TUBE JOUR­NEY

Smart de­sign and high out­put valves de­liver thrilling sounds from this ‘Spe­cial Edi­tion’ Ger­man am­pli­fier.

Sound+Image - - Contents - Jez Ford

This Ger­man valve amp achieves 120W of power. Read our glow­ing re­view.

If Oc­tave is not a brand you know, you’re prob­a­bly not alone — yet it has been mak­ing amps un­der this name since 2000, and for a quar­ter cen­tury be­fore that un­der a pre­vi­ous gen­er­a­tion, hav­ing been founded as a trans­former wind­ing com­pany in 1968 by the fa­ther of the cur­rent Ex­ec­u­tive Di­rec­tor and Chief De­signer An­dreas Hof­mann. Oc­tave’s prod­ucts are hand­built in the vil­lage of Karls­bad in Ger­many, where each am­pli­fier gets not only qual­ity con­trol but a 48-hour dura­bil­ity soak be­fore leav­ing the build­ing.

It’s not hard to like Mr Hof­mann’s de­signs. A fun­da­men­tal phi­los­o­phy is that while valves have that speed ad­van­tage and the de­light­ful di­chotomy of “mu­si­cal” even-or­der dis­tor­tion and soft clip­ping, Oc­tave in­tro­duces tran­sis­tor cir­cuits for con­trol, mon­i­tor­ing and pro­tec­tion. There is soft-start tech­nol­ogy and a con­trolled “power rise”, care­ful sta­bil­i­sa­tion and an auto-standby mode avail­able which shuts down the valves af­ter 10 min­utes, which the com­pany claims can de­liver them sig­nif­i­cantly longer life (five years min­i­mum for the out­put valves, it sug­gests).

With all this kept out of the au­dio path, the only dis­ad­van­tage we can see to such a ‘hy­brid’ is that un­like pure valve de­signs, the V 80 SE might not work af­ter a nu­clear at­tack and EM pulse. Darn.

Equip­ment

The V 80 SE was, as its name sug­gests, in­tended to be a tuned-up ver­sion of the V 80, but Oc­tave’s en­gi­neers ap­par­ently got some­what car­ried away and de­liv­ered a sig­nif­i­cantly new de­sign, with a new-gen­er­a­tion driver stage us­ing a push-pull pen­tode sys­tem, as well as a new head­phone am­pli­fier. We had our high-sen­si­tiv­ity speak­ers ready to use with this valve amp, but given it’s rated at a full 130W RMS per chan­nel op­er­at­ing from 20Hz to 80kHz, that’s less the re­quire­ment than with most valve am­pli­fiers; in­deed Oc­tave says this power am­pli­fier en­joys ex­cel­lent load sta­bil­ity so that “nei­ther the im­ped­ance nor the ef­fi­ciency of the part­ner­ing loud­speak­ers will af­fect the V 80 SE’s sound”.

This is also the com­pany’s first out­ing us­ing the heady power lev­els of KT150 valves, which are the first thing you un­cover when open­ing the sig­nif­i­cantly heavy box — and for once in our re­view­ing lives we sat down with the man­ual (and white gloves) rather than sim­ply get­ting into it. De­spite Oc­tave’s de­lib­er­ate ef­forts to make valve am­pli­fi­ca­tion easy, these are still glass vac­uum tubes de­serv­ing of re­spect!

The sup­plied man­ual was in Ger­man, so we got the English ver­sion up on­line, and fol­lowed the in­struc­tions. We re­moved four lit­tle Allen bolts (see pic­tures), lifted off the valve guard, then donned the white gloves to firmly in­sert the four gor­geous KT150s. Power on.

Per­for­mance

One of the V 80 SE’s man­age­ment (and life-sav­ing) tech­niques is a ‘soft start’, which takes about a minute in nor­mal use. But at ini­tial set-up you wait five or more min­utes for the valves to warm up be­fore check­ing the bias set­tings. This is made a won­der­fully sim­ple pro­ce­dure here (com­pared to some where you have to get in­side the am­pli­fier and fid­dle with screw­drivers alarm­ingly close to the high volt­ages in­volved. Here, in­stead, you turn the smaller right knob to ‘Bias’ and then look at the rows of LEDs that il­lu­mi­nate on the Oc­tave’s front panel dis­play (bot­tom right pic­ture). These in­di­cate ei­ther over or un­der bi­as­ing — or­ange when warm­ing up, a row of greens if all is well, red if over bi­ased. You in­sert the small screw­driver un­der any non-op­ti­mised LED, and turn un­til you get the green light. It’s su­per sim­ple and per­fectly safe. On our unit valves 2 and 4 proved spot on, valves 1 and 3 needed a tweak, though we ad­journed for cof­fee and a half-hour break first, in case this new amp just needed some more time. Just a lit­tle, as it turned out.

This easy sys­tem also sim­pli­fies sub­sti­tu­tion and bi­as­ing of other com­pat­i­ble out­put valves; the com­pany doesn’t rec­om­mend us­ing low power valves like KT66 or EL 37s, but mid-power (e.g. KT 88s) can be used with the bias set to ‘low’.

