A tat-puruṣa compound ending with the word sabhā 'court' is neuter, provided that it is preceded by (a word synonymous with) the word rājā or by a word denoting a non-human-being. ,
As इनसभम् 'the King's Court.' ईश्वरसभम् 'Lord's Court.'
But in राजसभा 'the King's Court,' the word is not neuter; for synonyms of राजा are only to be taken and not the word-form राजा; an apparent exception to Rule 1.1.68.
So also रक्षःसभम् 'the Court of the Rakshasas' पिशाचसभम् 'the Court of the Pisachas.'
But in काष्ठसभा, दैवदत्तसभा &c, the word is not neuter; for the word non-human has a technical significance meaning Rakshasa or a monster.,