Synergistic Research FEQReviewers' ChoiceDuring its first 17 years, Synergistic Research manufactured only signal and power cords. However, in 2008, the company introduced the first of what would become an avalanche of non-cable products: EM cell power conditioners and component platforms, active cable power supplies, AC outlets, interconnect and speaker cells, passive room-treatment devices, component feet, digital-to-analog converters, and fuses.

Many of these products, like most of Synergistic’s cords and cables, utilize technologies that are derived from the work that Ted Denney, the company’s ’s lead designer, has conducted concerning several areas of quantum mechanics, particularly the balancing of energy fields within active components. Undoubtedly, such technologies are not always completely understood or explained. Nor can their effects always be measured by traditional testing equipment. These technologies are, like almost everything in the world of high-end audio cables, controversial.

Nonetheless, Denney claims that Synergistic’s sales have doubled since 2008. Clearly, he’s doing something right.

Some of the newest Synergistic products are room treatments: the High Frequency Transducer, or HFT ($75 USD each, $299/five); and the Frequency Equalizer, or FEQ ($995) -- their launch has only further fanned the flames of audiophile controversy. Nor has Synergistic’s latest product, the XOT Crossover Transducer ($399/pair introductory price), cooled the heat.

Features: HFT, FEQ, XOT

Traditionally, room treatments have mostly been devices designed to diffuse or absorb sound. Eventually, other sorts of room treatments were introduced. These include the Shakti Hallograph Soundfield Optimizer, and several bowl-shaped devices, such as Synergistic’s Acoustic Art System.

In contrast to those passive devices, a number of room treatments have recently been introduced that consist, in whole or in part, of powered earth-waveform or other field generators. In fact, although not as red-hot as, say, DSD music downloads or pocket-sized DACs, such active devices currently seem to comprise one of the more active areas of high-end audio.

The general design theory of these powered room treatments is that they defeat component and room-based fields of radio-frequency interference (RFI) and electromagnetic interference (EMI). Some of them -- e.g., the Acoustic Revive RR-777 and the Kemp Elektroniks SR Plug -- are claimed to generate Schumann resonances: extremely low-frequency, electromagnetic, quasi-standing waves that exist in the 30 miles between the Earth’s surface and the lower border of the ionosphere. These waves begin at a frequency of about 7.83Hz and rise from there. Other devices, such as the Synergistic FEQ, use a proprietary technology, but whether or not it has anything to do with Schumann resonances, Ted Denney isn’t telling.

According to Denney, virtually all of Synergistic's room treatments, whether active or passive, have been designed to fix several fundamental problems. One of these problems, he says, occurs when soundwaves are emitted from the speakers of a stereo system and interact with hundreds, if not thousands, of resonators, or “strings,” found in the typical listening room: furniture, walls, windows, ceilings, equipment racks, light fixtures, knick-knacks, speaker and component enclosures, etc. Inescapably, Denney says, these strings resonate out of tune. This, he says, compromises soundstaging, reduces the perceived air around the aural images of instruments, shortens the decays of notes, and distorts harmonics.

Denney claims that his tiny, passive HFTs -- tiny cylinders of aluminum no bigger than a thumbtack (8mm in diameter by 8mm long) -- can be applied to various resonating surfaces in a room to alleviate this problem. (Each set comes with a supply of Blu-Tack, to nonpermanently attach them to walls and other surfaces.) Like the FEQ and XOT, discussed below, the HFT uses a proprietary Synergistic technology called Uniform Energy Field (UEF).

Synergistic Research HFT

According to Denney, HFTs work by canceling high-frequency harmonic noise, to replace random, out-of-tune resonances with resonances that complement the frequencies of the music. He claims that the upper and lower harmonics of a given fundamental tone are interconnected: when you affect high-frequency harmonics -- even those beyond the limits of human hearing -- you also affect lower-frequency, audible harmonics. Synergistic claims that the audible benefits of HFTs include an expanded soundstage, greater and cleaner high- and low-frequency extension, a lower noise floor, and therefore improvements in inner detail and microdynamics.

Two other fundamental room problems addressed by room treatments, according to Denney, are RFI and EMI. He says that these fields, which are created by Wi-Fi, cell phones, fluorescent and LED lighting, etc., are what can cause stereo systems to sound better late at night, when many of these devices are turned off.

Enter the active FEQ. Slightly smaller than a cigar box, it measures 7.25”H x 4.125”W x 4.125”D and weighs a little over 1.5 pounds. The case is made of a black synthetic material, with top and bottom plates of silver-anodized aluminum. There is an On/Off switch on the rear, and jacks for two AC cords: One attaches to a wall-wart power supply, the other to ground.

