I made the circuit with carbon film resistors and added tone control as in the picture, the tone control was working.
I made the same circuit with metal film resistors to minimize noise, and since the electret capsule (AKG ck31) I used works with 3mah, I changed the supply resistor from 4.7k to 3.2k. and strangely the tone control stopped working.
It worked for me a little in the first version, but it doesn't work anymore.
When I speak close to the microphone while recording, the sound comes out as it should. But when I want to increase the gain and get distant sounds. To provide a full and linear sound in distant recordings due to the treble of the recorded sound. I need to add (100hz) bass boost (with knob) or tone control.
Can you help me on how to implement this correctly?
Is there any adjustment I need to make regarding impedance compatibility?
Best regard..
That's not a very stable biasing method for a transistor - changing the supply resistor might affect the biasing adversely, but not sure how that could affect tone section's behaviour?
It is impossible that something in the transistor amplifier stage changes because of a change in R1.
Why did you change it in the first place?
Is the microphone specified at 3 mA? So no voltage left with a 3k3 resistor.
You can remove C3. C1 should have the + towards R1
Can you complete the schematic properly for the tone control part. Now you have a drawing of a potmeter. I want to see the electrical schematic.
If the recommended load impedance is 2000 ohms. What is the Ri of your transistor stage.
It is Hfe x Re. You have to look up Re in the spec. For the collector current you are drawing. If you cannot calculate it, measure it. R3 voltage drop etc.
Why did you change it in the first place?
Is the microphone specified at 3 mA? So no voltage left with a 3k3 resistor.
You can remove C3. C1 should have the + towards R1
Can you complete the schematic properly for the tone control part. Now you have a drawing of a potmeter. I want to see the electrical schematic.
If the recommended load impedance is 2000 ohms. What is the Ri of your transistor stage.
It is Hfe x Re. You have to look up Re in the spec. For the collector current you are drawing. If you cannot calculate it, measure it. R3 voltage drop etc.
Maybe the battery is almost dead, if there is one. When the transistor saturates, the effect of the tone control will get less, as will the gain.
It's quite unclear (to me anyway) what kind of circuitry the CK31 requires. It is not an ordinary cheap electret capsule, but a professional one that is normally only used in AKG microphones.
It's quite unclear (to me anyway) what kind of circuitry the CK31 requires. It is not an ordinary cheap electret capsule, but a professional one that is normally only used in AKG microphones.