2x Speaker Cab switch

[moonbird]

Wanted to run this past the brain trust here before actually trying it on a cab.

I like to mix and match different speakers from different makers in my 2x cabs. Problem is I always end up wanting to hear a particular speaker with a particular amp either as a test during tweaking or out of plain ole boredom. I also have been intrigued lately with discussions on some of the boards I watch about purposely mismatching speaker loads for differing tones. Doug Hoffman recently stated (somewhere) that it is pretty safe to experiment with differing speaker loads that are no higher than 2x nor less than 1/2x the intended speaker impedence.

Problem has been multi-pole switches have always intimidated me, so I never did anything about it. Well I decided to gave it a try. The switch I am planning to use is a heavy duty 4-pole 4-throw rotary Russian switch I bought a while back on the bay. No specs were published, but it looks up to the task. I will post a picture of one.

Anywho - This design is trying to offer Serial, Parallel and separate access to the two speakers in the cab. In cabs having two 8 ohm speakers for example:

          Switch position 1   --  Two speakers Serial connection    = 16 ohm load (via Jack "A")
          Switch position 3&4 -  Speaker A only                          = 8 ohm load   (via Jack "A")
          Switch position 3&4 -  Speaker B only                          = 8 ohm load   (via Jack "B")
          Switch position 2   --  Two speakers Parallel connection  = 4 ohm load   (via Jack "A")

So for an amp that wants an 8 ohm speaker load - this switch would provide all of the "acceptable" loads.

Let me say sorry in advance for the kooky way I drew the rotary switch. But it made it easier for my little brain.

Do I have this drawn up right??  

[PRR]

Does what it says.

The top-left pole does the same in all positions, is not needed.

The 4th throw is of course also redundant.

(Both come from getting a 4-P 4-T to do a 3P3T job, for cheap.)

In Pos 1 and 2, amp jack B is not loaded. You did bother to ensure extra position 4 was loaded on jack A, so this must be an issue. However it isn't easy to make jack B "safe" in all positions. Since top-left pole is empty, you could lift all that redundant wiring off it, and re-purpose it to throw 10 ohms 50 Watts dummy resistor on jack B in pos 1 and 2.

[moonbird]

PRR --

Thanks so much for looking at this. The dummy resistor re-purpose is a GREAT idea and a good use for the redundant lugs. Whew - I guess I am starting to figure out multi-pole switches after all!! 

[moonbird]

Here is version 2 - with the Jack B safety resistor (10 watt metal case type).