It is not the same bass.I have had 5 old 70s.Custom differs in sound very much.
Here You are real 70s:
[url="http://www.youtube.com/watch?v=s2s6-LlH5_w&list=UURa8hORy6H6Li5XsA58YjFQ&feature=player_detailpage"]http://www.youtube.com/watch?v=s2s6-LlH5_w&list=UURa8hORy6H6Li5XsA58YjFQ&feature=player_detailpage[/url]