An op-amped lampucera sans tubes

This is the description sent by Marc:

Dac mod with LM4562
Marc Legare , canada.
Sun, 25 May 2008 22:15:06 -0400

Hello Mr Fikus

Thanks for let us discovering the CS4397 cheap dac from Mr. Chan  Lawrence

I had the cheaper one with surface mount parts and I asked to Mr.  Lawrence if I could buy another dac but with two separate power supplys.

He showed me the version with double power supply and non SMD parts  you also tried but didn't enjoy much over the cheaper one.

I tried many topologys with these dacs but didn't tried the tube  output stage.

I want to share with you my experience with these dacs

1- Double power supply model with non SMD parts is for me way better  than the cheaper one.
2- Don't hesitate to use oversize transformers 100VA is fine and  there's a great increase of sound quality with BIG transformers
3- I hate caps in the signal so I bypassed all the caps in the signal.
4- Last op amp in the costlier model is not required and you must  bypass it
5- I used a LM4562 directly coupled to the dac.  There's 0.85 V at  the output of the op amp with 2.5V at IN- and in +
6- To get rid of this 0.85V at the output of the op amp, there's a 1k  in series with the output that goes to the RCA plugs,  After this 1K  resistor, connect a 14.7K that goes to the -12V that feeds the op  amp.  This will cancel the 0.85 V at the op amp output and the op amp  will be more in class A operation.  The DAC will be directly coupled  without any cap.  The LM4562 needs at least 100 hours of breaking  time to play correctly.

This is the best dac I had in my horn based biamp system.  It eats  dacs which are over $4000

Best Regards

Marc Legare

Quebec Canada

P.s I made an error in my drawing I wrote CS8497 instead of CS4397