I am busy with designing and building an EL84 PP amp (https://www.avforums.co.za/index.php/topic,69276.0.html). Part of the plan is to play around with different circuit ideas and configurations. Because I am a lazy cheapskate (and don't have a spectrum analyser), I thought I would bite the bullet and learn how to use LTSpice so that I don't have to spend hours fiddling around with changing components and having to buy lots of resistors etc. Many of the guys on the diyaudio.com forums use LTSpice and there is a wealth of information on its use there. So I downloaded the software, libraries and some sample circuits and started playing. It has been great fun, and by playing around with the circuits I have found that I am developing much more of a feel for the behaviour of valve circuits, more quickly than if I had been building them physically. I have been around long enough to know that there are limitiations to modelling of any kind, and it is no substitute for real knowledge, but this is still a great tool. I thought I would post this to encourage others and to learn more myself from feedback.
Initially I am modelling the preamp/phase inverter stages, which should accomodate up to a 2V input signal (apparently some CD players produce this), and produce a 24V p-p output to drive the EL84s. I have been through the exercise looking at the ECC81, ECC82 and ECC 83 triodes, mainly because that's what I have lying around, but they are pretty commonly used in many of the classic amps.
Initially I am modelling the preamp/phase inverter stages, which should accomodate up to a 2V input signal (apparently some CD players produce this), and produce a 24V p-p output to drive the EL84s. I have been through the exercise looking at the ECC81, ECC82 and ECC 83 triodes, mainly because that's what I have lying around, but they are pretty commonly used in many of the classic amps.
