Manufacturer: Tenor Audio
enor Audio, a tiny Canadian manufacturer that has merely a few products in its lineup, is best known for its hybrid amplifiers with a solid state output stage that works as a buffer instead of amplifying the signal (a unity gain configuration) and a tube-based gain stage. However, Tenor’s history began with completely different products: OTL tube amps. As François Lemay, head of sales, recounts in his interview with Mike Malinowski, it all began very innocently, with a meeting with Robert Lamarre in 1998 during an audio show in Montreal where Lamarre was selling his speakers (see the whole interview HERE).. Six months later it turned out he only lived a few blocks away from Lemay – a fortunate coincidence. At the next occasion Lemay showed his newly-made friend an OTL-type amplifier, which was quite a discovery to Robert who had been strictly a SET guy up to that point. François Lemay knew the right people, including Michel Van den Broeck who had performed a few updates in his amplifier. Lemay suggested to Lamarre that they should hire Michel and have him design and build a 15-watt OTL monoblock amplifier. And that’s how Tenor Company was started.
They did their first show in 1998, with a static display of the new 15-watt OTL designed by Michel, because the unit was not yet finished. The working prototype was shown in 1999 and 2000. In the same year, “Ultimate Audio” magazine reviewed the amp in what turned out to be their last issue. Lemay says that it was 2000 that was really the beginning of Tenor operation. That’s when they hired a cabinetmaker and Michel was designing and producing their first OTL amps. A year later, the company proudly introduced the OTL75 amp at the CES. Their first hybrid amp was designed in a record time of nine months – to put it in perspective, it took over three years to design their first OTL prototype. They planned to showcase it at the CES in 2003. Unfortunately, one of the amps along with an OTL was stolen. François still doesn’t know how they managed to get $500,000 worth of orders on the amps although no one had yet heard the hybrid. The only problem at that point was to keep up with all the orders.
They did the best they could to catch up on production, but at the same time the money was not pouring in as quickly. Around that time they introduced the amps at $28,000 retail. The problem was that they were selling them below actual production costs, which was a mistake. The second problem was that the US dollar began to drop, and the price list of the Canadian company was in United States dollars. It did help somewhat that Canada has a law that rebates some of the R&D costs back to the manufacturer. Since Tenor had huge R&D costs at the beginning, this rebate was essential for the company’s cash flow. In 2003, due to a minor technical glitch in the process the government failed to refund their R&D money. The same problem recurred in 2004 and, what’s worse, the company weren’t even get an answer or explanation why the rebate was refused. And we’re talking about $340,000 by that time. Although there were lots of orders pouring in, the start-up debt combined with the government’s failure to refund the money resulted in a very difficult cash flow position. Together with a few other minor unfortunate events, it forced the company to declare bankruptcy in December 2004. Up to that time Tenor had manufactured 85 pairs of OTL monoblocks, 26 pairs of the 300 amplifiers and 18 of the 150s. The company’s papers were extremely well-organized, every single penny was accounted for and nothing had been hidden – the bankruptcy receiver said never to have seen such an honesty in his life.
The same day they went to their creditor bankruptcy meeting, François and Robert met Martin Labrecque who was interested in amplifiers. One thing led to another and the gentlemen came to the conclusion that with a product this good and with such a great designer like Michel Vanden Broeck, the company should continue. With the help of Martin, along with three other new investors: Jim Fairhead, Tom Moynihan and Jacques Pilon, they were able to buy back the Tenor assets. That’s how a second stage in the company’s life began, under the name Tenor Audio. Jim Fairhead became the company’s president.
The Line1/Power1 was designed from the start as a reference product. And it has a corresponding price tag – it’s one of the most expensive line stage preamplifiers on the market. The twin-chassis design concept is used to separate gain circuitry and power supply. The whole preamplifier is big, heavy and powerful. Its aluminium chassis and wooden elements both play an equally important role. The electronic circuit is based on General Electric NOS 6463 double triodes. A look at the preamp’s rear panel reveals another thing: a headphone jack from Neutrik, with a clasp. We’ll come back to this in the audition section. The 6463 tube had been designed to work as a computer switch, so it can be expected to offer good performance characteristics, reliability and long-term stability. However, the original technical documentation provided by Philips states that the tubes shouldn’t be used in circuits susceptible to microphony, hum and noise. Michel Vanden Broeck has treated this warning very seriously and used a few design ideas as a preventive measure.
