I almost finished a AD1865 balanced sen DAC. It's playing, just the last battery board is to be produced.
I noticed that the AD1865 does not really like the digital volume (not sure why, but I get some digital noise if I put the volume lower than 80%). So I need a balanced volume control.
The question is: what kind of pot can the sen drive ? does it make any harm to the circuit to have the output shorted, like with a balanced to SE converter ?
Thanks,
Davide
I noticed that the AD1865 does not really like the digital volume (not sure why, but I get some digital noise if I put the volume lower than 80%). So I need a balanced volume control.
The question is: what kind of pot can the sen drive ? does it make any harm to the circuit to have the output shorted, like with a balanced to SE converter ?
Thanks,
Davide
> what kind of pot can the sen drive ?
You can change output level by just changing R_iv.
So that is your volume control, no need for extra pots.
> does it make any harm to the circuit to have the output shorted,
No harm if you short to Gnd.
> like with a balanced to SE converter ?
Why would you want to do that and not just use one phase ?
Patrick
You can change output level by just changing R_iv.
So that is your volume control, no need for extra pots.
> does it make any harm to the circuit to have the output shorted,
No harm if you short to Gnd.
> like with a balanced to SE converter ?
Why would you want to do that and not just use one phase ?
Patrick
If you have a true balanced circuit, i would recommend you to not pull the signals to ground, but rather to a virtual ground (both phases negative side of shunt resistor connected together) gives alot less noise at least when i have tried. Regarding impedance, Patrick is probably the best person to answer.
Edit: a bit late
Edit: a bit late
Yes, but not at the volume controller, bypass the volume with ground, and pull each phase to virtual ground instead, gives less noise at least it the two circuits i have tried it. Plus, it gives better matching volume controller (since the shunt resistor is always exactly the same on both phases, while the series can vary a little).
Use a variable resistor as Riv, and reduce its value to lower volume.
I believe you can use a fixed resistor in parallel with a linear pot to get close to a log curve.
It is current mode, so long wires should be no issue.
For HF filtering, I would have used a cap in parallel with Riv.
But then it only works with fixed resistor value....
Don't like to use inductors unless no choice, especially ferrite ones.
Patrick
I believe you can use a fixed resistor in parallel with a linear pot to get close to a log curve.
It is current mode, so long wires should be no issue.
For HF filtering, I would have used a cap in parallel with Riv.
But then it only works with fixed resistor value....
Don't like to use inductors unless no choice, especially ferrite ones.
Patrick
Dear FCCN75,
I checked and I have the four boards of the CEN/SEN evaluation kit if you are interested.
Their status is the following:
1) CEN unpopulated
2)CEN Fully populated with one pair per channel
3)SEN Populated with passive components
4)SEN Populated with passive components.
I can sell them to you if interested. I do not have the little heatsinks.
Happy New Year,
Davide
I am posting here as FCCN cannot receive private messages.
I checked and I have the four boards of the CEN/SEN evaluation kit if you are interested.
Their status is the following:
1) CEN unpopulated
2)CEN Fully populated with one pair per channel
3)SEN Populated with passive components
4)SEN Populated with passive components.
I can sell them to you if interested. I do not have the little heatsinks.
Happy New Year,
Davide
I am posting here as FCCN cannot receive private messages.
