MXL 770: Finally it’s a YES

I never get over feeling excited when an inquiry comes in about a mic rebuild. But a certain number of them turn sad when I realize they are asking about an MXL 770.

The 770 is an extra tall version of the 990 but the cool thing is that it has switches for Pad and Filter functions. The 770 (like the 990) is a Transformerless Schoeps-style mic with the same (or similar) small capsule as the 990. It also comes with all the same shortcomings.

I’ve wanted to do a Transformer-Coupled board for the 770 for a long time. There were two technical hurdles to overcome for me to design the board:

• Sourcing switches that would fit on the board and extend through the body.
• With all the room that those switches take up, figuring out where to put the transformer.

Fitting it all in

Since the 770 does not have a separate switch board like the Sterling ST55 or MXL 5000, it’s necessary to fit both external switches on the main board with all the other parts. Of course, I also wanted room for the optional pattern switch. The problem is that those switches take up a lot of real estate. The solution was to mount the switches on the bottom and most of the other parts on the top. But that still leaves no where to fit the transformer.

Transformer Daughter Board

Fortunately, the transformer mounting board that I already had for other common mics fits in the space and already has mounting holes for some stand-offs.

Production Ready

The 770 is now fully supported and available for rebuilds (your mic) or pre-mods (my mic) in the store. I’ve managed to find a few bodies on ebay and have built a few up in various configurations. One of them is now my new favorite in the studio for vocals. I am pretty sure that all this will work with a 990-s (s for “switch”) and the 990 “patriot” which also has switches. I’ll keep my eye out for donors and try it out.