Parallel/series extension cab

[Blooze]

I’m in process of building two 1x10 cabinets to use with various amps. Would something like the drawing I attached work if I wanted to use just one or both cabs together? Use the appropriate amp out impedance (4,8, or 16) depending on whether using the main cab, or serial/parallel with the extension cab?

[mrjomo]

Greetings Blooze.
I’m pretty sure that your sketch won’t get you where you want to go. I looked at it for a bit last night and then again this AM. Here is one way that will do it. I don’t THINK it has any boobytraps. In any event you realize that it is up to you the user to keep track of speaker loads and how they combine. The jacks and cables are just dumb; they won’t tell you that two 2Ω loads in parallel are not likely to be good.
My first have-at-it used a single extension jack and a DPDT switch to determine if the extension was going to be added in series or parallel. This seems more elegant and closer to what you were chasing.
Let’s see if I can really attach a file...

[Blooze]

I was trying avoid a switch, but I’m not sure there is a good way to.

So basically this, using a jack to the extension cab and setting the switch to parallel to use only the main cab (with no extension speaker)?

[mrjomo]

My drawing gives you a way to do that without a separate switch. The switching is done by useing the appropriate jack. The SERIES loop jack has an extra contact that dis-connects  a switch when a plug is inserted.

Your drawing WITH a switch will work BUT, as you noted, with NO extension cab, the switch MUST  be in the PARALLEL position or you wont have a speaker load on the amp. That could be bad.
i can work up a switch arrangement that doesnt have that flaw…

[mrjomo]

Blooze- i looked again at your first posting. Your sketch WILL do what you want. BOY! am i muddying the water on this one. DOH!! Really sorry, everyone, for the chaos. sigh…

[Blooze]

Blooze- i looked again at your first posting. Your sketch WILL do what you want. BOY! am i muddying the water on this one. DOH!! Really sorry, everyone, for the chaos. sigh…

Cool!  I super appreciate you looking things over. My only other question is should the extension speaker wires be swapped to keep the phase correct? I have a hard time following that.

[mrjomo]

Nope on the polarity swap; you got that right.
From my scheming and looking at yours, Dangers lie in not following the scheme. in a Series mode, there must be an extension speaker in the loop, otherwise you put no-load on the amp output.
i hope we’re almost there…

[Blooze]

I've updated the drawing in the original post to reflect that.