An op-amped lampucera sans tubes
This is the
description sent by Marc:
Subject:
Dac mod with
LM4562
From:
Marc Legare ,
canada.
Date:
Sun, 25 May 2008
22:15:06 -0400
To:
lukasz.fikus
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
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