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Tubes/transistors vs. transistors/tubes:
Listeners keen on the presence of valves somewhere in the signal path but reluctant to go all out routinely face the question whether to stick the glowing bits in the preamp or power amp. Common arguments supporting either choice would include the voltage/current situation—valves are perfect voltage gain devices, transistors excel at current gain and the latter is what speakers need—and the seniority of the amp/speaker interface where valve contributions will be dominant over low-level applications (preamp or source). Dan Wright clearly sides with the first argument. His LS100/KWA-100SE combo harnesses tube flavor for low-level voltage gain whilst muscular transistors deal with reactive speaker loads.
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As it happened Living Voice's top Avatar model the OBX-RW with outboard crossovers was in for review. This presents us with a deliberately valve-optimized load which was conceptualized and developed around Art Audio, New Audio Frontiers and Kondo tube electronics (brands carried by the Definitive Audio distribution/retail arm of Living Voice). During a weekend of delivery, setup and hardware substitutions designer Kevin Scott and his wife Lynn had most favored my Esoteric C-03 preamp/Trafomatic Audio Kaivalya combo. Having heard the OBX-RW in their UK residence driven from a Kondo Ongaku I was in full agreement. To make the Living Voice house sound their speakers plainly wanted to see tubes directly, not—just—upstream somewhere.
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Though clearly no apples-to-apples scenario (the class A push/pull IT-coupled
6P14P-EV/EL84 make 30 watts, Dan's Mosfets well over 100), the OBX-RW's 'to spec' performance with the valve monos as signed off by the designer erased concerns over power inequality. For an educational exercise on the subject, I thus decided to report on what qualities one might trade by substituting transistors/tubes for tubes/transistors. Having played such musical chairs many times with different speakers before, I'm quite confident that the core tendencies apply to most single-amp systems with passive crossovers (active multi-amp setups are a completely different proposition where power tubes can be exploited under more strategic idealized conditions).
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About which, humans breathe. That obviously goes for musicians as well. While only singers and wind instrumentalists literally carry sounds on their breath, good musicians coax bel canto qualities also from piano and strings. The essential quality here is a tacit sense of expansion/contraction or ebb and flow. This operates in both the amplitude and temporal domains. Movement occurs as dynamic shifts, as rhythmic irregularities over time and as a progression of sounds and gaps of actual or virtual inhales. All of this could be captured by terms like fluidity and elasticity. The counterpoint is metronomic. Successive damping—literal or virtual—minimizes fluidity. Temporal progressions become more rigid. Dynamic progressions occur as stutter steps rather than seamless swells. Here power tubes are more elastic than transistors. It's probably the key reason why listeners refer to valves as 'organic'.
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The better damping and superior current delivery of transistors nearly invariably means superior control. This manifests as greater bass intelligibility, better differentiation/articulation and more weight. While the twin 6.5-inch drivers of the OBX-RW were good for a solid 40Hz with the white tube monos, the ModWright KWA-100SE built things out downstairs particularly with the LS100. Comparing 6SN7s to the autoformers of Bent Audio's Tap-X, this frequency range seemed noticeably beefed up. On my customary ASI Tango R with their thrice-paralleled 8-inch woofers, the ModWright duo even for my large space becomes nearly too bass potent. I'm uncertain why. The KWA-100SE doesn't respond alike with my Esoteric C-03 with active gain. Even so it's been a very repeatable observation with the LS100. Into its stable mate's Mosfets bass is truly boffo.
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ModWright at CES |
Power tubes in general inject higher harmonic distortion. It's often equated with tone but also translates into what I call connective tissue or 'stuff between the notes'. On structurally simple music it appears as greater density. On structurally complex music it congeals, blurs and rather than stay separate and discrete gets confused and homogenized. At the levels I listen to, into loads like the OBX-RW and with the non-bombastic music I favor these liabilities manifest less but still could be noticed as light distillates versus the Mosfets. To extricate just the tone/timbre constituents I felt that the LS100 vs. the Tap-X passive or Esoteric C-03 did a very good job. Things got fleshier and texturally fuller yet the dreaded shadows of thickness, opacity and subliminal blurring were barely evident. Yes the Tap-X was more quicksilvery, lit-up and contrasty but it was tonally also paler, rhythmically less supple and down low distinctly leaner.
Bottom line, Dan Wright's strategic combination of 6SN7s (preamp) and Mosfets (power amp) offers a high degree of tube tone, a lesser degree of tube texturing aka warmth, then superior foundation detail and mass, greater dynamic range and a more lucid upper treble than power tubes. And, the latter's organic on-the-breath fluidity becomes more solidified and firm. Particularly owners of speakers not carefully optimized by their designers for tube drive who are still desirous of some 'breath' and 'tone' will be far better off pursuing the tube/transistor route than attempting the inverse. Here ModWright's combination of LS100 + KWA-100SE becomes very compelling. It's a very far cry from the lean nervous chalky pedantic archetype which valve lovers occasionally love to apply wholesale to transistor-based systems.
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Summary: Of all hifi components the linestage is most challenged and questionable. To justify its existence and expense in the face of functional redundancy where no switching is needed, where a source handles volume and where overall system gain means one operates exclusively below unity gain—very common indeed!—a linestage must unequivocally exceed a quality passive. That's easier said than done. As good as the LS100 is, it's not yet unequivocally superior to a premium passive of Tap-X caliber. That requires more than what ModWright charges (and more than my $10.000 Esoteric which on raw lucidity and suchness also still trails the $2.000 Bent).
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That admitted, the LS100 trades ultimate magnification power, contrast ratio and immediacy for textural sophistication, richer tone and structural suppleness. Particularly with solid-state amplifiers those qualities are often not fully accounted for. As unexpected bonus the ModWright then adds real bass muscle. While involving a trade-off in ultimate terms it will be an attractive trade-off in many instances. Very well built, cosmetically opulent and truly full-featured, ModWright's remote-controlled LS100 preamp with top-notch headphone socket, optional phono stage (or 24/192 S-PDIF/USB DAC module) is another winner from a designer who has paid his dues modifying other people's gear to now be apparently incapable of doing wrong; or simply exceptionally careful not to. He continues to author fairly priced electronics which nearly unanimously win high praise even at trade shows. There very temporary hotel-room showings are notorious disappointments. With amongst or outright 'best of' show votes across multiple publications, the LS100 has acquitted itself before a far larger audience than yours truly already. I'm merely the latest individual to add myself to the list of admirers. No wonder the LS100 is back-ordered... |
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Quality of packing: Oops and FedUp proof.
Reusability of packing: Many times.
Ease of unpacking/repacking: A cinch.
Condition of component received: Perfect.
Completeness of delivery: Perfect.
Human interactions: Always very friendly. ModWright is an enthusiast operation.
Pricing: Good value.
Final comments & suggestions: Luxuriously appointed mid-priced linestage which proudly but carefully wears its tubes on the sleeve. The 6.3mm headphone socket is a sonic stand-in for the $4.000 Woo Audio Model 5. John Chapman's custom chrome/black remote wand for his OEM clients runs the same IR codes for ±volume and mute to make a lovely luxury addition should you want to upgrade the stock plastic remote and not care about remote source switching.
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