There is a number 1 and a number 2 jack in the back of the amp. Currently I have the main cable speakers plugged into the number 2 jack hole and the ohms at 8 and the amp is set to 50 watts. Do I change the main speaker to hole number 1 when I switch to 100 watts?

You're not removing or re-inserting any tubes, right? Just using a half/full power switch?

I believe that you don't have to move the speaker-plug around at all, and will want to have the impedance-selector set for whatever the total combined impedance of the speakers is, no matter if it's set to half or full power.

That is:

If they're a pair of 8 ohm speakers wired in parallel, the load will be 4 ohms.

If they're a pair of 16 ohm speakers wired in parallel, then the load will be 8 ohms.

If they're a pair of 8 ohm speakers wired in series, the load will be 16 ohms.

If in doubt, give Carvin a shout- call 'em at 800 854 2235 toll-free. They'll set you straight, for sure.

Yup, speaker outs are wired parallel, so it doesn't matter which jack you use. In fact, you could disconnect the internal speaker and daisy-chain two 8-ohm cabs from a single output jack (using parallel inputs on the cabs) and the ohm load would be the same as if you'd connected each cab to a separate output jack.(4 ohms)

You'll want to switch the Ohm setting to 4 if you're using the internal cab AND an external cab-most single-speaker cabs that are designed for guitar are 8-Ohm cabs, but multi-speaker cabs can come in other flavors; 4X12 Marshall cabs are usually 16 ohms, for instance, so if you wanted to use your amp to drive a Marshall stack, you'd disconnect the internal speaker and connect each 4X12 cab to a speaker output OR connect from either output to the input of the top OR bottom cab and jumper to the next cab; either way, two 16 Ohm cabs in parallel equates to an 8 Ohm load, so you needn't move the Ohm switch in this case. Some amps are more forgiving than others if you mess up the impedance (Ohms) setting, just remember to NEVER operate a tube amp without a load connected. (this is good safe practice with any kind of amp)

A good thing to also remember is that impedance will roughly halve with each additional speaker you hook up; with your impedance switch set to 4 Ohms, you could drive three 16-ohm Marshall cabs, but there's a practical limit to how low you can go, most tube guitar amps shouldn't be operated south of 4 ohms-you can tell which ones, they won't have a 2-Ohm setting on the impedance switch.(some bass amps are capable of pushing 2 Ohms or even 1.5) You can run mismatched cabs if you know how to calculate the impedance, but it's not recommended and will most likely void your warranty, anyway.

The half-power switch does not affect the speaker load, but will affect the tone and gain structure; if you're using multiple cabinets, you'll get more headroom and punch on the 100 watt setting.

Hi guys, Im a newbie. Nice to join this forum.

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Hi, and welcome, Anna Lee!

What are you being a newbie with? I mean, what kind of music are you into playing, what kind of guitar do you have or want to have?