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Output transformers play a vital role in the performance of valve amps. Here Octave practices due excess. Primary and secondaries exhibit multiple boxes-within-boxes isolation as already McIntosh embraced many decades ago to minimize transfer losses with fluctuating load impedances. About further details Andreas Hofmann remains characteristically taciturn, citing intellectual properties and proprietary know-how he means to protect. He does however reveal that the isolation between the transformer winding layers is purely organic as artificial materials simply sounded ‘gruesome’. Unfortunately raw production of the transformers is costly and relies on heavily trained workers who spend three to four hours on either an OPT or power transformer. Octave proudly reports that not one of their transformers has ever yet failed in the field. To conform to company quality standards one builds "just about everything" in-house says Hofmann.

Octave’s insistence that their buyers will never encounter aggravation with their gear is sadly not a universally applicable sentiment in HighEnd audio. Octave’s amps are comprehensively protected and can thus be run without a load, without valves and even into a dead short between the output terminals. The only thing that’ll eventually wear out are the valves themselves. Like light bulbs those are designed for eventual expiration. Should one fail, nothing else happens unlike with other amps where the output tube resistor sacrifices itself when a bottle gives up the ghost. Andreas Hofmann expects his amps to run 20 years without any service issues.


The V70SE arrived with KT88 and I also had access to the optional €900 Black Box. That's essentially a capacitive array which gets switched in parallel to the onboard power supply filter caps to increase overall capacitance by a factor of 4. The €2.400 Super Black Box—see V80 review for details—increases that advantage to a ‘Warp 10, Mister Sulu’ factor of ten. Where others gussy up their power supply with so-called filter chokes, Hoffman regards this as a dead end. Filter chokes suffer too high an output impedance and thus also insufficient reaction times. His extreme caps of choice offer a lower Zout and are thus faster. In the final analysis many ways lead to Rome. This removes concerns over the how and instead lets us focus on whether a given designer actually ended up in Rome (or not).

Any tube amp review must invoke speaker compatibility issues. I had on hand three different loudspeakers, the Audio Physic Avantera, the Magnat 1005 and a JBL LSR6332 studio monitor. The Octave/Avantera pairing wasn’t the happiest. With a valve amp of V70SE price tag I don’t expect any pickiness regarding musical choices but the Avantera conveyed little fun on material with bass impulses in rapid succession. While the combo didn’t stumble, the high degree of differentiation and control that was so apparent higher up simply didn’t parlay into the bassment. And that obviously reflected back negatively on the upper registers too. Into this load the V70SE simply didn’t play as open and free as into the others.

Things looked up considerably with the Magnat and truly shone with the JLB. One might suspect that below 100Hz the Audio Physic exhibits a lower impedance than the JBL to overtax the current delivery of the amp. As it turned out, things aren’t that simple. The speaker specs and credible measurement graphs for either model show similar curves in the 4-ohm region. Even so Andreas Hofmann shared my sentiments during an inquiry that he too finds speakers with paralleled woofers to gel less happily in general with his amplifiers than those with a—to him preferably large—single woofer. There are thus other effects separate from nominal impedance at work.


How about the sound? This returns us to the beginning challenge of adding over what my colleagues already said.  I instantly recognized their commentaries in my own audition with the V70SE. Whenever machines from the same maker share such a recognizable house sound, it’s a sure sign that the designer knows his stuff and manages to securely arrive at ‘his’ sound via different avenues. When gear from the same maker sounds decidedly different I’m always suspicious of more or less accidental results. After having Ralph Werner ask me about my first take on the V70SE, the following dialogue developed: "Very precise but also a bit restrained. I’ll let it run for a few days." "Restrained as in not dynamic or slow? That would be strange." "Not slow. Precision rather than enthusiasm. The opposite of va-va-voom."