Berning ZH-270 Replacement

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

bpinder, why don't you contact Sonus Faber and see what they say, I don't know how much input Franco has anymore but he still owns a ZH-270 and the first introduction of the Stradivarius was done using the modest ZH-270, I think it was Fremer what visited Franco, look up the stereophile review.

It surprises me that the ZH-270 is strained at higher levels, have you played with the volume control.
There are several reasons why I am surprised but one mostly is that the ZH-270 does not act like most amps when pushed, because of the sophisticated auto bias, it senses when it's close to clipping and reduces power to the amp, this happens at a super fast rate up to thousands of times a second, so all that might be perceived is a slight reduction in dynamics.

One way to tell if you're reached close to output power is keep turning the amp up, it should react with very little difference in perceived volume, if there is a volume increase then it's elsewhere in your system.

These amps are used by so many manufacturers for designing it will surprise you, including the speakers mentioned here by jwmazar Chris Sommovigo's Stereolabs, what makes these amps great for this, is what makes it unforgiving for the average audiophile, they are not filters which is a limit of the typical design constraints, get it all right or this amp is going to tell the story.