Berning ZH-270 Replacement

06-24-09: Peter_s
I must digress, and I think I'll get alot of flack for this, but wrt to the ZH-270, I don't see what all the hubbub is (bub). I had one about 7 years ago, with the NOS tubes, and I felt that it sounded way too forward and aggressive. I heard it on multiple systems, four to be exact, and the sonic character was the same for all. I returned it to David Berning to make sure it was OK, and he said there was nothing wrong with it. I just don't get it. Several friends all had the same impression of the sound. Anyone here on Agon perceive it the same way?

I certainly do! I had posted similar comments re. the ZH270 in this thread way back in 2006:
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1141813144
I also did not hear anything special from this amp & I heard it 1 person's system & then invited the gentleman over with the ZH270 to listen to it in my own system. No cigar in both cases, I'm afraid.
In the above thread, you'll read that many others changed their minds over time to agree with my position but you got to go out & listen with an open mind. Once these other people did, they realized that the ZH270 was average, at best.
Now, Berning's new Quattro (I think I got the name correct) that I heard at RMAF2007 is/was an excellent product. Much more expensive but, my gosh, what great sound. superb!

Of course, these are my personal opinions. YMMV.

Chris74, I humbly suggest that you have no idea what you are talking about. The output transformer in the Berning is clearly visible in the patent schematic! -even if you take the tack that an air core transformer is not in fact a transformer (which of course it is), ignoring the role that the semiconductors play in the output section still puts it outside the category defined by the acronym 'OTL'.

It is true that in the early 70s and late 60s, Allied Radio Shack referred to some of their amps as 'OTL', but generally the term refers to a tube amplifier, not semiconductor, and also not an amplifier that uses both a transformer and semiconductors for impedance transformation in its output section.

Of course, cats are distantly related to dogs, so I guess all dogs are really cats, right :)

BTW, the Atma-Sphere approach to OTLs was patented in 1986, and is not a Futterman circuit or a derivative thereof. Contrary to your assertion, it is *unconditionally* stable, as the amp cannot be made to oscillate under any load condition, regardless of input signal condition. It was the development of a fully symmetrical circuit that is inherently low in distortion that allows for this, so feedback (a destabilizing feature in any amplifier design) was no longer required, unlike the prior art.

Bombaywalla - it's somehow comforting to know that I'm not the lone dissenter to this love fest! I really wanted to like the ZH-270 - I thought it would be the answer to all my needs. I don't think that it was the source components or the cables, as I listened to it on 4 systems - though I imagine there are better synergy combinations than what I experienced.

With the exception of a small input DC blocking cap, the ZH-270 is DC coupled, so how is this possible with a output transformer ?? I tell you how, it's not !!
We've gone down this road time and time again, it's obvious it's beyond comprehension for most, but an OTL it is.

A person has the tendency to believe what they can understand and doubt what they don't and since this is a highly technical piece beyond anything ever made in audio, it leaves a lot of open endness for somewhat misguided debate.

And as always listen and compare for yourself, not everything is for everyone.

I second Sbank's response. The ZH 270 benefits from a good preamp. I use a ZH 270 in a second (Summer) system with a FS pre and the sound is terrific. I use Joule amp (vzn 100) and Joule pre in the Winter when heat is not a factor. The Berning/FS combination comes close IMHO. I do not think you will find the ZH 270's performance in SS gear - mine replaced a Rowland Concentra II integrated and as much as I liked the Rowland the Berning was so much more involving. The Berning can also benefit from some tube rolling. I recently inserted some Telefunkens and the mids and highs improved - more open and extended.