After enjoying my last tweak on CDP950, its time to see 'What NOS is means to me'. I've got info from The Lampizator site a while ago and made a plan on real PCB, here it is on bottom side.
This operation needs careful surveying of actual pins on the PCB. The job is really bypassing the digital filter chip CXD1088 who does the oversampling. The 1088 got its inputs from CXD1125 then outputs to TDA1541. NOSing is going direct from CXD1125 to TDA1541 with the help of shifter 74HC164, more details please check Mr. Lukasz Fikus site.
The first step is lifting the jumpers and resistors on the far side (from the 1125 & 1541), I use solder suction to do that. Then the 74HC164 soldered and glued to PCB, I've bent flat all its pins for easy soldering, see below.
Second step is to insert the wires (UTP) into pin holes of lifted jumper-resistor to the top side of the PCB & soldering them
Woow..looks easy, but I've made one mistake, it has cost me my brother in law amp..hiks.. :(. No sounds at all came out from the RCA, then I tried to short the R's...yep, some music (Andrea Bocelli-Amore CD) then silence...the amp is dead. Then I checked the plan, yes a mistake. Wire from 1125's pins 76 and 78 is the other way around, the wrong one it is, shown on the last two pictures.
Fixed them and YES...I heard Andrea singing through my throw away cheapo earphone..I knew the sound is already very good even with this horrible earbuds.
How is NOSed CDP950 sounds?..well, I think I'm closer now to my goal. It is a leapfrog from my last tweak, here are my early personal review :)
My systems : source CDP950, PreAmp Aikido DIY-6CG7-6DJ8 tubes, Power Amp DIY Aleph J clone, Speaker Magnepan SMGa.
Ze Sound : Wide and Grand, all the details & ambiance, effortless, not one bit tiring at all, you can follow each instrument easily. Timbres are really more correct. I'm not listening to lows, highs and mids anymore everything are there.
Surprises, compared to second tweak :
Some fast beat & complex tracks I usually have skipped due to unbearable & tiring sound now just opened up, no more congestion--newest CD from Dianne Reeves, Renee Olstead are full of them, hey its not the recording! Its YOUR CD Player!..
I hear many clicks and ticks and garbles during track change, pause and stop. I think I will live with them, or I have to look for muting schematic later on :)
Don't blame your Pre Amp, Power and Loudspeaker just yet. It turns out that they are more capable than I've ever thought of, given the best possible source, that is, my CDP950-NOS..(..soon to be tubed ha ha hah...)
Now I urged everyone I know to NOS their old TDA1541 CD Player. Last but not least, really BIG thanks to Mr. Lukasz...