The Berning ZH270 and How I Found It.
It's pretty gratifying to post on a forum in the knowledge that the name Berning is likely to be familiar to a number of you. It's the same across many audio chatrooms the world over - the name Berning is increasingly being associated with some rather special amplification at real world prices.
Only a few years ago this wasn't the case - despite the amplifiers in question having been released towards the back end of the 1990's. So why did David Berning's amplifiers remain a secret for so long, and why the sudden explosion of interest?
There are any number of audio companies out there that operate on a marketing first basis. You only have to visit their flash laden web sites or read the glossy adverts to know the ones I mean. They promise the audio equivalent of the second coming and if you're not 100% convinced after purchase, they'll kindly offer you an upgrade path to sonic nirvana. I have yet to find one that delivers on any of its lavish promises. At the time of my first Berning purchase I was driving my Merlin VSM loudspeakers (a very fine loudspeaker by the way) with the (equally) very fine McIntosh MA2275 - an amplifier I had bought upon its UK release and enjoyed immensely ever since. The Merlin designer is a guy called Bobby Palkovic. Bobby's quite a character, and an audio alchemist well known for producing some of the best sounds year upon year at CES and elsewhere. I was ordering some new speakers from Bobby and in passing asked him for amp recommendations and what he thought of the McIntosh. His reply took the form of a total rave about an ugly little amplifier called the Berning ZH270.
A what I said? "But the McIntosh is the best amplifier I've owned" I said. " Are you sure you are familiar with the model?". I won't forget the reply. "Yes the Mac is a cool tube amp and solid", "but this little Berning is one of the best amplifiers in the world - it'll make your Mac sound broken!" So convinced was I that Bobby had shares in the company (I'm a hardened cynic I'm afraid), I then set about finding as much as possible out about the Berning operation and it's amplifiers.
It turned out the Berning was no flash in the pan. David Berning made a name for himself on the US audio scene back in the 1970's. At a time when Audio Research were starting to produce some decent tube amps, and everything was basically a rehash of old circuits from the likes of Wiliamson, David was getting of reputation for doing something different. As early as 1979, his TF10 preamplifier (with unique FET/Tube complimentary gain stages) was being compared to the finest preamps on the market. David is a scientist first, and an audiophile second. His knowledge of circuit design even back then shocked Stereophile reviewers and fellow designers alike. After early experiments with hybrids and solid state, he dedicated his work to extracting the best performance he could from the humble tube.
Over the next 20 years, David continued to hand build amplifiers that occasionally appeared on the radar with excellent reviews from Stereophile and the like, but in the main, they stayed a closely guarded secret amongst a select number of American audiophiles who were prepared to wait up to a year for their hand built amplifier to be delivered after placing an order. This was a small-scale operation. Every amplifier the David Berning Company has made in its forty-year history has been built by David himself. One look inside a ZH270 gives you an idea of the workload. As David himself said only recently 'There is just so much work in these things, I wish people could understand, you see those impedance matching devices, the one with all the little wires coming out of it, going to about 160 diodes, that has to be hand wound, all those secondaries, all those wires have to be kept track of as it's being wound, there is no other piece of equipment that uses anything like it, this is only one of about 24 big and little transformers in a ZH-270 that have to be wound by hand because nothing else uses anything like it."
I was beginning to understand. The reason I had not heard of Berning was not because of any shortfall in quality or lack of heritage, it was simply because we were looking at a low volume producer and one with a scientist's brain rather than a businessman's to boot. So I took the plunge and ordered a model from the US and waited to find out if it was all hype or indeed there was some substance for once.
The model that was recommended to me by Bobby Palkovic was the revolutionary ZH270. I use the word advisedly. The amplifier is described as using a ZOTL circuit. David wanted to get rid of what he sees as the weakest link of any tube amplifier - namely the output transformer. You may be familiar with the OTL designs of the past from the likes of Julius Futterman - the idea being to use multiple output tubes in provide sufficient current to drive the loudspeaker. Fraught with problems, the concept never really gained mass acceptance, given the need for tight matching of valves, the copious amounts of feedback involved, the need to run the valves very hard, and the consequential loss of reliability. Along with severe load limitations and excessive heat generation, these issues made the traditional OTL a labour of love for the few die hards who could live with such temperamental devices.
