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Speaker Cab Ohm Ratings


gtrwiz

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OK, I've posted this on a couple of the guitar forums, and the lack of response tells my that the kids over there would rather discuss porn than guitars.:rolleyes: So let's see what ya'll can come up with. (no pun intended)

 

I have a 2x12 cab with one greenback and one vintage 30. They are wired so that I can use them at the same time or plug into each one seperately. When I use the speakers together they have an 8 ohm load, seperately 16 ohm load.

 

My Delema: I want to, occasionally, use a different amp with each speaker, but my Matchless DC-30 only has an 8 ohm output. Will this blow the speaker, or otherwise effect the tone? Is there any way to convert my 8 ohm output to 16?

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Short answer to conversion: no.

 

If I understand you, using one or the other gives 16 ohms, and the 2 together in parallel gives up 8 ohms? This, of course, means that your speakers are 16 ohms each.

 

Your only option other than running them in parallel (or buying different speakers) is to wirh them in series: + lead from amp to + on speaker 1, - from speaker 1 to + speaker 2, then - from speaker 2 to the - lead of the amp. This will double, rather than halve, the resistance & you will wind up with a 32 ohm resistance.

 

NOW: given all this BS, :D you should be OK running the 16 ohm speaker alone. Generally, it's best to match for optimum performance - but what you want to avoid is running too low of a resistance. You would NOT want to run a 4 ohm or 2 ohm load from that amp - you'd definitely do some damage. However, going the other way shouldn't be a problem.

 

*NOTE* I do not have experience with Matchless amps. I'm just putting out the general amp/speaker impedance theory. You might want to ask Matchless what they think, just to be safe.

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To summarize my buddy, Chris' post;

 

You can run an 8 ohm output into a 16 ohm load (speaker), but your actual power output will be far less than into an 8 ohm load.

 

Running an 8 ohm output into a lower (say 4 ohm) load is dangerous because it is the equivalent of running down a steep hill. First it seems easier to run.. until you reach speeds such that your legs can't keep up and you wipe out. Running a higher output impedance into a lower impedance load will burn out the power transformer as it puts out more power than it's rated to supply.

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Just confirming what's been said above...running 8 ohms to a 16 ohm speaker is most likely safe, but will reduce level.

 

You might check with Matchless. They may be using a tapped transformer that is capable of matching a 16 ohm load, if you choose a different tap. Or, you may able to replace the output transformer with one that's compatible with your speaker -- they may even have one in stock you can install yourself. It's worth a try...

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