transformer attenuator directly from v-out dac

[serph1nia]

Hey guys,

so. I've read into transformer output from balanced v-out dacs (e.g. wolfson wm8740). I always thought 'screw that' I'll just use a cheap coulpling cap. A waste of a balanced output and impedance but I don;t need both of those aspects when i connect it to a simple pot meter.

But then. I came across some transformer volume control.

I'm thinking about the following setup:

wm8740 -> sowter 9335 (direct coupled, no caps or anything, so there will be dc on the transformers)

SOWTER ATTENUATOR TRANSFORMERS TVC VOLUME CONTROL


So...
1. Is this possible? can the sowters handle the dc from the wm8740?
2. has anyone experience with such a setup? does it makes sense?

Thank you

 

[Bill Fuss]

It makes sense to me, although I've never used a TVC. Unless the WM8740 needs an inordinately high load resistance it should work great.

The DC offset is a non issue. If there is no path to ground there is no DC current flow unless the output pins have differing DC potentials.

Best, Bill

 

[dirkwright]

What are you putting on the secondary side of the TVC? Be aware that any impedance there will be reflected back to the DAC, and that may effect the DAC's performance and output level. Also, the impedance reflected onto the primary side will change with changes in volume, since the secondary is tapped and thus the turns ratio effectively changes as well.

 

[pieter t]

Check datasheets guys, it's all in there.
Should work well; DC offset is 2.5V with a 5V supply.
In Sowter's application no path to ground (floating).
When secondary load impedance is 10k or higher it will work well.
Dirk, when the signal is attenuated the dac will see a higher (reflected) load, so it will actually have an easier job (output level for this voltage output dac will not be effected).

 

[dirkwright]

Check datasheets guys, it's all in there.
Should work well; DC offset is 2.5V with a 5V supply.
In Sowter's application no path to ground (floating).
When secondary load impedance is 10k or higher it will work well.
Dirk, when the signal is attenuated the dac will see a higher (reflected) load, so it will actually have an easier job (output level for this voltage output dac will not be effected).

I didn't read the data sheets, sorry, but I was just talking in general.