Reviews
Quadrature Z is Hi-Fi+ Magazine's Power Amp of the Year 2009
Issue 68, 2009 [PDF]
Quadrature Z follow-up by Roy Gregory, editor of Hi-Fi+ Magazine
Issue 61, November 2008 [PDF] "I gave these amps to CT for review because they would for both his system and my purpose - I wanted to stretch his appreciation of the possible. Well, now I'm duly humbled, for they've stretched my appreciation too."
Quadrature Z reviewed by Hi-Fi+ Magazine, Issue 60, October 2008 [PDF] "...I point the finger across the Atlantic at David Berning of Maryland in the USA, as it is his monobloc amplifiers that have had me totally hooked and continually capture my musical fascination in a way that so few products ever have."
ZH270 commentary and comparison by StereoMike on ZeroGain audio forum, August, 2007.
Starting at the bottom, the bass is wonderfully rounded and perfectly damped, yet solid as a sledgehammer unlike any valve amplifier I had heard before or since. ... Indeed the midrange and treble are utterly natural and delightfully transparent. People talk of veils. With this amp, all the veils are off before the first note's finished. ... I have not heard an alternative amplifier with this speed or openness regardless of price. And this speed is coherent - not varying at all across the audible response. This coherency all adds to the illusion of real musicians playing real instruments - something the Berning is extremely good at purveying. ... A remarkable performance for a 70wpc [push-pull output stage] device that can drive real world loudspeakers to real listening levels.
ZH270 reviewed by Rick Becker, Enjoy The Music, December 2006
"...more importantly, waves of goose bumps rolled over me as I listened... outstanding focus, combined with the outstanding transparency... the estimated tube lifespan being in the neighborhood of 15 to 20 years. Compare that with your own life expectancy. ... Acoustically, it leaps over almost the entire field, landing in the upper echelon of the finest sounding amplifiers."
ZH270 reviewed by Gary Beard, Positive Feedback, Issue 5, 2002 "'Visceral, delicate, beautiful, rhythmic, dynamic, in a word, incredible' were the descriptors I used in an email sent to another Berning owner shortly after my first taste of the sound of the ZH270. Today I would add 'lightning fast, extended, and musical.' In the high-priced world of audio, I believe the Berning ZH270 is a great value. It is a unique product, built by a designer dedicated to finding new and better ways to reproduce sound, and yet, unlike so many other 'new and different' components, it is one that fits within the real world."
ZH270 reviewed by Charles Hansen, Glass Audio, vol. 12 iss. 1-2, 2000
"Right out of the box, the ZH270 was a sonic pleasure. ... The bass was tight, far more so than I have ever heard on any tube amplifier. Acoustic bass was woody, resonant, and full of life. The extra harmonic richness in electric bass came through in spades, and kick drum had a lively pop...the bass never became tubby or boomy. The soundstage was spacious, wide, and deep. You could hear each individual instrument in even the most complex orchestral crescendo. Piano was portrayed as though you were standing right above the soundboard. You could hear each hammer and pedal in realistic detail. The sound never became confused, nor did the soundstage retreat even the slightest bit. This amplifier was absolutely unperturbed at even the highest volume. Complex pop music with layer after layer of synthesizer was more detailed than I have ever eheard. Yet the ZH270 also tames the bright, edgy CD mixes that seem to be in vogue these days. The best of both worlds!"
ZH270 reviewed by Martin Appel, stereotimes.com, 1999
"My system, however replaced with the Berning ZH270, immediately became more alive, with a good dose of vibrancy, not to mention a metaphoric veil was lifted between the music and the listener. This dear reader added an increase in palpability to instruments and voices with each and every disc. ... The soundstage is much more open, possessing more air that few amps can match. The mid-range, where the majority of music happens, is special. Clarity and articulation go hand in hand with imaging and depth. Instrumental timbres and voices are detailed, three-dimensional, and accurate, with dynamics to match. (Nothing mushy, boomy, or vague here.) High frequencies are clear and bell-like, and free of any grain, without that electronic etching that can irritate--I'm talkin' making music."
ZH270 reviewed by Dick Olsher, Fi Magazine, 1998
"In several respects, the ZH270 pushes the state-of-the-art envelope forward. ... The first and lasting impression was of speed and control-speed beyond ordinary tube amps and control in the class of the finest solid-state designs. It is felicitous of treble transients like almost no other amp in my experience. Transients were articulated with delicacy and a silky smoothness, unfolding with a totally believable organic wholeness. Plucked strings, in particular, were reproduced with convincing attack and decay. Midrange textures took on an electrostatic-like clarity. It was easy for me to resolve harmonies or to make out densely layered orchestration. Low-level detail and the decay of notes into the noise floor of the recording were clear. ... True to its tube origin, the ZH270 dished out a lifelike harmonic palette. ... Feelings and emotions are buried in the music's microdynamics. The Berning had no difficulty at all in retrieving the music's full emotional gamut. It excelled in highlighting inflections in human voice and the filigree-like nuances in bowed strings. It could deliver quite a punch into a compatible load and recovered quickly from overload conditions."
A personal amplifier. 1 Watt. Line or battery powered. For driving headphones. ZOTL technology.
microZOTL reviewed by Dick Olsher, enjoythemusic.com, October 2000
"There's undeniably a lot of magic in that little box. ... Just as a lark I plugged [headphones] into the Berning, and I almost fell out of my chair! All of a sudden, resolution and clarity galore! The ugly duckling was instantly transformed into a beautiful swan. Bass lines gained tremendous impact and precision. The midrange snapped into focus as though a thick veil had been lifted from the soundstage..."
microZOTL reviewed by Harvey "Dr. Gizmo" Rosenberg
"[microZOTL] is the best sounding headphone amp I have heard to date."
Single-Ended Amplifier. 5 watts. ZOTL technology. "A most amazing amplifier. Output transformerless using one Western Electric 300B output tube per channel. The amazing thing is it sure doesn't sound like what one would imagine a low powered amplifier should. It is, quite simply, the most dynamic (that's right), realistic presentation I've heard from any amp. It's all there from the frequency extremes to an eerily realistic midrange. Just magic." --Weldon K. Jackson, 19 Jan 1999, source
Siegfried review by Harvey "Dr. Gizmo" Rosenberg
"When I auditioned all the ZOTL circuits (push/pull, 811 and 300B) with master tapes there was no doubt that the Berning circuit was the best at creating the illusion of the Steinway concert grand that we just recorded, and all transformer coupled amplifiers sounded slow, sloggy and distorted. ... the ZOTL much more dynamic in the way single-ended circuits have that amazing midrange dynamism without sacrificing what ZOTL does that no other transformer coupled amplifier can do...complete balance from top to bottom. The upper octaves are there as are the bottom octaves. While listening to a wide range of music I noticed (now get this Pearsonism) there was an inner glow to the vibrato of strings, a shimmering grace fell over the harmonics of Cassandra Wilson's voice, it was as if an Angel of Tone was sprinkling fairy dust over each note, but what was most stunning was the silence between the notes, which become the background for a palpable sense of depth that I had previously only experienced when staring at Dolly Parton's bosoms. My epiphany was having goose bumps. This combination of harmonic purity, clarity, dynamism, and wave front wholeosity is completely unique. And let me go on record once again and state that David Berning pisses me off that this amplifier weighs under ten pounds."
"So let me state once again: this amplifier is not for everyone. It is too good for most systems. It is the kind of device that forces us to reconsider everything. It has given me a much greater appreciation how the best Wadia digital gear can reveal the subatomic nature of digits...and that is both good and bad. You absolutely must have the finest input devices for this amplifier. You must have high efficiency speakers of high refinement, and they are rare. This is absolutely the most stunning view of the edge of the art of tube amplifier. There are many good reasons that David is making other audio designers emotionally unstable."
