hmm.. I wouldnt say it sounds like a metal hammer on big metal object.
It's more like a "ticker, ticker, ticker,ticker" (say it out loud and quickly) similair to what the valve train sounds like but a bit louder and not in sequence (random) if you get what I mean?

Watch this.... http://www.phormula.co.uk/Player.asp...Analyser%20Pro

It's about 8 mins long but you get to hear a recording of Det towards the end!