Velo

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Laiv Audio Harmony DAC; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos & EX-M7 on subwoofer; Headamp: Enleum AMP-23R; Phones: Raal 1995 Immanis, HifiMan Susvara; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Earth, Furutech; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe; Preamp/filter: Lifesaver Audio Gradient Box 2; Amplifiers: Gold Note PA-10 Evo monos; Loudspeakers: MonAcoustic SuperMon Mini or Acelec Model One + Dynaudio S18 sub; Power delivery: Furutech GTO 2D NCF, Akiko Audio Corelli; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z230 work station Win10/64; USB bridge: Singxer SU-2; DAC: Sonnet Audio Pasithea; Clock: LHY Audio OCK-2;  Head amp: Kinki Studio THR-1; Speaker amp: Crayon Audio CFA-1.2; Speakers: EnigmAcoustics Mythology M1;  Headphones: Final D-8000
Upstairs headfi system: FiiO R7; COS Engineering D1; Cen.Grand Silver Fox; Headphones: Meze 109 Pro, Raal 1995 Magna
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: $2'100 with SMPS, $2'700 with linear PSU

The city of Velo. Were it built upon the remains of earlier settlements like London, Paris and Rome are, it'd take little digging to peel back layer upon layer of the past. Occasionally one might even find the bones of a Richard the III. With Linear Tube Audio's latest Velo, it's the same. It builds upon the Microzotl MZ3 which itself outgrew the MZ2 whose skeleton was the zero hysteresis output transformer-less ZOTL circuit of David Berning's 1997 patent. Though its OTL portion is arguably a misnomer, this all-analog circuit 'upsamples' the audio signal onto an UHF carrier wave which the tubes amplify. Subsequently so-called "impedance converters"—functionally equivalent to what classic output transformers do—'downsample' the impedance to match 4/8Ω speaker use; or in today's case, 25Ω to 600Ω headphones. Unlike big heavy classic steel-lam output transformers however, the puny air-core so very lightweight ZOTL parts apply turns ratios up to 300:1. As this page illustrates, they exhibit superior square-wave performance with steeper/cleaner rising edges than classic output transformers with their saturation effects and far higher parasitic capacitance. Velo's -3dB bandwidth is 2Hz-100kHz. Translated into common parlance, it all equates to faster circuits. And speed could have been Velo's namegiver. Velocity. If we dig into the past still deeper, we remember the late Lloyd Walker's Velocitor, a passive power distributor.

What the ZOTL trickery means for Velo's i/o impedances is 50kΩ in, 1.1Ω 6.3mm out, 50Ω dual RCA out. Hello push/pull class A headfi amp and preamp with three single-ended inputs. A rear-mounted toggle allows the use of 6SN7 or 12SN7 big-tone octal twin triodes whilst the input tubes can be either 12AT7 or 12AU7 without any adjustment. The lot packs into a 2.8" tall case with a 10" square footprint that weighs 6.5lbs. The tubes stick out from the top for easy plug'n'play. The central volume knob syncs with the included metal remote control to click through relay-switched resistors for volume changes—there's a volume memory function for each input—and also toggles through the inputs and mutes. The manual input selector and power switch are capacitive sorts triggered by the parallel capacitance to ground which our touching finger forms to temporarily increase the switch's cap value.

And presto, two short paragraphs just glossed over two years' worth of pushing patented intellectual property to further heights. For the full story, refer to LTA's own webpages which itemize the improvements this circuitry packs over its precursors. For the purposes of this page, it's enough to say that with Velo, the smart shopper bags a compact far from crazy-coined dual-purpose machine with illustrious DNA and glowing glass that's inexpensive to replace and runs far cooler than normal to last from twice to thrice as long. Unlike other 'desktop' headamps with pre-outs whose lack of remote won't readily convert to serious big-rig duty, Velo is all set to park on a faraway rack with its moving-dot LED indicator and natty wand. It's a serious preamp just without balanced XLR features.

If, as Berning-related review tradition predicts, we end up claiming that this machine doesn't sound like tubes, we'd be guilty of laziness. How can anything sound other than what it is? Being a proper vacuum-tube not hybrid gain circuit, Velo by definition must sound like it(self). Yet by omitting the classic output transformer's many fingerprints of limited bandwidth, associated phase shift, saturation, leakage inductance and general slowness, all ZOTL circuits I've heard and reviewed sounded faster, freer and more lit up overall. Whilst those qualities arguably parked them closer to solid-state notions, their glowing glass still made a distinctive difference. In just that sense one might perhaps call the underlying concept a sonic hybrid? Incidentally the same is true for my grounded-grid Vinnie Rossi L2 Signature DHT preamplifier which unlike Allnic and Manley 300B preamps that I reviewed direct-couples its glass without iron or capacitors. Hearing tubes liberated from the boat anchor of a typical output transformer is a very different thing.

Whilst Frederic on staff has his eyes on LTA's new R2R Aero DAC with ZOTL'd tubes—review forthcoming—mine alighted on Velo. To me, superior headfi comes closest to true high-fidelity and hi-rez sound. By not asking tubes to bench-press reactive variable low-Ω loads, driving headphones or the very high fixed input impedance of power amps makes for far more ideal conditions. Particularly with on-ear transducers, the biggest question now is noise; or hopefully, its complete no-show.

Tube-savvy shoppers know that the two allowable input types lower gain from 12AT7 to 12AU7; and that the SN7 types with 6/12V heaters are otherwise the same tube though the 12SN7's lesser popularity could mean lower prices. The stock power tubes are NOS 6SN7 and JJ 12AT7. LTA fans already know of the company's 14-day in-home trial privilege, US-made origins and 3-year warranty. The standard SMPS supports universal voltages, the optional linear power supply is 110/220V settable. Inserting headphones auto-mutes the pre-outs. Changing volume not only moves the positional LED but temporarily lights up all the LED below it to really show the setting change even from afar.

This is not a complicated machine. In fact, a ZOTL circuit cannot be damaged by feeding it signal without a connected load. Should you inadvertently hit 'play' before your headphones are inserted or accidentally pull them out mid tune, you won't cause smoke signals. Even though Berning circuits are exotic, in use they're the antithesis of fussy divas. Building them is a different story. The crew around Mark Schneider who licenses these circuits from David Berning was simply trained by the inventor to perfect their own manufacture before LTA ever launched. [Photo of their Aero DAC.]

This $650 12V/3A LPS+ combines a choke filter with overrated power transformers, big capacitive storage and Belleson regulators of super-low noise. With its customizable power ratings it's even compatible with DACs from Cambridge, Chord, iFi, RME and others. It measures 3.85" tall on an 8 x 7.5" WxD footprint. The included umbilical is 4 feet long.

When configured for Velo, the LPS+ sports an XLR3 power output.

Accessorizing influencers would point out that with Velo, the LPS+'s cosmetic match isn't; exactly a match. Of course David Berning is an old hand at designing his own audio-specific switching supplies. We needn't automatically view his pick of stock 12V/6.6A  lap-top brick from Taiwan's MeanWell with ill-disguised suspicion. My factory contact Nicholas thought it a good idea to include the LPS+ so our readers would know more than just how it looks. Now we've seen the map of our figurative city of Velo for some history and tech theory. Time to meet the actual Velo and learn whether it really equates to velocity in the Velodrome of Valves.