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Reviewer: Frederic Beudot
Financial Interests: click here
Source: Esoteric X03SE, Weiss Minerva [in for review], Acoustic Solid Classic Wood AS WTB211, Grado Reference Sonata 1, Denon DL103, Clearaudio Nano, SQ-PH-1t [in for review], ASR Mini-Basis Exclusive [in for review], Audia Flight FL Phono [on loan]
Preamp/Integrated: Esoteric C03 [on loan], Wyred 4 Sound STP
Amp: McIntosh MA2275, Genesis GR360 & MDHR, Esoteric A03 [in for review]
Speakers: FJ OMs, Zu Essence
Cables: Zu Varial, Zu Libtec, Slinkylinks RCA copper, Zu Mother, Accustic Arts Ferrite 2 [on loan], Esoteric Mexcel balanced interconnects [on loan]
Headphone: Musical Fidelity Xcanv3, AKG K701
Powerline conditioning: Monster Power HTS5100mkII
Sundry accessories: Isolpads under electronics and good 'ol wooden chest
Room size:12' x 13.5' x 8'
Review Component Retail: Nova $4695, Titan $3995


Unlike Paul or Marja and Henk, I have a hard time getting excited about power filtration and conditioning. At best, I look at those devices as necessary evils that deliver a needed clean-up of the incoming power yet like the devil, always take something in return. In the worst case, the soul of the music goes with them. Living in a rural area where most of the disturbance to the power grid comes from the milking machine at the neighbor’s dairy farm, the benefits of deep filtration have always seemed dubious to me - until of course the month of August arrived and with it the 24/7 air conditioning with all its associated spikes and noises. Up to now, my Monster power filter had been doing a more than commendable job for its $500 sticker. It kept the AC gremlins out while staying reasonably unnoticed in its nefarious side effects. Yet over the past six months, my system underwent a few radical changes that were to upset this pastoral picture of tranquility.


A dedicated quieter room treated with Frank Tchang’s resonators enabling a better perception of nuances and subtle differences; a far more revealing pre/power combo with the Esoteric C03 (or now Wyred4Sound STP) and Genesis GR360; and as cherry on top, the Zu Essence capable of superb microdynamics and transient fidelity - although the quieting effect of the Monster filter was obvious in this system/room, so was the damping of dynamics and transients. Think about cotton in your ears. While the ambient noise level comes down, everything sounds muffled. To a less drastic but related extent, that’s what the Monster filter did on this very revealing association of gear, the most damaging effect being obtained by plugging the Genesis Hypex-based amplifier in the filter.

In came the Nova and Titan filters by Isotek. This review started with Genesis being the US distributor. After Isotek worked through financial difficulties and rose again like a Phoenix, the Sound Organization is now in charge of US distribution. The Nova and Titan sit on top of Isotek’s product range. The Nova is intended primarily for front-end equipment (sources and preamplifiers) while the Titan is optimized for power amplifiers with massive current draw. I won’t pretend to understand how either of these work to instead point you at Isotek’s website* where most of the technical information can be found - although understandably, the real particulars of their circuit implementations are not fully disclosed.

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* In April 2008, I was solicited to do a review on the Sigma S and Titan units but never received the promised loaners. As is my habit however, I had already penned the obligatory tech section and exchanged e-mails with Isotek's Keith Martin. The following tech paragraphs are culled from that draft and then Frederic takes over again. - Ed


The Sigma S is a 6-socket complete systems solution sufficient unto itself. The Titan is a dedicated two-outlet high-current affair said to render further advances when feeding the power amplifiers separately. About the Sigma, one seller's website proclaims that it "takes the high current direct-coupled design of the Titan for the high current and combines Nova and GII MiniSub and Vision technology for the medium current components. IsoTek's current Titan design consists of a 9-stage cascaded design using natural roll-off and no Chevishev type characteristics, i.e. kink-less curves in the filter response. The Sigma uses 5 stages with additional delta filters at each end to emulate a full 9-stage design.


