Berning ZH-270 Replacement

Ralph, A basic principal of Futterman tube amps is they use banks of tubes in a series, agreed? Atmasphere amps do likewise yet you claim the Atmasphere are not derived from Futterman. Tweaked and much improved, yes and kudos to you for that!

Not fully understanding the highly advanced Berning design is something that you cannot be blamed for. However, to call it a non OTL design is absolutely mistaken and incorrect. The ZH is DC coupled for crying out loud! The DC to DC converters are NOT transformers, their role is for matching impedance in accordance to load. But you should know this already, as this has been explained on the threads and elsewhere time and time again.

Barry, how much power do you need to drive the Sonus? What is the impedance of the speaker like?

Hi Chris, if it were as simple as that!

The Futterman is a 'totem-pole' circuit and is asymmetrical. Our amps use a modified Circlotron which is half the output impedance and *is* symmetrical. Futterman amplifiers usually have output coupling caps and large amounts of feedback, our amps employ neither. Pretty big differences- they amount to reliability and performance, part of why I've been able to be at this for over 31 years, longer than Futterman at this point.

You can look all this stuff up on the web; mistaking our amps for Futtermans has been one of our biggest marketing problems. This is what I meant when I commented that you did not know what you were talking about- it was not meant in a mean way, just simply that that it is the case.

We have a direct-coupled output and so does the Berning, but the Berning uses a DC to DC converter *and* an air-core output transformer for the power tube(s). Neither the latter nor former will be found in an OTL, in which impedance conversion is done by the tubes and the tubes alone.

I have been very careful to underline my admiration of the ingenuity of Berning's concept in the past and that has not changed. I think its brilliant! -but an OTL it simply is not.

Guys please get off your OTL soapboxes and stop hijacking threads in order to display your supposed technical expertise and have a bit of respect for others if its not too much to ask.

Now back to the thread and thanks to all those who have assisted so far.

Keep your non OTL opinions and experiences coming please

Thanks

Hi Pubul57

The Berning has enough power at normal to resonable listening levels but if one starts to push it to anything more it starts to strain slightly.

As far as impedence of the Guarneris go I am not really sure to be honest as there are very conflicting specs.

Thanks
Barry