[davidl]

What does the Pimeta buffer do for high impedance cans?

I'm trying to build a Pimeta and am a bit confused. I took an electronics course about 20 years ago and have assembled a couple of kits so I know how to solder, but my understanding is pretty limited. In the explanation of the Pimeta it says that there is no resistor after the opamp because the buffer has an intenal resistance of 200 ohms. But if the cans have a resistance of 300 ohms wouldn't the opamp be putting out more current than the buffer. And if that's so, what's the point of the buffer? Hope somebody can clarify. Thanks,

Dave

 

[jerb]

i title with a more descriptive explanation of your problem will prompt more responses from our community. the word "david" has no correlation with your post but rather your screen name. a mod may change it for you but for future reference try to give a small explanation of your plight in your thread title.

sry to be mean but "welcome to head-fi and sorry about your wallet"

sorry i couldnt be of more help

 

[llmobll]

If you have no buffer, your opamp is raising the voltage of the signal aswell as supplying the current to drive your headphones. In simple terms, addding a buffer takes the burden of driving the headphones OFF the opamp, and dedicates driving the headphones to the buffers. Takes strain off the main opamp. If my beginner engineering serves me correctly, it just helps match impendances, but that is a whole other subject in itself. so...

1. buffers.. help drive HARD to drive headphones, with high impendances and low efficenciy.

2. no buffer - make the OPAMP, amp the signal AND drive the headphones. putting more stress on the opamp and resulting in less performance.(sound wise).