This has been a lingering project for me. Not of the utmost priority since I don't use the mic very often. Probably because it never sounded very good. I bought the mic in 2005(?) from a local music store. It was supposed to be good bang for the buck. It cost roughly $400 brand new, if memory serves. The company was called SE. I believe that stood for "Studio Electronics" and I think they went out of business several years ago. I never used the mic for much but I always thought it looked cool. 8)
Last year, I decided to make it a project. Phase one - I bought the RK-47 capsule from Microphone-Parts to replace the stock one. https://microphone-parts.com/products/rk47-microphone-capsule
What a difference that made! The original capsule lacked focus and had a very wide pattern. Just overall not good frequency response/character either. One thing I noticed was that the output of the mic went up considerably. My guess is that the amp was designed around an inferior capsule and the extra gain was probably an attempt to compensate for that.
I traced the circuit board inside the mic's body and drew it out the best I could. Drawing schematics is not my strong point. Some of the components.... I was unable to figure out what they were. I search the numbers printed on the body and came up short on (what I believe is) the JFET. It has an output transformer but I have no idea what the specs are.
Anyway, do any of you microphone savvy people recognize this circuit? Or recognize what it would be if it were drawn properly? It may not be conventional but.... my experience with these things is that most things are "inspired" by something else. Especially with budget gear. I feel like I have scoured the net looking for something that resembles this amplifier but most of the ones I find like Neumanns/Sennheisers/AKG/etc. seem way more involved. I've heard that the value of the cap going to the JFET can be changed to lower the gain. I'm guessing the 1uF cap sitting between those two 1Gigaohm resistors? Not sure though. I've built mic pres, compressors, guitar amps, etc. I can barely understand what is happening in those circuits but mics are super foreign to me.
I want to either modify the existing circuit to lower it's gain or replace it with something else. I'm leaning toward replacing. I looked at some of the mic boards on that same website and from what I understand they are all very good. I also like the idea of building something. Possibly something from the project specific area here.
Thanks in advance for opinions and feedback,
-Aaron
Last year, I decided to make it a project. Phase one - I bought the RK-47 capsule from Microphone-Parts to replace the stock one. https://microphone-parts.com/products/rk47-microphone-capsule
What a difference that made! The original capsule lacked focus and had a very wide pattern. Just overall not good frequency response/character either. One thing I noticed was that the output of the mic went up considerably. My guess is that the amp was designed around an inferior capsule and the extra gain was probably an attempt to compensate for that.
I traced the circuit board inside the mic's body and drew it out the best I could. Drawing schematics is not my strong point. Some of the components.... I was unable to figure out what they were. I search the numbers printed on the body and came up short on (what I believe is) the JFET. It has an output transformer but I have no idea what the specs are.
Anyway, do any of you microphone savvy people recognize this circuit? Or recognize what it would be if it were drawn properly? It may not be conventional but.... my experience with these things is that most things are "inspired" by something else. Especially with budget gear. I feel like I have scoured the net looking for something that resembles this amplifier but most of the ones I find like Neumanns/Sennheisers/AKG/etc. seem way more involved. I've heard that the value of the cap going to the JFET can be changed to lower the gain. I'm guessing the 1uF cap sitting between those two 1Gigaohm resistors? Not sure though. I've built mic pres, compressors, guitar amps, etc. I can barely understand what is happening in those circuits but mics are super foreign to me.
I want to either modify the existing circuit to lower it's gain or replace it with something else. I'm leaning toward replacing. I looked at some of the mic boards on that same website and from what I understand they are all very good. I also like the idea of building something. Possibly something from the project specific area here.
Thanks in advance for opinions and feedback,
-Aaron
