L-pad wiring

[Mann]

I'm soldering a l-pad http://www.marvac.com/fun/l_pad.aspx for use with my tubeamp (madamp m15mk1).
I am building the l-pad in a box which I can connect between amp and speaker using normal guitar cords. Now I'm wondering which wire to connect to which lug on the jacks.
Do I really hav to find out which wire is + and which is - ? The tip of the plug usually is the + side?
I made a top/box for the amp I wouldn't want to disassemble it for to look/measure the jacks/plugs.

[bancika]

You should determine which one is + because if you wire it reversly speaker membrane will move opposite than it's supposed to. Also I wouldn't recommend using guitar cables for that, speaker level is much higher than guitar level and it can damage the cable. Get some speaker cable and jacks and you can build one in a few minutes.

[d95err]

In general, which side is connected to + or - on the speaker doesn't matter - it's arbitrary. However, if the speaker output is referenced to ground, by convention, the + side should be the the tip and the - side (ground) is the sleeve. If you have multiple speakers, the + and - should be the same on all speakers or they will be out of phase and counteract each other.

As the previous poster said - do NOT use guitar cable for a speaker signal!

[Mann]

Thank you for your answer. I used the word guitar cord just to be clear what I'm talking about; I use proper speaker cable between amp and speaker (and inside speaker box).