Speaker connection question

[riverrick]

I have a Marshall 410H JVM head going into a MG series 4x12 cab. The speakers are rated at 8 OHM's There are a 5 different inputs to connect the head to the cab. I have it connected in the 2x16 OHM input. the other inputs are: 1x16 OHM, 1x4 OHM, 1x8 OHM, 2x8 OHM & 2x16 OHM. So which one is the correct place to plug in??? Or does it matter.

[bcdon]

It's based upon how the speakers are wired up (series vs. parallel). However, if the cab says 8Ohms like this one:
http://www.guitarcenter.com/Marshall-MG-Series-MG412CF-4x12-Guitar-Speaker-Cabinet-107201816-i2034726.gc

then I think you should just connect it to the 1x8 as it states it is an 8Ohm cabinet which I read as the overall impedance.

I have a Mesa 2x12 that has two 16Ohm speakers, but they are wired in parallel so the effective load is 8 Ohms so I connect it to the 8 Ohm output jack.

[riverrick]

OK....thanks Don

[markb]

4x12 cabs are usually wired in series/parallel. That is two series pairs wired in parallel... So, take 2 8 ohm speakers wired in series for 8x2 =16ohms, now add another pair in parallel and you get 16/2=8 ohms. Really, this is much harder to type than understand. I have no electronics background beyond A level physics. I worked this stuff out from basic principles while dealing with 4x12 cabs with blown speakers and trying to work out which hole to put the little jumper pin in on my AC50/AC30 heads :eek:

The short version is if you have a 4x12 cab filled with 16ohm speakers it will be 16 ohms. If 8 ohm speakers, 8 ohms. Manufacturers often confuse the issue these days by offering stereo wiring.

[deeaa]

My Cab is wired to dual 8 ohms but I use an Y cable that sums them into one 16 ohm output of the amp for Mono operation since the amp has no dual 8ohm outputs.

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