CS4397 dac

[Tripmaster]

Is it definitely pads 3+4 to short for the chip on the base of the board?

[fordgtlover]

Hi to all

This is my first post on this forum.

A brief intro first. My name is Rob, and while I don't really know a great deal about electronics, I do enjoy building DIY audio gear.

I'm posting here as it seems to be the most active site for mods to this neat little DAC.

I've had mine for a few weeks now, and have done a bit of tinkering. Now that I have a configuration that I think sounds pretty good, I thought I'd post it.

Here is my current configuration:
R2 - 3K (SMD)
C3 - 330uF 6.3V os-con
C8 - .22uf MKT EPCOS
C9 - .1uF MKP416 BC Components
C10 - .22uf MKT EPCOS
C11 - .22uf MKT EPCOS
C12 - .22uf MKT EPCOS
C13 - .22uf MKT EPCOS
C16 - 10uF 16V Tantalum
C17 - 330uF 6.3V os-con
C18 - 10uF 16V Tantalum
C19 - Rubycon MBZ 1500uF
C20 - 330uF 6.3V os-con
C21 - 470uF Panasonic FM
C22 - 22nF (SMD)
C23 - 1nF (SMD)
C25 - 10uF 16V Tantalum
Opamp - opa2107

Leo's bypass mod
C27,C28,C30,C31,C6,C54 - Bypassed
L & R out C - 2uF Obbligato PIO
L & R out R - 51 Ohm Kiwame

I am running this from my PC via a HAGUSB USB->S/PDIF convertor, which sound stacks better than the S/PDIF straight from my motherboard, into my DIY AMB labs M³ amp and finally out to my AKG K701 headphones.

This little DAC sounds better inplace of either of my CD players, a NAD 5320 and a Rotel RCD-855.

Thanks to all here (and other sites) for the ongoing tinkering and information - particularly Leo.

Cheers

Rob

[fordgtlover]

Sorry to be post-whore on my first day.

I just wanted to relay one of my experiences with this DAC.

One of the first mods I made was to replace C19 & C21 with a Rubycon MBZ 1500uF and an os-con 330uF respectively. I found that the bass rolled off dramatically.

Noting that Leo mentions in one of his posts that the os-cons can kill the bass, and that he used 10uF tantalums in these positions, I swapped the caps for the tants but found that the DAC sounded rather dull and un-dynamic (sorry Leo). I then swapped the tants for the Rubycon MBZ 1500uF at C19 & this time a Panasonc 470uF FM, rather than the os-con, at C21. The dynamics returned, as did the bass.

Cheers

Rob

[leo]

Reason I use a tant for C19/21 is because I use a far superior external psu , these two caps are for the input and output of the 3.3v regulator coming straight from the main 5v, if the main 5v isn't up to scratch you need to add some good low esr there, with my supply large values destroy this fairly neutral sound I currently have

C25 is the only place I'd recommend a 10uf tant as that cap is quite critical, it needs to be low leakage, of course some electrolytics may be better but tend to be more leaky , its something you just have to experiment with

I tend not to post fit this type of cap here and this type there mainly because my external regulated psu is nothing like the supplied unit so results would vary, what sounds good with mine may be crap with the standard one

[leo]

Is it definitely pads 3+4 to short for the chip on the base of the board?

Don't get too excited but I may have spotted the problem (unless its the pic you posted playing tricks on my eyes)

Look at the two pads next to that chip which we short out for the right channel, look closely, is the metal pad missing on both?
The third chip pin on the left must have continuity to the top pad to be shorted out and go to the tiny VIA on the left, if you can post a larger pic I can edit I'll try to explain what I mean and what needs measuring

[leo]

[alb]

Yes, i think it's very much a case of suck it and see, with this dac.

I posted details of mine because it works nicely and doesn't have any obvious weakness. A good starting point.
There are of course an unlimited number of ways that this can be achieved.

Another thing that i think is worth trying.
Remove the crappy pcb mounted phono socket and fit a BNC socket to the dac case and source. Connect with some proper 75 ohm cable and you should notice an improvement.
One advantage of doing this early on, is that it creates more space on the pcb, and makes life easier, especially when experimenting with input caps.

[leo]

Good point Al, those supplied sockets are really quite poor anyway, I had some problems with mine , intermittent SPDIF lock caused clicking/ticking noises

[Tripmaster]

Thanks Leo

I have revealed the copper track and if I put a meter between here and pin 7 on the opamp I get a connection. I didnt get a connection between the blob and the copper. I desoldered the blob and tried to solder a link between the copper and the blob but I ended up removing the solder pad ARGHHHH!!!

I also pulled away the pad from the C19 negitive side, double ARGHHHH!!!

This is one project thats definatly not gone to plan

Can you recommend any other hidden tracks?

[Tripmaster]

I have sorted C19. I scraped away some of the screen I now have a good connection to the cap