Hi everyone
Recently bought a Sony CDP-970 entirely to play with
It does indeed have 2 x PCM59P's but they are weirdly graded -1 NOT J or K
are the -s and -1 grades a Sony thing but equivalent? Any info appreciated here
Further (and more curiously) the -Vcc rail is at -8 volts not -12 as its supposed to be, after datasheet mining it seems *only* Sony did that and then only once. Any idea why? They've gone to some lengths to do it to with an op-amp regulated supply too rather than a fixed reg. Again any info is appreciated.
I don't feel able to settle on this as its not "normal" but before selling it on in ignorance I thought I'd at least TRY and understand it
To be fair, it also had polarised electrolytics in the signal path so the whole thing might just be an oddity - or more likely I'm not grasping what's going on. Pretty sure that Sony's professional electrical engineers are far more clued up than I am 🙂
My mods so far are 100uF non polar electrolytics instead of the 50uf polars in the output (C403 and C503) and I swapped the op-amps for OPA2134's because they were lying around.
Any advice appreciated. To me it seems an odd design, so I'd really like to learn what's going on.
Andy
Recently bought a Sony CDP-970 entirely to play with
It does indeed have 2 x PCM59P's but they are weirdly graded -1 NOT J or K
are the -s and -1 grades a Sony thing but equivalent? Any info appreciated here
Further (and more curiously) the -Vcc rail is at -8 volts not -12 as its supposed to be, after datasheet mining it seems *only* Sony did that and then only once. Any idea why? They've gone to some lengths to do it to with an op-amp regulated supply too rather than a fixed reg. Again any info is appreciated.
I don't feel able to settle on this as its not "normal" but before selling it on in ignorance I thought I'd at least TRY and understand it
To be fair, it also had polarised electrolytics in the signal path so the whole thing might just be an oddity - or more likely I'm not grasping what's going on. Pretty sure that Sony's professional electrical engineers are far more clued up than I am 🙂
My mods so far are 100uF non polar electrolytics instead of the 50uf polars in the output (C403 and C503) and I swapped the op-amps for OPA2134's because they were lying around.
Any advice appreciated. To me it seems an odd design, so I'd really like to learn what's going on.
Andy
Attachments
DAC V+ = 5V
DAC V- = -8V (would've been -5V, but a higher negative voltage is required, to obtain decent linearity out of that current-out DAC)
The +5 and -5 volts OP amp rails are probably there because the analog output stage was lifted from one of Sony's portable players; no need to use the higher voltage to start with, also no need for separate voltage regulators for + and - 12V DC, for example..... (cost savings in parts/design).... but I might be wrong.
DAC V- = -8V (would've been -5V, but a higher negative voltage is required, to obtain decent linearity out of that current-out DAC)
The +5 and -5 volts OP amp rails are probably there because the analog output stage was lifted from one of Sony's portable players; no need to use the higher voltage to start with, also no need for separate voltage regulators for + and - 12V DC, for example..... (cost savings in parts/design).... but I might be wrong.
Suspect the grading could be an I, not a 1 (?)
Maybe a 'Lower' grade than the J or K as it's earlier in the alphabet (?)
Just guessing here though.
P.
Maybe a 'Lower' grade than the J or K as it's earlier in the alphabet (?)
Just guessing here though.
P.
Thanks for replying
@Extreme_Boky
According to the datasheet the PCM58p requires +5/-12v. -8v is out of spec.😕
I hadn't spotted that the OP amps are only +/-5v either but I take your point it eliminates the need for an entire power section to service two op-amps. That said, the Headphone amp is +/-9v
@percival007
It's definitely a '1' there's also an 'S' grade for the fancy stuff. But that is the fear, despite the perception of the 970 being nearer top of the range, is it really... not looking like it at the minute TBH
Andy
@Extreme_Boky
According to the datasheet the PCM58p requires +5/-12v. -8v is out of spec.😕
I hadn't spotted that the OP amps are only +/-5v either but I take your point it eliminates the need for an entire power section to service two op-amps. That said, the Headphone amp is +/-9v
@percival007
It's definitely a '1' there's also an 'S' grade for the fancy stuff. But that is the fear, despite the perception of the 970 being nearer top of the range, is it really... not looking like it at the minute TBH
Andy
