EF86 Cardio/Omni G7/U47 style

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dbelousov

Well-known member
Joined
Jul 1, 2019
Messages
113
Location
Moscow, Russia
Hello!

I have some unused parts and an enormously huge mic body so I decided to experiment with the EF86. The circuit is cardio/omni only. It helps to make it as simple as possible and compatible with any standard Chinese PSU. Thus, I decided to use its pattern switch as a polarization voltage source.

I'm not very familiar with the tubes and absolutely unfamiliar with this one,  so there is my homework. Did I miss something?
 

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Thank you.

The main reason is to untie it from B+, so it will be possible to use it with almost any Chinese donor PSU.  One will always able to find something in the acceptable 50-60V range just with the pattern switch. The byproduct of this approach is this slightly simplified circuit without dividers so it's very compact and easy to build PTP just around the socket. I have plenty of space this time and don't want to make something extremely tight, but I think it's a good idea for some compact bodies if somebody else decides to build it.
 
If you have a switch on the mic body and you free up pin 3 or 7, why not externally supply 0-120V to the rear diaphragm? That way you can switch from cardioid only to variable pattern. I did this with my U47 in one of Dany's bodies and it works great. I also did it in my M49 with a relay instead of a switch.
 
I like the relay but want to save it for an another project. I have a great and almighty, but slightly dead 460 in my closet, so it's a good option because I'm going to build CK12 allrounder one day. I think I won't be using anything except for cardioid with this build, but capsules usually have two sides so I don't want to waste the second one in vain :)
 
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