Hi Karl, what is achieved when placing that cap across pin 8 and 1? Does it have to be a polarized electrolytic? I did come across a little liturature on the DAC and I thought it was a multibit and not a bitstream. Yeah this player is pretty low end, I just like the very simple design and cool aesthetics. Is there anything gained by moding the op amp to work in class a?
Whoops 
Thats no good is it, should be pins 8 and 4, it helps by providing rail decoupling as close to the I/C as possible. Decoupling is much better done this way, rather than caps fitted between each rail and ground. The reason is, that this stops any unwanted currents being injected into the "signal" ground. The Op-Amp (any Op-Amp) has extremely good rejection of electrical noise on the power supply but having said that every little helps. A favorite trick of mine is to place a 0.1 mfd "surface mount" capacitor between the legs of each electrolytic on the pcb. This counters the rise in self inductance that all electrolytics exhibit, which limits their effectiveness to "decouple" at high frequencies. As to the DAC , time shared means that only one convertor is used for both left and right channels. It actually decodes the sample for one channel, passes the result to the output, then gets to work on the sample for the other channel. This saved money when the technology was new, convertor chips were relatively expensive. One downside is that this introduced a small phase shift at high frequencies, the result was that the musical "image" appears slightly over to one side, as if the balance control is not quite centered. Sony on the CDP101 actually made the gains of the output stage of the player slightly different, one channel had a 15k feedback resistor, the other a 16k. Class A ? Under small signal conditions the Op-Amp runs in class A. I am sure you will not notice any benefit, all it does is to force the I/C to either sink or source an additional current, increasing power dissipation within the I/C .
Regards Karl
Thats no good is it, should be pins 8 and 4, it helps by providing rail decoupling as close to the I/C as possible. Decoupling is much better done this way, rather than caps fitted between each rail and ground. The reason is, that this stops any unwanted currents being injected into the "signal" ground. The Op-Amp (any Op-Amp) has extremely good rejection of electrical noise on the power supply but having said that every little helps. A favorite trick of mine is to place a 0.1 mfd "surface mount" capacitor between the legs of each electrolytic on the pcb. This counters the rise in self inductance that all electrolytics exhibit, which limits their effectiveness to "decouple" at high frequencies. As to the DAC , time shared means that only one convertor is used for both left and right channels. It actually decodes the sample for one channel, passes the result to the output, then gets to work on the sample for the other channel. This saved money when the technology was new, convertor chips were relatively expensive. One downside is that this introduced a small phase shift at high frequencies, the result was that the musical "image" appears slightly over to one side, as if the balance control is not quite centered. Sony on the CDP101 actually made the gains of the output stage of the player slightly different, one channel had a 15k feedback resistor, the other a 16k. Class A ? Under small signal conditions the Op-Amp runs in class A. I am sure you will not notice any benefit, all it does is to force the I/C to either sink or source an additional current, increasing power dissipation within the I/C .Regards Karl
I wish I knew more about the Yamaha ym3020 dac, there is very little info on the web. I was working at a library the other day and thought I should probably look it up in one of those ancient IC catalogs but I was pressed for time and had to head out to the next job. I read an article online that lauded the sonic benefits of forcing audio op-amps into class a, but like anything out there....you gotta take it with a grain of salt. Thank you for the great info so far
I got Proton AC-420 new-old-stock. After sitting in a box so long the belt was no use any more. I replaced it with one from odd CD-Rom drive and it works without a problem.
I like the sound of this player a lot, but the temptation to try upgrade eating its way into my system.
I think I would do opamp change to LME49860NA that I just happen to have a pair around. Since this player has many similar opamps I am a bit confused witch ones belong to audio path.
Also does anybody have a schematics for this unit?
I like the sound of this player a lot, but the temptation to try upgrade eating its way into my system.
I think I would do opamp change to LME49860NA that I just happen to have a pair around. Since this player has many similar opamps I am a bit confused witch ones belong to audio path.
Also does anybody have a schematics for this unit?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.