fabricating the chassis extension

 


The new second level panel will be formed from this 1+1/2" aluminum extrusion.  The front panel will extend across the full 24+1/2" width; there will be a 6" section in back which carries the two 12AX7 tubes.

As you can see, the best place to position this back section turns out to be offset from center towards the right, more or less underneath the "norm" channel EQ and the phaser knobs.  In order to keep critical audio wire lengths a bit shorter, I'm going to re-arrange the ordering of the control subgroups within this panel.  The VTX preamp controls (which are just switching logic, no audio) will be to the left, then the AB763+ preamp in the middle, then the power amp controls to the right.  This will put the input jack for the AB763+ preamp right near the center, rather than at the left end, which is a bit strange, but I think it's the best way.  The McGrath logo will go to the far left, then the three subgroups will be closely spaced in the given order.

I've added a switch for nfb in/out to the power amp.  No reason not to have this switch, all my other power amp designs have it (if they have nfb at all).






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