Roadster Combo Ohms question

[mikeweber74]

Hi All,

I just picked up a used Roadster combo and noticed that the speaker jack is plugged into the 16 ohm spot. Mesa site specs say it has 2 - 16 Ohm Celestion Vintage / Total Load = 8 Ohms. Does that mean it should be plugged into the 8 Ohm port? And if so, could there have been any damage done if the last person was running it from the 16 ohm port?

Thanks in advance for the help!

 

[mikeweber74]

then I looked at the zoomed in pic on the mesa site and they have the jack plugged into the 4 ohm spot. I'm confused...

 

[MrMarkIII]

The short answer: You can experiment with the different loads without damage - it's a Boogie and they're "robust", as the engineer-types say.
If you have 2 x 16 ohms in parallel, the 8 ohm jack is "normal".
The manual (also available at the website) says:
"Two 4 Ohm, one 8 Ohm and one 16 Ohm jack are provided for speaker interfacing. The Roadster is not very sensitive to speaker mismatches and will not be damaged by them, except that very low ohmage loads will cause the power tubes to wear faster. A single twelve-inch 8 Ohm speaker should generally be connected to the 8 Ohm output.

When using two 8 Ohm speakers, connect them both to the 4 Ohm outputs provided (because the total load is 4 Ohms in that case.)
(Yes, this is completely non-intuitive. But that's the way Mesa does it.)

Check out the information further back in this manual regarding speaker impedance and possible speaker hook-up schemes."

 

[mikeweber74]

Thanks for the reply. Yeah, I've seen the ohms diagram in the back of the manual. Its just that nowhere in the manual or on the back of the combo does it say what ohm speakers are used or if they're wired series or parallel. I guess I'll just go by the specs on the website where it says two 16 ohm speakers = 8ohm output.

 

[LithiumZero]

The 8 ohm jack is the correct one.