Product Review - Bruce Moore Companion II-c Vacuum Tube Preamplifier - May, 2000

Jason Serinus


Bruce Moore Companion II-c Vacuum Tube Preamplifier

Coaxial Inputs: CD, Tuner, Aux, Video, Tape

Gain: 20 dB

MFR: 1 Hz - 200 kHz  +0, -1 dB

Maximum Output: 25 VRMS

THD: 0.05% at 2 VRMS Output

 Input Impedance: 100 kOhms

Output Impedance:  1 kOhms

Tube Compliment: Two 6DJ8, Two 6922

Size: 3.1" H x 15" W x 9.5" D

Weight: 12 Pounds

MSRP: $1,650 with Series Attenuators; $2,250 with Stepped Ladder Attenuators


Bruce Moore Audio Design, Distributed by R.B. Electronics, 5492 Linden Street, Dublin, California 94568; Phone 925-875-1055; Web  


The path to audiophile heaven is a bit like the path to the right mate. Just as some people fall in love on the first date and live together ever after (happily or otherwise), some of us easily connect on the first match with a satisfactory set of synergistic components and cables. Our sonic mates - we're talking polygamy here - may even turn up right in front of us, already hitched together in a single luscious-sounding showroom system. Much of the time, however, our right mates come our way only after lots of one-night stands and short-term relationships. Sometimes we go on blind dates, buying sound previously unheard. We may even pass through a series of costly divorces, trying and trying again until the right synergy ultimately occurs. But eventually, if we have faith, and keep our ears and hearts open to the music we love, we can arrive at a system that provides sonic satisfaction.

Many short-term relationships have certainly marked my path to a system that not only gives me pleasure and companionship but serve as a solid, reliable reference for writing the classical CD reviews featured on this website. I have experienced more broken engagements and costly divorces than I prefer to recount in detail. To share the Reader's Digest condensed version of the story, I've arrived at my present system configuration after going through three other amps, three preamps, two CD players, two transports, one set of jitter-control/resolution enhancement devices, two DACs, one disastrous set of speakers and subwoofers, one power conditioner, and many sets of power cords/interconnects/cables. While some of my changes were made simply because better components came along, others were necessitated by initial poor choices. Those errors, I now know, could have been avoided if I had (a) adequately auditioned all components before purchase, and (b) had a clear set of sonic criteria in my head before auditioning.

Finding the Companion Preamp

Perhaps two years ago, I moved through denial and faced the fact that I had to replace my power amp. When paired with my preamp, the soundstage it threw was tremendous and thrilling (especially through my Chameleon III speakers), if a bit outer space. Its highs were also much clearer and more refined than my last amp’s, and its bass superb. Alas, this amp’s timbre was off. Everything, from solo harpsichord to dissonant, twelve-tone orchestral music, sounded equally sweet. Some music is meant to be sweet, but what isn’t loses its truth if its acid bite isn’t there. With this particular amp, all I could hear was sweet sweet sweet and slam slam slam. Furthermore, between sweet highs and slamming bass sat a recessed midrange, holding its hands over its head and doing its best not to be noticed. What on first audition had seemed quite seductive, now seemed far removed from the sound of unamplified music heard in a good acoustic venue.

Right before that amp was replaced by my current one - a far more natural sounding Pass Aleph 5 - I briefly borrowed my neighbor’s Audible Illusions Modulus 3a preamp. I only had an hour to listen after it had warmed up for a day, but the difference I heard from its line stage was so huge that I realized that my own preamp, bought used without prior audition, would also have to go. Sure enough, its dark top and lack of ultimate bass, which actually helped tame the old amp, was not a good match for the Aleph 5. A new preamp was definitely in order.

The first preamp I tried did not bring me much pleasure. Then, a Bay Area dealer who eschews opening an expensive showroom in favor of door-to-door service, brought over the Bruce Moore Companion II-b. It literally brought my system back to life. I can still remember how thrilled I was to listen to Susan Graham’s exquisite Reynaldo Hahn recital (La Belle Epoque on Sony Classical) through the Companion. Her voice and piano accompaniment sounded so rich and alive. So much more detail and midrange warmth came through. I could finally hear the body of the sound without the top edge predominating.

