DirectStream Snr output


#1

I’ve seen in the post that DirectStream uses output transformer. Does that means that it is not using opamp to output analog?


#2

I believe that is one of the main differences between the DS and the DS Jr.


#3
tkiat said I've seen in the post that DirectStream uses output transformer. Does that means that it is not using opamp to output analog?
As stevem2 said the DS Jr does have an opamp output, the DS Sr uses a passive output filter that includes a transformer. They have the same output impedance and the DS Jr output opamp is basically being used to simulate a transformer (including most of the transformer's common mode noise rejection.)

#4

Ted does that means that there is an op amp before the output transformer or the output transformer take over the role of opamp?


#5

In the DS Sr the digital signal is filtered with R C X C R where each R is a (pair of) resistors, each C is (a set of) capacitors and X is a transformer. In the Jr the “output opamp” takes the place of the X. They both use the same topology of output but the Jr uses a opamp for common mode noise rejection and the Sr uses a transformer.

I’m only being detailed since people assume that the output of the Jr is only an opamp and the Sr is only a transformer - but in both there’s essentially a passive output section driven from full scale digital outputs. Most DACs have a low level current output that gets converted to voltage and then amplified with output opamps. The difference being that in the DirectStream DACs the noise on the output rails is filtered by the output circuitry and in a typical DAC the noise on the outputs is amplified by the output opamps. There’s plenty of output current available both in the DS Sr and the DS Jr.