Common gate impedance matching

[Audioguru]

I really might look into buying that amplifier that somebody suggested here.

The Velleman preamplifier uses the LM358 dual low power general purpose opamp that is HORRIBLE for low level audio:
1) It is noisy (hiss).
2) It has awful crossover distortion.
3) It has trouble above 2kHz at high output levels.
But you can throw away the LM358 and plug in a good dual audio opamp instead into its IC socket.

 

[FvM]

I agree with the preamplifier circuit rating, but would add one point. The 100k resistors of the inverting input amplifier are the dominant noise source. The overall noise will only slightly reduce when using a better amplifier. The circuit has to be modified to work as low noise microphone amplifier.

 

[I14R10]

Then can you recommend me some preamplifier kit?

 

[I14R10]

How about this little thing https://www.amazon.com/6-3mm-Female-Transformer-Impedance-Matching/dp/B00CZGD91O? It's the 500 to 50k ohms impedance transformer. That should make my microphone behave like a high impedance transformer.

 

[Audioguru]

The spec's for the transformer are only its size. Frequency response?? Max input level?? Distortion?? Either they are hiding something or they do not have a clue about audio products.

 

[FvM]

The adapter is cheap enough to be sold without detailed specification. I would expect it's working for your purpose.