That's interesting on the 2604 - I actually wanted to like it the best because it was the most expensive. 
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But it just seemed to lack the dynamics and detail compared to the others, at least in my system. Perhaps if the desired goal were smoothness and firgivabiity with all source material. But we all hear differently anyway.
Oh, also, I did end up replacing the two old 47uF Duorex caps with Elna Silmic II since I had another order come in from Mouser. So those six caps near the opamps are all replaced now. Can't say if there was any diff before and after on those last two caps - I didn't try to do a before and after listen. But at least those Duorex caps won't leak and corrode the board.
I also bought a replacement pick-up laser -just the pick up head. Are those hard to replace and does it require tuning the pots after install to optimize? It was from China and cheap, so if it's easy and doesn't require tuning, I may just use the new one and keep the old as a spare to verify the new one is actually working during the eBay protection period.
. But it just seemed to lack the dynamics and detail compared to the others, at least in my system. Perhaps if the desired goal were smoothness and firgivabiity with all source material. But we all hear differently anyway.
Oh, also, I did end up replacing the two old 47uF Duorex caps with Elna Silmic II since I had another order come in from Mouser. So those six caps near the opamps are all replaced now. Can't say if there was any diff before and after on those last two caps - I didn't try to do a before and after listen. But at least those Duorex caps won't leak and corrode the board.
I also bought a replacement pick-up laser -just the pick up head. Are those hard to replace and does it require tuning the pots after install to optimize? It was from China and cheap, so if it's easy and doesn't require tuning, I may just use the new one and keep the old as a spare to verify the new one is actually working during the eBay protection period.
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Its always worth listening to different opamps for a few days (not because they change ) but rather your perceptions might. Not saying it will change how you feel about it in the end, but just that "experimenter expectation" is a real effect... you want it to sound fantastic... and somehow it isn't... so you just quickly revert back to something else.
Have a read at the single OPA604 data sheet attached and check out the sound quality section at the end.
What's the pickup ? Most Sony players have the full range of adjustments and you definitely need a scope to even attempt swapping one. This thread covers typical alignment although the KSS240 here is different in that it has some presets mounted on the pickup along with some of the electronics. The procedures are similar for any player though.
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
) but rather your perceptions might. Not saying it will change how you feel about it in the end, but just that "experimenter expectation" is a real effect... you want it to sound fantastic... and somehow it isn't... so you just quickly revert back to something else.Have a read at the single OPA604 data sheet attached and check out the sound quality section at the end.
What's the pickup ? Most Sony players have the full range of adjustments and you definitely need a scope to even attempt swapping one. This thread covers typical alignment although the KSS240 here is different in that it has some presets mounted on the pickup along with some of the electronics. The procedures are similar for any player though.
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
Its always worth listening to different opamps for a few days (not because they change
Have a read at the single OPA604 data sheet attached and check out the sound quality section at the end.
What's the pickup ? Most Sony players have the full range of adjustments and you definitely need a scope to even attempt swapping one. This thread covers typical alignment although the KSS240 here is different in that it has some presets mounted on the pickup along with some of the electronics. The procedures are similar for any player though.
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
I see your point - I did listen to the OP2604 for a couple of days, but it's easy to swap, so I can continue to swap opamps over time and see if something hits the sweet spot over extended listening.
This is the pickup I bought: KSS-210A for $8.50 shipped
Sony KSS 210A Laser Head KSS 212A KSS 212B KSS150A Optical Pick Up New | eBay
So sounds like just swapping a pick-up head/laser in/out isn't trivial. . .guess I'll keep my current one in until it fails then.
KSS 210's should usually work OK without much adjustment but to get it all optimal does need a scope. So if you do try the new pickup, don't turn any pots. (we used to fit these in the field to many music centres/portables)
That said, the focus bias adjustment maximises the RF signal and this can be set by ear. First you must mark the focus bias preset so you can put it back again. If you listen to the white noise produced by the pickup coils in play mode you will find that turning the focus bias pot increases this noise. The correct point is when the noise is at a minimum. That one adjustment gets you the best possible amplitude of signal off the disc. All the other adjustments which affect how well it tracks and copes with mechanical shock/disc defects/track searching etc need a scope.
That said, the focus bias adjustment maximises the RF signal and this can be set by ear. First you must mark the focus bias preset so you can put it back again. If you listen to the white noise produced by the pickup coils in play mode you will find that turning the focus bias pot increases this noise. The correct point is when the noise is at a minimum. That one adjustment gets you the best possible amplitude of signal off the disc. All the other adjustments which affect how well it tracks and copes with mechanical shock/disc defects/track searching etc need a scope.
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