| hollowman |
In reference to this schematic excerpt of the Pioneer DV-59i DVD-A/-V/SACD/CD player ...
CLICK HERE FOR LARGE VERSION OF THIS SCHEMATIC
... which op-amps would you recommend for the summing (I/V) stage? The stock chips are low-cost 5532's -- both for I/V and final voltage amplification (buffering).
For the final voltage amplification (buffering) stage, I think I'll stick with OPA627, AD825s, AD845s or, a personal favorite, the AD8620.
Thx for any info you can provide :) |
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| hollowman |
Let me clarify my query a bit...
I've replaced op-amps in CD/DVD players before, but only ones in which the DAC outputted voltage.
Is there a brand/model of op-amp that's better for I/V summing -- and specifically, better-functioning in the Pioneer DV-59i's topology -- than others? Can I get away with using less-expensive op-amps for the I/V stage, and use the money saved for the voltage-gain stage op-amp? |
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| stephensank |
Because this player, like the DV578A-S I grudgingly put in the home system to satisfy my son's urges to play various region dvd's, is so cheaply made that it uses a single +12V power supply for the output stages, you have to have the dc blocking caps. Otherwise, the final opamps would be driving 6VDC through the output load resistors, muting transistors & any direct preamp input resistive loading, and do damage.
However, despite this limitation, I was actually able to get this piece of **** to sound good with OPA2134 chips in both stages(just the front channels on this multi-channel piece), 100ufd Nichicon dc blocking caps, bypassed with as much film cap as would fit in the tiny space provided(in this case, 2uf/100v MP + 0.015uf/33v styrene), and the same sort of treatment to the power supply caps. Of course, I replaced all of the garbage caps in the main supply with the biggest Nichicons that would fit, and installed IXYS rectifiers. Those PCM1742 B-B dac chips must be awfully damn good, because this piece of **** DV578A-S now sounds ridiculously good.
Good enough for me to now think about changing the whole output circuit to +/-15V power supply operation, to then eliminate the dc blocking caps. |
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