Embed or link this publication



Popular Pages

p. 1

V 80 SE Review - English Version


p. 2

Test & Technology Tube Amplifiers 30 10/15 stereoplay.de 220 T&T Röhrenverstärker Octave V80SE stereoplay 2015-10.indd 30 04.04.16 14:38 220 T&


p. 3

Full Control Octave’s brand-new V 80 SE integrated amplifier raises the bars for sound and technology by several meters. Who might assume that tube amps were “developed to death“ a long time ago, is totally off the track! D on’t let this taciturn, win­ some man with his un­ wound attitude and that deep, relaxed voice fool you! Don’t allow yourself to get lulled when he’s rolling a cigarette with transcendental calmness! For you’re going to be hood­ winked. Definitely. In actual fact he’s a die­hard, restless super perfectionist. Who apparently has no nerves and will never give up. Until he has eliminated every mistake – or those trifles he deems as such. Until he has completely eradicated even the very smal­ lest imperfection and built a perfect amplifier which runs at least as precisely and silently as an ultra expensive Swiss watch. And fails just as often. Like always, Andreas Hof­ mann, head and founder of Oc­ tave Audio, is as cool as a cu­ cumber. Well, here it is, the new integrated amp, the V 80 SE. Which has just been accomplis­ hed and it uses, of course, the latest and highly efficient KT150 output tubes. If nothing else, it’s about the capability to deliver sufficient power for all circumstances – i.e. loudspeak­ ers. But one also has to get the power across to the speaker. And so he’s primarily interested in what comes out “from be­ hind“, hence the real interaction with the loudspeaker. Anything else would just be spoilage or a pious hope. Sure, it was about stability on a complex load, that would be the key to good sound. Such an amp would have to work kind of load independent. Besides, he also developed a new input stage which consti­ tutes indeed a dramatic impro­ vement (Hofmann hints a smi­ le, maybe the Hofmann equiva­ lent to an emotional outburst). At this point Thomas Brie­ ger, in charge for marketing and sales at Octave, cuts in on the peacefully flowing conversati­ on. As a matter of course, they offer an update for the owners of older V80s, because the im­ provement is really very subs­ tantial. Nota bene for the first time in the company history. Grant­ ed, without boosting the 10/15 stereoplay.de 31 04.04.16 14:38 16 14:38 220 T&T Röhrenverstärker Octave V80SE stereoplay 2015-10.indd 31


p. 4

Test & Technology Tube Amplifiers The huge pc board of the V 80 SE is almost as wide as the integrated amplifier. Yet the signal paths between the tubes are reasonably short. With the bias current measuring circuit of the four power tubes (which is based on precision OP amps) the plate currents can be controlled and set with utmost accuracy; the tolerance is specified at 0.3 per cent. output power in one go, but then again with the new input stage technology of the V 80 SE. Some facts on tube technology It’s about time to delve a little deeper into tube technology. On this, however, Andreas Hof­ mann merely comments in his bone­dry way that he simply had some new ideas. Thus, for example, the input and phase inverter stages were optimised; moreover he also revised the feedback loop – but too much of it would not be useful, either – for its significant job between output and input. In general he’s striving for an optimum beha­ viour within the transmission range, to which the pentode cir­ cuitry he prefers in his ampli­ fiers also contributes its share. At this point of the conver­ sation the author needs to exp­ lain that the pentode circuitry, which also entails a higher per­ formance yield, is nothing new, but can only be found very ra­ rely these days. Because many decades ago there was already a certain revolution in tube amp technology called the “ultra­ linear circuit“. It connected the second grid (in tube jargon: G2) of one output pentode to the secondary winding of the output transformer through a most commonly 43 per cent interme­ diate tap and, on balance, offer­ ed quite a few advantages. But if you take a somewhat more differenciated look at it, the pentode circuit with the G2 ly­ ing on a (normally) constant potential, is very attractive if the whole thing is masterfully calibrated. This was also appre­ ciated a long time ago by French tube authority Jean Hiraga whose regrettably not very stable JH50 power amp was highly acclaimed every­ where for its sound. Using the said grid 2 and his pentode circuit, one could still do some very different things, says Octave boss Hofmann with a cunning grin. For instance, A built-in moving coil phono stage is available on request. The V 80 SE can also be split into pre and power amp sections. The headphone switch (top left) enables the jack socket and lets you choose if the speaker outputs shall be on or off during headphone operation. The Ecomode switch below activates an energy saving function which cuts out the tube section in stand-by mode. 32 10/15 stereoplay.de 220 T&T Röhrenverstärker Octave V80SE stereoplay 2015-10.indd 32 04.04.16 14:38 220 T&


