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Positive Feedback ISSUE 30
march/april 2007



8011AM monoblock amplifiers

as reviewed by Marshall Nack







Kharma Exquisite-Midi.

mbl 5011 preamplifier, mbl 8011 AM and monoblocks, and Kharma MP150 monoblocks.

Linn LP12, LINGO, EKOS tonearm, ARKIV II cartridge, AHT Non-Signature phono preamp modified by Walker Audio, and an Extremephono Limited Edition cable. mbl 1521A transport, CEC TL1X transport, von Gaylord Audio 2 chassis DAC.

Interconnects are TARA Labs 0.8, Kubala-Sosna Emotions, Kondo, and Kharma Enigma. Digital cables are TARA Labs 0.8, Kubala-Sosna Emotions, and Kondo. Speaker wires are TARA Labs 0.8, Kubala-Sosna Emotions, and Harmonix. AC power cords are Tara Labs 0.8, Kubala-Sosna Emotions, and Harmonix.

TAOC Rack and TITE-35S component footers, Walker Audio Tuning Discs and Valid Points for LP turntable, Harmonix RFA-78i Room Tuning Discs, RFS-66ZX Tuning Feet, TU-888 Tuning Board, Acoustic System Resonators, Marigo VTS Dots, Argent Room Lenses, Echo Buster & Sonex acoustic panels, TARA Labs PM/2 and IDAT power conditioners, and Ensemble Mega PowerPoint outlet strips. ERaudio Space Harmonizer component platforms.


Unpredictably, it was the silken quality of string instruments that first caught my attention. Mind you, there wasn't any texture to speak of on those strings, but still… it ain't exactly what you'd expect to hear three hours after installing factory-fresh solid-state amps, is it?

The next day, I found myself engaged in those repetitive, unhealthy, head and neck reflexive double-takes, you know, the "What the heck???" kind, as I tried to comprehend the low-frequency impact punch delivered on track one of Manu Katché's Neighbourhood (ECM 1896). The kick drum had detached itself and was doing its pummeling underneath the upright double bass. Where did that come from? What I had heard as a single event was now two. Fresh from a pair of Kharma MP-150 mono amps, it's as if I've added a powered subwoofer.

All in all, those first four days I could have sworn I was listening to the most powerful, most tube-like, solid-state amps ever made. They even evinced some of the flaws associated with those devices, appearing soft, rounded, and thick in the middle. These qualities would largely disappear within a week, leaving behind a slight residue, which the 8011AMs would never fully escape: they became defining traits.

the Big Dynamics

I had waited for the 8011AMs to arrive before I dared play something like Mahler's Symphony 2, because I knew the system didn't have enough muscle to do it justice. Oh, it would have been quite good, for sure, but I like my Mahler to be riveting. Now, with the 8011AMs in line, I expectantly loaded Pierre Boulez and the Wiener Philharmoniker's new Mahler Symphony 2 into the tray (DG B06684-02). In the opening moments of the first movement the tension is tangible, if not quite the palpable drama I remember from the well known Maurice Abravanel and Utah Symphony Orchestra recording from 1967. That performance, captured in the Mormon Tabernacle, revealed a vast space. The Boulez has less hall and I wasn't getting the impression of 90 or so heads on the stage in front of me. But wait, the old Frenchman was holding back, gearing up for the first big crescendo a minute in. The Kharma Exquisite-Midi speakers said "Bring it on!" They want all the watt-piles you can deliver and, by golly, the dynamic range seems too wide. I'm not used to this: soft passages are way down, necessitating upping the volume, only to be hammered a second later by the smack of the bass drum.

Ah, 'twas delicious; just what I was hoping for! I needed to put on the Abravanel Mahler Symphony 2 right away (Vanguard Classics CD, SVC2), and then the LP of the same, to double-check my memory. Yes, there is a hall echo clear across the room. Part of the Utah recording's magic is in the generous allotment of air and bloom on woodwinds; part is in the exceptional acoustic of the Mormon Tabernacle captured in this recording. (This is characteristic of almost all Vanguard Abravanel issues on the original black label LPs. Sometimes it's on later reissues—most often, it's lost.) Abravanel moves the piece forward at a leisurely pace, whereas Boulez's rendition is tighter, more determined, in terms of both sound and direction. Boulez knows where he wants to go and how he intends to get there. It's a keeper.

