Using rectifier as power amp

[jakeleigh]

Does anyone know why Mesa recommend to use the Vintage or Raw settings when using the Rectifier as a power amp?

Also, why doesn't the presence control work on the Modern setting if used as a power amp? I always assumed that the presence control works on the power section of the amp.

Thanks.

 

[RectoStudioGuy]

I'm assuming that the presence is in the final gain stage of the preamp section at that point. Just a guess, as I use the Recto Rec Pre.

 

[94Tremoverb]

That's correct. The presence controls are at the end of the preamp, but they're also fed from the negative feedback loop for the power amp. In the Modern mode, the feedback loop is disconnected. That's what gives the Modern mode it's loose, resonant tone, but it also leaves the power section slightly unstable, and if it was being used as a separate power amp that wouldn't be a good thing, as well as the presence control not working.

 

[Triple Cheeseburger]

i think the manual says to use the clean channel when using as a power amp

 

[jakeleigh]

i think the manual says to use the clean channel when using as a power amp

Well, my manual definately says channel 2 or 3, raw or vintage although modern is usable.

That's correct. The presence controls are at the end of the preamp, but they're also fed from the negative feedback loop for the power amp. In the Modern mode, the feedback loop is disconnected. That's what gives the Modern mode it's loose, resonant tone, but it also leaves the power section slightly unstable, and if it was being used as a separate power amp that wouldn't be a good thing, as well as the presence control not working.

Thanks for that 94Tremoverb, what exactly do you mean by leaving it unstable? Thanks

 

[94Tremoverb]

That it's prone to resonate or even self-oscillate, and can be sensitive to the resonant frequency of the speakers or cabinet, which might cause odd peaks in the sound or false overtones that you can't dial out with the preamp controls. This would generally not be a good thing for a power amp since it's supposed to cleanly amplify whatever input signal it gets. It does have an interesting character for a guitar amp - it's part of what give the Rectifier such a huge, aggressive tone - but you still need to be able to control it really.