diy knock ears

[triple j]

http://www.rx7club.com/2nd-generation-specific-1986-1992-17/diy-knock-ears-980837/
I made one of these up for myself, i never tried it out yet but am sure it will work fairly good, has any one used the likes.

 

[AdamB]

This way is ok, but I much prefer the copper wire method, its a direct way of listening to knock and is able to pick up small amounts of knock due to the frequency.

 

[Sheldon]

done one myself.. never tried tyo use it.. i used helicopter headphones so its almost 100% that you wont hear background noise. and a small old tape recorder