I finally got all the parts is parts put together for my DIY power supply design:
 






 
 

Looks sharp, Mike.  When are you going into business? ;-)
 
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Wow, very clean build. I recognize the Edcor transformer and the supply layout looks very much like a guitar amp supply. That's a huge amount of filtering. I really like the chassis. What are the specs Mike?

Hi AT,
 Thanks, maybe when I try to "retire"... but find I need some money for the grocery store. :-)
 
Hi John,
 Thanks. I have you to thank for introducing me to the Edcor brand. The transformer is 120vAc to 120vAC at 50mA and 12.6vAc at 1000mA. The circuit is set up for a 120vDC B+ and a regulated 6.3vDC heater supply. I have a switch that can send two additional 6.3vDC signals down the 7 conductor mic cable to motivate switching relays that splits the 120vDC B+ to the mic capsule for the extra polar patterns. The tube can handle a lot more B+ but the mic capsules need to stay down near 120vDC max. I haven't decided exactly what tube I'll use so I made the B+ feed adjustable by using a 5 watt wire wound potentiometer as a series resistor before the last filter stage.
 
 I bought the case from a DIY supplier and then I did the math for the circuit and ordered the transformer and eventually all the other parts. The part that took the most time was figuring out how to fit all the parts into that case. I made the circuit boards out of garolite G10/FR4 and placed all the eyelets etc after I determined that I could actually fit them alongside the transformer. I'm hoping Edcor will make me a smaller transformer for future builds, They had worked up a price for a custom build for me but now they say they have ceased making small run custom orders due to schedule constraints.

Awesome! I want one!

Thanks Geoff,
 A solder iron and a box of parts is parts and you can have one too... :-)
 
...and then you have to build the microphone. That's the next phase of the project. :-)

This is so cool Mike. I can't wait for the mic build.

What type of tube do you require Mike? Dual triode or Pentode?

 From what I understand the active stage in a condenser mic doesn't have a lot of gain. The primary role is to provide an impedance converter for the very high impedance of the capsule so that you don't have a drastic voltage drop when the mic sees the actual preamp. 
 
 Most tube tube mics use a single stage. The tubes used vary. It is common to either use a pentode, or one half of a dual stage triode. A very few modern tube circuits use two stages in an effort to reduce the noise floor, but many people react to that idea with concern that the resulting sound differs from the traditional tube character. These newer circuits either use two pentodes or both sides of a dual stage triode.
 
 Tubes that have been used by the traditional designs include the EF86 pentode and the 6072 dual triode.
 
 The Germans famously used the VF14 steel case pentode in the U47 mic but that tube hasn't been built since circa 1960. There is a German tube known as the AC701 that is said to be the only tube ever developed exclusively for a condenser microphone. It has the ideal impedance for a circuit mated to a condenser capsule. That tube isn't made any more.  The traditional German VF14 and AC701 tubes are very expensive these days so they are mainly used by people trying to keep high priced antique mics at factory spec.
 
 Contemporary traditional designs employ 6072, (12aY7), 12AT7, and 12AX7 dual triodes. A popular tube is the mini 5840 pentode. There are many nine pin pentodes used; EF86, EF800, EF802, EF804, and the E80F. Some of those pentodes were designed as RF tubes but they work good in the audio range too.
 
 I have collected a stash of the pentodes to add to the triodes I already had. The tubes I will focus on are the 6072, 5840, and E80F.
 

WOW!
All groupies must bow down!
May I sit humbly at your feet and kiss the hem of your robe?
WOW!
T