386 input impedance

[lightningfingers]

Is 20Kohms too big too drive an LM386?

[Hal]

why is this in the lounge?  This is an on topic post, if i've ever seen one....

and i dont know the answer to your question :-D

[niftydog]

Is 20Kohms too big too drive an LM386?

huh?

Are you saying that you have a source output impedance of 20kohms, and you want to drive an LM386 with that source?

Well, it depends on your circuit design, but given that the datasheet gives a typical input impedance of 50kohms it's probably not that good. best case scenario;

loaded voltage = unloaded voltage from source x [50k/(20k+50k)]

loaded voltage = 0.71 x unloaded voltage.

How have you calculated the output impedance? It seems very high.

[lightningfingers]

I didnt calculate, I asked the person who had worked on it before me, Its for that old tube radio that tried to kill me. It works now, but I want more volume, hence the 386 question.

Well, it depends on your circuit design, but given that the datasheet gives a typical input impedance of 50kohms it's probably not that good. best case scenario;

Does this mean I should use an interstage transformer?

EDIT: I don't know why it was in the lounge, coulda sworn I was in this forum :?    :?

[niftydog]

It works now, but I want more volume, hence the 386 question.

what are you proposing to do?