According to Synergistic, the FEQ generates an ultra-low-frequency radio-wave pulse that overpowers RFI and EMI fields. Unlike with the HFT, only a single FEQ is needed to treat a room. Also incorporated into the FEQ is a proprietary ground plane that grounds the FEQ’s active circuitry in a unique way, and is also used in Synergistic’s active Tranquility Base component platform and Powercell power conditioners. Synergistic found that using this technology caused the FEQ to perform as a Tranquility base for an entire room. The claimed benefits include improved weight and definition in the lower frequencies, increased high-frequency “air” and refinement, greater midrange palpability, and expanded layering.

Denney says that while either a set of HFTs or a single FEQ will substantially increase sound quality when used alone, the real magic occurs when the devices are used together. In such cases, he says, the FEQ’s low-frequency pulse excites the HFTs, thus amplifying their effects.

Synergistic Research XOT

Finally, the XOT is a high-frequency crossover filter that attaches to a loudspeaker’s binding posts. According to Synergistic, the XOT further increases resolution, lowers the noise floor, and creates a more holographic sound. These tubular devices come with spade or banana terminations, are a little less than 3” long, and have a diameter of just under 1".

The HFT, FEQ, and XOT come with an unconditional, 30-day, money-back guarantee. There’s not a lot of downside in giving them a shot.

I had never seen anything even remotely resembling the HFT, and I don’t really know how it works. Denney’s explanations sound reasonable enough, but leave me with many unanswered questions. To move along with the review and preserve my sanity, I stopped trying to figure out the technology and focused on the sound.

Setup: FYI

Unlike Synergistic Research’s Acoustic Art room treatments, the HFTs and FEQ are easy to set up. On their website, Synergistic outlines five levels of implementation for the HFTs, each level requiring an additional five-pack of HFTs; most rooms, they say, should reach the point of diminishing returns somewhere between Levels III and V.

For Level I, five HFTs are placed on the room’s front wall: at center mid-height between the speakers, at the left and right corners at mid-height, and at 2’ above those spots.

For Level II, HFTs go on the front wall at center-low height between the speakers, on the ceiling at the room’s center point, halfway between the speakers and the listening position, on the left and right sidewalls at mid-height halfway between the speakers and the listening position, and on the center of the rear wall, 6’ or higher.

The remaining three levels place HFTs at various other places in the room, as well as directly on the speakers and electronic components.

Synergistic Research FEQ and HFT

Synergistic states that the FEQ should be positioned near the front wall, behind and about equidistant from the two main speakers. They also recommend that the FEQ’s cords should be plugged into different wall AC outlets. I plugged the FEQ’s AC cord into my Powercell 10 SE power conditioner and its ground cord into a wall outlet.

At Denney’s direction, I didn’t remove his Acoustic Art system from my room. Instead, I used that system together with the HFTs and FEQ. Denney states that although the two products operate differently, they do many of the same things. Moreover, he states that while the HFTs work in frequencies far above the range of human hearing, the Art system works within and slightly above the audioband to provide improvements in layering, harmonic texture, and warmth that the HFTs alone do not.

The HFT-FEQ combo is the least obtrusive room treatment I’ve seen. If you don’t point out these little critters to guests, they likely won’t even notice that they’re there.

Hooking up the XOTs is also simple. Synergistic states that you should select the termination type that is the opposite of what you use on your speaker cables. My Synergistic Element speaker cables have spade connectors, so I chose banana-terminated XOTs.

Since my YG Acoustics Kipod II Signature speakers have four binding posts, for biwiring or biamping, Synergistic sent me two sets of XOTs, for a total of four.

Synergistic states that all of these products will break in over time, but should perform well right out of the box. So, perhaps for the first time ever, I began my critical listening without first running in the product being reviewed.

Performance: POV

When a significant change in a system is made, an audiophile will often hear a difference in sound from the first note or two of music. But with only five HFTs in place, in the Level I (front wall only) configuration, I noticed something remarkable before I heard a single note: The analog tape hiss that precedes “Midnight Rambler,” from the Rolling Stones’ Let It Bleed (16-bit/44.1kHz FLAC, ABKCO), was crisper and more detailed than I had previously heard. Something unusual was going on here.

With each additional Level of HFT, ending with Level IV, the promised improvements in sound materialized. The noise floor dropped, exposing all kinds of previously hidden microdetails. Voices became less congested, more timbrally accurate and detailed. Imaging greatly improved. Bass lines firmed up and exposed previously masked resonances. High frequencies lost their edgy hardness. The soundstage increased in both height and width.

