Preamp Bypass in 1970's 60 watt Boogie

[Muso57]

I've just bought a Line 6 HD300 and want to use it as a preamp for my 1970s 60 watt Boogie Mk 1, # A652, bypassing the preamp stage so that I can use the power amp only. It has a beige vinyl covered cabinet, a cloth face and is equipped with a 12" Altec-Lansing 417-8H Series II speaker. It's panel has a pull out GAIN BOOST on the VOLUME 1 pot and BRIGHT BOOST and VOLUME 2 pot. It has zero reverb or EQ nor is it switchable between 60 watt and 100 watts.

I believe there is a preamp bypass input at the back but which one is it? Help requested please ......

 

[tonejam]

I'm not sure what input/output sockets are provided on your particular amp. On my Studio 22, if I wanted to bypass the preamp, I'd plug into "power amp in".
Good luck.

 

[Muso57]

I'm not sure what input/output sockets are provided on your particular amp. On my Studio 22, if I wanted to bypass the preamp, I'd plug into "power amp in".
Good luck.

Thanx for your reply, tonejam. At the back of my amp there is a labeled SLAVE output socket above it's pot, to it's right a labeled PRESENCE pot and, between it and the three speaker sockets, an unmarked socket. Could this be the preamp bypass input?

 

[jpdennis]

Muso57,

Did you go to this site and see the photo of that back? Maybe you can compare and then read the description. Other option is to call Mesa since they are the best source for an unmarked socket.

http://homepage.mac.com/mesaboogie/MarkI.html

Dennis