Thai consonants according to etymological pronunciation, for the benefit of learners trying to make heads or tails out of the abundance of confusing homophonous retroflexes in the orthography.
Based on Wikipedia’s colour scheme:
The colour of the letters themselves represent the modern Standard Thai reflex (in onset position); the legend for those appears in the ‘old vocal folds’ column.
Generally, when tonogenesis occurs, voiced consonants tend to entail low tones, and aspirated ones entail high tones. This explains why sonorants and etymologically voiced consonants are in the ‘low’ class, even though they have merged into the aspirate set some time in the 14th–16th century.
The fricatives are voiceless, as aspirated fricatives are generally very marked, and the phonological feature of [spread glottis] generally manifests in fricatives as simple voicelessness.
The generally obsolete letters indicating velar fricatives have both merged into the velar aspirate.