Product Review

Bruce Moore Companion III Two-Channel Tube Preamplifier

July, 2003

Jason Serinus




● Gain: 23 dB
● 5 Line Inputs, Main Out and Tape Out
● Frequency Response: 1 Hz to 500 kHz +0,
● Maximum Output: 25V RMS
● THD: < .03% @ 2V RMS Out
● Input Impedance: 75K Ohm
● Output Impedance: 500 Ohms
● Noise: -98dB below 2V RMS output
● Absolute Phase: Non-Inverting
● Tube Complement: Three 6DJ8/6922, Two
● Power Consumption: 30 watts (detachable
    line cord)
● Dimensions: height = 3.6" (79 mm), width =
    16" (381mm), depth = 12" (241mm)
● Shipping Weight: 20 lbs.
● MSRP: $3300 -$3700 depending upon

Distributed by RB Electronics



I have spent many years experimenting with and enjoying Bruce Moore Electronics. My first encounter was with the Companion II preamp, which I reviewed at Secrets many moons ago. Then came the Dual 70 amp, also reviewed. Each of these components was eventually traded in for higher quality products, resulting in my current pairing of a maximally upgraded Bruce Moore Companion III preamp (very much in production) with a Dual 100 power amp (currently out of production).

Since the original Bruce Moore Companion III and Dual 100 entered my system, a series of upgrades has left the sound far more revealing. My Talon Khorus X speakers have gone through two major upgrades, resulting in far more open and extended sound, as well as far more clarity in the lower midrange; interconnects and speaker cables are the superb Nordost Valhalla; and power cables, save for a Shunyata Python on the transport, are either Elrod EPS-2 or EPS–3, with a superb EPS Signature-2 power cable on the preamp. (I will soon have a second Signature-2 for the transport).

I have also done much experimentation with different tubes for the amp and preamp, striving to find the most compatible combination for my particular component configuration (more on this later). Each upgrade has allowed me to hear further into the heart of recordings, making it easier to determine an individual component's strength and weaknesses.

My relationship with Bruce Moore Electronics' main distributor, Bob Bergner is a most unusual one. Ordinarily, some reviewers make it a point to have minimal contact with manufacturers and distributors once a product is in their hands. Though some reviewers may invite manufacturers to their homes to insure optimal set-up, others allow absolutely no exchange of information until a review is completed. If the product arrives defective, and the problem lies with the manufacturer rather than the delivery service, the review is written with a defective piece of equipment. (If a manufacturer can't get it together to send a fully functioning unit to a reviewer, what can the consumer expect in way of quality assurance)? Only after a review is completed is the manufacturer granted the ability to see the review and offer comments.

In my case, however, since my ability to accurately review components and music depends upon the reliability and accuracy of Bruce Moore Electronics, I have consistently engaged in dialogue with Bergner and, by extension, the reclusive Bruce Moore, as to ways to improve the products. This has resulted to significant upgrades to aspects of the original Companion III design.

Since beginning the Companion III upgrade process, three other preamps have arrived for review chez Serinus. Though each costs more than the Companion III, they have provided the opportunity to more clearly assess the strengths of Moore's creation.

The Design

The Companion III, totally configured for RCA (single-ended) inputs and outputs, comes with one main output set, a tape output, two CD inputs, tuner input, tape input, and auxiliary input. There are two attenuators (volume controls), one for each channel; an input selection control; and an off-mute-on control. Because there is no built-in delay between off to mute to on, purchasers are counseled to wait three minutes before switching to the on position.

Tubes are two 6922s, two 12AU7s, and a fifth 6922 for the power supply. All tubes save the power tube are operated in triode mode. This means that only 1/2 the tube is in use at any given time. When a tube shows signs of wear, it can be moved to the other channel, which utilizes its other half. This results in tubes lasting twice as long.

I plug all my components, except for the power amplifier, into a Multiwave I-equipped PS Audio P600 Power Plant. Some tube components do not work well with Multiwave I. This is not a problem with Bruce Moore gear; it works fine on all Multiwave I settings. As I write this review, I anticipate the arrival of Multiwave II, whose new tubewave setting is reportedly compatible with all tube gear. It will be interesting to discover if it at all alters the sound of the Companion III preamp.

Preamp Models and Upgrades

The entry-level Companion III ($3300) comes equipped with Arn Rotocap Gold Point shunt attenuators (specially designed for the Companion III), Roederstein resistors, and Solan capacitors. Tubes are Tesla 6922s and Chinese 12AU7s, with a NOS (New Old Stock) Jan Philips 6922 in the power supply.

When I discovered the entry level unit lacking in transparency and detail, and found the highs a bit splattered and edgy, I first began to experiment with other tubes. For the longest time, I used a combination of NOS Siemens CCA Gold pin tubes in place of the Tesla 6922s, and NOS Telefunken ECC 82/12AU7s smooth plate in place of the Chinese 12AU7s. While this certainly smoothed and sweetened highs, increased midrange weight, and demonstrably extended the bass, it did not fully resolve issues of transparency and three-dimensionality. Highs still lacked refinement, the image was too opaque for my taste, and there was a stolid one-dimensionality to the experience. What I heard was still pleasing, yet the inescapable feeling that I was listening to bit-bound recorded music lessened pleasure. I found myself spending more time at live performances, and less time with my system.

