Hi all:
In reference to this part again:
MAX4469 microphone preamplifier
Would it be suitable if I add a variable feedback resistor for volume control? Or would I need to keep the pre-amp gain fixed and use another opamp to do that?
I've read from some references that volume control should not be done on the pre-amp, but I don't know why.
Thanks!
Because it may alter the operating characteristics of the preamp in ways you don't want. Such as the noise of the device.
But, you don't need a whole stage just to add a volume control.
Just have a pot hanging off the preamp stage to ground, and take the output from the arm.
Michael
Thanks, Michael! After looking at the datasheet more closely, I think I do need an extra stage. The GBWP of the opamp is only 200khz, so a gain higher than 20V/V already drops the bandwidth lower than 10,000kHz. I'm expecting the microphone voltage levels to be between 1mV to 10mV, so that would be pretty low.
By the way, can you clarify your last statement regarding the pot hanging off the preamp stage to ground? I'm picture a pot hanging at the pre-amp output connected to ground. Is this what you are saying?
Thanks!
The traditional way to connect a volume control is to ground one end of the pot and connect the audio out from the previous stage to the other end of the pot. The wiper of the pot then connects to the input of the next stage.
** Yes.
** How do we know what you " read " somewhere ?
Was it on the back of a dunny door - maybe ?
Having variable gain ( using a pot or multi-way switch) IS the STANDARD way to make a mic-pre amp.
This way, headroom and signal to noise is always optimised.
....... Phil
Whose standard would that be?
Sean
"Sean"
** Fuck off - you illiterate ASD f***ed cunt head....... Phil
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.