"Only the courageous will use this amplifier, because not everyone is ready for triode heaven on earth."
Siegfried - 811 Svetlana reviewed by Harvey "Dr. Gizmo" Rosenberg
"When Mark Conese and I compared the sound of David Berning's new ZOTL single ended circuit 811 amplifier to the 300B version we thought that there something wrong with the 300B amplifier... Marco the pianist completely agreed with us. The 300B amplifier sounded warm and fuzzy compared to the 811. The 811 was much closer to the sound of the Steinway, and the 300B was not!"
Siegfried - Directly Heated Triode review by Harvey "Dr. Gizmo" Rosenberg
"David's patented circuit, for the first time, solves the impedance problems endemic to all conventional OTL circuits; lack of stability at low impedances: all OTL amplifiers are very weak in the bass region. The ZOTL circuit is the first OTL circuit that doesn't go bonkers into low impedance loads, and this is the only tube amplifier on the face of earth, since the Futterman OTL-1, that doesn't have an output transformer and has regulated power supplies, and ZOTL is far superior in every regard! And this is a major big deal..THIS IS A DIRECTLY HEATED TRIODE OTL... it lets us hear the tone of directly heated triodes in an OTL circuit. This is unquestionably one of the major breakthrough in the thermionic arts. Those of you who are using OTLs that have video compactron/pentodes output stages are in for a big thrill when you hear the totally superior tonal qualities of directly heated triodes. But rather than rave about this circuit here, just check out Dick Olsher review in March 98 FI Magazine (also available on this site) where he puts David's amazing technical wizardry in perspective."
Tube pre-amplifier. Tube + FET hybrid technology.
TF-12 reviewed by Absolute Sound Magazine, vol. 70, Mar/Apr 1991
"The TF-12 delivered soundstage-creating performance at a truly spectacular level in my room, using two phono sources, Magnepan MG-III speakers, and three different amplifiers. For me, the Berning preamp has no superior in its ability to craft a large, no, a gigantic stage, and to place specific images in or on it with eerie focus and precision."
TF-12 reviewed by Stereophile Magazine, vol. 11, no. 7, July 1988
"The first thing I noticed about the TF-12's sound was its incredible liquidity. There is no spurious texturing whatsoever; the sound has all the limpid clarity of a dewdrop in the morning sun. It reproduces an impressively wide, spacious soundstage, while stage depth and front-to-back perspectives are rendered as well as from any preamp I've ever heard..."
Tube amplifier. Resonant power conversion technology.
EA-2101 reviewed by Absolute Sound Magazine, vol. 80, June 1992
"If the Berning's soundstage is wide, deep, and filled with stable images, even more impressive is its ability to present detail-to make subtle aspects of performances audible, and previously obscure details recognizable. ... The point is that the Berning starkly revealed the phenomenon."
EA-2101 review in Stereophile Magazine by Dick Olsher, September 1992
"The EA2-150 was a copy of nothing; it represented an original and sophisticated design statement. Features such as variable feedback control and digital automatic bias adjustment were well ahead of their time. Dave symbolizes for me the quintessential high-end designer: someone with a glint in his eye who pushes the art forward because of the desire to uncover the truth. Of course, the guy wants to make money, but this is secondary to the creative process. The art is not driven by business. You wouldn't go up to Van Gogh and say: paint me a $299 or a $499 painting. That's low-fi. Instead, allow the artist to express himself freely with a complete palette on a large canvas. If the result costs five kilobucks, so be it. No one has ever sold a ton of $5k amps, but that wasn't the point in the first place. After experimenting with hybrid circuits, Berning settled down to using nothing but tubes; the EA-2101 represents his latest thinking on amplifier design. ...the Berning is capable of conveying an intensely musical experience, with soundstage transparency and dynamic bloom that rival those of any amp out there. Its bass balance nicely complemented the dynamic speakers I used it with. The Berning can also generate quite a punch at the low end, though its bass extension is somewhat restricted by solid-state standards. When it's sitting pretty, the Berning is a lot of fun. It's not a ponderous, fuzzy teddybear of an amp, ŕ la the stock Dynaco Mk.III; its quickness and articulation dispel that notion instantly. The midrange is lucidly transparent, so that spatial outlines are focused palpably within the confines of the soundstage. Its lively nature, however, will dictate the sort of choices you make at the front end; such as phono cartridge. Your audio world will surely revolve around this amp. It has the potential of becoming the cornerstone of one hell of a system."
