Quote:
Originally Posted by 1100 man
Interesting that even on a set of this quality, there is no black level clamping or DC feed to the CRT. This certainly can't be down to reasons of cost. I am more and more convinced that manufacturers actively decided not to maintain rigid black level for a variety of reasons in nearly all UK receivers. I get the impression that it was considered an undesirable feature, rather than down to cost cutting.
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The attached book excerpts, one from Davies (“Understanding Television”) and one from Hutson (“Television Receiver Theory”) provide some background as to why full black level retention was often avoided in domestic receivers.
One reason was that if done, it required better EHT regulation than was the norm for domestic receivers in order to avoid other deleterious effects. As Hutson put it:
“The partial loss of the d.c. component is the lesser of two evils, and involves a commercial compromise. In terms of absolute picture fidelity both complete retention of the d.c. component and a well regulated e.h.t. system are necessary.”
Cheers,