Then we en­coun­tered what was for us its high­light — de­liv­er­ing vinyl. The phono stage on the V80 SE is an op­tion, and comes ded­i­cated to ei­ther mov­ing mag­net ($POA) or mov­ing coil ($999) curves, not switch­able. Dis­trib­u­tor BusiSoft AV kindly sup­plied a V 80 SE with a mov­ing-coil phono stage though, shame­faced to re­late, we had no mov­ing-coil car­tridge to hand. So in­stead we used our usual Mu­si­cal Fi­delity phono stage and preamp in or­der to con­nect our Thorens turntable, tak­ing ad­van­tage of one of the Oc­tave’s points of ver­sa­til­ity to do so. If you switch the right­hand small knob to what Oc­tave calls the ‘Ex­tern’ func­tion, you can use the V 80 SE as a two-chan­nel power amp, in this case with our sep­a­rate preamp plugged into the “Mas­ter In­put”. This doesn’t, how­ever, head at full level di­rect to the power amps, since the Oc­tave’s vol­ume knob is still in cir­cuit — cer­tainly safer, but leav­ing you a choice of two vol­ume con­trols. The man­ual says “When us­ing this op­tion, you should gen­er­ally set the vol­ume con­trol on the V 80 SE to max­i­mum and ad­just the vol­ume with the ex­ter­nal pream­pli­fier.” It seems cu­ri­ous to sug­gest crush­ing the wave­form at source in this way (also rais­ing the noise-floor of the not silent V 80 SE), un­less per­haps the V 80 SE’s per­for­mance is com­pro­mised at low lev­els — but this is not usu­ally, and cer­tainly not here, an is­sue with valve am­pli­fiers, quite the re­verse. So we went the other way, giv­ing the V 80 SE a full-level di­rect out­put from the preamp/ DAC and hav­ing the usual con­trol range avail­able us­ing the Oc­tave’s vol­ume knob.

While the knobs on the V 80 SE are nicely weighted, vol­ume con­trol is most con­ve­niently en­joyed us­ing the sup­plied heavy two-but­ton re­mote. (Yes, just two but­tons, vol­ume up and down — that’s enough, isn’t it? What else do you plan to do?) The re­sponse of the but­tons is per­fectly smooth, even through tran­si­tion from nudg­ing down to ramp­ing down, and the fade oc­curs suf­fi­ciently fast to be used as a mute if, say, the phone rings.

You might just want to park that call, mind you, given the heights of de­light this am­pli­fier con­jured from the grooves of the very first disc we ran­domly plucked, side three of a 2-LP Mor­ri­cone com­pi­la­tion, and from Once Upon A Time in Amer­ica to The Falls from ‘The Mis­sion’, there was a scin­til­lat­ing spir­i­tu­ally mu­si­cal de­liv­ery of every el­e­ment; the com­bi­na­tion of rich­ness and clar­ity to the strings was glo­ri­ous. Ruth­lessly re­veal­ing too — in­deed on the cli­max of The Falls the dif­fi­culty of cut­ting the com­plex and rich bass to the in­ner grooves was clear to hear. It barely dented our en­thu­si­asm.

With sound this good, we were quick to head to our Led Zep­pelin 180g re­mas­ters. We span up the main disc of ‘Zep II’.

Dear God. The size of the bass on the in­tro to Moby Dick; the weight and speed of Bon­ham’s kick drums.! If you’re one who gen­er­ally skips the Moby Dick drum solo, well, we lis­tened to it three times over here, partly for the dy­nam­ics and depth that made it real at a ref­er­ence level, and partly to con­firm an edit we’d never no­ticed where the level jumps up and the left kick drum goes from per­fectly recorded to slightly over-mod­ded. New dis­cov­er­ies on a Zep al­bum? Mu­sic geek heaven.

Since with all this we were us­ing our usual phono stage and preamp, this showed the mer­its of the power amps in par­tic­u­lar. We have had large re­serves of power to hand be­fore, but none that so well matched the abil­ity to de­liver such spec­tac­u­larly snappy dy­nam­ics with such author­ity. Some can turn the tap on quickly but not off; this was slam with­out over­hang. Riv­et­ing lis­ten­ing.

With ev­ery­thing firmly warmed up by now, we rechecked the bias. Still per­fect.

Of course, one down­side of this am­pli­fier is the lack of a DAC — there are no dig­i­tal in­puts, no USB, no op­ti­cal. But we had our usual Mu­si­cal Fi­delity USB DAC wired into it, and lis­tened to all kinds of files, high-res and low, both play­ing through our own preamp and through the V 80 SE’s own un­bal­anced CD in­put.

