Experience with this DIY DAC ?

[Havoc08]

It is mentioned somewhere in the thread that you should not short the dac chip. It needs alittle load, but I dont remember the exact ohms.

[McGyver]

As I mentioned earlier Lundahls 1517 have DC resistance about 9 ohms. If it's directly connected to CS4397/8 it's practically short. You can fry the DAC in this way.

[cadaverdog]

I have one of these in my system- and I am using UTC A-20's. The L/R coupling caps were removed- and the transformers are wired right to the dac pins. It sounds great, but it's just a bit too "tweaky" for my taste.

I know it sounds contradictory to say this on diyaudio.com, but I'd rather be listening than tweaking.

You'll get the dac with the transformer- and the A-20's.

Let me know if any of you are interested.

Thanks

[Havoc08]

McGyver do you know the preferred impedance the dac chip would like to see?

Just scrolled through the datasheet and couldn't find anything on the subject?

[Bill Fuss]

The cs4398 data sheet clearly states 1k minimum. The source impedence is around 120ohms.

[Havoc08]

ahh yes.. so does the cs4397 datasheet. I found it now. Thank you.

Connecting a LL1517 with no resistors should then be considered a really bad idea .

[GerardA]

Who knows the minimum DC-resistanceload the DAC can handle?
My monacor trafo's are 150 Ohm DC, with the 2 x 47 Ohm I'm at 244 Ohm.
I'd like to go lower but how low can we go?
The optimum source impedance of the monacor is 50 Ohm.
This is possible with a parallel R of about 100 Ohm, but I am not going to try that!!
Without Resitors the DAC sees 150 Ohm, will that be enough??
I know the datasheet says 1k, but as stated before I think the optimum values for the trafo are more important then for the DAC,
unless it breaks down...

[Bill Fuss]

Nobody knows that answer, it's your dac, try it if you must. I wouldn't add any parallel load though.

You could add a parallel load if you keep some series resistance, but it would act as a voltage divider also.

[Ryssen]

I lowered the seriesresistance from 2 x 220 to 2X 47 ohm.

My monacor trafo's are 150 Ohm DC, with the 2 x 47 Ohm I'm at 244 Ohm.

Maybee I shouldnin go lower than 2x560 ohm with the LL1517,as they are 9 ohms.
May I dare to try around 200 ohms..

[ch33ta]

Just a little favor...
I need the UTC A-20 dimensions...
Two pieces arriving soon and I planned to put them on the DAC pcb (removed opamps and anything related to them) - PICTURE (currently testing with Monacor LTR-110)