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Reviewer: Steve Marsh
Financial Interests: click here
 Analog Source: Nottingham Analogue Mentor turntable with 10” Anna tone arm, Benz LP-S moving coil cartridge
Digital Source: Vecteur D-2 CD Transport, Audio Note DAC Kit 1.2 with upgrades (ps choke, tantalum resistors, Black Gate caps, copper grounding bars on digital chips wired to central ground, VTV silver foil/oil output coupling caps), Accuphase DP-70 CD player with reclocking circuit board mod from Tom Evans Audio Design
Preamp: Doshi Alaap Purist Mk. II full-function tube preamp, Cello Audio Suite
Power Amp: Tron 211 SET amp with upgraded exotic-core interstage transformers (General Electric 211 power tubes, Western Electric 417A/5842 input tubes, RCA black plate 5U4GB rectifiers), DIYHiFiSupply Lady Day 300B tube amps, Cello Performance amps
Speakers: WLM LaScala floorstanders, Bastanis Prometheus Mk. II open baffle speakers with Chrystal drivers
Interconnect cables: Audio Magic The Natural, Music Metre Fidelis digital, Harmony Audio, Acoustic Systems Liveline, Bastanis Epilog I
Power Cords: Bastanis Epilog II on Tron amp, industrial-sourced power cord on Doshi preamp, Nordost Heimdall 2 (on loan), Nordost Frey 2 (on loan), Shunyata Taipan Helix Alpha cords on transport and DAC.
Speaker Cables: Audio Magic The Natural, Bastanis Epilog Mk. II, Acoustic Systems Liveline
Equipment Rack: Adona 6-shelf, low profile isolation rack
Power Line Conditioning: Nordost QRT system [QBase 8 outlet strip, Qx4 power purifier unit, Qv2 AC line harmonizers, all on loan]
Sundry accessories: Audio Prism Ground Control, Stein Harmonizers, Stein Magic Stones, Isoclean Fuses, VPI 16.5 record cleaning machine
Downtairs room size: 29’ long x 16’ wide x 10’ high (sunken living room with open floor plan, listening across width of room)
Upstairs room size:  22’ long x 17’ wide x 10’ high, with eaves
Review component retail price: HFT $299 for pack of five or $75 individually; FEQ $750
Publisher’s foreword. Just a few years ago, the subject of ‘acoustic resonators’ was not only new but highly controversial, with commentators who’d never experienced them quick to denounce them as voodoo tweaks which couldn’t possibly work. It wasn’t long though until the first outright clones of the original Acoustic System Intl. devices appeared like the Dutch Zilplex. Now forward a few years. With the effectiveness of such devices no longer in doubt, a number of manufacturers inspired by Franck Tchang’s resonators and sugar cubes have entered the market with their own take on related acoustic treatment devices. This review discusses two of them to add user data on the general subject.

I was first introduced to the Synergistic Research high-frequency transducer (HFT) and frequency-equalizer technology (FEQ) acoustic devices at the 2013 Rocky Mountain Audio Fest. In my show report I describe the demo of these products as possibly "the single most impressive demo I heard at this show (and possibly any show)."

After this demo I chatted with Peter Hansen of Synergistic Research about exploring these products further. I assumed that he had a lot of interested reviewers but a month or so later Peter squeezed in a visit to my home on a multi-stop trip to promote Synergistic products to reviewers and potential dealers. I invited two dealer friends to my home to help maximize the potential benefits of Peter’s cross-country trip.

Peter had me remove my Stein Music harmonizers and magic stones from my listening room before beginning to place the HFT and FEQ devices, claiming that the two technologies were incompatible. Peter began the demo with the HFT devices. The below excerpt from the Synergistic Research website explains how the HFT devices work to improve the sound of your system: "HFTs are tiny high frequency transducers that clean up high frequency harmonics in your listening room. You see, harmonics are interconnected. When you affect harmonics—even those beyond the limits of human hearing—you also affect the lower frequency harmonics you can hear. HFTs literally cancel harmonic noise on any surface they are placed. And as you follow our easy placement guidelines, 5 HFTs at a time, you systematically overcome your room’s tendency to fight with your system. HFTs replace random out-of-tune resonance with sympathetic resonance that complements the music."* To read the above excerpt in full context, please click here.
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* Publisher's comment: As was the case for the ASI Intl. products, the various explanations given for the precise workings of this group of devices often seem vague, the associated language unscientific. In fact the language usually just describes the effects, not really *how* they're achieved. This would indicate a lack of understanding. That of course doesn't deny their effectiveness. It's simply that scientific-minded people tend to shy away from products whose workings hide behind quasi-magical descriptions. That's why reports like Steve's who spent considerable time to experiment with them helps to legitimize such products until such time that more properly scientific explanations as to their actual operation become available.

Peter began by placing the first pack of five HFT on the front wall behind the speakers just as outlined on the Synergistic Research website. The HFT devices are attached to the wall or other surfaces with the supplied Bostic Blu-Tack or equivalent. The most prominent and readily discernible effect was an expansion of the soundstage laterally and behind the speakers.  Concomitant with this was a sense of more air within the soundstage. Peter proceeded to add two more five packs as described in the above link for Level II and III.  The soundstage expanded out toward my listening seat and to the sides of the room, following the direction of the HFT placement. At this point Peter got out the Synergistic Research FEQ and placed it behind my system rack on top of three Synergistic Research MiG mechanical interface grounding component footers, and plugged it into a nearby AC outlet. One must be sure to plug in the adaptor with its cord exiting the adaptor toward the ground connector in the outlet (i.e. toward the floor in most homes I would imagine). A separate ‘ground plane’ wire has a three-prong plug on the end that is inserted into a separate nearby AC outlet (not into your power conditioner if you have one).