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</head><body style=""><div>Hi Neil,</div>
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<div>The transformer-diode ring modulator is not "just a switching modulator", it is sort of half way between a true switching modulator and a product modulator, as the diodes are operated in the area where they are not fully on or off.</div>
<div>It should be no coincidence that germanium diodes are preferred in this circuit, as they have a softer current-voltage knee.</div>
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<div>Best regards</div>
<div>Simon</div>
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<div>> Op 17 januari 2016 om 15:10 schreef Neil Johnson <neil.johnson71@gmail.com>:<br>> <br>> <br>> Hi,<br>> <br>> Simon Brouwer wrote:<br>> > I imagine a big part of the sonic difference between the<br>> > transformer-and-diode-ring modulator and analog-multiplier circuits is the<br>> > nonlinear behaviour of the diode ring.<br>> <br>> A ring modulator is just a type of switching modulator - only the sign<br>> of the carrier is important, and the sharper the switching edges the<br>> cleaner the resulting output.<br>> <br>> Whereas the analogue-multiplier circuits are in the class called<br>> product modulators.<br>> <br>> There are many different ways of making switching modulators. The<br>> original advantage of the diode ring and transformers was cost - in<br>> 1934 "op-amps" didn't really exist, and diode choices were either<br>> thermionic or copper-oxide.<br>> You can kind-of emulate a switching modulator with a product modulator<br>> by driving the carrier input with a square wave.<br>> <br>> > If the transformers do not contribute a lot of distortion (assuming that in<br>> > this application they are not driven to saturation), they might be replaced<br>> > by opamp circuits without losing much of the characteristic sound.<br>> <br>> You can make a switching modulator with a single op-amp and a transistor.<br>> <br>> Cheers,<br>> Neil<br>> --<br>> http://www.njohnson.co.uk</div></body></html>