Monster MPA 5150 Multi-channel Power Amplifier 
Home Theater Power Amplifiers Multi-Channel Amplifiers
Written by Brian Kahn   
Sunday, 01 July 2007

Introduction
The ever-present Monster Cable brand is expanding. Not a company to rest on its laurels, Monster’s vast portfolio of products will now include power amplifiers to go along with a robust offering of cables, accessories, furniture, speakers and beyond. Monster power amplifiers, like their recently reviewed loudspeakers, are not being prominently promoted on their own, but rather as part of an entire Monster products solution. One day you will be able to walk into a Monster Cable M Design dealer and purchase an entire Monster system.

The Signature MPA 5150 five-channel reference power amplifier ($3,500) is one of three amplifiers in the Monster Power amplifier lineup. The MPA 5150 is a five-channel amplifier rated at 150 watts per channel into eight ohms and 250 watts per channel into four ohms. The MPA 5150 chassis is anything but your ordinary black box amplifier. The styling is consistent with Monster’s line of power conditioners. The 75-pound, 17-inch-wide by 20.25-inch-deep and seven-inch-high chassis, with the exception of the front panel, is made of a heavy gauge black metal. Much of the body is perforated to increase cooling.

The front panel aesthetics are unlike those of any other amplifier I have seen. Detachable rack ears flank a five-section, brushed silver aluminum front panel that is reminiscent of five leather-bound volumes on a bookshelf. Each of the five sections has an oval LCD window in the top section. Below the LCD window are two LEDs, vertically stacked. Finally, there is a retractable knob halfway down the panel. The center section also features two buttons, the discs of which appear to be made out of the same material as the front panel. Each of the LCD windows is a power meter. These are reputed to be laboratory grade digital power meters that will depict the actual wattage being used by each channel. The meters have a peak hold feature. The LEDs depict power and clipping; the potentiometers are for input sensitivity. The center mounted buttons are for power and a 12-position brightness control. The back panel is not as fancy as the front panel, but it is similarly full-featured with balanced inputs, unbalanced inputs, a switch to select between them and five-way binding posts for each channel, IEC power receptacle, grounding pin, voltage selection switch, main and channel fuses, remote on/off input and output. Build quality is topnotch and the amplifier is as solid as they get.

The MPA 5150 is not only full-featured, it comes with everything that one would need to get the amplifier installed in your system, with the exception of audio cables, which of course Monster will be happy to sell you. Inside the box, in addition to the amplifier, I found all the hardware necessary to rack mount the amplifier, a comprehensive owner’s manual, remote power cable and DC power transformer (to act as a remote trigger if there is no other trigger in the system).

The MPA 5150’s guts are substantial as well. Even though Monster Cable has plenty of smart engineers and designers on staff, they were wise enough to employ the services of someone with a great deal of experience in the world of amplifier design. The amplifier was designed by Richard Marsh, a name well known in audiophile circles in connection with power amplifier design. Twin transformers and power supplies insure that the amplifier can exceed its power specifications, even with all channels driven. Peak power output is over 500 watts per channel into four ohms and the amplifier is stable below two ohms. The signal to noise ratio is greater than 113dB A weighted, THD <.01 percent at 1kHz, <.02 percent at 20kHz at rated power into eight ohms. Speaking with Mr. Marsh about the amplifier, it became clear that the MPA-5150 is a high-current design and that the specifications are extremely conservative. There is much more power on tap than 150 watts per channel while keeping within the above performance specifications.

Mr. Marsh and I discussed the amplifier’s design and he explained the Monster Mirrored Amplifier Technology (MMAT), a current feedback circuit topology that is said to lower distortion and increase clarity by mirroring the input signal at the output stage through fully complimentary differential circuits. A balanced, complimentary push-pull stage is reported to be ultra-wide bandwidth to take full advantage of today’s 192kHz recordings. Mr. Marsh feels that it is important for amplifiers to be able to reproduce these higher frequencies for superior soundstaging. High-current MOSFET output transistors permit quick, high-current transfer for increased dynamic capabilities.