Having made a number of poor choices in the past, I was not about to make this one in an hour. The preamp was left with me, and I had many weeks in which to audition it. To get assistance with my decision, I called the friend in the industry who was a fan of the preamp I had first rejected. This man has an extraordinary sonic memory, which he frequently calls upon when matching cables with components. When I asked him if he had ever heard of the Bruce Moore preamp, he replied, “Oh yeah, I was just listening to it last night.”

“You were?” I responded with amazement.

“Yes. My Pass preamp was loaned out to a client, and I missed being able to listen to music. So I pulled the Bruce Moore out of the closet and hooked it up. You know, I think it has just about the best sound of any preamp for the price.”

On top of this came the information that Bruce Moore, a reclusive Silicon Valley engineer with whom I have never spoken, had designed the initial Audible Illusions Modulus preamp. I listened some more, and made the Bruce Moore Companion II-b my new line stage.

The Companion II-b lacked the option of a detachable power cord. It also had non-detented volume controls that made balancing left and right channels difficult; only one set of outputs, and internal wiring that I felt could be bettered by Nirvana hook-up wire. (I had previously used the Nirvana to rewire my Chameleon speakers, and found it superb.) With the help of my technical wizard friend David, a detachable power cord receptacle, a second set of outputs, and Nirvana internal wire were installed. All made noticeable improvements.

The Bruce Moore Companion II-b preamp especially excels in midrange and bass. When plugged into my superb PS Audio P300 Power Plant, the Moore/Pass combination FINALLY began to deliver the lively highs, full midrange, and tight bass I had been searching for. In addition, I experienced lots of depth, natural timbres, a wonderful sense of three-dimensionality and air around instruments, and good location of sonic images on a wide soundstage.

And . . .

There was only one major problem. Shortly after I installed the preamp, my Theta General Va DAC blew. I ended up sending it to Theta for repairs. Theta said that they had experienced only one other case of a similar occurrence. In that situation, the culprit was a preamp that shorted to ground all unused inputs.

After Theta fixed the unit, it blew again a few days later. This time, Theta was sure the problem was with my preamp, not with their unit. I had to pay a good $100 plus shipping for repairs. David surmised that every time I had the Theta turned on and selected a preamp input other than the Theta's, the preamp shorted the Theta to ground, causing the Theta's output stage to burn up. He assured me that installing either isolation resistors or blocking capacitors at the Theta's outputs would prevent the possibility of again shorting the Theta's output and destroying its output transistors. When Theta refused to perform such a modification, claiming it would negatively affect the sound, we performed the removable modification ourselves.

David claims that all classic Macintosh preamps short their unused inputs to ground to reduce crosstalk. He therefore suspects that the Mac preamps would have the same problem with Thetas that my Companion had. David also believes that most manufacturers of solid state units that have a current-sensitive output stage provide resistors to protect against shorting. As far as he can tell, Theta does not do this. This resulted in the shorts, and our need to modify the Theta (or ditch the preamp). My friend modified the Theta, inserting high quality blocking capacitors right before the Theta's outputs. It worked. If in fact the modification did negatively affect the sound of the Theta, what still comes through sounds, to these ears, quite glorious.

The whole experience was a real drag, and cost me several hundred dollars and a few gray hairs. If I had not already known that the II-b was an excellent preamp, I probably would have returned it immediately and continued a search for a unit more compatible with Theta’s topology.

The Review Process

Not many months after the preamp and restored Theta had settled in, I received word that Bob Bergner, a Northern Californian who reps Bruce Moore’s line of amps and preamps, wished to have Bruce’s products reviewed. Upon contacting Bob, I learned that upgrading my Companion to II-c status by installing the gold-stepped volume attenuators and capacitor/power supply upgrades described at the end of this review would make a big difference in my listening. I went for it, and $600 later, began the review process of my upgraded Companion II-c.

