Tubes or transistors -- which sound better? Ask a typical group of audiophiles, then stand back as the argument heats up. Octave Audio, a German company, is firmly in the tube camp, contending that “true musicality in high fidelity can only be realized with tubes.” Their wide range of preamplifiers, amplifiers, and integrated amplifiers all use a combination of tubes and modern circuitry.
Octave Audio’s V 70 SE certainly looks like a modern integrated amplifier. Available in black or silver, it measures 17.8”W x 5.9”H x 16.3”D and weighs 48.5 pounds. It’s low-slung in front, with a streamlined tube cage that protects the tubes, and tiny fingers and noses, from contact with each other. I’ve never seen a tube cage that I could call handsome, but the V 70 SE’s looks better than most. Unlike in older designs, the V 70’s transformers are inside its case, which certainly looks sleeker. The V 70 SE sells for $7000 USD, or $7600 with optional moving-magnet or moving-coil phono stage. The phono board uses solid-state devices, and the MC version has a fixed input impedance of 150 ohms, with a signal/noise ratio of 73dB and an input sensitivity of 0.5mV. Those values should work with a wide range of MC cartridges, but wouldn’t with my van den Hul Platinum Frog cartridge, with its recommended input impedance of 500 ohms (I prefer 1000 ohms).
As its name suggests, the V 70 SE’s rated power output is 70Wpc RMS into 4 or 8 ohms. Although the delightfully complete and well-written manual specifies that the V 70 SE uses 6550C output tubes in its push-pull pentode design, the review sample came equipped with Electro-Harmonix KT88EH tubes. But you can also use 6L6, KT66, EL34, KT77, 5881, 6CA7, KT90, or KT100 tubes, if any of those tickle your fancy. You could also use KT120 tubes, though there won’t be any increase in power; for that, you’d need Octave’s V 110 amp, which uses KT120s to produce 110Wpc. Octave thoughtfully includes a spare power-output tube -- something I’ve never seen any other manufacturer do. The V 70 SE also has three low-level signal tubes: one ECC83 or 12AX7, and two ECC81s or 12AT7s.
The output tubes occupy a kind of trough that runs the width of the amplifier; the smaller, low-level tubes are partly enclosed by the front of the case, only their tops peeking out. I didn’t pry the low-level tubes out of the chassis to see what brand they were, nor did I do any tube rolling (i.e., substitute tubes of the same type from new old stock or different manufacturers to tweak the sound quality). All tubes are warranted for a generous one year. Unlike most tube amps, the V 70 SE’s expensive output transformers won’t be damaged if you operate it without speakers connected to it. The protective circuitry also instantaneously shuts down the amp if it encounters a short circuit while playing at a high level.
You can connect speakers of 3 to 16 ohms impedance to the V 70 SE’s single pair of output terminals. I wish all amplifiers had speaker terminals like the V 70 SE’s; they may not accept banana plugs, but they’re easy to grip and turn by hand, making it possible to firmly tighten spade lugs or bare wire without tools.
The V 70 SE’s signal/noise ratio is -100dB below 40W. The negative feedback is a moderate 10dB. The input impedance is 50k ohms, which should be an easy load for any competently designed source component, and the input sensitivity is 180mV for full output, which means that the Octave is quite sensitive -- a low volume-control setting should be all that’s needed to produce a loud output.
The front panel is very simple: two knobs flank a display window. The left knob is the input selector, and can turn on the V 70 SE’s tube-biasing circuitry (more about that in a bit). Its Front Channel setting bypasses the volume control so that you can use the V 70 SE only as a power amp. On the right is the volume control, a motorized design that’s also operable via the hefty aluminum remote control. And that’s all the remote does: raise and lower volume. It won’t let you select the source, mute the amplifier (handy when the phone rings), or turn the amp on or off. The on/off switch is on the left side of the V 70 SE, just behind the faceplate’s protruding edge, where it’s easy to reach without requiring an unsightly hole in the front panel.
