Building OPA Alice with KM84 coloration. The mic of the new century.

[Papa Tango Charly]

Hello to you all. I’m vocal coach. From my point of vue Alice Opa microphone is one of the top 4 of the microphones I like the most.
With a 34mm capsule C12 or K87 , the Alice Opa circuit + hex inverter is a great microphone. I love this circuit.
I am also a fan of the KM84 with a large C12, K87, K7 or M7 capsule. (also in my top 4)
I would like to create an Alice + Hex inverter circuit with an OPA amp and add a transformer to give the color that KM84 have
This would solve the problem of the bias and it would add some db to the output signal VS KM84
Would it be possible to build a KM84 with a OPA amp or would it be possible to add a little transformer in the Alice circuit?
This could be the perfect mic
What do you think? is there such thing anything existing in the market?
Best

 

[Khron]

This would solve the problem of the bias and it would add some db to the output signal VS KM84

Who says you can't add a bias booster circuit, to a KM84 board?

Would it be possible to build a KM84 with a OPA amp or would it be possible to add a little transformer in the Alice circuit?

Opamps, even more so than discrete circuits, don't really care what they drive. But for that reason, there might be that much less "interaction" between the circuit and the transformer, so you might not get as much "colour" as you might expect (which may or may not come from the JFET itself in the KM84 circuit, rather than the transformer).

 

[Papa Tango Charly]

I guess i will keep using my 610UA preamp to shape the sound. Thank you khron

 

[kingkorg]

Opamp will saturate differently than single stage fet (km84) once it gets closer to clipping point. Opamps (in my experience) tend to have lower thd overall but have sharp knee once they start saturating, and go into hard clip very fast.

It's not just about transformer, it's about fet-transformer-preamp interaction, and impedances between these. Fet into 9:1 transformer will interact differently than opamp into 1:1 transformer.

I'm oversimplifying this but the way i see it fet has direct interaction with preamp through the hransformer. While first stage within opamp is isolated by all the electronics that follow before it even hits the transformer, not to mention preamp. The same would be true if you added transformer to Schoeps circuit.

 

[Papa Tango Charly]

Thank you very much Kingkorg