DIY D1 I/V STAGE

[merlin el mago]

I want to know if i can use this old DIY D1 I/V STAGE schematic for a SE PCM1704 DAC or it's necessary to change something or if needed I am open to use another suggestion

The mosfet must be matched, if yes wich value?

 

[Iloveswan]

I want to know if i can use this old DIY D1 I/V STAGE schematic for a SE PCM1704 DAC or it's necessary to change something or if needed I am open to use another suggestion

The mosfet must be matched, if yes wich value?

You should raise R2a's value a little bit unless you can accept around 1Vrms output. If you raise R2a's value, you need to change source resistors value accordingly too.

About Mosfet match, it's easy to get a 1% Vgs matched pair from same production batch.

 

[merlin el mago]

Thank you

 

[merlin el mago]

Wich power have to be the transformers 25VA per winding or less?

Wich resistors & values exactly have I to change to get 2Vrms?

 

[merlin el mago]

About Tx I got the information is 50VA, now I only need to know wich resistors & values for 2Vrms?

 

[merlin el mago]

About Tx I got the information is 50VA, now I only need to know wich resistors & values for 2Vrms?

I think Tx 2x30VAC & 50VA is per channel or is in total?

 

[qusp]

About Mosfet match, it's easy to get a 1% Vgs matched pair from same production batch.

vgs yes, transconductance not so much

 

[merlin el mago]

I need to know wich resistors & values for 2Vrms?

Tx 2x30VAC & 50VA is per channel or is in total?

 

[Iloveswan]

vgs yes, transconductance not so much

Yes. That is always the problem.

 

[merlin el mago]

I need to know wich resistors & values for 2Vrms?

Tx 2x30VAC & 50VA is per channel or is in total?

Please help.

 

[Zen Mod]

can you calculate from this schematic that power consumption of channel is under 1W ?

 

[merlin el mago]

I got it the informtaion I think its 10-20mA per channel.
So 10VA would be minimum.
I will use only 1 tx 2x30VAC 50VA for stereo.

 

[qusp]

yes its much lower than owens d1, where each fet is operating about 130ma

 

[Zen Mod]

I got it the informtaion I think its 10-20mA per channel.
So 10VA would be minimum.
I will use only 1 tx 2x30VAC 50VA for stereo.

well - you asked , and I wrote exact currents on schematic , which you obviously didn't looked .
anyway - power cons. is under 1W/per channel

exact requirement for xformer depends of reg used ;
I know that with regs I usually prefer , 50W will suffice for both channels

in your case , you can probably feed 10 stereo D1's with 50W

 

[merlin el mago]

I will use Salas Low Voltage Shunt Regulator, I find 1 tx 2x30VAC 60VA can be enough?

 

[Zen Mod]

well - either ask Salas , or post exact schematic here , or post link to it .

 

[Zen Mod]

besides that - you need to know on which DC level is output of PCM1704 , so you'll need to set input of D1 to same level

 

[merlin el mago]

You should raise R2a's value a little bit unless you can accept around 1Vrms output. If you raise R2a's value, you need to change source resistors value accordingly too.

Wich value for R2a (R2b) & wich resistor is source resistor & value needed to get 2Vrms?

 

[merlin el mago]

besides that - you need to know on which DC level is output of PCM1704 , so you'll need to set input of D1 to same level

The I/V is designed for DAC current output PCM1704, PCM56, etc.

 

[merlin el mago]

well - either ask Salas , or post exact schematic here , or post link to it .

Minimum diff. to work 8-10V Vin-Vout, so for 42.3Vin can regulate 30Vout

Thanks for help.