On the rear panel are four sets of RCA jacks for input connections: CD 1, Tuner, Aux 1, and Phono/Aux 2. There’s also a set of XLR input jacks labeled CD 2. The review sample lacked the optional phono board, but one can be retrofitted. A preamp output is provided, for connection to a subwoofer or other external device. This has an impedance of 240 ohms, which is low enough to drive most subs.
A small switch on the back of the V 70 SE, labeled Ecomode, has three settings: Eco Off, Eco On, and Amp Off. In Eco Off mode, the amp draws full quiescent power when it has received no signal for a longish period. In Eco On mode, the V 70 SE reduces its power consumption after nine minutes without an input signal, which saves electricity, lengthens tube life, and reduces the amount of heat generated. When the V 70 SE senses a signal, it switches itself on, but there’s a delay before you’ll hear any music -- you’ll probably need to restart the track to hear it from the beginning. Actually, this happens any time the V 70 SE is turned on, to minimize stress on the tubes and thus lengthen their lifespan. The Amp Off setting turns off the output tubes but keeps the low-level tubes powered up. This saves even more electricity, further lengthens output-tube life, and lets the amp run even cooler. Go green!
There’s also a jack labeled Black Box Converter. The optional Black Box is an external bank of capacitors that augments the V 70 SE’s internal power supply to improve the sound. Even more improvement is said to result from using the Super Black Box, with even more capacitance. Neither Black Box came with the review sample. Despite their names, the Black Boxes aren’t necessarily black. An IEC connector lets you plug in the stock power cord.
Setup and use
While the V 70 SE was shipped with its ECC83 and ECC81 tubes already installed, the large KT88EH output tubes arrived in a separate, foam-padded box. After installing the tubes, turning on the amp, and letting it sit an hour to reach full operating temperature, I had to set the grid bias. Don’t panic -- Octave makes it almost fun to do this. When the tubes are warmed up, turn the selector switch to its bottom position, and you’ll see three LEDs colored yellow, green, or red. Insert a tiny 3mm screwdriver (provided) in a small hole under a given LED and turn it until the LED glows green -- that tube’s bias is now correct. If you want to experiment, you can set the bias so that more than the green LED is lit; for KT88s, a higher bias can be used, so both red and green LEDs can be lit. Just don’t let the yellow or red LEDs light up alone -- that signifies under- or overbiasing. And don’t lose that little screwdriver -- I’m not sure you could find a replacement at Home Depot. For the V 70 SE’s KT88 tubes, I thought the higher bias setting sounded a bit richer.
At first, I connected the V 70 SE to some speakers rated at 96dB sensitivity: fairly, though not extremely, sensitive. The V 70 SE’s volume control didn’t allow much adjustment between the off and too loud positions. With my normal horn speakers, the sensitivity was perhaps even higher, but the volume control worked fine over the same range.
Because my rack was chock full of other equipment, I placed the V 70 SE on a solid wood table nearby. The stock power cord looked flimsy, so I used a Purist Audio Venustas, which has never failed to bring out the best from any component I’ve used it with. I used my standard Clarity Cables Organic speaker cables; Audience Au24e balanced and Crystal Cable Piccolo unbalanced interconnects linked various source components to the Octave. Since the V 70 SE has only one balanced input, CD 2, I connected that to the output of my DAC. The review sample had seen some use and was already broken in; the manual warns that some tubes need up to three months’ break-in time.
In use, the V 70 SE was quiet as a tomb: no hum or tube rush, no thumps when I turned it on or off.
The Octave V 70 SE didn’t sound like solid-state, nor did it exhibit some of the extreme characteristics of some tube amplifiers -- i.e., distortion. It did have one characteristic of a good solid-state amplifier: transparency. It revealed plenty of detail about the information on a recording -- not the fake detail of excess treble, just a lot of natural-sounding information across the entire audioband. “The Panther,” from Jennifer Warnes’s The Well (16-bit/44.1kHz WAV, SDR), opens with an assortment of percussion instruments that produce a variety of high-frequency sounds, and the V 70 SE pretty well nailed them -- not with too much faux detail, or with the kind of rolled-off sound that suppresses genuine detail.
With my favorite evaluation track, “Folia Rodrigo Martinez,” from Jordi Savall’s La Folia 1490-1701 (16/44.1 WAV, Alia Vox), the V 70 SE performed two tasks that sometimes counteract each other: It revealed the rich harmonics of the stringed instruments while still providing lots of detail. The percussion instruments (wood block, castanets, sleigh bell) at times emerged from and at others receded into the background, and the V 70 SE tracked those changes clearly. It also tracked two other characteristics of this recording: the constant shifting of level within a wide dynamic range, sometimes gradually and sometimes in steps; and, even more challenging, the variations in tempo as the musicians speed up and slow down to shape their phrasing. This latter accomplishment is rare; most amplifiers just portray this performance as having a constant musical tempo. The deep bass on this cut was reproduced with plenty of detail and impact, though I’ve heard a few amplifiers that go slightly deeper. But darned few.
Pitched Gershwin’s Rhapsody in Blue, performed by pianist Jon Nakamatsu, with Jeff Tyzik conducting the Rochester Philharmonic Orchestra (24/88.2 FLAC, Harmonia Mundi/HDtracks), the V 70 SE knocked it out of the park. The opening clarinet riff was tonally spot on, reminding me of an audition tape I recorded for a local clarinetist, and Nakamatsu’s piano entered forcefully, but with a concert grand’s full harmonic envelope. This is a great orchestral recording, and the V 70 SE’s tubes really showed off their ability to capture the full harmonic richness of a symphony orchestra.
Audiophiles have seemed to love “Spanish Harlem,” from Rebecca Pidgeon’s The Raven, ever since it first came out on LP, in 1994 -- and in Bob Katz’s high-resolution remastering (24/176.4 FLAC, Chesky/HDtracks ), it’s pristine. The V 70 SE reproduced Pidgeon’s voice with delicious delicacy, floating a palpable, three-dimensional image of her between the speakers. And I haven’t used the word palpable since I reviewed a single-ended-triode tube amplifier.
The V 70 SE showed me something new about my longtime favorite track for evaluating soundstage reproduction: Allegri’s Miserere, sung by the Tallis Scholars (24/96 FLAC, Gimell/Gimell). This a cappella setting of Psalm 51 is sung by two choral groups: a larger group in the foreground of the church where the piece was recorded, and a smaller group some distance behind them. When the distant group sings, its sound is embedded in a reverberant field that makes it clear that the group is in the background. The V 70 SE didn’t omit the reverberant field, as some components tend to do, and its portrayal of it was cleaner and less blurred than I’ve heard through many other components -- which, I now realize, were making the field sound fuzzy and smeared.
Fed Ottmar Liebert’s One Guitar (24/96 FLAC, Spiral Subwave International/HDtracks), the V 70 SE depicted strong initial transients, and realistic sustain followed by a decay, all sounding like what I’ve heard at guitar recitals. Sometimes there’s a tendency to overemphasize the leading edge of a transients, which makes a recording sound more detailed, if less realistic. Not the Octave. The sounds from the guitar’s body and its strings were perfectly integrated.
I didn’t have another integrated amplifier on hand to compare with the Octave V 70 SE, so I used a separate amplifier and line stage: Audio Research’s VS115 and LS27 ($6995 each). With its original 6550C tubes still installed, the VS115 produces 115Wpc. The Wireworld Cable Gold Eclipse 7 balanced interconnects between line stage and amp added $1600, for a total of $15,590 -- over twice the cost of the V 70 SE.
With Jennifer Warnes’s “The Panther,” the ARC combo didn’t have the Octave V 70 SE’s high-end extension; in other words, it sounded ever so slightly rolled off. The highs weren’t missing, just a tad less evident. With “Folia Rodrigo Martinez,” the ARC combo showed excellent microdynamic differentiation and deep, impactful bass -- but, like the V 70 SE, both were a smidgen short of the best I’ve heard. Tempo variations were perhaps a bit more distinct and easy to follow through the Octave.