Again the sound was solid-edged in pre­sen­ta­tion, the pi­ano en­try per­cus­sive on Diana Krall’s Alone Again Nat­u­rally, a de­light­ful del­i­cacy to the brush­work and her voice vel­vet with its sibi­lants im­pec­ca­bly hu­man, effs and esses with no em­pha­sis, no spit. It was still an un­flap­pable sound, just oc­ca­sion­ally thin­ning a vo­cal — McCart­ney on Every Night, Glenn Shor­rock on Rem­i­nisc­ing. We had it paired with Dynaudio’s Spe­cial Forty speak­ers for a while, and the imag­ing was down­right foren­sic, every in­stru­ment on its axis — those panned har­monies on Rem­i­nisc­ing a spa­tial thrill, if just a bit light; we found the per­for­mance more con­vinc­ing through the MF preamp to the Oc­tave’s out­put stage. We were just lov­ing that out­put stage.

A higher Oc­tave

We re­mem­bered, then, that the V 80 SE can be up­graded with one of two lev­els of Black Box. That’s what they’re called — the Black Box and the Su­per Black Box (pic­tured above left). Both up­grade the power sup­ply by adding ad­di­tional ca­pac­i­tance, the Black Box ($1699) said to quadru­ple the orig­i­nal farad count, and the Su­per Black Box ($3999) to mul­ti­ply it by ten.

Well we’d been sent a Su­per Black Box, so we plugged it in along­side... you couldn’t be putting it on top, since the Oc­tave runs hot — not quite hand-burn­ing hot, but pretty close. (The cage is a safety ne­ces­sity, as well as a le­gal one.) The Su­per Black Box re­quires no mains, looped in via a multi-pole con­nec­tor on a fly­ing lead to the back panel. It’s not some­thing you can eas­ily A-B in a lis­ten­ing ses­sion, and it will be most use­ful for as­sist­ing the V 80 SE in dom­i­nat­ing any dif­fi­cult speaker loads at times of high den­sity and dy­nam­ics. We found it didn’t vastly al­ter things with our sen­si­tive horn speak­ers, though with one par­tic­u­larly stub­born stand mount pair it seemed to add an ex­tra level of con­fi­dence to per­for­mance, an un­flap­pa­bil­ity when punch­ing out dy­nam­ics and han­dling high den­sity mu­sic.

Head­phone lovers will suf­fer a bizarrely placed head­phone socket, po­si­tioned be­tween and be­low the speaker con­nec­tions — con­ve­nient for ad hoc use it ain’t. But there’s a three-po­si­tion DIP switch on the back — no head­phone out­put, head­phone and speaker out­put, or just head­phone out­put. So you can have a 6.5mm ex­ten­sion lead per­ma­nently plugged in at the back, then use this switch to turn it on and off. (Why a po­si­tion for both? Some peo­ple like it that way, en­joy­ing the de­tail of open head­phones and the phys­i­cal im­pact and room ef­fect of speak­ers. It works best with bass-light and open de­signs, like Sennheiser’s HD 800.) And we should thank Oc­tave for in­clud­ing a head­phone socket at all — it’s not un­usual to omit them on valve amps, and in­deed this one uses a solid-state out­put stage, and one which has im­mense head­room; our AKGs are nei­ther es­pe­cially high sen­si­tiv­ity nor low im­ped­ance but we kept them firmly in the first third of the dial, enough to en­joy the V 80 SE’s preamp per­for­mance via that out­put.

As for Eco­mode, we pow­ered things down and up man­u­ally most of our time with the V 80 SE us­ing the rocker switch on the left side of the glow­ing chas­sis — the auto ‘switch off’ wasn’t on by de­fault when the amp reached us. But af­ter leav­ing it glow­ing away for a cou­ple of days by mis­take and re­turn­ing to rather over-ra­di­ated room warmth, we en­gaged Eco­mode via the sec­ond DIP switch on the back, so the am­pli­fier’s valve cir­cuitry would be turned off dur­ing per­ceived breaks of more than 10 min­utes in play­back. That’s a pretty short break, with the price of a minute’s Soft Start wait when you re­turn, but the re­ward is longer valve life, less heat, and a lower power bill from those for­got­ten mo­ments, since its nor­mal idling con­sumes 180W while the Eco­mode con­sumes 30W — it’s not a full standby mode, as the head­phone out­put and ‘record’ cir­cuits re­main ac­tive… 30W is still a good few light­bulbs’ worth, so we switched it off en­tirely af­ter lis­ten­ing. If we re­mem­bered.

Con­clu­sions

Great joys from the Oc­tave V 80 SE dur­ing its stay, driv­ing a se­ries of vis­it­ing speak­ers as well as our usual sus­pects. While the Black Box con­cept will be use­ful for those pair­ing it with de­mand­ing speak­ers, for us the ver­sa­til­ity of con­join­ing of a vinyl source and sep­a­rate preamp with the Oc­tave out­put valves proved par­tic­u­larly divine, cre­at­ing true hi-fi mag­nif­i­cence of re­al­ity at the high­est lev­els.

1 Un­pack­ing the KT150 valves; 2 Allen-key­ing the grille; 3 Look­ing from above: the front valves (2 x 12AU7, 1 x 12AT7) are pre-fit­ted, the KT150 tube sock­ets await their valves; 4 The Oc­tave’s easy bi­as­ing sys­tem us­ing the bot­tom screw­holes and LED...

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Oc­tave V 80 SE valve am­pli­fier

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