Summing (I/V) op-amps for Pioneer DV-59i

hollowman · 12th March 2007, 12:31 AM

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

hollowman · 12th March 2007, 08:04 AM

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?

stephensank · 12th March 2007, 04:46 PM

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 crap 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 crap 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.

12th March 2007, 12:31 AM	#1
hollowman diyAudio Member Join Date: Jan 2007	Summing (I/V) op-amps for Pioneer DV-59i 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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12th March 2007, 08:04 AM	#2
hollowman diyAudio Member Join Date: Jan 2007	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?

12th March 2007, 04:46 PM	#3
stephensank diyAudio Member Join Date: Oct 2006	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 crap 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 crap 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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