I heard glorious dynamics that kept me on the edge of my seat (and sometimes with my finger on the remote). With these amps, you have a sense of power lurking in the wings, ready for the slightest provocation. With something like Tchaikovsky's The Nutcracker (Philips 289 462 114-2), wherein Valery Gergiev drives the Kirov Orchestra to crescendos beyond reasonableness, I had to ride the volume control, vigilant to reduce peaks. In my room (12' x 31' x 8' ceiling), sounds beyond a certain SPL are not pleasant. These peaks excite nodes and lose transparency, but it's not the amps' fault. They were still grander and cleaner than any comparably priced amps. I can put anything I want on the player and feel confident the amps can handle it.

the Absolute Sound?

A couple of years ago I attended a music festival at Planting Fields, in Old Westbury, NY, one of those Long Island estates from the bygone robber baron days described so well in F Scott Fitzgerald's The Great Gatsby. It's now a public museum.

The first program took place in what must have been the maintenance equipment storage facility, a large, empty, aluminum, hangar-like shell of a structure. The well-known string quartet on the makeshift stage was good: the sound, however, was terrible. Zippy, fast as blazes, with a snappy transient all right, so scratchy, thin and disembodied as to make my thoughts immediately turn towards, "What's the most gracious way to make an exit RIGHT NOW?" no more than a minute into the performance. Mission accomplished, I moved on to other delights, such as the animal petting zoo. Ah well, not an auspicious beginning.

Later in the day, the same string quartet was slated for another performance. This one was held inside the mansion, in a large, wood-paneled, book-filled library. As I sank into a plush sofa, they tuned up. Ah… and then a cushion of warm, sweet, inviting sounds washed over me. Was this really the same players and the same instruments?

When people talk about the "absolute" sound (even the title of that magazine), they are misleading you. There is no single, real thing, but a spectrum of possibilities, all real. Believe me, there are plenty of lousy sounding halls hosting major artists. This is real, but it is to be avoided—don't model your system on it. While I can't speak for you, I can tell you the Platonic ideal in my mind is what went down in the library.

In the Library Seat

A few years ago, my sound was all too close to that of the hangar. This was in the timeframe when my nom de plume was "The Tweakaholic". I wore it like a badge of honor, for it implied I was a master of audio Rx know-how for any number of system ailments. I never stopped twiddling with third-party accessories, 'cause there was always something I didn't like that I knew (or hoped) I could fix. Tweaks piled upon tweaks. In the consensus of a certain group opinion, the use of footers, platforms, weights, etc, offered verifiable improvements and was justified, although I occasionally had to wonder why multi-thousand dollar components needed them. (Do you know many manufacturers use the cheapest supports available, often plain old furniture bumpers, with the expectation you'll be using third party footers.)

I first encountered gear that put me in the sonic milieu of the library when I reviewed some Lamm Industries components. (Actually, I was led to this gear: it's imperative to have good guides.) The Lamm L2 pre and the ML1.1 amps were the eye-openers. What a revelation! There are certain things that no quantity of Band-aids can overcome—one of them is the characteristic voice of a finished design. Not that the Lamm gear is without problems—just that it spoke to me in a way I'd not thought possible. The mbl 8011AMs share that. I will briefly describe one aspect for you—how they handle the life cycle of a note.

the Life of a Note

A component's task is to pass along the signal capsule intact, without adding commentary or removing information, that is, without messing with it. It begins with the initiation of an event. In the library, this was almost a non-occurrence. Being intimate with the cello and oboe, I can tell you that this is how it happens in a good room with string and wind instruments. (It's not the same for plucked or struck instruments: for them, each phase of the note's life is different.) One moment there was silence; the next instant the note was present. The transient arrived almost unnoticed, without any sort of heraldry or fanfare, wholly formed and temporally coherent. Furthermore, the sustain part of the note sounds much like the transient for these instruments. That is what I heard in the library: that's what I hear with the Lamm gear and the 8011AMs. The amps render transients wholly consistent with their treatment of the sustain. Most components don't do that. What was totally absent was the excited or uncontrolled edge many components throw in.