p. 5

control the amp in a certain way, also power it up and down smoothly. After all, this is a “luxury“ integrated amplifier, Thomas Brieger hastens to add, one that has all kinds of nice features such as sophisticated power management systems, comprehensive protection circuits which would also prevent secondary failures in case of a defective tube. And, of course, one should not forget the convenient, super clever bias current adjustment which also makes changing tubes a breeze for the user. Little advanced electronic helpers That’s true. Andreas Hofmann is, admittedly, a fan of all­tube circuits for the signal path, but he’s not afraid of using the latest little electronic helpers to sort of “organise“ his amps. At this point the story gets really complex, because in the V 80 SE all kinds of logic cir­ cuits plus software play their part in contributing to operatio­ nal safety and durability. With his “double safety“ systems Hofmann was even able to cut the overall failure rate (except tubes) virtually down to zero. As he states, he’s not up for re­ pairs. Last, but not least the immu­ nity to mains voltage fluctua­ tions, as the chief points out; after all the amp doesn’t care, so to speak, if the mains volt­ age is 210 or 250 volts, the Q­ points will nevertheless remain constant. And when it comes to saving energy, the integrated amp will go into an economy mode whenever no signal is present. This is also the case when the built­in headphone amp – a novelty in an integrated ampli­ fier by Octave – is used. True, the socket is still located a little timidly on the rear side to not interfere with the visual effect, but behind it we once again find an extremely sophisticated so­ lid­state headphone driver. Which the stereoplay listening jury flat out forgot to check ... In the meantime Andreas Hofmann has commenced a short digression on his output transformers which are produ­ ced in­house. Because that way they have a full control of the quality, which also applies to the mains transformers. More­ over, he’s not necessarily a great believer in the usual four and eight ohm taps, they would cer­ tainly not make a transformer better. Which the author can confirm. Meanwhile Thomas Brieger is taking a pc board out of a box, quasi the heart of the V 80 SE with all the tube sockets. For photographing purposes, so we wouldn’t have to unscrew the beautiful new amp. Very good, because it has already arrived at the listening room, where it is wired to Thomas Gauder’s new Vescova. Andreas Hof­ mann, now on his way back home, had also gently remarked that the V 80 SE was not bad at all. Yes, this we can truly con­ firm. Hardboiled connoisseurs of the subject matter will con­ sequently need no more than ten minutes to get their jaws back up into the normal posi­ tion. A pearl ... Octave V 80 SE from 9250 Euro (manufacturer information) Distribution: Octave Audio Phone: ++49 (0)7248 3278 www.octave.de Agencies abroad see internet Dim.: B: 45 x H: 16 x T: 42 cm Weight: 23 kg Measuring values Frequency response charts Quick and easy: speaker con­ trol, emotionality, room im­ aging and dynamics on a level hardly conceivable before. A pearl if ever I saw one! Without fuss or quibble, totally irrespec­ tive of the price and by far the best integrated tube amplifier we’ve tested so far! Well, Mr Hofmann. The fat’s in the fire. Finally, we now want to see a broad, long­lasting smile! Or maybe even a jig of glee? Behind closed doors? Alright! Roland Kraft ■ Neutral and broadband, slight level drop @ 4, higher @ 2 ohms Distortion analysis (k2 to k5 vs. power) harmonic, dominating k2, still good behaviour above k3 stereoplay compatibility scheme Voltage 8Ω Frequence response Current into 3Ω 26,1V ∆ 4dB 6,3 A High performance level, will drive most loudspeakers less extremely impedance critical and power-hungry types RMS output power (1 kHz, k=3%) 8/4 Ω Kl. 4: 80/110 W Music output power (60Hz-Burst) Kl. 4: 85/113 W S/N ratio Line 98 dB S/N ratio Phono MM - dB Power consumption Standby/op.11,3/194 W Two 12AU7s (equivalent to an ECC82, far left) are used as driver tubes. A 6072 (ECC81, centre) is used in a split mode to act as the input stage. The big KT150s (far right) are rated here at 120 watts into four ohms in a push-pull operation mode. Rating Sound Measuring values Practical use Value 0 10 20 30 40 50 60 61 9 10 10 70 ■■■■■■■■■■ ■■■■■■■■■■ ■■■■■■■■■■ Octave’s new sound miracle turns out to be not only very performance-capable and universal with regard to suitable speakers, but is also a playground for tube nerds. Our evalution refers to the standard equipping. stereoplay Verdict Sound absolute top class 61 points 90 points High-end Overall score Outstanding Price/performance 10/15 stereoplay.de 33 04.04.16 14:38 16 14:38 220 T&T Röhrenverstärker Octave V80SE stereoplay 2015-10.indd 33


