DIY D1 I/V STAGE

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#21
for your needs - you need to decrease sum current for regs to - say ~ 60mA max ( increase R1 in both regs to 10 ohms)

there is no need for more of that , if active stage is drawing 20mA

that way - roughly -overall consumption per channel is 60mA x Vdc = 60mA x 1,41 x 30V x2

regarding needed amplitude of output signal

considering that current output of PCM for full blast is +/-1.2mA - just divide your needed p-p amplitude with 2,4mA and you'll get value for R6

this way ( with R6 1K5) , you'll have 3V6pp on output

if you're going to use set of regs for both channels - go for 100mA as programmed current ; in that case R1's must be around 6R5
 
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#26
Iloveswan said:
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.
Click to expand...

@ZM
So don't need to change R2 as Iloveswan suggested & he do bad calculations 1Vrms instead 1.8Vrms?
 
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#33

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#37
Hi,

Didn't check the datasheet of the chip for specs but if it wants 0 volts at it's output you're doing fine. the dac will have a compliance range for dc offset at it's output and your offset is very very low. but check again after connecting to the dac. check the datasheet of the dac for it's output compliance.

regards
joris
 
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