There’s actually nothing ambiguous about the by-laws. They operate over and above the standard council rules, rather than instead of. In short, your neighbour can’t make a noise that disrupts the peaceful enjoyment of a lot (if you have that by-law) at any time, night or day. That’s why there’s no time stipulated – it apples 24/7.
The difference with the council by-laws is that you can get the authorities involved as well as the Owners Corp, if the noise goes past the statutory hours.
Now that polite discussion has failed, you could try applying to your District Court for a noise abatement order. Or you could even threaten action at the Supreme Court, although you would have to have a case for damages for them to even take an interest.
In fact, a call to a strata lawyer might be well worthwhile. A lawyer’s letter explaining owners’ responsibilities under the Act often has more effect that a knock on the door.
But really, this is an EC issue and you should ask them why they are even on the committee if they aren’t interested in upholding the by-laws.
Apart from that, your only recourse is an application directly to Fair Trading for a Notice To Comply which comes with the threat of a fine attached if he continues to ignore this. Because by-law enforcement isn’t compulsory in NSW, individual owners and tenants can take cases to Fair Trading themselves.
You’ll find the necessary forms here. Try to get a couple of neighbours to support you to both share the cost and bolster your case.