Only recently I came across a still very interesting article about Cascode amp design written by Nelson Pass (see link). I saw that the article dates from 1978, so I am sure many off you know this article for some time (or years).
It’s plain from a technical point of view that the Cascode topology is favorable in many cases. But after searching this forum and reading some of the threads, the general opinion seems to be that Cascodes are liked in VAS stages but are disliked in Output Stages.
Technically, I don’t understand the reason for this. This means apparently that in Output Stages the disadvantages are greater than the advantages (besides the extra components). But what are these disadvantages? Why is the result of a Cascode Output Stage not what one would expect regarding the technical benefits.
I also wonder; did anyone perform a FAIR a-b comparison between a normal Output Stage and a Cascode equivalent? And which one sounded best? With fair I mean that in an amplifier only the Output Stage was modified between non Cascode and Cascode and the rest of the circuit and poer supply was left the same.
Peter
http://www.passlabs.com/pdf/articles/cascode.pdf
It’s plain from a technical point of view that the Cascode topology is favorable in many cases. But after searching this forum and reading some of the threads, the general opinion seems to be that Cascodes are liked in VAS stages but are disliked in Output Stages.
Technically, I don’t understand the reason for this. This means apparently that in Output Stages the disadvantages are greater than the advantages (besides the extra components). But what are these disadvantages? Why is the result of a Cascode Output Stage not what one would expect regarding the technical benefits.
I also wonder; did anyone perform a FAIR a-b comparison between a normal Output Stage and a Cascode equivalent? And which one sounded best? With fair I mean that in an amplifier only the Output Stage was modified between non Cascode and Cascode and the rest of the circuit and poer supply was left the same.
Peter
http://www.passlabs.com/pdf/articles/cascode.pdf