Experience with this DIY DAC ?

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Mush

Mush

Member
Joined 2005
Baby DAC input transformer

I'm waiting for the CS4397 little DAC to arrive. I've noticed in the photos that it doesn't have an input transformer. The big CS8498 DAC has a Sumlink. Is there a better choice? Does anyone have any recommendations on what to get, where to get it and how I should hook it into the CS8416? I can't find a good circuit to inform me.

Thanks for all of your help.
 
johnm

johnm

Member
Joined 2003
Well I added a 10K loading resistor to the Digitecs and... I'm not sure I can hear any difference at all... perhaps a slightly more open sound but it's really hard to tell.

Where should I go from here (being a novice)? Is it worth trying with 20k, 50K etc? Not really sure what I'm looking for - does the sound suddenly 'snap' into focus or something?

To be honest I'd rather work it out properly rather than by ear, but need someone to tell me how to do this.

The input impedence (according to manufacturer) of my kingrex Preamp is: 100K @ 1kHz.

Thanks,

- John
 
S

surfstu

Member
Joined 2008
howdy all, if anyone with a lttle knowledge has a moment to check ths lnk:

http://uk.farnell.com/jsp/search/br...ch_001&Ntt=transformer&Ntx=&_requestid=359351

am trying to trace some transformers and this is my local supplier of all things electronics, i narrowed the search to 600ohms primary and 600 secondary? is this needed? any clues as to what will work well in this dac? without spending over 50 pounds?

cheers stuart
 
S

surfstu

Member
Joined 2008
in the words of mush: i've jumped on them...

would still like to hear your verdict on the tamuras legarem, seeing as you seem to have plently to compare them to.

well, the postman now has my dac and transformers, I should get on with the 12b4 pre amp that i'm building....

cheers guys
 
Franz Gysi

Franz Gysi

Member
Joined 2007
Does this transformer and/or the circuit quoted work well for 192 Khz?
Click to expand...

Uuups, maybe not? This is a input circuit from a 44.1kHz DAC.

Franz

BTW:

Digitec owners: just connect the primary with two 10 Ohm resistors to the DAC, and they'll be singing!
And when you want to filter, just add a 470nF cap in parallel to the primaries (but I dont like it filtered).
 
H

hoverdonkey

Member
Joined 2009
Thanks Franz. Based on my learning from this thread, I see that it has decoupling caps too. That is useful to know because last night I finally went for the upsampling version of the DAC board (from Ebay seller gigawork), which does not have the input transformer.

Those GA80080 Tamura's were also winking at me, so I have a pair of those coming as well. I guess it is time to plug in my soldering iron now if it needs to get to 750°C!

Thanks to Kevin & Franz for their responses and for everyone elses contributions on this thread which have led me to this point. I will report in as soon as I hear music!


Cheers

Oli
 
johnm

johnm

Member
Joined 2003
Franz Gysi said:

Digitec owners: just connect the primary with two 10 Ohm resistors to the DAC, and they'll be singing!
And when you want to filter, just add a 470nF cap in parallel to the primaries (but I dont like it filtered).
Click to expand...


Hi Franz.

With the above I take it you are now not using loading resistors on the secondaries? I'm currently using 10K here but really can't here much - if any - difference between that and no load resistors. I'll try a higher value later today.

In the above mod you mention, are you using two 10 ohm resistors per transformer? I.e. 10 ohm from the transformer to the L- and L+

Cheers!

- John
 
Franz Gysi

Franz Gysi

Member
Joined 2007
With the above I take it you are now not using loading resistors on the secondaries? I'm currently using 10K here but really can't here much - if any - difference between that and no load resistors. I'll try a higher value later today.
Click to expand...

John

I think the secondary load does only very marginal difference.
Later, I will measure on the scope if I see ringing and will then fiddle out a RC combination. I will post it here.

In the above mod you mention, are you using two 10 ohm resistors per transformer? I.e. 10 ohm from the transformer to the L- and L+
Click to expand...

Exactly, two resistors per transformer. On each side of the primary one connecting to L- and the other to L+.

Then you can add 0.33uF in parallel to the primary as lowpass filter.

This combination, I like very much!

Franz
 
johnm

johnm

Member
Joined 2003
Many thanks Franz - look forward to hearing about your results with the scope too.

This DAC really is something special with the transformers isn't it. Surprisingly, I've also found that the optical input seems to be every bit as good as the coaxial one, unless its my cloth ears of course! Using a USB Trends UD10.1 and an optical cable, playing lossless files via Foobar2000 with the WASAPI plug in for Windows Vista, I'm in audio nirvana :D So a BIG thanks for all your help thus far Franz, and indeed everyone else on here who's helped/contributed in some way.

- John
 
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