Adding a 2x12 cab to a Line 6 Spider III 120 Combo

[wilsa]

Hey all.

So a few years back my Fender Pro 185 died and I have just turned it into a 2x12 speaker cab for when get around to/can afford a tube head.

In the mean time I have a Line 6 Spider III 120 combo. It runs 2 60W solid state channels (is that the right word?) each to a 10 inch, 8ohm speaker.

What I am looking to do is add the fender cab to it but am not sure how this will work out and was wondering if anyone would be able to advise if it is a good idea or not. Here is the plan:

I will run each 60W channel to two speakers in series, one of the 8 ohm 10 inches and one to the 8 ohm 12 inches. This should create a 2 60W 16Ohm circuits I think.
So a couple of questions:
a.) What effect will having a 16ohm ciruit as apposed to an 8ohm circuit have on the amp? (From what I understand doubling the resistance is safe but will reduce the load sent, where as halfing the resistance will increase the load but possibly fry the amp, hence putting them in series and not parallel).
b.) If the above is correct what will happen to the reduced load? I think I read somewhere that it will result in quite a bit of heat being given off but not sure.
c.) I am 95% sure the speakers in the Fender Pro 185 have a resistance of 8ohms but could be wrong. It does not state on them what they are and I haven't been able to confirm on the net if that is the case. Has anyone had any experience with them?

Regards

Sam

[Cdog]

Hey Sam, welcome to the forum.

Doesn't the spider have an extension cab jack?
I'm not sure your idea will work, assuming they are all 8 ohms you could only get either 4 or 16 ohms per channel... either would probably kill your amp.

[wilsa]

Thanks for the welcome.

The amp does not have an extension cab jack which is a bit of a pain.

Yeh the main issue is that it would be a 16 ohm circuit but my electrical knowledge is slim so I have no idea what the consequences of this would be. From what I have read it can be done with tube amps but not sure about SS. May just end up running the amp to the 2x12s and see if they sound better than the 2x10s.

[Rog]

Those 026488s are Eminence 8Ω speakers.

[hamo]

Sell the Spider and get a cheap tube head?

[calling card]

Plenty more clever people here than me. As I understand it SS can tolerate open circuit on the speaker out where as tube amp would self destruct. I'm thinking 16ohm would be preferable to 4ohm in this case. If the spider is designed to handle 4ohm load it would be fine.
16 = quiet/cold
4 = loud/hot
8 =

[rocklander]

Plenty more clever people here than me. As I understand it SS can tolerate open circuit on the speaker out where as tube amp would self destruct. I'm thinking 16ohm would be preferable to 4ohm in this case. If the spider is designed to handle 4ohm load it would be fine.
16 = quiet/cold
4 = loud/hot
8 =

this

[wilsa]

Tried it out at a gig last Friday (small hall, about 80 odd people). Worked out really well, sounded a lot better with all four speakers than just through the 10s. Volume wasn't an issue either, didn't have it passed 4 or 5 (I think, I have no panel or knobs on the line 6 so have to guess)