Set-up
The Monster MPA-5150 was quite simple to set up in both my reference stereo and theater systems. In my stereo system, I utilized my Krell KAV-400xi and McIntosh Laboratories C-220 as preamplifiers, with the Krell driving the 5150 through its single-ended inputs and the McIntosh through the balanced inputs. I used B&W DM604S3, Krell LAT2000 and Monster’s own THX towers for speakers in my two-channel system.

I used the balanced inputs of the MPA-5150 when it was installed in my theater system, driven by the balanced outputs of the Halcro SSP100 and Krell HTS 7.1 processors. The speakers utilized in my theater system with Monster Cables MPA-5150 included Dynaudio’s Audience series speakers and Monster THX Select speakers. The binding posts, like the rest of the amplifier, were sturdy and solid. I had no problems connecting all the cables to the MPA-5150. While each channel had its own individual level control, my speakers were close enough in sensitivity that any level adjustments were easily handled by my processors.

Music And Movies
I used the MPA-5150 for casual listening for about a week before I sat down for a careful listening session. Having recently watched a television special on Norah Jones, I decided to start my review with her debut album. Come Away With Me turned out to be one of, if not the most, commercially successful albums on the historic Blue Note label. While listening to the title track, the MPA-5150 reproduced a soundstage starting a little before the front plane of the speakers. The depth of the image was not quite as great as when I used the Krell 400xi, but it did extend to the front wall. The breadth of the soundstage was appropriate for this track. The vocals were clean and solid at normal listening volumes.

The MPA-5150’s sound quality was as solid as its 75-pound chassis. The sound was sharp and clear and the amplifier had no problems keeping a tight reign on all of the speakers I tried with it. A close comparison with my reference Krell indicates that the MPA-5150 has a slightly higher noise floor with a touch of grain. The amplifier is slightly forward and, at high volumes, I noted a bit of glare on the high end. At normal listening levels, the MPA-5150’s high end was well extended with some air, but not quite as much as the amplifiers two and three times its price.

I moved on to Dire Straits’ Brothers in Arms album (Warner Brothers). “Money For Nothing” is an all-time favorite of mine. The momentum-building opening riff was easily handled by the MPA-5150. The instruments were all individually portrayed with clarity and weight, maintaining their separate space without blending together. The imaging on “Your Latest Trick” was solid. The vocals were crystal clear, as was decay of the cymbals. When listening at normal volumes, the cymbals were slightly on the bright side, but still sounded natural, just a bit more energetic than usual.

Paula Cole’s “Tiger,” the first track on the album This Fire (Warner Brothers), has a great dynamic range. The track opens with her vocals solidly placed center stage. I listened to this track with the McIntosh Laboratories C-220 tube preamplifier driving the MPA-5150 and found the combination to provide a well-balanced combination of lushness and detail. The vocals were still crisp and clear, but with a touch of that magic midrange bloom associated with tubes. The track’s deep bass line was portrayed with good detail and speed, reaching deep down to provide a tactile performance.

My stereo listening sessions with the MPA-5150 proved the amplifier to be a very capable performer. Like most components, proper system matching provides maximum benefit. This was clearly demonstrated with the components I was using. The preamplifier section of the Krell is quite good, very detailed and slightly forward of neutral. The MPA-5150 shares similar sonic attributes. Each component by itself is fine – add two of them in a row and the sonic characteristics are magnified. On the other hand, the McIntosh C-220 preamplifier is also very neutral and detailed, but it is slightly to the relaxed side of neutral. This made the McIntosh/MPA-5150 stand out above the Krell/MPA-5150 combination. This is neither criticism nor praise of any specific component, just a reminder that most components are not perfectly neutral and their sonic leanings should be considered when compiling a system.

