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Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S; Opera Audio Reference 2.2 Linear
Preamp/Integrated: ModWright SWL 9.0SE; Music First Audio Passive Magnetic; Bel Canto Design PRe3; Wyetech Labs Jade
EQ: Rane PEQ55 active merely below 40Hz
Amp: 2 x Audiosector Patek SE; Yamamoto A-08S; Canary Audio CA-308s; FirstWatt F3 & F1; Bel Canto e.One S300; Eastern Electric M-520; Butler Audio Monad A100s [on review]
Headphones: AKG K-1000 w. hard-wired Stefan AudioArt harness; audio-technica W-1000
Speakers: Zu Cable Definition Pro; Anthony Gallo Acoustics Ref 3.1
Cables: Zanden Audio proprietary I²S cable, Zu Cable Varial, Gede, Libtech and Ibis; Stealth Audio Cable Indra, MetaCarbon & NanoFiber [on loan]; SilverFi interconnects; Crystal Cable Reference power cords; double cryo'd Acrolink with Furutech UK plug between wall and transformer; Crystal Cable Ultra [on extended loan]
Stands: Grand Prix Audio Monaco Modular five-tier
Powerline conditioning: 2 x Walker Audio Velocitor S fed from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option; Furutech RTP-6 for 240V connection via Crystal Cable Reference
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio Extreme SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer
Room size: 16' w x 21' d x 9' h in short-wall setup, with openly adjoining 15' x 35' living room
Review Component Retail: $8,000
A clever solution to an old problem
Tube lovers with sufficient experience in the thermionic trenches already know - different tube types offer different strong points. A circuit with a 2A3 driving a 211 will be different than a similar one with a 300B driving an 845. Never mind a 5687 or 6SL7 driving a 300B or 12AT7s driving 5881s or KT88s. In fact, the myriad combinations of driver and output tubes present a deliberate and intimate tango of ying and yang. It's a dance of mutually beneficial interactions intended to balance out the output valve's various known qualities to best overall effect. Therein hide inherent compromises. Rather than utilizing a tube over the range it is best suited for, it is asked to cover the full audible bandwidth. Unless you biamp of course. Many audiophiles in fact do exactly that, even if it's with an active subwoofer. Essentially, biamping delegates the more challenging bass register to a dedicated muscle amp. Brawn on the bottom, finesse on the top. That's indeed the fundamental rationale for biamping.
|Naturally, the same issues plaguing 20Hz-to-20kHz tube amps also apply to tube preamps. Unless you biamp. Say what? How does biamping apply to a preamp? Enter Mick Maloney's new remote-volume Supratek Cabernet Dual. It is an offshoot of custom tube preamp/active valved crossovers [one recent example to left, with temporarily labeled blue trim pots adjusting gain for fixed crossover bands]. Our crafty Australian designer figured that since bi-amplification requires two outputs (and ideally separate gain provisions for each), he could author a novel bi-amp preamp. It'd sport two discrete circuits, one optimized for bass, one for mid/treble. This would allow him to cherry-pick specific tube types whose typical strengths the listener would harness over only a limited frequency range. To make the twinned Cabernet universal, both its outputs send a full-range signal. It is the divider frequencies of the hi- and lo-pass networks in your speaker that set the operational cut-off values for each preamp circuit. Variable gain levels for each leg; options for bass circuit damping; an RCA or XLR input choice for the mid/treble half; five single-ended inputs plus one balanced; and an outboard power supply with tube rectification round out the feature set.|
The power supply sports a 5AR4 rectifier (GZ32/34/37 or 5V4G may substitute) and 5881s (or 6L6GCs or KT66s) drivers. The signal tubes for the mid/treble circuit are current production TJ 101D globes. Bass is handled by 6SN7s. A rear-mounted 5-pole rotary switch sets gain for the "upper" preamp section (the first position leaves the output transformer unloaded while subsequent stops load the transformer for consecutively lower gain).
|Two three-pole toggles in front of the transformer covers set the output impedance for the bass circuit for each channel while a top-mounted Alps potentiometer fine-tunes the circuit's precise output signal strength prior to the master volume. The 3-pole toggle between the transformers sets standby-mute/power, its central position turns input 5 into an HT bypass (mains volume bypassed). Two inset chromed rotary controls on the front panel adjust master volume and input selection while the power mains resides in front of the power supply rectifier valve. In keeping with Maloney's preamp philosophy, the Cabernet Dual is a very high-gain device to maximize drive and tone. Different trim levels substitute the black paint of the top cover and tranny casings for chrome and the high-gloss black fascia and side trim for different exotic woods. 3.5' long locking 5- and 8-pin umbilicals connect the power supply to the control unit to keep the power transformers' electromagnetic fields away from the deliberately unshielded wiring in the signal path circuitry.|
The unreviewable preamp
In a very strange commentary on the Brazilian Audiopax Model 88 monos, legendary UK reviewer Ken Kessler once opined that they were essentially unreviewable because their adjustable TimbreLock controls -- altering output impedance and THD behavior -- meant that the amps lacked a factory default setting. How was a reviewer supposed to know the sound of the amps? Naturally, the best achievable sound in any given scenario. However, Kessler failed to grasp that apparently outré concept by insisting on only one fixed right way of doing things. He would throw a veritable conniption fit -- squared -- over the dual Cabernet. Various stages of gain for the 101D circuit, variable output impedance for the bass circuit plus the continuously variable bass pot and the remote-driven master volume make for near endless permutations of different values, all of which should add up to the same eventual output voltages but different sonics. In the consumer sector, a similar rationale -- albeit not dedicated to bi-amping -- saw itself applied to the Audiopax Model 5 solid-state preamp. It sports two adjustable gain stages in series. One is the stereo master control. The dual-mono controls preceding it are, once again, dubbed TimbreLock. Exactly how the two gain stage values are strategically offset affects how the preamp sounds with any given amp.
Back with the Supratek, we haven't even mentioned tube rolling yet. On that subject, Maloney voices each of his circuits around standard bottles. That's also what he supplies (here with glass by Electro-Harmonix, Sovtek and TJ). Expensive NOS designer valves are viewed with a bit of suspicion whenever they're claimed to be instrumental to obtaining good results. Supratek machinery, he holds, wins its races just fine on regular unleaded.
Point-to-point wiring may look like a snake pit but is said to be more reliable than PCB due to the high voltages involved
Anyone looking for today's preamp' to have a set-in-stone factory default voice naturally barks up the wrong tree. He better stay glued to the plush seat of his lazyboy. The Cabernet Dual demands that you get involved. Its designers have made the deliberate effort to offer comprehensive tuning facilities. So let's spell it out in no uncertain terms: If you can't handle choices; if you don't trust your ears to make the ones that best suit your needs... don't touch this Supratek preamp with a 10-foot pole. Don't insist on labeled connections either. Supratek's customized approach means that each piece is tailored to its owner. Hence standardized silk screening has been abandoned. Everyone else intrigued rather than scared off by this piece -- and in possession of the requisite two stereo amps (or four monos) to power bi-ampable speakers -- gather 'round for a Maloney-style snippet of common sense: