| Re: Why parafeed? [message #93795 is a reply to message #87874] |
Thu, 20 May 2021 23:52  |
positron
Messages: 113
Registered: May 2020
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Viscount |
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I think the RCA Radiotron Designers Handbook, Edition 4, by 26 engineers,
page 519 sheds some light on the subject of parafeed operation.
"In all cases when making use of any resonance effects involving the inductance of the transformer primary, it is important to remember that this is a variable quantity. Not only are there considerable variations from one transformer to another, but there are large variations of inductance caused by the a.c. input voltage.
The series resonant circuit presents a low impedance to the valve at the resonant frequency, thus tending to cause serious distortion, particularly when the valve is being operated at a fairly high level. For these reasons the resonance method is not used in good design."
For ease of understanding for newbies, the inductance varies with power/spl, the load line varies, and the low frequency resonance frequency varies, the bass varies with loudness.
Cheers
pos
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