As far as I'm concerned, this is the way transients should behave, but it may not be everyone's cup of tea. Some people want transients to pop and startle, because that's the way they hear them in real life and that's what they like. I've heard them do that, too (in the hangar, for example), but I have a decided preference for the way the 8011AM handles it. And given that I've never encountered a system that can do both, a choice must be made.

Grain and other Nasty Business

For a solid-state device, the 8011AMs handle grain in a unique way—there isn't any! Somehow, they manage to eliminate the underlying, sub-surface carpet, and replace it with a buff smoothness. This gives sounds a taut, somewhat large, undifferentiated exterior, not unlike the way certain tube components render it. Understand the 8011AMs have no difficulty providing texture where it is most expected. It's in low-level passages, in the realm of micro-dynamics, that an unchanging surface is discerned. In other words, I'm not hearing the level of micros I got with the Kharma MP-150s, for example.

For an idea of what's possible, listen to the way the Art Audio Vinyl Reference phono stage (VR), handles surface and you'll see what I mean. The waveform released by the tube-hybrid VR is fluid in terms of texture, image shape (zaftig or lean), harmonic balances, and dynamics. It is imbued with continual ebb and flow from one moment to the next—and this is in spite of it having more grain and less purity. The result is the VR is endowed with exceptional ability to convey the musician's intent—how he shapes the note and the phrase. The 8011AMs don't go there. They sound like a tube amp, but it's definitely a push-pull type of tube sound, not for a moment to be confused with one of the SETs. (And anyone who knows tubes would have a problem, because he would not be able to identify which power tube, they're like: is it a 6550, or EL34?) This is the only area I noticed anything less than Class A performance: their micro-dynamic capability comes in about average.

Finally, the 8011AMs are tidy on the trailing side of the note. Decay is not shortchanged, but when the time comes, and only then, the large and buff notes depart without leaving residue. The decay is as unexcited as the arrival.

These amps are highly resolving, but I wouldn't call them resolute because they don't have an aggressive bone in them. There is an ever-present ease that prevents truly unpleasant sounds from reaching your ears. (The downside here is this precludes them from reproducing real edginess.) It's a funny thing: while the picture may be towards the pretty side, the soft filtering or editing did not get in the way of resolution—it was benign. A change anywhere was very apparent. The amps did not disrupt the source capsule.

The softness, the smoothness and the unexcited transient are OK by me. It means I can listen to more of the music in my collection, not just the carefully prescreened discs that I know will sound good. (Isn't this so often the case—guys with megabuck systems will only play a dozen or so CDs that they know sound good. Other than showing off the system, what's the point of that? Doesn't it get boring? I'd rather forgo extracting the max from the golden dozen and in return be able to enjoy the thousands more I paid good money for. In my personal play list, I give equal weighting to sonics and performance.) To be honest, there are a lot of recordings in my collection I know I'll never listen to, because they sound awful. I keep them because they are important or historical.

The 8011AMs have wider dynamics and scale upward more effortlessly than the Kharma MP-150s. While we're at it, compared to a bi-amped pair of MP-150s, the 8011AMs are darker, with more bottom and more flesh. They crescendo beautifully and never sound like they're straining—over a three-month period I never heard these amps distort. When they run out of gas, they just flatten out.

the Modern Sound

Perched in the sweet spot, as I look out at this array of mbl gear, there's not a third party footer or stick-on dot in sight. And the sound is wonderful, to the extent that I pass whole evenings without fiddling with wires or venturing behind the rack. That's no small achievement, but I feel I can't take much of the credit. After all, it didn't require any work on my part. These mbl components are plug-n-play. My job was just to make sure I didn't screw anything up.

I suppose some will say, "Sure, the 8011AMs sound great. Fed by all those mbl electronics up front, they ought to." Of course, there's something to be said for the synergy of a single brand. But don't overlook the obvious: I bought the transport and the preamp because they demolished my references. So far, every mbl component I brought in turned out to be a category killer. Scary thought: I may wind up with an all-mbl Noble lineup.

The 8011AMs conform to the sonic profile of the family, i.e., the 5011 preamp, the 1511 D DAC and the 1521 transport. First, they're all warmish-neutral, non-fatiguing and have an introvert personality type. Second, they are comparatively dark. Some people run when they hear the adjective "dark", but it is really just a comparative thing. Expect the tonal balance to shift downwards. For me, this is highly desirable. You may have noticed I've stopped talking about weight, or rather, the lack thereof (that's a relief, huh?) The mbl line up in the front of my room is the main reason why.

Third, frequency response is a model of linearity, with great bass, full and proportionate allotments of body throughout the range, and sweet treble. Fourth, the noise floor is uncommonly low. Ain't no artifact or extraneous noises present, and there's not a peep out of the speakers when the systems at rest. Fifth, they don't exhibit a solid-state grain structure.

8011AMs in situ

New amps always start out on a Harmonix TU-888 System Tuning Board, usually with a set of Harmonix TU-66ZX footers between them and the board. They also get a dedicated TARA PM/2 passive conditioner and The One PC. Almost all remain that way for their residency. The only exception to the rule was the time I had the big mbl 9007s. These Reference Line amps were the first ever to sound best situated directly on my parquet floor.

Based on that experience, I began with the 8011AMs on the parquet. The first two days, my thoughts ran towards throwing a maple platform under them to ameliorate the thick midrange and the tubey gauziness. By the third day, the gauze lifted and such thoughts disappeared. Then, after a week, they returned, but now it was because the 8011AMs had gone and swung in the other direction on me.

At this point, I put the Harmonix TU-888 boards in. Yikes! By golly, those ninety heads in the Mahler Symphony 2 were suddenly accounted for. The space just exploded in front of me; the revelation of depth and 3-D cues was startling. I was reminded once again of stereophonic sound's potential for creating magic, something that belies what two channels of information are supposed to be capable of. How a pair of stereo speakers can re-create 3-D is baffling—quite beyond any theories I have come across regarding this phenomena. How a board, albeit a very expensive one ($2400 ea), can engender involvement and intimacy is pretty far out—quite beyond all our measuring tools. Those objectivists have no idea what we're talking about. Nevertheless, the evidence is there right in front of me. Everything got better; dynamics, weight, body, you name it. Except for one thing: they injected a dose of coloration and moved a step away from neutral. The effects are hugely impressive and compelling, but now less realistic. I wish it didn't have that artifice, but you know what, given all the wondrous effects, I'm gonna indulge, at least for a little while.

the mbl 9007 monoblocks

As I said, the Reference Line 9007s were the first amps ever to sit on the floor, totally untweaked. The sonic family resemblance was there, however those next-up amps managed to do everything with an added dollop of goodness. They had extra spoonfuls of flesh, timbre, dynamics and control. And they had soul.

That's what was missing in the 8011AMs, and that's what the boards introduce: space and the soul factor. (Funny thing, I noted the same differences between the Noble Line 5011 and Reference Line 6010 D preamps. The voicing within and between the lines appear to be consistent.) You see, the line up, which is currently an all-mbl Noble Line food chain from transport to amp binding posts (and unbelievably, as I said, all of it is in the virgin state: no special footers, no stick-on dots), while warmish, is a bit too neutral for me. I want a little schmaltz somewhere. The analog side has it, what with a Harmonix matte on the Linn LP12's platter, Harmonix RF-66ZX footers under the Lingo speed control, not to mention the tubed, SET-like Art Audio Vinyl Reference phono stage. A Harmonix tweak was needed somewhere: while a single RF-57 dot stuck on the DACs' IEC jack might have satisfied, the TU-888 boards under the amps do splendidly.