When it came time to attach the HFTs to my speaker cabinets, for Level IV, everything improved even further. The speakers themselves “vanished” even more than they had before, leaving only the music, which was remarkably distributed across the soundstage. And the noise floor somehow dropped even lower, which only enhanced the density of tonal colors.

Adding the FEQ brought further improvements that were no less dramatic. Voices became more intelligible. The soundstage again grew, and was now more three-dimensional. High frequencies were more defined, with increased “air” and no hardness. Bass was tighter and went deeper. The acoustical properties of recording venues became much more audible. Transparency, refinement, and image specificity also further improved.

Seeking a further level of improvement prior to trying the XOTs, and following Denney’s advice, I placed the FEQ atop three Synergistic MIG footers in pinpoint configuration: round side up.

I have no idea why, but in “Walking on the Moon,” from the Yuri Honing Trio’s Star Tracks (CD, Jazz in Motion 9920102), the decay of Joos Lybaart’s drum strokes were more pronounced and had longer decays than without the MIGs. The improvement was subtle enough that I likely wouldn’t have noticed it had I not been listening for it. Still, it was there.

Finally, hooking up the XOTs brought even more clarity, focus, and resolution to the sound. Rather than dramatically affecting soundstaging and imaging, they cleaned up everything and further lowered the noise floor. Everything was tighter and transients improved.

The cumulative effect of adding the Synergistic FEQ, HFTs, and XOTs was nothing short of astonishing. The sound was now so lifelike, transparent, and unveiled that the emotional content of recordings came through much more easily. For example, they allowed an incredible amount of singers’ personalities to pass through my speakers. On the Doors’ Live at the Bowl ’68 (CD, Elektra 60741), the Synergistic products rendered Jim Morrison’s voice with a vivid immediacy that was much more resonant. It was almost as if the Lizard King himself had walked through my front door to issue his (allegedly) acid-induced rants from about a foot away from my left speaker.

Ditto Neil Young’s Live at Massey Hall 1971 (16/44.1 FLAC, Reprise/WEA), where holographic imaging and low-level detail retrieval combined to bring not only the singer but all of Massey Hall damn close to being in my room. With “Old Man,” this included hall resonances, audience coughs, and the sounds of Young adjusting his microphone.

Also clearly noticeable with both of these albums was that I could now discern individual hand claps, rather than a wash of poorly defined, collective applause.

With E. Power Biggs’s performance of J.S. Bach’s Fantasia and Fugue in G Minor, BWV 542 (CD, Sony Classical 89955), the Synergistics rendered ultra-low organ notes in a way so extended and powerful that they resonated in my gut. The bass modules of my YGA speakers unquestionably own the lower frequencies even without external assistance -- but never had they sounded like this.

Particularly noticeable was how the XOTs let me disentangle complex music with greater ease. An example of this was the first movement of Beethoven’s Symphony No.5, with Jan Willem de Vriend conducting the Netherlands Symphony Orchestra (SACD/CD, Challenge Classics CC72550). The piece is replete with tutti passages in which the orchestra plays the all-important tonic chord that reveals the key in which the movement is written. In these passages, the XOTs caused a clearer delineation of not only the orchestral sections, but the instruments within those sections: wood and brass instruments for winds; timpani for percussion; and violin, viola, and cello for strings. More apparent was the number of constituent parts that were synchronized to create a single sound. There was no escaping the fact that my system’s previous sound had been somewhat smeared, thus causing a fair amount of the orchestra’s instrumental diversity to be lost.

Finally, I removed the Synergistic products from my gear and room. The soundstage shrank in height and width. Layering decreased. Highs became hotter and more fatiguing. Bass lost control and definition. The magic disappeared.

But just stating that things improved with the Synergistic products doesn’t tell the whole story. They not only made the improvements listed above, they did so dramatically, and in a very good, high-resolution system. The truly remarkable thing was that, unlike ultra-transparent products that act as sonic X-ray machines, the HFTs and FEQ didn’t sound at all sterile. Nonetheless, the HFT-FEQ combo did uncover grisly recording flaws that I hadn’t known were there.

In “Loreta and Desirée’s Bouquet, Part 1,” from George Winston’s Summer (CD, Windham Hill D106994), extreme high-frequency piano notes were strident and distorted. With several recordings of female singers, I heard the type of failings that occur when a microphone runs out of headroom.

These were not problems with the HFTs-FEQ. Instead, they had so lowered the noise floor of my system that its resolution was increased to where it uncovered the limits of the recordings themselves. But with great recordings, the HFTs-FEQ made everything better and nothing worse.