After much dialogue with Bergner and Arn Rotocap, the attenuators were first upgraded to series, and, a year later, to ladder. With each change, the quality and extension of highs, as well as transparency, depth, and accuracy of image markedly improved.

I also had the attenuators recalibrated to meet my needs. Regardless of attenuator type, each initially adjusted volume in 3 dB increments. I frequently could not get the volume right; it was either too loud or too soft, especially on jazz, rock, and pop. While I could play classical music at low volume late at night, even the attenuators' first setting was too high to play pop music or use my FM tuner after my neighbors had gone to bed. There were times when I'd listen to the radio on only one channel, hoping my neighbors wouldn't be disturbed. (This is a common problem with such attenuators. Even after my friend Joey had the attenuators on his Audible Illusions Modulus 3 preamp recalibrated to allow finer adjustments, the unit would play either too loud or too soft. Joey eventually traded the Modulus 3 in for a Companion II-C equipped with specially calibrated Gold Point series attenuators that had originally been designed for my Companion III. He is much happier; the sound, albeit not as full as the Modulus 3a, is far more refined).

I therefore had my attenuators redesigned to permit 2 dB increments in the critical listening range. The first increments are now set low enough to allow playing any kind of music at a comfortable level either day or night. I am also far more capable of matching volume levels between preamps here for comparison.

After all that was said and done, attendance at shows and visits to fellow audiophiles' homes enabled me to hear things on favored recordings I still could not hear chez Serinus. The clincher was a visit by local designer Alexander Peychev, who brought over his own preamp/DAC design. Hearing Alex's achievement further convinced me that I needed a preamp capable of higher resolution and greater transparency.

This resulted in months more dialogue with Bergner, any number of gray hairs, and some major resistor/capacitor upgrades. All critical resistors were changed from Roederstein to either Caddock or IRC, and major capacitors were changed from Solen to Auri-Caps. (Resistors and capacitors in the power supply remained unchanged, since these were not considered critical to the sound).

The preamp's price range reflects the range of options available. The basic $3300 unit comes with shunt attenuators, Tesla 6922s, Chinese 12 AU7s, and a Jan Philips 6922 in the power supply; it also features Roederstein resistors throughout and Solen capacitors in key places. Series attenuators, which help to further extend and fill out the highs, cost somewhere in between. For $3700, you get ladder attenuators, Electro-Harmonix gold pin 6922s, and Jan Philips 5814s, with a third E-H gold pin 6922 in the power supply; in critical places, you'll find Caddock and IRC resistors, as well as Auri-Caps.

I unequivocally recommend that anyone drawn to the Companion III's many virtues spring for the ladder attenuator version. For $400 over the base price, this Companion III fully realizes the strengths of Moore's design.

Note: One of the Companion III's CD inputs comes hard-wired with an extra resistor to soften the sound of bright, edgy digital electronics. After discovering that the resistor accomplished its objective by making the sound softer, darker, less detailed, and far more opaque, I had the resistor removed. I advise any purchaser who does not own early, harsh-sounding digital components to do the same, so that both CD inputs are capable of producing the same quality sound. This is essential for those with separate CD, SACD, and/or DVD-A set-ups.


As with all tube gear, the sound of the Companion III is tube-brand-dependent. Though I have listened to this preamp in its various configurations for over two years, the recent arrival of Electro-Harmonix gold pin 6922s (recommended to Bergner by Genesis' Arnie Nudell at HE 2003) and Jan Philips 5814s has presented the opportunity for some fresh observations.

Here are notes I took while listening to three wonderful recordings:

1. Terry Evans' “Blues No More” from Puttin' It Down (JVC XRCD):

Using Jan Philips 5814: Quite open and alive on top. Very transparent, clean attack, fast transient response, highs leaping out at me. The widest soundstage I've ever heard with this preamp. The cymbals are bright and alive, perhaps a little too bright, without being steely/aggressive. These tubes certainly reveal the slightly steely quality of the Talon Khorus X tweeter and super tweeter. On the one hand, I wish the sound were a bit mellower. But what I hear is so alive and revealing that I am hooked. This is the best my system has sounded with this preamp.

Using Telefunken smooth plate ECC 82/12AU7s: Mellower, with a warmer, less brash sound, but less transparent. Highs seem less extended and open. While not in the least bit fatiguing, it is a bit gray and laid back.

2. Songs of the Auvergne (CBC Records)

Everyone who has heard this recording has commented on its quality. A chamber music reduction of Canteloube's original orchestral arrangements, it features playing so light and colorful, and singing so exquisite as to rate as my favorite vocal recording of the year. I took this recording from room to room at HE 2003. While the highs are not as drop-dead delicious as on the $30,000 Tenor Audio amps, Philips 1000 CD player modified with Meitner DACS, and Kharma Mini-Ceramiques – I can't remember whose preamp they were using – the EH gold pin 6922/Jan Philips 5814 combo is working wonders on it chez Serinus.

