Have you tried an advanced search* for keywords clamp and extension, searching only the Mics & Setup & TSKB / Archive | Mics & Setup forums? Doing so reveals to me 3 pages of results, many of which highlight similar discussions.
* To do so, simply click the Search button at the top of the page, specify the keywords, and in the Choose a board to search in, or search all, untick the Check All checkbox, expand the view to see all the forums, and tick only the Mics & Setup & TSKB / Archive | Mics & Setup forums.