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Grateful Dead Music Forum

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 #154882  by Deadhead85
 Mon Dec 12, 2016 1:51 pm
I have a Mesa Boogie MKI combo, and am throwing around the idea of adding a power amp. I know its capable of being done, as the Dead have done in the past. I was wondering though, how it would be done? What would it consist of? Any modding to the amp head needed? Thanks yall!
 #154885  by hippieguy1954
 Mon Dec 12, 2016 3:05 pm
Deadhead85 wrote:Yes is does. I currently use the effects loop for a Rocktron Hush IIB for noise control.
The effects loop "send" is a line out of the preamp section of the combo. If it is line level (which it probably is), you can run an instrument cable from the send to any external power amp. The return would not be used. That goes to the power section of the combo. Also, you do not want anything between the line out of the send and the power amp you use.
 #154886  by mkaufman
 Mon Dec 12, 2016 3:43 pm
I have a Mark I head and have looked into using a McIntosh power amp. I've read, and have been told that you can't leave the Mark I speaker out disconnected without risking damaging the amp. I think there's a device which can be connected to absorb the load?

ace
 #154887  by TI4-1009
 Mon Dec 12, 2016 3:47 pm
For my Jerry stuff I go out the effects loop of my Mesa Lonestar Classic to my MC50, from there to my JBL cab. Works fine.

I don't know how critical it is, but I make sure to keep a speaker plugged in to the Mesa combo so the power section sees a load- even though the signal isn't going through the power section. I can't remember if that's more important with tube or solid state?
 #155295  by TI4-1009
 Wed Jan 18, 2017 3:22 pm
pablomago wrote:My MK I RI has a Slave out which comes off the output transformer. That's what I'd use to run a power amp.
Just a caution that the slave output jack is the signal from the preamp and the power amp. It's a lot more powerful than the measly little preamp signal and it would include any tone shaping that the power amp section might add. If you just want the preamp, use the loop out and- as always- read the manual. Boogie manuals are pretty detailed. And be sure your nice expensive Mac can handle that big signal before you....