Without taking this route however, the problem of converting the high voltage low current output of a tube into a low voltage high current requirement of a loudspeaker had been insurmountable without recourse to the traditional output transformer and its attendant limitations at the frequency extremes. David's patented ZOTL circuit uses HF switching converters to perform this operation. Impedance converters based on DC/DC converters in SMPS are used. Some recaltriant valve amp owners/designers have tried to compare the arrangement with a modern day class D switching amp (although it should be noted that the design predates these by a good few years anyway!). The Berning circuit is in truth and indeed in spirit, far closer to a traditional valve amplifier than it is to any modern day Class D derivative as it's output is faithfully modulated by triode connected tubes, the transfer characteristics of which are what show at the outputs. The circuit found favour with the late great Harvey Rosenberg who waxed lyrical about the Berning's sonic qualities on that bastion of thermionic fundamentalism, the Triode Guild.
He firmly asserted that this was the future of valve amplification prior to his untimely death. For me the circuit is a very real solution to a very real problem that cannot be easily classified as it really creates a whole new classification of it's own. But how would all of this translate sonically. What would be the strengths? Weaknesses? I've now owned Bernings for some two years and I'll start this sonic appraisal by saying they are by far the closest product I have heard to many peoples ideal of an amplifier that combines the best of both solid state and tubes in a single box. When I read of other amplifiers claiming, "valve like smoothness with solid state grunt" I generally laugh these days. The reason is that these designs might sound smooth but they never have the qualities that a well-designed triode can bring a system. The difference is that to my ears the Berning actually does. Often one inserts a new amplifier into a system, settles down, and gradually notes the differences and improvements it has brought to the system, and indeed any losses that might occur. In this case, and against the McIntosh MA2275, I did genuinely did think the Mac was broken! Indeed when later comparing the fabled McIntosh MC2000 Millennium anniversary amplifier with the Berning, two hardened audio nuts did spend a good half an hour trying to work out what we were doing wrong connections wise with the Mac -- and this was a Stereophile Product of the Year!
The difference with the Berning was more akin to a big loudspeaker upgrade. 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. Timing is undoubtedly at least on a par with Naim -- a NAP 500 owner being similarly shocked that a valve amp could behave like this -- latching onto the rhythm like a limpet and rocking along without any sense of enhancement or any lack of naturalness. 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. This is like a good SET in that it also removes the body, allowing a clear view of the heart and soul. Like a spiritual x-ray machine laying bare both the recording and more importantly, the recorded intensity and emotion. 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. I have recently had the opportunity to compare the ZH270 with a well regarded 2a3 SET (The Audion Silver Note One) and again the Berning made this sound congested, slightly treacley, and lacking in a little transparency. A remarkable performance for a 70wpc PP device that can drive real world loudspeakers to real listening levels.
So downsides? Well it can't be perfect -- nothing is. It's too noisy for 100dbw + horns if used on low feedback settings. It's designed for speakers up to 95dbw in reality before noise levels get slightly intrusive. For this reason, and this reason only, I have recently bought a SET Siegfried for use on my midrange horn. And it's not as lush and romantic as some of the SET's out there. Slightly less plump and fleshy, more open and ethereal. Interestingly the Triode Guild had the ability to record grand piano onto half speed tape and play it back whilst comparing this to the piano in the studio. They found that the SE Berning was less romantic but far closer to the real sound of the real Steinway than any of the other amplifiers they subjected to the test over the years. Truth before beauty? I say a fair dose of both please -- and the Berning designs give me that like nothing else I have heard or owned.
I would still like to hear a really top SET in my system purely for comparisons sake. But the Berning weighs just 10lb. The tubes are inexpensive and should last between 10 and 20 years. It has auto biasing and four individual protection circuits to prevent damage to speakers or amp. It has variable feedback settings allowing me to tune the sound to the speaker, room, recording even. Hell it even has two inputs and a volume control! And it cost just $3,000. I honestly cannot think of any amplifier anywhere near that price point, that I would even begin to want to listen too. Looking at my personal needs the ZH270 offers a fairly unbeatable combination of virtues. For me the Berning was beyond the hype, a product that delivered on a huge scale and went far beyond my wildest expectations. How rare that is in today's audio world.
Last edited by Stereo Mic : 12th August 2007 at 19:23.