The Phase Inverter

This is almost equal to the MESA PI, that in its turn is very similar to the Fender design.

When the MESA/Fender switch is at the Fender position, you have a Presence control like in a Tweed Fender or in an early Mark. You have also an added FOCUS control that varies the amount of negative feedback (and so the speaker damping).

When the MESA/Fender switch is at the MESA position, if you turn the Presence knob to a preset position of about 2/3 of its range, then the FOCUS control will work like the Presence controls in later Marks. It's a darker sound. Of course, you can ignore this preset position and tweak both knobs at the same time to get sounds you can't in the Fender or MESA originals. It's not something awesome, but it can help dial the sound you want.

I used a 12AT7 for the PI, but you can try other tubes like a 12AX7 or 12AU7. The 12AT7 is my favorite for this position.

Back to the AR-15 index page.

This page hosted by Get your own Free Homepage