors was a classic two-channel recording and the new 5.1 mix is superb. In addition, the Eagles' Hotel California was a great demonstration of the artistic creativity that goes into these new multi-channel recordings.

It's not surprising that JAK Productions used M&K speakers for their sound design and picture editing suites for the Star Wars films - The Phantom Menace and the recent release of Attack Of The Clones. Compromise in sound quality on films such as these is not an option and that's the primary reason why so many professional studios around the country are currently using M&K speakers.

The performance of this system went well beyond any home theater speaker setup I've experienced in the past. The pinpoint accuracy and clarity of the front mains, especially at high volume levels, was an exceptional experience. The matching surround channels with the addition drivers for the Tripole effect proved to be highly effective while watching movies. Listening to both DVD-Audio and multi-channel SACD enveloped the room with five high-quality channels with little compromise. The low frequencies handled by the MX-350THX subwoofers blended seamlessly with the mains, giving the listener a realistic full range system. While this system is not cheap (close to $10K retail), the performance coupled with M&K's reputation in the professional industry, may very well justify the cost. To further tempt you, M&K offers solid build quality and an impressive warranty (ten years, 5 years on the subwoofer amplifier) . We've had this system running for months now and we never get tired of listening to it.

- Kevin Nakano

See the latest MK Sound S-150 System Review

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OPPO BDP-103 Blu-ray Player

Review System

Pioneer Elite PRO-610HD 58-inch HD-Ready TV (ISF calibrated)

Parasound - AVC-2500u THX-Ultra Certified DD/DTS Preamplifier/Processor

Parasound - HCA-2205AT THX-Ultra Certified Five-Channel Power Amplifier

Set-top Box
RCA DTC100 HDTV/DSS Satellite Receiver

Sony DVP-NS900V Progressive scan DVD/CD/Multi-channel SACD Player

DVD Audio/Video Player
Kenwood DV-5900M 400+3 Disc DVD Audio/Video Changer

Laserdisc Player
Pioneer Elite CLD-99 Laserdisc Player

Room Treatments
Echo Buster panels and Bass Buster towers

Interconnect Cables
Ultralink's Platinum Series Ultima Mk II

Laser Tools
Checkpoint Laser Tools - Sound Alignment System

Audio Analyzer
Sencore SP295 Audio Analyzer

Review - At a glance
Miller & Kreisel S-150THX Speaker System


S-150THX, S-150ACTHX

  • Three 1" soft dome tweeter
  • Two 5 1/4" polypropolene drivers with rubber surrounds
  • THX-Ultra certification
  • Phase-focused crossover
  • Magnetically Shielded
  • S-150AC is an angled center channel
  • Recommended Power: 25 - 400 Watts (RMS)
  • Frequency Response: 77Hz-20KHz ± 2dB
  • Impedance: 4 ohms
  • Weight: 24 pounds
  • Dimensions: 12.5" H x 10.6" W x 12.5" D
  • Warranty: 10 years
  • MSRP: $1750 (S-150THX LR pair), $875 (S-150ACTHX Center)

    SS-250 Mk II Tripole®

  • Three 1" soft dome tweeter
  • Two 5 1/4" polypropolene drivers with rubber surrounds
  • Four Side Firing 3" drivers
  • THX-Ultra certification Pending
  • Phase-focused crossover
  • Recommended Power: 25 - 400 Watts (RMS)
  • Frequency Response: 77Hz-20KHz ± 2dB
  • Impedance: 4 ohms
  • Weight: 26 lbs. each
  • Dimensions: 12.4" H x 10.4" W x 14.5" D
  • Warranty: 10 years
  • MSRP: $1499 each

    MX-350THX Mk II Subwoofer

  • Drivers: (2) 12" long-throw, magnetically shielded drivers
  • Push pull configuration virtually eliminates even harmonic distortion
  • Built-in 350 watt RMS amplifier
  • Active Headroom Maximizer IV design to prevent clipping
  • Selectable low-pass filters
  • Switchable bass extension
  • Adjustable 50Hz-125Hz low-pass filter with bypass
  • Frequency Response: 20 - 125 Hz ± 3dB
  • Weight: 82 lbs
  • Dimensions: 23" H x 15.25" W x 19 5/8" D
  • Warranty: 10 years, 5 years on the internal amplifier
  • MSRP: $1899

    Company Information
    Miller & Kreisel Sound Corporation
    9351 Deering Avenue
    Chatsworth CA 91311
    818-701-7010 FAX: 818-701-0369

    Source: Manufacturer Supplied

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