Hi,
in Pioneer PD9300 with 2 x Pcm58-K there are complementary (selfbiasing (?)) fets on the op amp output, drains to V+/V- , gates together to op amp output , sources together form output, no other parts, very simple.
Same for filter stage.
What is that good (?) for ???
Can it raise distortion ???
Btw. 8 PCM58 I have, measure all worse than PCM56, lower noise but more distortion
in Pioneer PD9300 with 2 x Pcm58-K there are complementary (selfbiasing (?)) fets on the op amp output, drains to V+/V- , gates together to op amp output , sources together form output, no other parts, very simple.
Same for filter stage.
What is that good (?) for ???
Can it raise distortion ???
Btw. 8 PCM58 I have, measure all worse than PCM56, lower noise but more distortion
i suspect it is good for giving your CDP a low output impedance. And, yes, it does add ~~~ distortion ~~~ (feel fear now)
But i suspect the distortion added will be much less than from the opamp, or the opamp with a high output impedance driving a following lower input impedance stage.
But i suspect the distortion added will be much less than from the opamp, or the opamp with a high output impedance driving a following lower input impedance stage.
It sounds like pedjas (i think it was at least) IV stage.
It has the benefit of giving a very low input impedance for the DAC to feed. As for distortion it should be very small since the DAC will try to feed the current through the transistor.
It has the benefit of giving a very low input impedance for the DAC to feed. As for distortion it should be very small since the DAC will try to feed the current through the transistor.
If it is before the buffer nothing.
If it is after everything, in this case the dac will se 0 ohm resistance while the current is still terminated by the resistor.
Could you draw a schematic?
If it is after everything, in this case the dac will se 0 ohm resistance while the current is still terminated by the resistor.
Could you draw a schematic?
The op amp is a 5532 and should be able to deliver that one mA for the DAC, so I kick the FETs out and measure again.
carlosfm said:
Never listened to that player, bought it for the PCM58-K.
Could be it sounds green. 😱
Those FETs are indeed for boosting maximum output current. This seems common knowledge to me, max. output current of opamps is 20 to 50 mA with modern opamps in general with distortion. It also gives the opportunity to write "class A output stage" on the case 😉
In time I have had several Pioneer oldies ( like the very nice PD-8500 ) with those magnificent linear transports and auto-servo electronics ( no potentiometers inside except for laser current ). They always sounded better without the buffer and even better with better opamps ( and a better clock but one does not have to believe that ).
These series also have the too large 1000 or 2200 uF caps behind the regulators. Please measure the supplies and don't be surprised if they "motorboat" during startup. 100 uF was enough for them. Removing the digital volume control can't hurt either ( PD0026 ??? ).
I stopped using them as their laser dies earlier than the old Philips types and the lasers are more pricey too.
In time I have had several Pioneer oldies ( like the very nice PD-8500 ) with those magnificent linear transports and auto-servo electronics ( no potentiometers inside except for laser current ). They always sounded better without the buffer and even better with better opamps ( and a better clock but one does not have to believe that ).
These series also have the too large 1000 or 2200 uF caps behind the regulators. Please measure the supplies and don't be surprised if they "motorboat" during startup. 100 uF was enough for them. Removing the digital volume control can't hurt either ( PD0026 ??? ).
I stopped using them as their laser dies earlier than the old Philips types and the lasers are more pricey too.
Bernhard said:Never listened to that player, bought it for the PCM58-K.
Could be it sounds green. 😱
You are taking side steps, as you need players with PCM56s, you have to collect 64 of them.😎
jean-paul said:
Some 13~14 years ago I had a PD8700 (If I remember the model), first generation with the "inverted" transport, but before the "Legato Link" brigade.
Sorry, I meant the models that had linear transports with "floating" laserunit. Not that Stable Platter things that make a normal person mad with the need for putting the cd in upside down 😉
jean-paul said:
It made me mad for some time, true.😀
But the first generation Staple Platter mechanism on my CDP was very sturdy, mostly metal construction.
The player had two quite big trafos inside.
Never had a problem with it, sold it to a friend and he still uses it today.
But worse sound 🙄
If you want it, I have the service manual ( as always ) of this one. I still miss it too. Because its laser had died I trashed it myself
If you want it, I have the service manual ( as always ) of this one. I still miss it too. Because its laser had died I trashed it myself
Thanks, but I do have it.
I just remember I have a brand new laser PWY1011 (expensive) which I bought to try to repair it.
No success though (inserted flat cable wrong way
)
Anyone interested drop me a pm
I just remember I have a brand new laser PWY1011 (expensive) which I bought to try to repair it.
No success though (inserted flat cable wrong way
)Anyone interested drop me a pm
carlosfm said:
It would be 2 x 64 =128 as PCM56 is a mono DAC.
But I doubt if I take the risk that the glue logic will not work or will disturb sound more than it helps.
So it looks like I will end up with something like 20 or 30 per channel.
My current stock is around 25 🙄
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