CS4397 dac

[Ciu]

Hello !

That's what I 've done :

http://img206.imageshack.us/img206/3...cfecc86rt8.png

I redrawn an original schematic published by JR Broskie in Tubecad.com
This is a buffer with no gain, and filtered input, with low voltage tube ECC86/6GM8
The B+ is 24v, simple LM317, with a slow turn-on , about 30s
The heater,6.3v, 600mA, is also a simple lm317, with a slow turn-on , about 10s
Works perfectly for a symetrical voltage DAC...
R.C.

[Makgajwer]

Your link not works

[Ciu]

Hello !
Works better now!
Sorry

[Tripmaster]

Im back!

Here are a few more photos of my project.
















Here is a list of the components changed so far...

C3 Jamicon 220uf
C18 Jamicon 220uf
C11 3.3uf Tant
C10 Vishay 0.1uf ERO 1837
C7 Vishay 0.1uf ERO 1837
C9 Vishay 0.1uf ERO 1837
C16 Oscon 150uf
C8 3.3uf Tant
C12 3.3uf Tant
C25 Oscon 150uf
C26 Oscon 150uf
C13 3.3uf Tant
C41 Wima 0.1uf
C19 Panasonic FC 2200uf
C21 Panasonic FC 470uf
C17 Oscon 150uf

Bypass caps are SCR 8uf with R68 resistors
Using standard JRC opamp and have also tried LM4562

The output sounds a little bit veiled and lacking sparkle. The internal coax is a 50ohm cable from Maplin. I was after 75ohm to match the 75ohm socket but the chap at Maplins said it would not make any difference because the cable length was so short.

Leo recommended keeping the transformer close to the DAC. Do you think I have mine too far?

Can you recommend changing any of the parts to help improve the sound?

Thanks

Richard

Hello again

I have been running this for a while and the bass is still poor. I don't like a really pronounced bass but after listening to a variety of music it is obviously lacking.

Can anyone provide a suggestion?

Thanks

Richard

[leo]

Hi Richard,

I still think the bass issue maybe the choice of caps fitted, ideally you need to look at the datasheet for the dac etc to see what each of the pins are for.
The cap on the dacs CMOUT has an influence, a tant will be different to say an Oscon.
I currently use a 5mm spaced 10uf MKT cap there, I wouldn't fit much higher than 10-22uf there

Seriously though I'd remove most of those tants,Oscons and FC's and fit some cheap normal ESR types to start with, see how it sounds and then do changes to lower ESR parts in stages

Also it seems you still use the original values for the differential output stage, changing the values to whats posted earlier does improve the sound , it also measures much flatter on the output

THE CS4397 bass is reported to be light , mine sounds pretty deep and tight

[gurusan]

So....without any warning my DAC started buzzing a whole ton through the outputs...the little crappy transformer that came with the DAC got VERY hot and started to melt my case.

Any idea what could have caused this? it was working fine for over a month. Just a cheapo transformer? What kind would you recommend for a cheapish but good replacement?

Also this morning I desoldered some bits from the PSU board to check out the components and see if I wanted to replace anything. The little green caps look very cheap and I don't know what sort of brand they are. According to the writing on the front I assume they are rated at 100V and .0035uF?

What caps would be good replacements for these? I was looking at Wima MKP10 .022 or .033uF? Anything cheaper?

And the big electrolytic caps are Rubycon YK for the 4700uF, and Elna RJB for the 1000uF.

Would I benefit in changing these to something else? What would you recommend?

[Tripmaster]

Hi Richard,

I still think the bass issue maybe the choice of caps fitted, ideally you need to look at the datasheet for the dac etc to see what each of the pins are for.
The cap on the dacs CMOUT has an influence, a tant will be different to say an Oscon.
I currently use a 5mm spaced 10uf MKT cap there, I wouldn't fit much higher than 10-22uf there

Seriously though I'd remove most of those tants,Oscons and FC's and fit some cheap normal ESR types to start with, see how it sounds and then do changes to lower ESR parts in stages

Also it seems you still use the original values for the differential output stage, changing the values to whats posted earlier does improve the sound , it also measures much flatter on the output

THE CS4397 bass is reported to be light , mine sounds pretty deep and tight

Hi Leo

What would you recommend I remove/replace to start with?

Do you have a list of the components/brands you have used on your board and their location?

I really appreciate your time

Richard

[leo]

I'm not using that standard regulated psu (I just brought the dac module only) so the caps I use may not work so well with that supply you use, problem is your using a lot of low ESR caps like Oscon and Panny FC/FM which are good caps but can cause stability problems if a standard reg like LM317/337 is used, the output pin on those regs can ring with too low ESR.
Apart from measuring worse ringing can make the sound bad too

I mainly started the thread as it was a fun and a cheap project, the dac as standard has obvious flaws like having all its 5v and 3.3v supplies shared from a single source, the PLL filter values are wrong and so is the Differential output filter, most things can be improved though and most is covered in the thread.

TBH I'd have changed each cap in stages and evaluated the differences, its easy to go changing a lot of parts at once but this can make things hard trying to isolate which parts are ruinning the sound


Only thing I can recommend is taking out the Oscons,tants and replace with a decent quality general purpose type, give it a few days to run in and see how it sounds. I'd then try changing the caps in stages, this also ensures you don't go too far in the wrong direction.
Modding this stuff to your own personal preference can be tedious but with a bit of patience usually pays off

BTW don't always trust what you read regarding low ESR caps, their not always better in every application

[JDMz]

Hi, I am planning to get this DAC and mod it according to the lampucera website AND the mods Leo showed. Will this have any conflicts?

Thank you

[Tripmaster]

I'm not using that standard regulated psu (I just brought the dac module only) so the caps I use may not work so well with that supply you use, problem is your using a lot of low ESR caps like Oscon and Panny FC/FM which are good caps but can cause stability problems if a standard reg like LM317/337 is used, the output pin on those regs can ring with too low ESR.
Apart from measuring worse ringing can make the sound bad too

I mainly started the thread as it was a fun and a cheap project, the dac as standard has obvious flaws like having all its 5v and 3.3v supplies shared from a single source, the PLL filter values are wrong and so is the Differential output filter, most things can be improved though and most is covered in the thread.

TBH I'd have changed each cap in stages and evaluated the differences, its easy to go changing a lot of parts at once but this can make things hard trying to isolate which parts are ruinning the sound


Only thing I can recommend is taking out the Oscons,tants and replace with a decent quality general purpose type, give it a few days to run in and see how it sounds. I'd then try changing the caps in stages, this also ensures you don't go too far in the wrong direction.
Modding this stuff to your own personal preference can be tedious but with a bit of patience usually pays off

BTW don't always trust what you read regarding low ESR caps, their not always better in every application

I was foolish to change so many components at once. Having read the http://www.lampizator.eu/ website and and also heard a friends modded DAC I decided to go for it!

I normally like to take things slowly and evaluate each change. I have recently built Peter Daniels Shigaclone transport with great results and wish I had taken the same approach with this project.



Should I stick with 150uf for the Oscon replacements and 220uf for the C3 and C18? And what about the tants, should I choose a larger value than 3.3uf?

Thanks Leo

Richard