I have an intercommunicator, that have an speaker/mic. I want to connect it in parallel and using an comutator, to a mic and speaker. For impedance fix I'm using an op-amp(lm324) in buffer configuration. I get notorious distortion, so I'm using a 6.8kohm connected to ground and out, that is ok?. The mic have 500ohm rate impedance output. The connections in the figure are ok?, how can improve?
There are several points that don't work as shown, some possibly just drawing errors. As a fundamental point, LM324 can't drive a 8 ohm speaker. You'll want a low power audio amplifier like LM386 for this pupose.
Hi again
You can use a transistor circuit as buffer for high powers . for example a complementary stage . it would be ok . or a complementary stage with an op amp ( takes feed back from out put to do it's best as a buffer ! )
Best Wishes
Goldsmith