How does Berning ZH270 compare to Cary Cad211 AE ?

I agree with Tubegroover, the Berning ZH270 should be more than a match for the Cary Cad211, especially if you are sensitive to noise and hum. The Berning does not have a power transformer or a heavy output transformer (the amp weighs less than 5 kilograms!) so there is absolutely no transformer buzz at all. Furthermore, the tubes in the Berning -- 2 pairs of 12AT7/ECC81 tubes for voltage gain, 1 pair 12AV7/5965 tubes for driver tubes, and a quad of 6JN6 sweep pentodes (wired as triodes) for output are heated with radio frequency AC. The two voltage gain stages and the driver stages are single-ended, without interstage coupling capacitors. In fact, there is only one input capacitor in the entire signal path, otherwise the amplifier would faithfully amplify DC. The Berning ZH270 is the quietest tube amplifier I have owned and the most transparent amplifier I have owned period.

The Berning ZH270 also has three feedback settings -- normal(a low 12 dB), medium (a lower 7 dB), and low (3dB); which you prefer will be a matter of taste and the impedence of your speakers. Without the conventional output transformer in the way, the first thing you will notice about the Berning ZH270 is the bass extension and the high frequency extension, relative to the Cary. The Berning also has two sets of inputs as well as internal volume control -- I run my DAC straight into one set of inputs and bypass my preamp altogether. There is no preamp, like no preamp, I know ...

As for the palpable mid range of SET amps, you can achieve that sound in the Berning with a judicious choice of input tubes. If you like the rich mid range of single ended amps, then using richer sounding NOS input tubes such as the mid 1960s (or earlier) Mullard Blackburn ECC81 or the 1950s RCA black wing plate 12AT7 at the lower feedback settings will give you this style of sound, plus keep the bass and high frequency extension of the Berning.

:-)

One strong tube recommendation I would offer would be to purchase a quad of the matched, cryo-treated output tubes from Allan Bhagan ([email protected]) as well as getting the internal silver wire and capacitor upgrades from Allan too. At least with the output tubes, you can listen to the amp while you wait for the tubes to arrive.

If you prefer an extremely transparent, live sound then the Berning ZH270 works very well with any of the top 12AT7/ECC81 types known for their transparency -- e.g. Siemens, Telefunken, etc. -- exactly which one is a matter of taste. The Berning is so transparent that you can easily hear the (not always subtle) differences between the different highly regarded vintage 12AT7 tubes available from top NOS tube dealers such as Tubemonger (here on Audiogon) or Andy Bowman at Vintage Tube Services. The Berning ZH270 autobiases all of the tubes and tube sections separately using servo cicuits to keep the DC plate current constant. This means that the Berning ZH270 will find the correct negative grid voltage bias for each dual triode section independently so that they stay in their correct operating points over their entire lives. This feature alone makes the Berning ZH270 one of the most user-friendly tube amps in existence.

Back to answering Nr9's questions ...

"I have heard that the new units are supplied with better cabling and capacitor. Do you know anything about this?"

As far as recent model Berning ZH270 amplifiers being supplied with the upgraded silver wire and upgraded capacitors, I believe that is a premium option that needs to be requested when ordering the amplifier. My understanding is that most buyers have lately requested these options when ordering, based on the feedback here on Audiogon. I purchased mine used here on Audiogon with the silver wire and capacitor upgrades already installed plus the cryo-treated 6JN6 output tubes. I suggest contacting Allan Bhagan for a more definitive answer.

"I’m looking forward to receive the Berning amplifier and maybe mach up with new cables."

As for cabling choices with the Berning ZH270, I would recommend trying what you already have and experiment with the different feedback settings first followed by input tube rolling.

The primary voltage gain stage 12AT7 tubes (the pair closest to the BACK of the amplifier) are where you can most readily tailor the sound to suit your tastes. If your system leans toward the bright/lean side, then a warmer/richer sounding pair of 12AT7 tubes in the primary and/or secondary gain stages would be a good choice.

In my experience, input tube selection in the Berning ZH270 can be as dramatic as selecting cables, perhaps more so once the cables hit a certain level of quality (defined by high conductivity, plausible geometry, low dielectric, low capacitance, and SHORT LENGTH). Since the ZH270, like other good OTL designs, has such a clean and simple signal path -- the lack of interstage capacitors helps here -- and optimally biases the tubes/tube sections, different tube manufacturers tubes sound very different.

The 12AT7/ECC81 tube type was originally designed as a Radio Frequency amplifier. (Ever wonder why many of the top NOS supplies come from ex-NATO stock? They were used in military radars right through the end of the Cold War). 12AT7/ECC81 tubes can perform well in the audio frequency range, and were probably adapted slightly to do so during the post WWII high-fi boom, but all of the vintage manufacturers' designs have noticeable sonic profiles (even different designs from the same manufacturer). The "lush, rich, musical, walk in the forest, etc." sound is quite achievable with the Berning ZH270 by using the lower negative feedback settings in combination with input 12AT7/ECC81 tubes that have those same qualities (e.g. early Mullards, early RCAs, early Sylvania, etc. -- all of which are still available NOS, see my previous post in this thread for sources).

Selecting driver stage tubes (the pair closest to the FRONT of the amplifier) in the Berning ZH270 is also important -- especially to avoid doing any harm. Electrical properties do matter. The 12AV7 and 5965 types were specified for a reason: they work well and can supply current to the driver tubes at peak signal voltages approaching 600 Volts at full power. Many of the dicussions on the web regarding "better sounding" premium alternatives to the humble 12AV7 and 5965 types (e.g. the 7062/E180CC and 6829) are based on listening to these different tubes in preamps at much lower DC plate voltages and peak signal voltages.