I will be getting a small tube combo amp with a single 12" speaker for Christmas. I am sure it will be plenty loud enough for my garage, and who knows if it will ever leave the garage? Still, it has an external speaker jack, and that has me thinking about an extension cab...
When you plug in an extension cab, the jack disconnects the internal speaker. I want to have the option to run the amp with both the internal speaker and the extension cab. I thought I could do it more or less they way the guy in this video did it:
Like the amp in the video my amp says it needs an 8-16 ohm load. HOWEVER, the dude in the video has 16 ohm speakers in his combo amp and extension cab so he can run simple parallel wiring. Since I have an 8 ohm speaker in my cab, I will need series wiring.
Here is my idea:
I clipped a bit out of the schematic for the graphic above. Hope the bits I added are readable.
The only mod to the combo amp would be the addition of a "direct speaker in" jack. Could be just like the one that the video guy put in his. This would avoid opening the case and voiding the warranty.
I would attach a lead from the "external speaker jack" to the extensions cab's "amp in" jack I would attach another lead to the "series out" jack which would go to the "direct speaker in" jack on the amp. So I would need two speaker leads rather than just one, but that should not be a problem. If I have done this right, this should be a series circuit with a 16 ohm load.
I used a switching jack for "series out", That should allow the cab to be used as a conventional 8 ohm cab if nothing is plugged in to the "series out" jack.
Does this look like it will work, or has Dyslexia Man struck again?
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