Although the Tenor’s heart operates on tubes, a 19th century technology, its microprocessor control is straight from the end of the 20th century. The microprocessor, which allows the user to change many settings in the menu, can be updated – there’s a USB port available on the board. The preamplifier is operated with a neat remote control.
Albums auditioned during this review
I come back to this like a drunk to a bar, but I just can’t help myself: the audition of the TechDAS Air Force One turntable, and particularly the way it played the album Teatr na drodze (“Theatre on the road”) by the Polish band 2 Plus 1, was nothing short of a revelation for me (see HERE). I thought I knew how an audio system should sound like, as I had heard more outstanding systems than I could remember, but what I heard at home on that day was like an epiphany.
But if we take analog album releases as a reference point, digital releases of 2 Plus 1 (alternatively 2+1 and Dwa Plus Jeden - the band used several types of spelling) are junk. In fact, the only CD release that I can recommend with good conscience is a reissue of a concept album with music dedicated to Zygmunt Cybulski, a well-known Polish actor who died tragically in 1967, titled Aktor (1977). In addition to the original material, the reissue also features a song recorded and sung by Justyna Steczkowska (see HERE). The album has been remastered by Mrs. Anna Wojtych who worked for some time as a sound and mastering engineer for DUX (by the way, this Polish label regularly advertises in a major British magazine dedicated to classical music, "BBC Music"). I was able to talk to her about her approach to remastering; our conversation can be found HERE.
What I'm getting at is that digital album releases from this group (only two original albums and countless compilations) sound dynamically flat, are devoid of color and dynamics. However, if we play any of the compilations, for example Greatest Hits Vol. 2 digitally remastered by Sonic, on good audio equipment, the magic returns. It's still only an approximation of the quality offered by vinyl originals, but it is acceptable. On the best systems, or those whose sound is shaped in the right way, it sounds very, very good indeed. And even if in the back of my head I still keep what I once heard from Mr. Hideaki Nishikawa’s turntable, playing it back on a quality audio equipment gives no less fun.
The primary role of the preamplifier in the audio path is that of volume control. All other functions, like input switching, DAC, signal buffering or amplification, are secondary. Hence, the simplest possible preamplifier can be reduced to an ordinary potentiometer, and this type of device bears a misleading name: "passive preamp."
The Canadian preamplifier is on the other side of the rainbow. I have very rarely come across an audio component of such an intense, so clearly defined sound - clearly in the direction of body and mass. The preamp creates the kind of tonal quality the audiophiles dream about at night, never heard by sound engineers in good recording studies, unless it was while listening to live music. This is a powerful presentation with a clearly favored, fairly broad bass range.
The music is good and velvety, with a powerful foundation at the bottom end. We don’t pay attention to individual instruments, but rather to the way they correlate with the others. Vocals suddenly appear in front of us, and if it weren’t for the fact that they are soon followed by an extremely well differentiated, powerful bass, we would have been left dumbfounded.
Resolution, just like selectivity, does not seem too high. While this is true in the case of selectivity, as the preamplifier relies on tonal differentiation rather than on "drawing" phantom images, it is not so about resolution. The latter can be characterized as the amount of information we get. Not the amount of "detail"; this is different than detailness. Resolution means density and naturalness, warmth and "flow". The Tenor has plenty of it all.
Actually, this line is only symbolic and there is no feeling that the sound is closed in any particular body or shape. Thanks to an active bass, especially the midbass, the presentation has a hell of momentum. The volume of sound is large, helped by a strong lower midrange.
To treat the Tenor as a line stage preamplifier is normal and understandable, since that’s its main task. Moving the headphone jack to the rear panel only seems to confirm that. This time, however, the decision was based something else. I assume it was an aesthetic consideration.
There is no hiding the fact that the Canadian preamplifier modifies the signal. It would be even more difficult to hide the truth that all audio products do exactly the same. What’s really matters then is how they do it. The Line1/Power1 makes for an easier listening. It will make each record sound at least interesting, of course as long as the music is interesting. The unit offers an exceptionally well-differentiated tonal quality. Hence, it does not replace every album with one and same disc, nor does it make recordings sound similar to each other. While the bass is strong and we will often hear it where we don’t expect it, it is very well differentiated, both in terms of pace and color. The top end is rather sweet and recessed. The Takumi K-15 from Robert Koda, reviewed some time ago, is quite different in this respect (see HERE). A similar sounding treble is offered by the Soulution 720 preamplifier. The Ayon Audio Polaris II and Spheris II would be somewhere in the middle. Audio Research preamps sound similar, except that the Tenor does everything better and is more dynamic and colorful. It has its own distinct character. It makes recordings sound interesting, not tiresome. At the same time, it doesn’t break them down to their constituent parts. The unit sums up what it receives from the source rather than analyzes it. It is a top high-end with a human face, without pretending that "neutrality" is possible in audio. The message it sends is clear and easy to read: the world is beautiful!