Design and Cosmetics

The 8011AM is the latest amplifier in mbl's Noble Line, the middle of their three lines. They call it compact. While diminutive compared to the 9007s at 75 lbs, they are not small or light (55 lbs), although one person can easily hoist an amp.

Superficially, the 8011AM has the Reference Line look, scaled down of course. They come suspended between Styrofoam bookends inside a corrugated shipping carton—not the fancy metal trunks used with the Reference Line products. The appearance is no frills and functional, a black metal box with a big, gold painted mbl logo and a bar of indicator lights on the front. Front panel controls are push-button activated Sleep and Standby. The lighted power on / off rocker switch is on the rear, along with inputs and outs. A corrugated metal heat sink runs along the right side. (The amp gets merely warm, but the EU requires the heat sink.) The built-in plastic footers are taller than usual, taller than any of the third-party ones I have on hand—I couldn't swap them in even if I wanted to.

The 8011AM is a mono, internally balanced, amp. RCA and XLR inputs are provided, it's your choice; just remember to flip the toggle switch to the input type you're using. Balanced inputs sound better.

The system warms-up in the usual 45 to 60 minutes; however, I do recommend leaving the 8011AMs on 24/7. Engage the Standby switch when not playing music over a long time. This keeps them fully powered up but with the outputs muted. One feature that I didn't find useful was the Standby button on the remote control: this switched off both the mbl preamp and the amps. But I use Standby when changing LPs; I don't want to de-activate the amps for that, I prefer to control the amps separately. The upshot is I have to go over and push the Standby button on the preamp.


Even though it is not a stereo amp, the 8011AM comes with two pairs of binding posts. They are not segregated for different ohm speakers—either pair can be used to run the speaker full range. The extra set is for bi-wiring, if you so choose, and mbl strongly recommends that you do. Bi-wiring with a mono-block is desirable and audible. Within a single speaker cable, low frequency current can modulate the higher frequencies—separating the two removes that potential distortion. And bi-wiring improves the amp's damping capability by better controlling the speakers' back EMF (back Electro Motive Force).


The mbl 8011AM amplifier may be an introvert (non-aggressive, not outgoing), but you'll find it the strong, silent type, holding back its large power reservoir until provoked, whereupon it ramps up cleanly and effortlessly. It is in total control as it lays out a precise soundstage with tons of non-invasive detail for your delectation. But it leaves it up to you to pick and choose what to focus on: as is the amps nature, nothing is forced.

These solid-state mono-blocks are on the accurate side of the fence, but it's an accuracy tempered by many tube-like qualities. They are warm and full-bodied, and lend the surface of the soundstage a softness that never sounds abrasive. In the big picture, they are capable of pretty much anything you might throw at them. Performance is a high Class A level everywhere except micro-dynamic capability, where they come in about average. The Kharma MP-150s have better micros, for example. However much they resemble tubes, they don't trespass on the micro-dynamics SET amps are known for.

I found their voicing just my cup-of-tea. I do hope it points to the incoming trend and is not the exception to the rule. Solid-state gear from ASR, another German manufacturer, McIntosh, and even Krell now have similar hallmarks. Let's describe it as post-modern solid-state to make it sound trendy—the voice of blended technology. But you may prefer something more dramatic and exciting. You may want a speed demon with some edge. That is not the mbl 8011AMs—keep looking.

If I seem at all reticent, it's only because I wanted them to be even more like their bigger sibling, the Reference Line 9007s. With the 9007s mated to the Kharma Exquisite-Midi speakers, I arrived at the portal of sonic nirvana: everything was happening on a very high plane. Without question, the 9007s are the best amplifier to cross my threshold ever. (They are also among the most expensive to do so, at $27,660 pair.) The 8011AMs are looking like the best in their neighborhood, at $12,400 pair. Marshall Nack

8011AM amplifiers
Retail: $12,400 pair

mbl Akustikgeräte GmbH
web address:

US distributor

mbl of America
6615 E. Sleepy Owl Way
Scottsdale, AZ 85262
TEL: 480. 563. 4393