These products don’t appear to cost a lot to manufacture, though I don’t know how many hours were spent in their development. Also, on the basis of performance for price, their value is jaw-droppingly high. I can’t imagine getting a similar boost of performance by spending as much -- or even significantly more -- on a new component, or even a new pair of speakers. Ultimately, you’ll have to be the judge.

Comparison: A/B

I may have never heard of a product that even resembles the HFTs. But I have spent much time with several products that, in operation or appearance, at least vaguely resemble the FEQ and XOT.

One such product is Acoustic Revive’s RR-77 ultra-low-frequency pulse generator, now replaced by the RR-777. Both are claimed to emit a Schumann pulse. I mostly liked the RR-77’s effects; it increased air and detail, improved soundstaging, made individual instruments easier to follow, and the music more involving. But I also found that, unlike the FEQ, the RR-77 altered the sound of my system in ways I find difficult to articulate but that I was uncomfortable with. After a fair amount of deliberation, I concluded that the sound of my components with the RR-77 was likely not what their manufacturers had intended. I got rid of the Acoustic Revive.

The improvements in sound that I experienced with the FEQ alone were qualitatively and quantitatively superior to what I had experienced with the RR-77. Perhaps it had something to do with Synergistic’s proprietary ground plane. And adding the HFTs brought the sound to an even higher level.

Two other room treatments I’ve spent time with are Bybee Technologies’ Golden Goddess Super Effect Speaker and Interconnect/Phono Bullet, which at least externally resembles the XOT. I found that Bybee Bullets improved weight and detail in my system, but caused the soundstage to become more diffuse. I got rid of them too. I’ve heard of at least one other audiophile who has gotten the same results with the Bybees, as well as numerous others who found the Bullets to have only positive effects.

Conversely, I couldn’t hear a single downside of using the HFTs, FEQ, or XOTs. Nor did they shift the tonal balance.

Conclusion: TTYL

Synergistic Research’s HFT, FEQ, and XOT work, but their effects were not on the usual scale of audiophile tweaks; e.g., “I definitely heard a difference.” In fact, relegating these products to the category of “tweak” would be a mistake. They fundamentally improved the sound of my system. I suggest that you rush to a Synergistic dealer to give these remarkable products a listen. I doubt you’ll go home empty-handed.

. . . Howard Kneller

Associated Equipment

  • Amplifier -- Esoteric A-03
  • Preamplifier -- Esoteric C-02
  • Sources -- Esoteric K-01, laptop computer running Windows 7, JRiver Media Center 17
  • Speakers -- YG Acoustics Kipod II Signature
  • Interconnects -- Synergistic Research Element Copper-Tungsten-Silver (components, active bass modules of speakers)
  • Digital cables -- Synergistic Research Tricon USB and Active FireWire 800
  • Speaker cables -- Synergistic Research Element Copper-Tungsten-Silver (tweeter) and Element Copper-Tungsten (midrange driver)
  • Power cords -- Synergistic Research: Element Copper-Tungsten-Silver Analog (amplifier, preamplifier), Copper-Tungsten-Silver Digital (disc player, DAC), Tesla Precision AC SE (speakers), Element Copper-Tungsten (Powercell 6 SE and Powercell 10 SE Mk.III power conditioners), Element Copper-Tungsten-Silver Analog and Digital (Enigma power supply fed by two power cords), Tesla Hologram A (QLS Lines strips with Galileo MPCs)
  • Power conditioners and distribution -- Synergistic Research Powercell 6 SE (digital components only) daisy-chained to Powercell 10SE Mk.II
  • Isolation devices -- Synergistic Research Tranquility Bases (sources, preamp), Custom Isolation Products amp stand (Enigma power supply), Silent Running Audio VR fp Isobase (amp), Synergistic Research MIGs, Mapleshade Heavy Hats, DIY amp stands
  • Misc. -- Synergistic Research Galileo Universal interconnect and speaker-cable cells, Synergistic Research Acoustic Art System, Walker Audio Talisman Demagnetizer, Acousence Giso LAN isolator

Synergistic Research High Frequency Transducer (HFT)
Price: $75 USD each, $299 USD/five.
Synergistic Research Frequency Equalizer (FEQ)
Price: $995 USD.
Synergistic Research XOT Crossover Transducer
Price: $399 USD (introductory price).
Warranties: HFT and XOT, lifetime; FEQ, 1-12 months, replacement; 2-3 years, repair or replacement (at manufacturer’s discretion).

Synergistic Research
17401 Armstrong Ave., Suite 102
Irvine, CA 92614
Phone: (800) 578-6489
Fax: (949) 476-0800