M50 diy pcb, did I do a good job?

Hi all,

Not to belabor you all with this M50 mic project, but I'm getting so close now! Can you please tell me if you see any errors for this PCB layout I made? I should probably call this a component layout as I probably won't etch this and will go point to point. Who knows...

Anyway, here it is, as well as my modified schematic for the 5703WB. Things are looking REAL good. Have the capsules (KK83), transformers (Cinemag CM-2480 16.5K : 150 (10.5 : 1)), PSU design done (ended up bastardizing Max's PSU, no regulators though) with parts list, PSU boxes, yada yada.

So I did my best to keep all the high impedance stuff away from everything else. The two spots marked "capsule" will be raised delrin posts, and all connections at that point, then to the capsule, are raised off the PCB. The tube grid lead will go straight to the top delrin post, insulated with teflon. Heater leads from the tube will have to go underneath the tube, insulated of course. Am I better off running my traces up to where the leads exit the tube instead?

PCB will measure 60mm round, close to the original.

Hi,
not directly to your posting, but these pictures might help you to improve your layout. It´s my M49.

schematic M49:



closeup:



sideview:


Good luck.
kind regards
Bernd

Hey thanks a lot! These are great pics!! Answers a lot of questions, like C5 on the underside next to the tranny. Neat plastic RF shield on top(rectangular piece), is this in addition to the stock plastic cap that goes on top of the entire PCB, or this an earlier mic?

Hi,
yes, your right. The plastic cover with the capsule on top is not shown.
regards
Bernd

Why are the leads of the tube coiled up?

A. Desire to leave the full lead length intact, so coil it up to save space.
B. Heat sinking effect for when the tube is soldered in place to protect the tube.
C. Reduction of RF effects (I doubt that.)

What is the teardrop shape contact for near R11? I'll guess that it's for disconnecting one side of the capsule from the signal path...

A) B) Yes
As you said, disconnecting backside of the capsule.
regards
Bernd