BB PCM63 DAC only for CD transport

[merlin el mago]

Tried to search for the schematics of this but failed - borbelyaudio.com seems not to be responding. If its using passive I/V then the DAC power supply becomes extremely critical. These days I don't recommend passive I/V for this reason.

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It's active I/V conversion.

 

[merlin el mago]

Attached information Erno Borbely I/V DAC

 

[abraxalito]

Thanks for that, I see its a 'discrete opamp' style of I/V - the very low input impedance is as a result of NFB, it means during the DAC state transition the input impedance becomes much higher until the output finishes slewing.

 

[merlin el mago]

I will try with PCM63K.

 

[mefistofelez]

Hi merlin el mago, abraxalito,

could you please point me to Ian's NOS for the BB PCM63?

Thank you,

M

 

[abraxalito]

I'm not familiar with Ian's NOS. However if you're interested in an I/V schematic I posted one over here today - http://www.diyaudio.com/forums/digital-line-level/227677-using-ad844-i-v-42.html#post4983888
It doesn't have resistor values - some of them depend on the DAC you connect to it. If you need help working out how to choose the Rs for the '63 then please do ask.

 

[merlin el mago]

I'm not familiar with Ian's NOS. However if you're interested in an I/V schematic I posted one over here today - http://www..com/forums/digital-line-level/227677-using-ad844-i-v-42.html#post4983888
It doesn't have resistor values - some of them depend on the DAC you connect to it. If you need help working out how to choose the Rs for the '63 then please do ask.

Yes, I'm interested, could you let me know the resistors and capacitorss values for PCM63 and the voltages?

TIA
Felipe

 

[abraxalito]

I'll get on to it over the next couple of days. What output voltage do you want and are you going to run NOS or oversampled?

 

[merlin el mago]

I will use the Erno Borbely series regulators to power the digital side of the DAC, attached pic.

 

[merlin el mago]

Thanks for your time and to share your schematic, Vout 2Vrms, still I do not have it determined.

 

[mefistofelez]

Hi abraxalito,

I'm not familiar with Ian's NOS.

Thank you for your reply. I have a vague recollection that someone (iancanada?) designed a generic board that could be used for older chips like PCM63. But, I cannot not find the thread.

Kindest regards,

M

 

[merlin el mago]

Hi abraxalito,



Thank you for your reply. I have a vague recollection that someone (iancanada?) designed a generic board that could be used for older chips like PCM63. But, I cannot not find the thread.

Kindest regards,

M

Link: http://www.diyaudio.com/forums/digital-line-level/220407-drive-nos-ad1865-62-pcm1704-02-63-tda1541-fifo-universal-i2s-pcm-driver-board.html

 

[abraxalito]

Thanks for your time and to share your schematic, Vout 2Vrms, still I do not have it determined.

Here's the schematic from running some simulations in LTSpice. If you'd like the simulation file I can also give you it.

Notice that because the PCM63 is bipolar output and the circuit is single-ended, we have a current source (bottom left of the picture) to provide an offset. Since the PCM63 has a -5V supply I've assumed it will be powered from that. The rest of the circuit needs around 10V supply. DC offset is not controlled so a coupling capacitor will be called for.

 

[merlin el mago]

Thanks abraxalito for your present, today is mi birthday.

 

[mefistofelez]

Hi merlin el mago,

Link: http://www.diyaudio.com/forums/digital-line-level/220407-drive-nos-ad1865-62-pcm1704-02-63-tda1541-fifo-universal-i2s-pcm-driver-board.html

That is it. Thank you very much,

Kindest regards,

M

 

[abraxalito]

Thanks abraxalito for your present, today is mi birthday.

Oh cool Many Happy Returns, hope the present is useful

 

[merlin el mago]

Hi merlin el mago,



That is it. Thank you very much,

Kindest regards,

M

Your welcome.

Oh cool Many Happy Returns, hope the present is useful

Sure, thanks again. The transistors have to be matched? If yes what Idss?

Cheers
Felipe