Activating all 4 speakers in 4 by 12 Cabinet

[6thAvenue]

Hi!

Just recently purchased a Blackstar HTV 412 & HT Stage 100 Head.

Back view of my amplifier head: http://medias.audiofanzine.com/images/normal/blackstar-amplification-ht-stage-100-241626.jpg

Back view of my cabinet: http://kitarablogi.files.wordpress.com/2012/02/blackstar-htv-412a-e28093-inputs.jpg?w=300&h=225

How would I get all 4 speakers to run at the same time?

Currently have got my speakers connected and run through 2 out of the 4 speakers.

Any help would be much appreciated.

Thanks folks!

 

[VidaK]

connect a speaker cable (NOT instrument cable, please check) between the 1 x 16 ohms output from amp and mono 16 ohms input on the cabinet