Hey all,

Bought a 2-3 yr old Vox AC30 C2 the other week and had a look at the back to see what features it has... there are two jacks, one for an extension speaker out and another for a external speaker out. Both of these are right next to an impedance switch for 8 or 16 ohms, but the switch does not specify which jack it is for, or if it relates to both. The speakers in the unit are 8 ohm Greenbacks, making the whole thing 16 ohms (I believe).

From what I know about impedance and speakers is that if you have two speakers equalling 16 ohms there is no way that can be changed to 8 ohms without kicking out one speaker. So then how does the impedance switch for the extra/external speakers relate to both output jacks? If it is specifically only for one of the jacks (the external) then why doesn't it specify this to make people like me understand better that it is not for an additional set of speakers? Because surely you couldn't just set the impedance to 8 ohms and plug in an 8 ohm cab into the "extension speaker" out (allowing the combo speakers to work as well as an external cab) because the combo is set to 16, right?

I ask this because I use a Marshall Plexi into a 16 ohm quad, but wanna run the Vox alongside it plugged into my old 8 ohm 2x12 that I never use anymore, but want to also have the speakers in the Vox running if possible to make it full like a quad.
Running stock speakers, use the 16 ohm switch position. Add another 16ohm cab and switch to 8ohm on the amp. Run an 8ohm and a 16ohm cab together and risk letting the smoke out of the amp.

"The Vox AC30C2 amp makes use of 3 x 12AX7 preamp tubes and use 4 x EL84 tubes to deliver 30W of power. It uses 2 - 12" Celestion G12M Greenback speakers, and includes a switchable 8/16 ohm output jack for powering an external speaker cabinet when you need to speak with a little more authority; using this jack will mute the internal speakers. Additionally, the 30W guitar amp's 2nd extension speaker jack allows you to run an extra 16-ohm cabinet along with the internal speakers for a fuller sound."
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
Last edited by Cajundaddy at Jul 28, 2014,
ah, so it be true... I figured as much. I'll just have to sell my 8 ohm cab and get a 16 ohm if I wanna do a 4 speaker thing.

Such a pain because I spoke to an amp tech when ordering speakers for my 2x12 cab and the guy told me to get 16 ohm speakers to make it a 16 ohm cab (he actually builds amps too)... this was years ago so I had no idea. What an idiot. Now I'm stuck with a limiting 8 ohm cab