2. Rachmaninoff: Symphonic Dances (Reference Recordings)

Critically lauded, especially when reproduced with HDCD (which I don't have). But with the Companion III in its current state, I'm finally hearing what all the fuss is about. I'm not hearing all the bass and lower midrange detail I wish to hear, but in my apartment, given my neighbors, that isn't a bad thing.

The excellence of the top-of-the-line Companion III comes to the fore when compared to the Reflection Audio OMI-Quantum, a solid-state preamp which costs $2500 more than the Companion III when powered from the wall. (The OMI-Quantum costs $7500 when powered by its optional AC4 power supply. Since designer Stephen Balliet considers the battery pack essential to the preamp's optimal operation, I have been listening to it in that mode). The comparison is in one sense unfair, given the sizeable price difference between the components. But if we hold the OMI-Quantum as some kind of ideal, comparing it with the Companion III allows us to hear what an expenditure of several additional thousand dollars can deliver.

With the OMI-Quantum powered by the AC4, there is no question that it has a lower noise floor than the Companion III, optimal transparency (no tube or electrical hum), stronger and better-defined bass (bigger power supply), more lower midrange information (the bottom of the tone is more filled out), and an impressive soundstage. On Hilary Hahn's superb recording of the Brahms Violin Concerto (Sony), the OM1-Quantum provides more lower bass information both in the orchestral introduction and when the violin enters; low end inner detail is clearer, the sound of the violin is more filled out, and the contrast between the first aggressive entry of the violin and its transition into heart-tugging sweetness is more clearly felt. But the Companion III's tubes provide a magical liquidity and a touch of additional sweetness that is quite lovely. This special liquidity and sweetness is equally apparent on the clarinet and oboe solos which follow the opening outbursts on the Rachmaninoff; these sound just a bit drier on the OM1. While I certainly hear more orchestral detail on the OM1-Quantum/AC4, what the Companion III delivers is quite satisfying.

When all is said and done, the Companion III/EPS Signature-2 combo ($5400) is a more than credible second to the OM1-Quantum. Both offer a timbral accuracy and near neutrality missing from the two other tube preamps here for review, both of which cost considerably more than the Companion III. The Companion III falls short in lower midrange/deep bass extension and detail – I wish it had a bigger power supply – but everywhere else, it's a winner. And it also saves on electricity; the bigger the power supply, the more electricity you use, especially when components are plugged into a less-than-efficient PS Audio Power Plant.

On the Bench (JEJ)

With a 1 kHz sine wave input, distortion is low, and the principle component is even-ordered (second order), with only a small third order component, and nothing significant beyond that.

IMD, using 1 kHz and 1.5 kHz input signals, is low.

IMD is again low, using 5 kHz and 6 kHz input signals.

THD is low, using a 10 kHz input. The peaks near 40 kHz are noise, not harmonics. A very small harmonic is present at 30 kHz (compare with graph when no signal is input, shown below).

With 10 kHz and 11 kHz input signals, there is a noticeable IMD peak at 1 kHz and two at 19 kHz and 21 kHz, although the total amount is still a low value.

There is a measurable amount of AC ripple from the power supply, as shown by this graph when the power is on, but no signal is input to the preamplifier. There is also some high frequency noise at around 40 kHz.

The measured frequency response is within ± 0.5 dB, 20 Hz - 96 kHz.


The Companion III preamp has been a work in progress for several years. In its ‘'final” $3700 iteration, it delivers sound many steps beyond the entry-level Companion III. For a tube unit, it is surprisingly neutral sounding, with far less of the artificially euphonic sweetness that characterizes the sound of many tube components. Its bass is fast and solid, if less than realistic in size, its transient response superb, and its resolution of harmonic nuance and detail is excellent. Any lover of tube gear who uses RCA-terminated interconnects owes it to themselves to audition this unit.


- Jason Serinus -

Associated Equipment:

Digital Front End: Theta Gen. 5A single-ended DAC
Perpetual Technologies P-1A with Modwright modified Monolithic Power Supply
Audio Alchemy DDS-Pro transport
Amplification: Bruce Moore 100W dual mono tube power amp with Electro-Harmonix KT-88 and Siemens CCA tubes
Preamp: Bruce Moore Companion III tube preamp
Loudspeakers: Talon Khorus X speakers (with final modifications)
Cabling: Digital: Nordost Valhalla interconnects and digital interconnects
Analog: Tara Decade and Nirvana SL-1 to phono preamp
Nordost Valhalla bi-wired speaker cable
Powercables: Shunyata Python, Nordost, AudioPrism Super Natural S2, Elrod EPS-1, 2, and 3 plus EPS Signature-2.
PS Audio P600 Power Plant power synthesizer with MultiWave I
PS Audio Ultimate Outlet; PS Audio Power Ports
Michael Green Deluxe Ultrarack, Basic Racks, room treatment, and Audiopoints
Black Diamond Racing Cones
Inner tube, maple cutting boards, bags of sand
Shakti stone and Shakti On-Lines
Bedini Quadra Beam Ultraclarifier
Audioprism Stoplight and Blacklight,
Sheffield/XLO and Ayre degmagnetiser/break-in discs


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