Modded my Fender Stage 112se to 2 external speaker outputs. Did I do this correctly?

[CTWFTP]

I blew the factory speaker in my stage 112se combo amp a long time ago and have been using the external speaker jack output to power my Mesa 4x12 cab for years now. I decided I needed more power output because my cabinet is either 8 ohms, or split into into two 4 ohm inputs with 2 speakers on each input. The amp is stable at 4 ohms so I said what the hell, more power! The speaker wires that were running to the original combo speaker have been capped off for years, and the combo speaker has long been removed, so I decided to wire the combo speaker wires to a jack for another speaker cable. I drilled a hole beside the original external cabinet jack and wired up the original combo speaker wires to it.

I got the schematic from here : http://www.electronicstudio.net/sche...tage_112se.pdf and I'm not sure what to make of the 4 wires going to the original external speaker jack. What is going on with those? Everything seems to be working great as I have it connected currently, but I'm thinking I actually have less than a 4 ohm load on the amp with this configuration as the mesa cab inputs both say 4 ohms.

I've been using it cranked LOUD for about a month and a half and everything seems fine. It's WAY louder and much cleaner at higher volumes than it used to be. Does anyone see any issues here and am I actually running less than a 4 ohm load as is? When I measure the dc resistance of each of the 4 ohm inputs on my cab I get about 4.8 ohms ( which I know isn't the same as AC impedence) so I'm thinking I may have around a 2 ohm load on the amp, which isn't good. Am I correct in my thinking and if so, any solutions you can think of?

Also, this amp has always, at least as long as I can remember, had a loud hum even with the volume completely off. From what I've read this is normal with this amp. Is this the case?

Thanks!

[eschertron]

if you have 4 nominally-rated 8 Ohm speakers, they can be hooked in two pairs of 4 Ohms or 16 Ohms each (you have the two halves at 4 Ohms each).
You can hook the 4 speakers up to result in either 8 Ohms or 2 Ohms. Internally the 4x12 set it up as 8 Ohms, if you parallel the two 4 Ohm sections you get 2 Ohms, which is what it sounds like you have done.

If you don't like the sound of 2x12 at 4 Ohms, you can get another Mesa cabinet and run 8x12 at 4 Ohms

I'll let someone else chime in on how long the amp runs at nominal 2 ohm load. It's all about how hot the power components get during operation.

[CTWFTP]

Thanks for the response. I'd love to have another mesa cab but they ain't cheap! It's good to have some verification on my line of thinking. Maybe I could install a small externally powered fan in the back of the amp to help keep it cool. I sure don't want to melt it down but I like having the extra power lol!

Apparently the other 2 wires on the external output jack are there to bypass the power circuit, as one goes straight to ground and the red wire goes to the power amp input jack, so that's no concern. Don't know why I didn't notice that sooner.