With Rhapsody in Blue, and particularly the piano, the Audio Research rig sounded ever so slightly smeared compared to the V 70 SE. Rebecca Pidgeon’s cover of “Spanish Harlem” sounded equally pristine through both amps, but the bass was just slightly more full through the ARCs. This was pretty much a tie.
Allegri’s Miserere, too, was a close race. Both the V 70 SE and Audio Research combo portrayed this recording’s soundstage exceptionally well, without exaggerating or smearing the reverberant field. The ARC combo showed off Ottmar Liebert’s One Guitar as well as did the Octave. The hi-rez version of this guitar recording sounded quite realistic.
Overall, both the Octave V 70 SE and the Audio Research/Wireworld combo sounded great. I’ve listened to the latter many hours, and while other components may surpass it in certain areas, I still find it very musically revealing and enjoyable. Yet the V 70 SE had a more extended high end and an equally extended low end. In some ways, it let me hear familiar music in ways that were different, and probably slightly more revealing than I’d previously heard, and gave me a better understanding of the musicians’ intent. And remember: the Octave V 70 SE costs less than half the price of the ARC/Wireworld.
When I was a kid, the paradigm for a high-end stereo was a separate preamp and power amp serving a wide variety of sources: turntable, FM tuner, open-reel tape deck, cassette deck, maybe a graphic equalizer. Later, a CD player was added. It made sense to keep the preamplification stage and controls in a chassis separate from the large, hot, heavy power amp.
Today, things are different. Many audio systems now have a single digital source. A single integrated amplifier like the Octave V 70 SE has all the functionality needed for virtually all systems, and it’s not unmanageably hot and heavy. It can fit on a single shelf in most equipment racks, and it produces enough power to drive a lot of speakers. So these days, all you need for a respectable high-end audio system is a digital source, the V 70 SE, and some speakers and cables.
A list of everything the V 70 SE did wrong is short. With that out of the way, let’s review the Octave’s strengths. It’s quiet, and easy to set up, use, and maintain. It portrays music with great transparency, letting you appreciate the musicians’ intent and phrasing. Its ability to use a wide variety of power-output tubes adds flexibility for those who want to experiment with the different sounds of different tubes. Its sound equaled or surpassed that of a highly regarded amplifier and line stage costing more than twice as much, and it produced enough power to drive a wide variety of speakers. It looks great and sounds great -- just what you’d expect of a great amp. I can’t think of many amp-preamp combinations that have equaled this integrated. An easy Reviewers’ Choice.
. . . Vade Forrester
- Speakers -- Affirm Audio Lumination
- Amplifiers -- Audio Research VS115, Atma-Sphere S-30 Mk. III, Art Audio PX-25, Pass Labs First Watt J2
- Preamplifier -- Audio Research PH5 phono stage and LS27 line stage
- Sources -- Linn LP12 turntable on custom isolation base, Graham Engineering 2.2 tonearm, van den Hul Platinum Frog cartridge; Meridian 500 CD transport, Sony SCD-XA5400ES SACD/CD player; Hewlett-Packard dv7-3188cl laptop computer running 64-bit Windows 7 Home Premium, foobar2000 music server v.1.1.17; Auraliti PK100 music player; all servers and digital players connected to an Audio Research DAC8
- Interconnects -- Audience Au24e (balanced), Clarity Cables Organic, Purist Audio Design Venustas (unbalanced), Wireworld Cable Gold Eclipse 7 (balanced)
- Speaker cables -- Audience Au24e, Clarity Cables Organic, Purist Audio Design Venustas
- Power cords -- Audience powerChord e, Clarity Cables Vortex, Purist Audio Design Venustas
- Digital -- Wireworld Platinum Starlight USB
Octave Audio V 70 SE Integrated Amplifier
Price: $7000 USD; $7600 with internal phono stage.
Warranty: Three years parts and labor; one year, tubes.
Phone: +49 0-72-48/32-78
Fax: +49 0-72-48/32-79
North American distributor:
Dynaudio North America
1140 Tower Lane
Bensenville, IL 60106
Phone: (630) 238-4200
Fax: (630) 238-0112