Adding A Cabinet Impedance Question

[HowellsP]

I'm presently running a Peavey Valve King 212 100 watt all tube combo amp and want to add another 2x12 cabinet. The new cabinet is a Marshall 2x12 130 watts at 4 ohm. The Peavey has a 3 way switch on the back for 4,8,and 16 ohms, what would I set it at for the new Marshall cabinet?

[4x12]

Well unless theres something I don't get here, If the cab is wired for a total of 4 ohms then select the 4ohms on your amp...

[HowellsP]

No it's actually more like something I don't get. I have never done this before so I don't know how these things work

[dr_iggi]

Unless he wants to use both the internal speakers and the cab and the impedances do not match.

The internal speaker of my Zinky Blue Velvet is 16-ohm. When I use a 2x12 8-ohm cab together with the internal speaker, I set the knob to 8-ohm.

I can also set the knob to 4-ohm if I want the internal speaker and the 2x12 cab to give me a bit more low end and a smooth tone. Now Zinky trannys are designed for this.

I am not sure about the PV. If you are only using the cab, simply match the impedances.

EDIT: do NOT turn on the amp unless the internal speakers and/or the cab is/are connected.

[HowellsP]

Yes I want to use the Peavey amp and the other cabinet at the same time

[JSX/6505]

That's tricky. Is the Marshall cab only 4 ohms? Not 16/4 mono and 8 ohms stereo?
What ohms is your VK set to when using the interal speakers? 16?

Mismatching impedances isn't really a good idea. Your tone and output will suffer. I would have bought a 2x12 cab that was the same ohms as the amp/combo I was planning on using with it. Example: 16 ohm amp/combo into a 16 ohm cab = 8 ohms setting.

[Glasstone Amps]

What is the impedance of the internal speaker on the amp?

[HowellsP]

The amp combo has two 16 ohm speakers

[Glasstone Amps]

The amp combo has two 16 ohm speakers

And they're probably in parallel for 8 ohms total for the internal speakers. If you then connect another 4 ohm cabinet in parallel you would have a combined impedance of 2.67 ohms. You would want to set the switch on the amp to 4 ohms. It's not usually a problem to have a lower impedance load than what the amp is set to.

[guitarman2]

That's tricky. Is the Marshall cab only 4 ohms? Not 16/4 mono and 8 ohms stereo?
What ohms is your VK set to when using the interal speakers? 16?

Mismatching impedances isn't really a good idea. Your tone and output will suffer. I would have bought a 2x12 cab that was the same ohms as the amp/combo I was planning on using with it. Example: 16 ohm amp/combo into a 16 ohm cab = 8 ohms setting.

Yes. This is what I'm doing with my setup. I have a Dr Z 2X12 combo, internal speakers 8 ohms. I added a 2X12 Z best cabinet 8 ohms I run both the internal speakers and the cabinet to a y adapter and plug in to the 4 ohm jack.

[warplanegrey]

do you have the manual?

it should tell you in there.