How to add “LOW CUT" in "NT1" circuit

[ZHAOMENG]

 

[Khron]

Is this a question, or a guide?

 

[ZHAOMENG]

这是一this's a question

 

[Khron]

This seems to be the NT1-A, anyway.

http://cdn.recordinghacks.com/images//mic_extras/rode/NT1A_pcb.jpg
https://groupdiy.com/threads/rode.61032/post-902381
Plug the circuit into LTspice and mess around with capacitor values perhaps?

 

[gyraf]

in the NT1A there is no obvious place to introduce a highpass filter stage IIRC - circuit is rather well thought out and methodically tight.

/Jakob E.

 

[RuudNL]

Everything is DC-coupled.
As a last resort, it would be possible to lower the gate resistor at the price of a higher noise level.
Let's assume that the capsule is ~80 pF.
A gate resistor of 33 M.ohm would in this case result in a -3 dB point around 60 Hz.

 

[ZHAOMENG]

Everything is DC-coupled.
As a last resort, it would be possible to lower the gate resistor at the price of a higher noise level.
Let's assume that the capsule is ~80 pF.
A gate resistor of 33 M.ohm would in this case result in a -3 dB point around 60 Hz.

I think we can try your plan. Can you mark it in my picture? , hahaha

 

[RuudNL]

The gate resistor is marked in the picture.
You can simply place a 33 M.ohm resistor in parallel with the existing gate resistor.
The value of the gate resistor on the PCB is so high (1 G.ohm?) that it can be neglected compared to 33 M.ohm.
(The two resistors in parallel would give you about 32 M.ohm.)

 

[ZHAOMENG]

The gate resistor is marked in the picture.
You can simply place a 33 M.ohm resistor in parallel with the existing gate resistor.
The value of the gate resistor on the PCB is so high (1 G.ohm?) that it can be neglected compared to 33 M.ohm.
(The two resistors in parallel would give you about 32 M.ohm.)

Ok, I will buy 33M resistors and switches to verify your scheme. Thank you, senior

 

[Khron]

What about reducing the output DC blocking capacitors? With a DPDT switch...

Kinda like in the sE X1 / Apex 435 / Alctron HSMC-001.

 

[RuudNL]

The advantage is that you don't have a switch in the part of the circuit with a very high impedance.
A disadvantage might be that the effect of the low-cut is load dependent.

 

[Khron]

True, but it's also the most easily-feasible option, in the given circumstances. Unless one wants to insert an active buffer/filter stage into the existing circuit...

 

[kingkorg]

上面的JF1晶体管可以用什么型号代替呢

https://www.google.com/url?sa=t&sou...cQFnoECAMQAQ&usg=AOvVaw3EEAuXzQmLdH6kbzNDoAtN

 

[gyraf]

In English, please?