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
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
Attachments
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!
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!
..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:
That sounds good!
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:
That sounds good!
CeeVee said:..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
Stones said:
ceevee mention receiver just as info ;
hehe - even if I think that he certainly need that receiver , for functional cd .........
D1 - in original - if used for this ,balanced out DAC........ sorta sad/half solution - using just one I leg of DAC ;
yes , with D1 he'll have bal out ( needed for his UGS based preamp , but still just unbal input in D1 ;
makin' balanced in D1 , or anything like that - certainly messier than plain resistive I/V with xformer , with or w/o output buffer .
if I calculated correctly - 1738 gives enough voltage directly for line output ;
while we are at it ........ CeeVee - can you make small test :
-toss out all OPamps ;
-put 1k2 parallel with 4n3 - between + and - I outputs (DAC pins 17 and 16 , 25 and 26 ,respectively ) ;
-desolder one side of resistor placed across I/V conversion/filter OPamps (first to DAC);
-route output signal (via 3u3 in each (+/-) leg to output ;
-just listen - if you like what you hear in that raw test , we are on something
I hope that I'm clear enough , without attaching schmtc
edit:
attached test schematic
Attachments
Zen Mod said:
ceevee mention receiver just as info ;
hehe - even if I think that he certainly need that receiver , for functional cd .........
I think you miss the point, If you need a receiver for it to work, you might as well consider an outboard DAC. If not for the separate supplies alone then consider that you can mod it without risking loss of music while playing with it and having a direct baseline (however good or bad) to judge against.
Thanks guys for a very lively discussion, and yes the as ZM says i just mentioned the reciever as info, to transmit a picture, so to speak.
It is indeed an upsampler as well, 96k/24bit.
and as ZM says' the original idea is to upgrade a bad DAC output stage, but it could go further if the conclusion/test show that that is the way to go....and ZM is willing/interested.
For myself i'm certainly open to sugestions that will get this " cookbook" CD player to produce decent sound.
For now i'll do the testing you sugest ZM, later today ...for now the guys flying the planes need my atention.
edit: ahhh the transformers,...no i don't have any, since i will need them what do you sugest i get ?
It is indeed an upsampler as well, 96k/24bit.
and as ZM says' the original idea is to upgrade a bad DAC output stage, but it could go further if the conclusion/test show that that is the way to go....and ZM is willing/interested.
For myself i'm certainly open to sugestions that will get this " cookbook" CD player to produce decent sound.
For now i'll do the testing you sugest ZM, later today ...for now the guys flying the planes need my atention.
edit: ahhh the transformers,...no i don't have any, since i will need them what do you sugest i get ?
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