Wanted NOS AD1865 + CS8414 Dac Design

[Gcollier]

Hi I am looking for a good non onversampled DAC using the CS8414 reciever and the Analog Devices AD1865 DAC. I have searched and and found a few designs, but most have a transforemer or tube on the output....I am looking for something ultra simple. I've done quite a few DIY designs but this will be my first DAC.

Thanks.

[tobias_svensk]

Gcollier, i was about to ask the same question

[Elso Kwak]

Simple is inverting the latch for one audiochannel and using opamps for IV-conversion like OPA627s. Or you can even use the built-in opamps of the AD1865.

[tobias_svensk]

A single AD1865 or two like This take away the tubesection and replace with Lars Nielsens Here could that work out fine?

Thanks

[Extreme_Boky]

If Iout is used, pins 6 + 8 and 17 + 19 on AD chip should be grounded...

Extreme_Boky

[tobias_svensk]

Extreme Boky

If CS8414+AD1865 is used and i want to use groundplane, should DGND&AGND on CS-chip be togheter with DGND on AD-chip forming a "digital groundplane" and AGND on AD-chip forming "analog groundplane" togheter with the following stage?

In This layout he has no groundplane but DGND is tied with DGNG and AGND with AGND

thanks

[Gcollier]

Originally posted by tobias_svensk
A single AD1865 or two like This take away the tubesection and replace with Lars Nielsens Here could that work out fine?

Thanks

Tobias (notice I spelled it right this time)...that looks like a fairly reasonable design, anyone got a PCB for something like this, or up to designing one. I've got all the parts I need, just noe time right now to work on a PCB design. I'd much rather not use the AD1865 built in opamps but instead go with something like tobias suggests....granted for the price of the OPA627 I could probably go with tubes...any advantages to this?

[Extreme_Boky]

If CS8414+AD1865 is used and i want to use groundplane, should DGND&AGND on CS-chip be together with DGND on AD-chip forming a "digital groundplane" and AGND on AD-chip forming "analog groundplane" together with the following stage?

Yes, you are right. Bigger part of your ground plane on PCB1 should be DGND plane covering the whole CS chip and 1/2 of AD chip(s). The rest (smaller part) should be your AGND covering analogue sections / parts of AD chip(s). They should be connected together at only one point via single wire link. No need for ferrite beads here.

There should be a separate PCB - I'll call it PCB2, for balanced analog stage with its own ground plane. Notice that you could feed only Iout+ and Iout- (per each channel) from your PCB1 to PCB2 via short solid core wire links with no ground links between two boards here! The AGND of PCB1 and ground of PCB2 should be linked at the power supply board only, as design suggests, through short - very low resistance copper ribbons and star ground point on power supply PCB.

Design is for balanced Iout to balanced Vout (XLR).

Extreme_Boky

[quantran]

I am also using the opa627 with this dac utilizing the internal Rf. The ground is as Extreme_boke described. The opa627 output through Evox MKP caps. Sounds very detailed BUT the midrange is thin. Bypass caps are WIMA MKS and ELNA Duorex II 10uF.

The AD844 sound thicker BUT its treble is not as good as opa627. Currently I can�ft think of any solutions.

Any recommendations will be much appreciated

[Extreme_Boky]

I am not 100% sure if you are using Iout or Vout?

AD844 and OPA627 are very different IC's.

Vout - I would try AD826 or OP275. Midrange is OP275's middle name.

Iout - stick with OPA627 (ot try AD8065...)

The "problem" you described is the reason why people try to avoid IC stages in DAC designs... You have to learn to leave with compromises if you opt for IC stage.

Regards,
Extreme_Boky