The bigger the groove is cut into the record, the louder it can sound. A tune cut onto one side of a twelve inch can be cut much louder than the same song cut onto one side of a 7", because of the space limitations. Take 70's disco singles as an example. Surely techgoody was just pullin everyone's chain.
Quote from
http://www.recordtech.com/prodsounds.htm:
"the louder the music is cut, the wider the groove wiggles, and the less time can fit on the side."
..depends on the length of the tune. If you do the maths it follows that a 7" single of a tune from an album that has 5 tracks on each side will probs be louder.
Statin the obvious but there it is anywayz!