p. 6

Test & Technology Tube Amplifiers Octave V 80 SE: Output power preselection and alternative power tubes EL 34 6L 6 KT 88 KT 0 15 KT 12 0 Four of these tubes (from left to right) are well-known classics of tube technology, which are used in umpteen amplifiers worldwide: the slim EL34, a rare “Coke Bottle“ version of the 6L6, the chubby KT88 (probably the most often faked tube of all) and finally the old workhorse of hi-fi tube technology, the 6550. KT120 and KT150 (far right) are yet new designs from Russian tube specialists which have immediately gained pots of laurels. The sophisticated bias current setting of the Octave integrated amplifier also allows to use other power tubes than the KT150 high-performance pentode which are fitted as standard and rated at 120 watts per channel. To this end a so-called “Power Selector“ sets the basic plate voltage to distinguish between “high-power“ and “lowpower“ output tubes. Here the choice of suitable tube types ranges from the relatively feeble EL34 to the good old KT88, which is highly esteemed for its sound, to the KT150’s little sister named KT120. The KT66, 5881, EL519 and EL156 will definitely not qualify. Regarding the usability of the “musician’s tube“ 6L6, the otherwise really praisable and very detailed manual of the V 80 SE bears a discrepancy which Octave will still have to clarify. Together with the plate voltage preselection the bias setting, which offers two bias plateaus specified as “High“ and “Low“, allows to determine four different 65 50 The Octave’s exemplary distortion spectrum is also determined by the power tubes. Differences in sound will therefore manifest themselves in the distortion quiescent points to fully cover the possible output tubes (which in this amp won’t need to be matched). The achievable output power depends on the tube types employed; Octave defines the “low power“ level at 70 watts per channel or maybe lower, depending on the tube type. The use of other output tubes is both a matter of taste and speakers, whereby classic power tubes like the famous KT88 will undoubtedly sound different from the newly designed KT150. In principle we suggest to not overdo the tube research work in the V 80 SE, for the reason alone to save the (highquality) tube sockets ... Another point is the mere certainty that there will always be output tubes available for the Octave V 80 SE! 34 10/15 stereoplay.de 220 T&T Röhrenverstärker Octave V80SE stereoplay 2015-10.indd 34 04.04.16 14:38



no comments yet