Berning interview with Ken Kessler, Stereophile Magazine, Vol.11 No.7, July 1988
Tube pre-amplifier. Tube + FET hybrid technology.
TF-10 reviewed by J. Gordon Holt, Stereophile Magazine, May 1979
" The thing that makes the TF-10 unique is its hybrid amplifying circuitry. Each amplifying stage consists of a triode tube and an FET in what David Berning describes rather evasively as a "patented special complementary arrangement." The basic idea behind this is that the tandem hookup of a tube and an FET having complementary distortion characteristics will tend to cancel out the distortion from each device. The entire TF-10 preamplifier uses minimal negative feedback, and this is local feedback only. No loop feedback is used—at all—thus eliminating any possibility of instability or of any of those kinds of distortion (such as TIM and SID) that relate to feedback. The phono equalization, too, is entirely passive, to minimize any interaction between the equalization circuitry and the electrical characteristics of the cartridge.
"Measurements showed that the frequency response of the high-level section was flat from 10Hz to beyond 200kHz (within 0.1dB) and that the RIAA equalization was accurate to within 0.2dB from 30Hz to 15kHz (which is the limit of the range specified by the RIAA standard). This is the highest RIAA-equalization accuracy we have ever encountered in a preamp, but when one considers the fact that designer David Berning works for the US Bureau of Standards, it seems somehow less surprising that this should be so. As a result, our bypass tests (using tape as a source) revealed no audible difference whatsoever between the signal going directly to the power amplifier and that passing through the entire preamp.
...
"Let it first be said that this is unquestionably the most listenable wideband preamplifier that we have auditioned to date. It seems to be entirely free from any sonic texturing, producing the most liquidly transparent sound we have ever heard from discs. ... Hard transients—those producing the fastest rise times—are reproduced with incredible sharpness, yet there is no trace of that irritating edginess at the top which has characterized every other preamplifier having comparable rise time. ... The TF-10 is an unprecedented amalgam of quickness and accuracy with musicality.
"The high end is open, delicate and downright exquisite, sounding as if it has no upper limit. Instrumental timbres are reproduced flawlessly, without a trace of hardness or edginess, and depth, detail and inner definition are for all intents and purposes indistinguishable from that Of the original program source. The low end is full and rich, yet as taut and detailed as the best we have heard from all-solid-state preamplifiers, and the entire middle range has that textureless liquidity we have only heard previously from tubed preamplifiers that fell short in various other ways. In other words, this is now the preamplifier by which others must be judged."
Tube amplifier. Screen drive technology.
EA-230 reviewed by Stereophile Magazine, vol. 5, no. 1
"Like Berning's TF-10 preamp, the EA-230 is almost perfectly neutral in perspective, having neither the forwardness of typical tubed equipment nor the slightly laid-back character of good solid-state amplifiers. Because of this, it avoids one of our major criticisms of most audiophile-type audio systems: Their tendency to sound recessed and more distant than most recordings are supposed to sound... In other words, this is THE amplifier of choice for driving electrostatics. ...the EA-230 has finally unseated our long-time favorite power-amp: The Infinity HCA. ... We just never expected the massive, 80-pound HCA to be outperformed by a pair of relatively-diminutive 28-pounders."
David Berning's Burning Brain
alien abduction
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