Speaker Combination Question

[TFridgen]

I want to pick up a couple of 8ohm g12k100's. I will be pair 1 k100(8ohm) with 1 v30(16ohm) in one 212 cab and then the other k100(8ohm) with another v30(16ohm) in another 212 cab. My question is, how do I hook these up to my Roadster's speaker outs? These combinations don't give me nice clean numbers that match the output jacks on the Roadster's back panels. Also which jack would I connect only one of these cabs to? Any help would be greatly appreciated!

 

[94Tremoverb]

If you haven't bought them yet, get 16-ohm K100s, not 8 ohm. That will give you two simple 8-ohm cabs and you run them from the 4-ohm outputs on the amp.

If you already have the speakers, you can use them, but you will get two 5.33-ohm cabs. This isn't really a problem because in each cab, 2/3 of the power will go to the 100W speaker and 1/3 to the 60W speaker (which is the right way round) and gives a 180W cab in total. You would normally treat this as a 4-ohm cab, but you can run two of these from the 4-ohm jacks too, the combined impedance will be 2.66 ohms which sounds very low but is actually only a 33% mismatch from 4 ohms. Mesa amps are usually fine with mismatched impedances.

 

[YellowJacket]

I'd run the k100s in one cab and the v30s in the other.

 

[94Tremoverb]

I would agree with that, because it gives you two cabinets with 'proper' standard impedances - you can still run them together if you want (from the 4-ohm jacks). But this won't work if you want the option of using one cab or both, with the same sound...

 

[YellowJacket]

If you want to run a speaker combination in each cab, the best advice is to get 16ohm G12K 100s. Running 2 5.33 ohms would be better if you build a series box and connect both boxes to the 8ohm output on your head via one speaker lead. The series box will give you a big series parallel 4 x 12 wiring. Hmm, one other option: Wire up each speaker to a separate jack so you have two speaker jacks on each cab. You can label them as 8 ohm and 16 ohm. When running a 2 x 12, you can run the 8ohm speaker into the 4 ohm output on the amp and the 16 ohm speaker into the 8 ohm jack on the amp. No mismatch.

Then, you should build a series box and a parallel box. (I've done it, it isn't that hard. Each box needs a trip to the hardware store and the music store. Some speaker wire, a drill with drill bits, and 3 quarter inch jacks. You just wire up the thing, put it together, and voila) The next thing to do is to buy some decent speaker leads to use as jumpers so you can shorten them up significantly.

This is what I'm thinking. Build one series box and one parallel box. Wire up the 16 ohm speakers in parallel for 8 ohms and wire up the 8 ohm speakers in series for 16 ohms. If you do this, the parallel box goes into the 4 ohm output on the back of the amp and the series input goes into the 8 ohm output on the back of the amp. Sure it is a complex wiring method but it does help you avoid the ohm mismatch if that is what you want.

Of course, buying all 16 ohms speakers would be much easier . . .

 

[TFridgen]

I just can't seem to find 16ohm k100's. I'm wondering if they're some kind of rare breed or something. If any of you guys see a couple of them, PLEASE let me know!!

 

[94Tremoverb]

Ah... you're right. According to Celestion's website they only come in 8 ohm.

In that case, you may be better to consider other models. The Classic Lead 80 and the Mesa C90 (which you can only get from Mesa) both come in 16 ohm, are in the same general ballpark as the K100 (H magnet, clear/deep tone) and both sound good paired with the V30. Or, you could look for some old G12H-100s from the 1980s, which are closer to the K100 (and a really great speaker) and did definitely come in 16 ohm. They aren't too rare because Marshall model 1982 'Heavy Duty' 4x12"s from about 1984 to 1990 contain four of them...

You *can* use 8-ohm K100s and 16-ohm V30s together if you really want to, but it will definitely cause some compromises.