Wrapping up my stereo listening, I watched The Chronicles of Narnia: The Lion, The Witch and The Wardrobe (Buena Vista Home Entertainment). The MPA-5150 kept the vocals clear and easy to understand, with distinct enunciation. The sonic signature was consistent from channel to channel, with voices retaining their distinct identities as they moved from channel to channel.

I was a bit anxious to see how the MPA-5150 would do when all five channels were being fed dynamic material. The big battle scene, even at high volumes, remained dynamic. There were no signs of compression. The slight glare I noted when listening to higher frequencies at volume during my stereo sessions was not as noticeable on movies. Despite the amplifier’s relatively modest rating of 150 watts per channel, it performed as though much more power was on tap when needed.

I then watched Superman Returns on HD DVD (Warner Home Video). As with the Chronicles of Narnia, the voices were natural and clear. This was an especially tough challenge in the congested newsroom scenes, but the MPA-5150’s clarity and crispness prevailed.

Moving on to the HD DVD presentation of Million Dollar Baby (Warner Home Video), I listened closely to the sound of the bags being hit. My most recent gym (no, I don’t go as much as I should) was the gym where Hilary Swank trained for the movie and the sound of bags being hit was consistent with my personal experience in the actual space. Ambient sounds were also portrayed with a good sense of envelopment and space, whether in the confines of the gym or the crowds in the arenas.

Listening to Sting’s album Brand New Day (A&M – DTS), I noted that the MPA-5150 easily controlled the bottom end of my full-range speakers on the bass-heavy first two tracks, “A Thousand Years” and “Desert Rose.” Despite the power the full-range speakers were eating up at louder volumes, plenty remained for all the various effects in the center and surrounds. Sting’s vocals remained clear and solidly placed, unaffected by the activities in the other channels.

While listening to the horns in “Perfect Love … Gone Wrong,” I was able to detect some of the brittleness I noted in my stereo listening, but only at higher volumes. This track does not have much in the way of horns, but if you listen closely to the horn sections and even the upper ends of the piano’s range, there is a slight grain. Again, this is something that I think most people would never notice if they weren’t listening for it.

The amplifier has some features that I did not use very much, such as the power meters and adjustable level controls for each channel. During a few loud and complex movie scenes, I found it interesting to watch the power level meters to see how much it really took to drive my speakers to those levels. I doubt that the power meters will be used on a regular basis by most listeners. They definitely add to the coolness factor of the aesthetics but, for most people, I think they will not be a needed item. The level controls may come in handy if there are extreme variances in the relative speaker levels or if you wanted to use multiple channels to bi-amplify speakers. I can think of a few other uses as well, but I think the majority of listeners will not use the individual channel levels.

The Downside
Monster Cable’s MPA-5150 is a feature-laden, solidly built piece of equipment that offers much for its selling price. From a construction standpoint, the majority of the amplifier is built like a tank. However, the feet are made out of relatively lightweight plastic. I would like to have seen higher-quality feet on the amplifier.

Sonically, the amplifier surprised me; it does most things extremely well. As noted above, I found it to by slightly forward of neutral. I would take care not to pair this amplifier with other components that are forward or bright-sounding, as it would compound this slight attribute and turn it into something more noticeable.

Conclusion
Monster Cable’s MPA-5150 is a solid performer in the world of multi-channel amplifiers, especially at its price of $3,500. If you need any of the special features that the MPA-5150 offers, the decision to purchase it is quite easy. If you are simply looking for a good, solid, quality amplifier for your neutral or slightly recessed five-channel system, the MPA-5150 deserves a listen. Do not let the relatively low power rating scare you away; it performs like a more powerful amplifier, especially when it comes to controlling speakers. If your speakers have a more relaxed or polite top end (as many currently do), the MPA-5150’s forward treble should not be noticeable.

All in all, Monster Cable’s first five-channel amplifier benefits greatly from Richard Marsh’s talents. While not perfect, this amp is a contender that should be taken seriously.
Manufacturer Monster
Model MPA 5150 Multi-channel Power Amplifier
Reviewer Brian Kahn





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