The first thing I did was to compare my upgraded II-c preamp with a II-c that lacked a detachable power cord. It became immediately apparent that using the power cord of one’s choice (in my case, a Synergistic Master Coupler) makes a difference. With a good power cord, everything sounds clearer, with the “blacker black” that comes with a lowering of the noise floor especially in evidence. I am told that future versions of the II-c will allow for a detachable power cord via an umbilical cord receptacle.

The gold-stepped attenuators, plus capacitor and power supply upgrades, also made a difference, but the results were mixed. On the plus side, everything sounded tighter, significantly smoother, and more refined. Dynamic range increased, making classical music that had wide dynamic contrasts far more compelling. Sonic images also gained in focus. But where before I had volume controls theoretically capable of a limitless number of gradations (albeit very difficult to match between left and right channels), I was now stuck with the pre-determined, detented intervals. Time and time again, I found that my ideal volume was somewhere between the clicks.

As many owners of newer Audible Illusions Modulus 3a preamps can attest, volume attenuator intervals often need to be changed. As a result of my experience, I believe that buyers of future Companion preamps will have the option to request volume controls that adjust  in 2 or 3 dB increments rather than 4 dB increments.

With the upgrades, the fundamental sound of the preamp had also changed a bit. I now found the highs a bit brighter than I wished. (I cannot state this with absolute certainty. I have tunable Chameleon III speakers, and engaged in much tuning and retuning after first purchasing the Companion.) First, I tried closing down my tunable Chameleons. While this tamed the highs, I soon realized that my temporary success had been achieved by choking off part of the sound. A far better solution surfaced when I discovered the magic of tube-swapping.

Companion II-c vs. Modulus 3a

Although the Audible Illusions Modulus 3a contains both a phono and line stage, it shares much else in common with the design of the Companion II-c. Both use only two tubes, and both invert phase, necessitating a switching of speaker cable leads at the speaker terminals. (Bruce Moore does not recommend “changing phase” at the DAC or other device instead, since this puts an additional switch in the signal path).

Upon first comparison, I heard two major plusses from the Companion II-c. The sound was fuller, and the bass far more substantial. The Modulus 3a, on the other hand, sounded smoother, with highs better integrated with midrange and bass. Everything it produced was thinner and smaller scaled, with much less information and richness to offer on the low end, but the sonic picture overall was smoother and easier on the ears. However, upon replacing the Companion’s two stock Tesla 6922s with either old stock, gold-pinned Siemens E188CCs, or Svetlana 6N1Ps, the Companion’s highs sounded simply delicious, while the midrange and bass shone even more. This tube change may not be necessary in many systems, but in mine, it did the trick. Sound was now even throughout the range, everywhere fuller than the 3a's, and far superior in the lower midrange and bass.  The change of tubes left the Companion the clear winner.

The CDs I auditioned during my comparison included classical, jazz, blues, and pop. The most telling featured Murray Perahia playing the second movement of Beethoven’s Piano Concerto No. 3, lovingly accompanied by Bernard Haitink and the Royal Concertgebouw Orchestra. With the Modulus 3a, everything had a very nice, smooth, eminently listenable sound. With the Companion II-c, however, I was able to get a much greater sense of both the resonance of strings vibrating within the wooden body of a concert grand, and the air around the instruments of the accompanying orchestra. The Companion offered that extra layer of audiophile reality that brings satisfaction to careful listeners.

Final Thoughts

I have since auditioned both the soon-to-be-released, non-phase-inverting $3,000 Companion III preamp and $5,600, top-of-the-line dual mono preamp. Both use two Tesla 6922s plus two 12AU7s. The III has a fifth National 6922 in its power supply, while the dual mono unit has two 5687s in its separate, umbilical cord-connected power supply.

The Companion II-c is anything but entry-level. It’s a wonderful line stage, capable of delivering highly convincing, emotionally satisfying sound. In the below $2,500 price range, the Companion II-c, even in its basic $1,650 version, is a must-audition.

- Jason Serinus -

Note: The Companion II-c is the latest iteration of the Companion II preamp series. The II-c contains new Infinity Signature Series capacitor and power supply upgrades. Owners of Companion I-b, Companion II, and Companion II-b units can have these upgrades put into their preamps for $100 (plus shipping).



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