CS4397 dac

[jackenhack]

Thanks for the heads up on the FR. Did you change the resisters as discussed by Leo in this post?

Where he suggests R8,R9,R14,R17 to 30k and C32,C33,C34,C35 to 150pf.

Yes, changed to 30k.

Jacken

[madigwann]

Yes, changed to 30k.

Jacken

Hi everyone ! Thank you for all the good infos provided here ! I've been reading about your mods with interest ! I'm not expert when it comes to electronics...I'm trying to get good results from this pretty dac too. Do you need to change the caps WITH the resistors, or can just the resistors be changed to 30k to get that amazing response curve jackenhack showed ? Thanks...

[fordgtlover]

I thought I might try the output stage that Leo previously posted here. So, I thought I would put my newly developed Eagle skills to work, and try a PCB layout.


I have recreated the schematic here:


And, here is my PCB layout:


The board is 40mm x 60mm and will require two for the complete output stage.

I have assumed BC550C for Q1, Q3, Q4 & Q6 & a BC517 for Q2.

I have used the Murata 1800R inductors, but I might swap them for the small Murata 2200R from Farnell.

You might note that for the output cap I have provided the option to use either a large(ish) film cap (c2) or an electrolytic bypassed by a small film cap (C9 & C10). Is this a sensible option and implementation?

Does C2 need to be 10uF? Can it be a smaller value?

I'd be interested in any feedback about the layout or the parts selections.

This is my first board layout, so all comments welcome.

Cheers

Rob

[jackenhack]

Hi everyone ! Thank you for all the good infos provided here ! I've been reading about your mods with interest ! I'm not expert when it comes to electronics...I'm trying to get good results from this pretty dac too. Do you need to change the caps WITH the resistors, or can just the resistors be changed to 30k to get that amazing response curve jackenhack showed ? Thanks...

I would go for both changes, but to alter the filter, change the caps. Here's a comparison with both res and cap change (MOD5) and just the resistors.


Click for full size - Uploaded with plasq's Skitch

[StanleyB]

Very nice longtailed pair cct. No feedback in the O/P stage?

[leo]

This circuits proven to work well with the CS4397 Stan which is already high enough output, its also dead simple and cheap.
Its just a differential input to line out using a simple emitter follower.
Normally the emitter follower is a Darlington

[fordgtlover]

I wasn't very happy with the middle part of my board layout so I've redone it, I've also changed the indiuctor to the smaller version.

Any comments before I go ahead and get a couple of test boards made?

[madigwann]

I would go for both changes, but to alter the filter, change the caps. Here's a comparison with both res and cap change (MOD5) and just the resistors.


Click for full size - Uploaded with plasq's Skitch

Hello ! Thank you very much ! I'll make both changes as I like to see that white curve so much ! How good was the sound after you did that change (MOD5) ?

[leo]

Just noticed , Q1 emitter should go to R3
You can alter the gain by adjusting the emitter resistors on the differential pair

This circuit is based on this http://home.quicknet.nl/qn/prive/ra....ancer_evo3.pdf

[leo]

Another version here including pdf with layout http://home.quicknet.nl/qn/prive/ra..../index_en.html