Experience with this DIY DAC ?

[McCrackers]

Originally Posted by McGyver

PCM1798 do DAC ' lampucera ' na przejściówce (763208844) - Aukcje internetowe Allegro

Hello McGyver,
Other than learning Polish do you know where/how I could order one of these?

[legarem]

What is bothering me with this PCM1798 board is the two op amps we see under the board. I want to get rid of op amps. Op amp are devil for me.

[McGyver]

Originally Posted by legarem

What is bothering me with this PCM1798 board is the two op amps we see under the board. I want to get rid of op amps. Op amp are devil for me.

But I did it. I got rid of opamps, I desoldered them and connected transformers right to the chip's legs. And grounded center taps.

[Lucas_G]

I am listening to my DAC with Lundahl LL 1674 for some weeks now.
I attach a picture with how I connected the Lundahls. I use two 1K resistors for R1 and R2 and no resistor for R3.
I also have a 1nF MKP cap connected between the output sides of R1 and R2 as a very light filter for high frequencies at the input side of the Lundahls.

Today I measured the output of this configuration, and I wasn't pleased to see the frequency response. As you can see on the picture, already at 20 kHz the level is down by some -6 dB

These Lundahls should be quite flat up to 20 kHz, so apparently my connection is not optimal.

Can anyone give me a clue as to get better results?

[Tony X]

Thanks, Havoc08, for directing me to this thread. It's taken me about three days to read and although I cannot pretend to understand everything, I am convinced already go the transformer route. Which transformers is a decison yet to be made.

It still looks to me, however, that the DAC you suggested is a baby brother to the ones talked about here.

I don't see any obvious reason they shouldn't, but can someone please confirm that these mods also apply to this DAC.

My aim is to place this DAC between a Shigaclone (still to be built) and a MyRef amp via a Lightspeed attenuator and finally going into 98db full range speakers.

I also have a T-Amp which I like to use during trials. Are we saying here that the T Amp needs a special arrangement and so we cannot just swop amps around ?

[Tony X]

Although I have the DAC mentioned in the previous post on order, I had been looking at this one which is locally available. As it is PCM1798 based, I thought it might be of interest seen McKyver's recent comments. It even has a Chinese price and might have originated there for all I know.

SPDIF only!!

Anybody have any experience with this one?

[McGyver]

Originally Posted by Tony X

Although I have the DAC mentioned in the previous post on order, I had been looking at this one which is locally available. As it is PCM1798 based, I thought it might be of interest seen McKyver's recent comments. It even has a Chinese price and might have originated there for all I know.

SPDIF only!!

Anybody have any experience with this one?

Looks good, nice layout and quality components. But Yoy should bear in mind that PCM1798 is not a voltage output DAC. It is a current output DAC, and requires completely different analogue stage than CS4397 or CS4398.
For PCM1798 I'm using Sowter transformers for I/V conversion, desymmetrization and analogue filtration followed by tube amplification stage.

[Ryssen]

McGyver,I contacted you via your website,regarding the PCM1798.

[QUOTEFor PCM1798 I'm using Sowter transformers for I/V conversion, desymmetrization and analogue filtration followed by tube amplification stage.
][/QUOTE]
Do you have a drawing how this is done?

[McGyver]

No, I haven't. I just soldered it. I must draw it and post it here.

[Tony X]

Originally Posted by McGyver

PCM1798 is not a voltage output DAC. It is a current output DAC,

OK Thanks