There is one main reason behind two-piece audio components, whether digital players, preamplifiers or power amplifiers: to separate sensitive audio amplification circuits from the power supply. This is done, for example, by Ayon Audio, Ancient Audio, Audio Research and others. The American VTL goes even further, additionally moving a microprocessor to its own separate enclosure. Tenor Audio uses the classic division: one enclosure houses amplification circuits and the other one is a power supply unit.
The front panel of the amplification module sports a blue VFD display in the center. It shows the volume, currently selected input and output. The unit has a fairly extended menu where you can change all the settings. This is also where you can select the voltage gain: 14 or 21 dB. The display has a rather low contrast. Under the display there are four small buttons, the same as in the remote control unit, which is also largely made of wood. More important, however, seem to be two large knobs on the sides, also acting as buttons. They can be used to change the volume and select inputs, but also to move around the menu. The front panel of the power supply unit also sports a window in the center, but only with LEDs. They indicate power-on (red), plate and filament voltage (blue) and control (green).
The amplification circuit is tube-based, with four General Electric 6463 (CV5304) dual triodes per channel. Originally designed for use in computer systems, they sport accordion-like heat sinks with rings made of carbon fiber and mica for additional vibration damping. At the input you can see huge, really massive polypropylene MKP capacitors from Epcos. These capacitors can be seen in other places, too, for example in cathode bias circuits. The main audio board is decoupled with soft rubber suspension grommets. This is one of many steps used for vibration control. The output circuits seem to be housed on separate boards, mounted to the sides. You can see large shielded transformers, which seems to be output coupling transformers. Input connectors are soldered to a board mounted to the rear panel. Input switching is via relay switches. The whole interior looks great, but the attenuator is a real treat to the eye. It is a huge motorized potentiometer with a microprocessor-controlled stepper motor, mounted vertically on an isolated board away from the main circuit. I saw a similar potentiometer used in the best preamplifier I've heard so far, the Octave Jubilee Pre. The Octave potentiometer was not motorized, though. The entire Line1 remote control circuit was built by Tenor in-house. The same board also sports more coupling transformers - could inputs also be coupled in this way? The majority of internal wiring uses silver-plated copper wire in Teflon insulation, terminated with ultra-precise connectors used in microwave applications.
You need to be careful when moving the power supply unit as its center of gravity is near the front panel. The reason for that is that this is where four EI type 100 W power transformers are located, shielded in heavy steel cases. They are separated from the rest with a thick plate. There are also four inductors. On a large fully populated board you can see five voltage regulator circuits per channel. Each of them has a slightly different rectifier diodes and capacitors. It looks as if they have been selected for sonic qualities.
Specification (according to the manufacturer)
Preamplifier Type: Dual Mono/Dual Chassis
- Turntable: AVID HIFI Acutus SP [Custom Version]
- Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
- Phono stage: RCM Audio Sensor Prelude IC, review HERE
- Compact Disc Player: Ancient Audio AIR V-edition, review HERE
- Multiformat Player: Cambridge Audio Azur 752BD
- Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
- Power amplifier: Soulution 710
- Integrated Amplifier: Leben CS300XS Custom Version, review HERE
- Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
- Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
- Real-Sound Processor: SPEC RSP-101/GL
- Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
- Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
- Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
- Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE
- Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
- Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
- Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
- Loudspeaker Cables: Acoustic Revive SPC-PA
- Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
- Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
- Power Line: fuse – power cable Oyaide Tunami Nigo (6m) – wall sockets 3 x Furutech FT-SWS (R)
- Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
- Power Distributor: Oyaide MTS-4e, review HERE
- Portable Player: HIFIMAN HM-801
- USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
- LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
- Router: Liksys WAG320N
- NAS: Synology DS410j/8 TB
- Stolik: SolidBase IV Custom, read HERE/all system
- Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
- Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
- Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
- Quartz Isolators: Acoustic Revive RIQ-5010/CP-4
- FM Radio: Tivoli Audio Model One