Experience with this DIY DAC ?

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#203
I just attached this 1:0.62 transformers, completely bypassing the output filters:

An externally hosted image should be here but it was not working when we last tested it.
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This is amazing, a very big step. I am surprized, give me some time for an opinion...

Even when I have to turn my amplifier now a little louder, the output level is still high enough. And I drive very short cables, 1ft.

Franz

/Edit
With this setup, I clearly prefer the upsampling version!
 
#204
Franz Gysi said:


Your values are for input sampling rates between 96 and 192kHz.

Don't you play 44.1 and 48kHz?

Franz
Click to expand...

I only use a standard CD transport (44.1) and changing the values gaves better sound. I didn't know that the new values were for 96 and 192 khz. I didn't saw that in the Cirrus Errata bulletin.
 
#206
Franz Gysi said:
I just attached this 1:0.62 transformers, completely bypassing the output filters:

An externally hosted image should be here but it was not working when we last tested it.
[/url]

This is amazing, a very big step. I am surprized, give me some time for an opinion...

Even when I have to turn my amplifier now a little louder, the output level is still high enough. And I drive very short cables, 1ft.

Franz

/Edit
With this setup, I clearly prefer the upsampling version!
Click to expand...

Congratulation ! You have done what i considered the best for this dac. With this setup you forget op amps, fets, tubes and everything.

This is what i'v done and it ended all the circuits I tried to get better and better sound.

Here is mine:
 

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#210
If buying from scratch what would be the best value of input transformers to use on the outputs? 1:1? I'm very keen also on by-passing op-amps altogether and having to forget having to desolder all those components with the hard to melt ROHS solder!

Cheers.

- John
 
#211
Re: LPF components

Segran said:
I haven't removed the second OP yet since I'm contemplating the best way to do it. I want the mute relay still to work.
Click to expand...
Can't we just make wire/bridge from the caps between opamp #1 and #2 to the output pins of removed opamp #2?
Please elaborate if this is not the right approach.
 
#212
Hello,
i bought another similar DAC from ebay seller snow48_6, it's very similar to Franz's one but without the ASRC and with the USB interface unpopulated

An externally hosted image should be here but it was not working when we last tested it.


some things i noted: there are no coulping 'lytics from cs4398 to first opamp and the arrangement of resistors and capacitors for the LPF are different from what i see on post #138 from Kevin.

The frequency response from RMAA:

An externally hosted image should be here but it was not working when we last tested it.


I have to correct the component for the LPF.

Ciao
Andrea
 
#213
Can't we just make wire/bridge from the caps between opamp #1 and #2 to the output pins of removed opamp #2?
Click to expand...

I would take the signals from between R23/C26 and R38/C29 and connect it to pin 1/7 of the 2nd opamp. You also need to remove R4, C44, R37 and C55.

I haven't got round to do this myself yet so it would be interesting if you could tell us if this mod will make much of a difference.
 
#215
hafp said:
Have a schematic of a similar DAC I got a few months ago on eBay.
It may not be exactly the same as the model you guys recently purchased, but is does use the CS4397/8416 chips and 2 opamps.
Would be interested in any successful mods you come up with on bypassing the second opamp and coupling caps.
PM me with your email if any of you want a PDF of the schematic.
I can't post is as the file is too large.
Cheers.
Click to expand...


Hi hapf,
can you send me the pdf
anbello_at_gmail_dot_com
_at_ <-> @
_dot_ <-> .

Thanks
Andrea
 
#216
Hi guys. Could anyone tell me where to get some of those output transformers Franz Gysi has used on his output stage please? or any similar will be appreciated.

I have a dac kit on the way at the moment and it'd be nice to get everything ready for when it arrives.

Thanks and kind regards,

Lee.
 
#217
Hi guys. Could anyone tell me where to get some of those output transformers Franz Gysi has used on his output stage please? or any similar will be appreciated.
Click to expand...

This trannies, you will hardly find some. Look for used Studer equipment...

I work with Studer and I found them in the garbage box, really!

But you will find suitable transformers from Lundahl or Sowther or other manufacturer. Look for 1:1 versions.

And be aware: this is not a good solution to drive long cables to the preamp!

Franz

An externally hosted image should be here but it was not working when we last tested it.
 
#219
Lee

I am not an expert in trannies, I just had good luck 🙂

The trannie should not have to low impedance. 1k or greater is O.K. for the CS4398.

And it should be 1:1

Everything usable as line driver or input-trannie with above specs is suitable.

Maybe there are also more cheap solutions? I remember, some people bought Behringer DI boxes just to remove the trannies.

Here a foto from my desk (sorry, explicitly content):

An externally hosted image should be here but it was not working when we last tested it.


In the back, the disks where the uncompressed sound is coming from. In front the DAC and blue the FE83E double bass reflex box with fronthorns, driven by a small TA2024 amp.

This setup reveals everything, a perfect nearfield setup. Quasi a extended headphone.

And it sounds absolutely great with this DAC. I will build it in the Studer 52 amp directly as it is now.

Franz

/Edit
The trannie solution allows further buffer, line driver or filter circuits! One of the best DAC's I ever heard, was a Zhaolu D2 CS4398 with coupling trannies to balanced Aikido amps, at the European Triode Festival.

/second edit
Be carefully, when buying DI boxes: today, most of them don't include trannies anymore.
 
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