Join Date: Aug 2012
Location: books at londonpower.com
The dome topology has nothing to do with the JLH 10W, rather more to do with Lin. The heart of the JLH-10 is the use of the driver/CVAS as a splitter driving both output devices directly. This contributed to ghastly distortion while allowing a low parts count.
Both use a single-BJT input stage, which in modern terms forms a CFP wit the voltage amplifier and could also be described as a "current feedback" amp - see Rod Elliot's similar design, but biased class-B.
Input stages like this are easy to stabilise and compensate because the signal path is a tight loop - not convoluted by a third member as with a diff-amp input. The downside of this approach is that the collector current of the input devices must flow through the feedback resistor. This drives the R value lower to maintain reasonable DC setting of the output, in turn driving the shunt R value for the FB loop down. The design has come full circle with the CFB/CFA rage.