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Old 04-23-2017, 10:52 AM
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For two different low level schemes (both with two stages, demod and matrix/amplifier), with similar gains per stage, the bandwidth advantage will be about the same. It's a matter of overcoming stray capacitances.
However, the RCA circuit has the DC restoration advantage.

Direct high level demodulation is cheaper than having two stages. But any imbalance gets carried right through to the CRT grids, possibly messing up grayscale tracking. in some cases you see balance controls, either a service adjustment, or in some cases a third customer control that can turn the grayscale tracking towards either blue or sepia. If these adjustments are omitted for further cost savings, it may mean that replacing the demod tubes will require a tracking adjustment.

The CTC-5 "Super" chassis has reduced DC coupling in the color difference outputs, which reduces the effect of demodulator offsets, but that means there is also some background shift due to scene content. When everything is set for good general pictures and you put on a test pattern of a full screen red, for example, it gets reproduced with reduced saturation because
1) the demodulator DC balance shifts a bit toward cyan
2) the reduced DC coupling in luma makes the luma output shift upward from the correct 30%
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