"IsoTek's Polaris X circuitry is used to avoid cross contamination between components. For the medium current output side of the Sigma this is combined with a refined version of the Adaptive Gating initially developed for the Nova. For this IsoTek designed new and very unusual common mode chokes, being quite possibly the only ever company to consider the sound quality of these vital components. The aim was a sonic balance between a dark, low-noise background and a clean extended sound with full top-end sparkle. The Sigma also uses special MCB* fuses which are far superior to conventional cartridge fuses, offering outstanding safety both physically and for the connected equipment (fast acting whilst allowing true transients).

"The highly specialized protection circuit uses special VDR** devices to detect over-voltage. The threshold level is set where transformer saturation of the equipment no longer limits DC voltages on the secondary side (in an amplifier power supply for example). This is seldom appreciated. The VDR trips the fuse, nothing else. With cartridge fuses this won't work, thus a compromise device has to be used. An unexpected bonus of using these special VDRs is that they represent a high-quality capacitor when idling, thereby acting as a valuable shunt filter. Finally the quality of components used is of the highest order. Most components in an IsoTek product could be substituted by perfectly safe cheaper alternatives providing, in theory, identical filtering. Despite these components costing only 25% of those actually used, IsoTek insists upon components such as Rifa paper capacitors, silver-plated 7N purity solid-core copper wiring with FEP dielectric as well as the use of silver and ceramic materials throughout the design, all in order to attain the elusive balance of effective filtering and true high fidelity performance."

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*MCB: A miniature circuit breaker that's not a thin-wire sacrificl cartridge fuse but a switch that trips when its current rating is exceeded.

**VDR: A voltage-dependent resistor or varistor (variable resistor) that's often used to protect circuits against excessive transient voltages by shunting the excess current created by over voltage away from the sensitive components.

***RCBO: An RCD or residual current device is similar to an MCB but connected to both the live and neutral wires to become a double-pole switch while an MCB connects onto the live side of a circuit. An RCD also detects the fault which caused an overload condition rather than just the overload current as an MCB does. An RCBO or residual circuit breaker with over-current protection for every associated circuit is a combined MCB and RCD.
For the Titan, the relevant specs are a maximum continuous current of 16 amps; 3,680/1,840 nominal watts at 230/115V respectively; continuous circuit rating of 4,600/2,300 watts; and 10 millisecond transient capability of 23,000/11,500 watts. Nominal power delivery for the Sigma is identical, albeit shared of course between up to six connected components. The extreme instantaneous transient headroom is unique to the Titan whose circuit has been optimized for a high degree of common-mode rejection with "the highest degree of differential mode rejection and balanced operation at high frequencies where it arguably outperforms its isolation transformer-based predecessors." On VDRs, Keith Martin also called them "back-to-back zener diodes though generally faster than zeners. If chosen with care, they suppress voltages typically hovering around 1000 to 1500V peak. Any lower is not advisable as there is some possibility for audible degradation of dynamics. To suppress lower voltages also is not to understand the problem. Equipment will seldom have adverse reactions below 1000V peaks as the saturation of the equipment power supply will happily absorb that. 1000 to 6000V peak is the danger area (above that plugs tend to ark which is a crude limiter ) so a well-chosen VDR will have much to offer."

"Re: direct coupling, many advocate isolation transformers and we used to. Our measurements prove them to be less effective than thought and limiting transient power. Generally we do not isolate, however we do try to create balanced live and neutral outputs (balanced outputs are one isolation transformer virtue). This is possible when frequencies above the 1kHz region are reached. Arguably isolation transformers are less balanced than our solutions by comparison. This would surprise many but they should measure what they believe in. At IsoTek, we really tried hard to remove any voodoo. We deal with technical facts and achievements and lots and lots of listening tests because as I'm sure we all know, measurements are only half of the picture. While our products measure far better than the competition (85dB noise reduction at 120kHz), it is also important that they 'sound' right and not destroy or restrict the musical harmony or dynamics of the system they are providing power for. It is our mission to provide the best operational environment for all electronics coupled with IsoTek - to be, if you like, a solid foundation for the audio or audio visual system." [This concludes the editorial addition. The reader of course noticed that the Sigma unit discussed is not the Nova Frederic reviewed. Nonetheless, I deemed this background data a useful adjunct - Ed.]