Weaponized with our trusty electric screwdriver, we undid the lid to find a heavy layer of poly foam surrounding and protecting the amplifier inside. After removing the foam, the amp could be lifted out of its confinement and carried up the stairs to our listening room. Lifting and carrying are the physically hardest parts of the review process. Fortunately the amp with its 51.5 x 45 x 23.5cm dimensions had plenty of room for firm grips even if its 30kg felt more slippery. Once landed in the listening room, it was time to pop the bonnet. For additional transport protection, the interior of the ISA-2 was filled with bubble wrap.


Contrary to what we expected, the tubes were already fitted - all 22 of them. With the protective material removed, we started a visual inspection of the innards. At first glance the amplifier seemed built with a fine eye for detail. We spotted quality parts all over the three horizontal and one vertical boards. Then we saw something unexpected. The input selector switch attached to the inputs via ribbon wire had broken in half. At the bottom of the amplifier were the broken pieces of tiny plastic hooks that had held the switch together. It appeared that the selector knob had been forcefully pushed in, causing the back of the switch to come loose from the part affixed to the fascia. This had to be due to poor transport handling. Probably the crate had been dropped hard onto its side, putting the amp's full weight on the poor switch and with significant down force to boot.


We reported the damage to Panikos Kontemeniotis who exports NVO products from Cyprus on behalf of NVO owner and designer Andreas Hadjiminas. He promised to dispatch a new switch immediately. In the meantime, we examined the damaged switch and concluded that its clean break could be fixed with some super glue. After gluing its two parts together, it worked fine and we continued with the preparations of the review. Prior to receiving the amplifier, Andreas and Panikos had emailed instructions on how to set bias for the output tubes. At the back of the amp, a switch selects which output tube's bias is being measured to check whether it needs adjustment. A simple multi meter and fine-tipped screwdriver will do the rest. Measurements should be taken after the amp had some 30 minutes of warm-up. With the lid still off, we connected the ISA-2 to the grid and flipped the power switch at the front. Initially the LED above the switch was red. This changed to green after a minute or two. We then left the amp idling for the recommended half hour before inserting the meter's pins into the designated banana sockets at the back.



Alas, there was to be no stable reading. What did show was far from the recommended 0.35 - 0.6V. Whilst working close to the amplifier, we noticed a sweeping sound from near the power regulators. Its pitch rose for some five seconds, then a click interrupted it before the sweep began all over again. It sounded a bit like a charging capacitor but was in fact a Sovtek 5881 which turned blue in parallel to the sweeping sound. Something was wrong. Something had broken, likely during the same incident that had knocked out the selector switch during the amp's journey from Cyprus to the Netherlands.


We contacted Panikos and Andreas who made arrangements to retrieve the amp for repair. We repacked its crate and handed it over to DHL for a return to Nicosia/Cyprus. We felt sorry for Andreas who he had done a meticulous pre-ship test and even wanted to save us from having to fit 22 tubes by preinstalling them. That kindness had backfired. Whilst waiting for the return of the ISA-2, we looked further into NVO and the ISA-2. We learnt how Andreas Hadjiminas had been infected by the tube virus in high school when he encountered a friend's Leak amplifier. That amp died and Andreas took up the task of fixing it. Working on the amp he step by step dove into electronics and the effects of upgrading a circuit with better parts. His supplier for those was the same Panikos who today represents Andreas' company to the world at large. That company New Valve Order—with a wink at the New World Order—started business with an all-tube phono stage with separate power supply [below]. Former 6moons colleague Jeff Day reviewed it favourably for his blog Jeff's Place and not only praised its sound quality but material value.


For an encore, NVO now builds a limited edition integrated based on the KT-88, KT-120 or KT-150. For all of these varieties, the output power is ~120wpc. That's achieved with just two bottles per channel. That's bloody remarkable when competitors need at least four to achieve similar power. To manage, Andreas uses a so-called split-mode output stage. This is quite a complex circuit based on the output transformer's primary being split in two. One section works across the two plates/anodes of the push-pull pair, the other across its two cathodes. This halves the output transformer's winding ratio, lowers distortion and increases stability due to the self-balancing nature of symmetrical operation. When needed, the output tubes will also deliver more power without a high increase of distortion. As may be derived from the above, this output transformer can't be run of the mill. Andreas designed it with 5 primaries and one 4-8Ω secondary "wound in bifilar series-connected multi sections with five interlaced secondary sections connected in parallel. Thin parallel wires on the secondaries ensure wide frequency response." Here must be the origin of the huge bandwidth at low power. It is obvious that the production of these output transformers ought to be quite time consuming.