Upgrade output Shanling CD-S100 MkII

[CeeVee]

Hi guys,

I'm starting the thread because it does not make mutch sense in the UGS one, although it happens as direct conclusion of tests with the Shanling and the UGS.

It seems like the Shanling suffers from a severe bout of DAC output overengineering...as a result the sound is ....nothing to write home about.

Here are pictures of the output section...with it's 6 op-amps.

I'm counting on the knowledge, wisdom and goodwill of ZM to help me along here, ...to get this thingy to sing !

DAC is:1738
Op-amps: OPA604AP and one double OPA2604AP

[Zen Mod]

I'll catch ya later this evening ....

[CeeVee]

Thanks ZM will do....gotta work some as well.

[Zen Mod]

just locate what's used as DAC(s) ; knowing that and - hopefully , what raw PSU voltages you have - we can work from there .

edit:
anyway , I'm googling right now .....

[Zen Mod]

BB1738 DAC

just count how many of them are inside

[CeeVee]

Yes ZM, you are right ( I said so in my first post )

Dac is BB1738E, only one, the one in the picture i uploaded.
Reciever is Cirrus Logic CS8420Cs.
the 3 legged thingie you see next to the DAC chip is a 317 regulator.

Available voltages are:

+15V,-15V, +5V, +3.3 V on the DAC board, also +25V on the display board.

The silkscreen is very clearly labeled on all connectors, even the signals between receiver chip and DAC are labeled!

[Zen Mod]

Originally posted by CeeVee
Yes ZM, you are right ( I said so in my first post )

Dac is BB1738E, only one, the one in the picture i uploaded.
Reciever is Cirrus Logic CS8420Cs.
the 3 legged thingie you see next to the DAC chip is a 317 regulator.

Available voltages are:

+15V,-15V, +5V, +3.3 V on the DAC board, also +25V on the display board.

The silkscreen is very clearly labeled on all connectors.

hehe- you edited your first post ( adding DAC ) , but I didn't looked after ..........

so - one PCM

probably something straight from datasheet :

[CeeVee]

..It's a safe bet, they just followed the app note, but i'll take the board out just to check, it's easy.
At least the number of op-amps is right, 6 !....6 too many?

Finished checking.
...yep, that's the schematic they used.

All small electros and yellow nonpolar are power supply filtering.

Only the caps at the output are added by them ( initial picture , big white caps, large elctrolytics and relay...).

...from another forum:

The '1738 has differential current output and no opamps, so you can mess around a bunch with the I/V stage. Lotsa versatility.

That sounds good!

[Zen Mod]

Originally posted by CeeVee
..It's a safe bet, they just followed the app note, but i'll take the board out just to check, it's easy.
At least the number of op-amps is right, 6 !....6 too many?

Finished checking.
...yep, that's the schematic they used.

All small electros and yellow nonpolar are power supply filtering.

Only the caps at the output are added by them ( initial picture , big white caps, large elctrolytics and relay...).

OK - I need some time to think what solution is easiest and have best PITA/result ratio

can you measure DC voltages ( ref. to gnd ) on pins 16,17 and 20 ?

do not measure directly at DAC pins , but on traces or - even better - on adequate OP pins

[CeeVee]

Hi ZM,

all 3 pins have 2,41V DC ref to signal ground.