|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
166.137.240.126
In Reply to: RE: Capital Audiofest 2016 posted by Ralph on July 12, 2016 at 10:12:21
Inside of the Linear Tube Audio ZOTL 40.
I did not see any output transformers in there but maybe they were hidden from view.
Follow Ups:
A linear audio amplifier includes a push-pull pair of vacuum tubes operating in a linear amplification mode coupled through a pair of dc-dc switching power converters to an external load impedance. Each power converter includes a transformer with one or more secondary windings that drive rectifier circuits, and the resultant dc voltage sources are loaded by their respective tubes.... The effective turns ratio between primary and secondary windings of these converter transformers determine the voltage/current step-up/step-down relationships between the tubes and the external load impedance.
I've added the emphasis. This is from the introduction to David's patent.
The 'ZOTL' acronym was created by Harvey Rosenburg and has no actual meaning by his own admission.
The circuit being referred to as ZH- was more accurate, but as (as you know) the transformers are quite different from the output transformers used with other tube amplification with transformers, and the operation of the amplification quite different, using "ZOTL" is much easier than engaging in a discussion of semantics or more involved technical explanations when explaining to most people what makes the amplification unique. At LTA we're trying to get people not to call the amps "OTL" and to instead explain the circuit and use "ZOTL" to differentiate between the two.
I think when David used the 'ZH' (Zero Hysteresis) identification (as in the ZH270), he was on the right track. He later dropped that as it was "difficult to explain".
However, the fact is the amplifiers are unique and the explanation is needed. In time people would have accepted them for what they are. Instead today we still have the same market confusion 20 years on.
It appears that the transformers in this are part of the rectifier and are not for the final audio output, unlike a conventional tube audio amplifier.
As I understand it, the Berning design is the closest analog to a Class D transistor amplifier. There is a high frequency power 'carrier', which is modulated by the signal.
"It is, therefore, an object of the present invention to provide an amplifier that eliminates the traditional output transformer. It is also an object of the present invention to provide an amplifier that is optimally matched in impedance to the load. It is a further object of the present invention to provide an amplifier that enjoys the sought-after transfer characteristics that tubes possess, which seem to influence the subjective qualities of the amplifier."
It appears that the transformers in this are part of the rectifier and are not for the final audio output, unlike a conventional tube audio amplifier.
This is incorrect.
The output transformer is loading the output of the power tube(s) and provides the proper matching as per the quote from the patent I posted earlier (as output transformers have been doing for nearly 100 years). Please note the bold in that post. The difference is that in the Berning amplifier, the output transformer is an air-core device.
The amplifier has little in common with Class D. It can be built class A, class AB or class B.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: