how to connect transformer on DAC output

Albrerta

Member
2007-06-26 3:24 am
I want to mod my dual AK4495 DAC with output transformers, by looking at the board I can see that the DAC chips parallel the output so each handle one channel. but it happens after a resistor, see pic below

Now I wonder where the connection of output transformer goes, should before those resistors, or after
 

Attachments

  • IMG_0005.jpg
    IMG_0005.jpg
    149.3 KB · Views: 171
Last edited:
The resistors are most likely for creating a LP filter at the DAC output..
Transformers themselves are a LP filter and in most cases do not need the LP filter before them.
It shouldn't make a difference if you put the transformers before or after, although I can say that my new project will not have the resistors in the circuit. Try your luck.
Make sure that you ground the transformer cases.
Transformers took my project from cute to professional, got rid of the most minute artifacts.
Good luck

S
 
Since your DAC is a dual AK4495 this most likely means one chip is devoted to L channel and the other to R channel, meaning they're running mono. Therefore probably the resistors are there to parallel the outputs. You haven't said anything about your transformer - if it has two primaries then you may well be able to connect each primary to an output directly and dispense with the resistors. But then again, resistors have the function of ensuring the output opamps don't go unstable with capacitive loads so you might still need them even with the transformer - the trafo primary should go to the summing junction of the resistors (that's after the resistors).
 

Albrerta

Member
2007-06-26 3:24 am
....But then again, resistors have the function of ensuring the output opamps don't go unstable with capacitive loads so you might still need them even with the transformer - the trafo primary should go to the summing junction of the resistors (that's after the resistors).

That's what I thought about, the resistors may have stability purpose because essentially dac chip 2 channels output need to connect together

Thanks