New Small DIY Gigawork Dac?

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#245
Hi,

I am a happy user of this kit (see mine in the attached picture). I modified the original kit by changing the original AD op-amps with LM4562. The only singular behavior, compared with the other dac I have (DAC 707 Superpro), is the higher output level of signal also reported by other people in this thread. I am using the coaxial PSDIF input connected asyncrhonous to a Mac via a M2tech usb interface.

However, since I switched to a chip amp I noted that the chip-amp was getting very warm even without playing music (not with the other dac or CD player I have). Then I measured at the new Gigawork dac 750mV DC at signal out when the dac is connected to the Mac on both channels. If the dac is disconnected from the Mac I measure 2mV.

Connected to the Mac, the Superpro dac gives 9mV out.

I can hear a very high hum noise from the speakers when the amp volume is at maximum level.

Is there something wrong?

Thank you for your feedback

Renato
 

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#246
blackbird84 said:
I plan to buy this DAC but wonder how it compares to a decent soundcard like Asus Xonar DX or other of the same price/quality. Did any of you have the chance to compare them?
Click to expand...

Sounds very good if you rebuild the analogic part on a separate (new) board. The included I\U and buffer are built with wrong components and is almost imposible to change the smd resistors/capacitors.
 
#247
board resistor components!

I have to agree with Atupi, i own 2 of these DAC boards and both of them have components around the I/V an buffer stage with incorrect component values!
In my case even the two boards have both wrong component values but there are also differences between the two boards.

I use a seperate I/V stage to overcome these problems.
 
#250
Hi,

with reference to my post #245, I solved my problem by inserting an AC couplig cap at output (my amplifier is a DC coupled chipamp). Unlikely, I did not believe how much important was the influence of a cap on the audio signal: the cap added a veil to the music.

There is not sufficient space in the chassis to put a polypropilene cap, so I used a an electrolytic 4.7microF/35V Rubycon ZA.

Have you a suggestion for a better choice (forgetting BG N that I cannot find)?

Thank you

Renato
 
#251
Hi northernsky,

I think i am having the sane issue.

I removed the multiplexer mute chip.
I Also added the four 470 ohms to reduce output voltage.

I realized one of my amps didn't work.
So I tried a little SEP amp with capacitors at it's inputs and it sounded well.
So I am guessing I have the same DC problem.

Now I am adding 2 PIO .33 UF caps to test with my main amp and see how it goes.

Even with this work arround, there should be a cleaner way of fixing this issue?
I am afraid of those bypass caps ruining the sound..

Cheers
 
#252
Listening to the new setup now.
It sounds well, distortion seems to have dissapered.

I don't have a pre, just volume on a Mac.
My speakers are super sensitive so I guess I will adjust again those opamp resistors to reduce opamp gain a little more.

What makes me happy about this setup is that I am not noticing a high frequency roll-off as when using a potentiometer before the power amp Push Pull el84.
 
#253
But even when my system performace has improved
Is a coupling CAP between dac and power ideal?
I guess, a less component approach is aleáis better when possible.

Ideas to remove opamp stage bias:
1) test upgrade opamp power supply?
2) matching resistors in opamp section?
3) or just use a very boutique cap ?

Thanks
 
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