Some question from noob about capsule rk-12

[Андрій Чубака]

hello guys. I have some capsule rk-12 and want build some mic with it. I am already made some trying with it but i have no succses. I build standart opa alice circuit, but level of noise is very high and level of mic output is very low. With second circuit situation about same. And I don`t know what i can do next for starting this capsule. I using focusrite solo 3 gen. I tested it with small electret mic and it is working good. maybe anybody know some solution with trasfomerless and tubeless circuit for at least starting this capsule

 

[Khron]

OPIC LDC

 

[Андрій Чубака]

thanks maybe i will try

 

[Drosselmeier]

maybe anybody know some solution with trasfomerless and tubeless circuit for at least starting this capsule

Easy circuit, friendly boss from Uzbekistan thread ))

 

[oscarhuang]

Did you install DC-DC Hex Inverte？

 

[Андрій Чубака]

I have one and i try it with alice opa. But i guess main problem here not with it beacause wifh dc dc hex sound from mic is about same. Bit more low noise and mic output is also very low.

 

[oongbac]

I have one and i try it with alice opa. But i guess main problem here not with it beacause wifh dc dc hex sound from mic is about same. Bit more low noise and mic output is also very low.

Did you omit and install jumper in position of D8 and Trimpot of voltage multiplier board?

 

[Андрій Чубака]

I have dc-dc hex from rode nt1a circuit

 

[Андрій Чубака]

here is example of sound from alice opa first part without dc dc hex second part with it. I used clicking of fingers for creating some sound but mic output is very low

 

[oongbac]

I have dc-dc hex from rode nt1a circuit

Ah… I thought you used Jules’s pcb. Let’s wait other replies.

 

[rock soderstrom]

here is example of sound from alice opa first part without dc dc hex second part with it. I used clicking of fingers for creating some sound but mic output is very low

It sounds to me like the capsule is not in a closed Faraday cage and therefore extremely loud noise is amplified. Is the capsule in a closed microphone body? Do all these body parts have direct contact with the ground? Electrical continuity checked?

 

[Андрій Чубака]

No i tested capsule in plastic box. So important place it in microphone body?

 

[rock soderstrom]

No i tested capsule in plastic box. So important place it in microphone body?

Yes, very important! It will not work without it. You need a grounded Faradays cage (=metal microphone body) around your capsule. This will solve your noise problem completely.

 

[Андрій Чубака]

Thanks. I will do it befote trying anything esle.

 

[Icantthinkofaname]

Thanks. I will do it befote trying anything esle.

This will be all you'll need to do. Your getting an electrical hum because you didn't properly shield the capsule. Placing it in a metal body with a metal headbasket will get rid of the issue. It's like when you get noise in a guitar because the pick up cavity isn't properly shielded.

The exact same thing will happen if you plug in a microphone and take the body tube off.

 

[Андрій Чубака]

yes it is really working thanks

 

[Андрій Чубака]

Jules’s pcb

Maybe anyone have this Jules pcb circuit diagram? now all working here but I dont have good quality of sound. Looks like when I add hex dc dc voltage to capsule low frequencies just gone. And without additional voltage on capsule sound is not so bright and level of output is low.

 

[neowalla]

This Instructables from Jules has links to the PCBs, (including the hex inverter), BOM, and schematics, I believe. Plus a build video. I built two of the dual output ones and one of the cardioid-only mics. They're really quiet and sound great.

 

[Андрій Чубака]

For me now important how conect opa and hex pcb. I try made some full circuit diagram. So as I think ground go to ground and to XLR1 on both pcb then tr3 from hex to vcc_a1 on opa pcb. But I not sure about Pol from hex pcb and vcc_a2 on opa pcb. Vcc_a2 go dirrect to 8 pin of opa1642 and it is pin of power suply opa1642. There only can be up to 40 volts from datasheet. And zener diod 12V from opa circuit create 12 volts direct to pin 8 on opa1642. So I clearly not understand how I must conect this 2 pcb.

Maybe Pol from hex pcb just go to the ground of mic insted of ground of opa board and vcc_a2 from opa pcb just not in use. Pleace let me know how is corect.

 

[Андрій Чубака]

Looks like I found answer. So I have opa pcb almost same as I need and hex pcb I will do new. Lets see what I will have from this. I guess it is will be my last try. THis capsule under 20$ price so I not sure about I can have from it something really good.