Mark II-c+ 9-ohm out into higher ohm loads

[RocketRick]

1. I was told I can use the amp into higher ohm loads but not lower ohm loads.

2. That doing so may overheat the amp and may cause tubes to burn out faster..

Are these true and are there other considerations?

thanks :?:

 

[dodger916]

Mesa specifies a 2:1 mismatch into a higher load as safe. For instance, you can run an 8 ohm load (speaker cabinet) from the 4 ohm amp tap; 16 ohm load from the 8 ohm tap, etc.

It is said that running it the other way around (4 ohm load from the 8 ohm tap) will cause the tubes to burn faster. However, there is a school of thought that says it is safer for the transformers to run it this way, and running into a higher mismatch (as specified by Mesa) it is potentially more dangerous for the transformer.

Here's the link for viewpoint the suggests running higher load off a lower tap is potentially dangerous: http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#mismatch

Bottom line: a 2:1 mismatch into a higher load (8 ohm load from the 4 ohm tap) will be safe whichever theory you subscribe to!