question on upgrading old board

synap2012 · 5th May 2008, 04:25 AM

Hello, newby question for everyone. WHat would be an upgrade in quality from a " JRC 4558dy" op amp

I know very little about what I am looking for in compatibility between op-amps.

the reason I ask is I have a old Yamaha MR1642 that needs work, I want to try to upgrade a few things on it to help my DIY skills, before I tackle something that I would care if I destroyed.

anyone know where I can get schematics for such a board?

Mooly · 5th May 2008, 04:56 PM

The 4558 is like a dual 741 type OpAmp. You can do much better, but I would not go overboard on something like this. Fit TL072 OpAmps, and see what you think. Use solderbraid to remove the old ones.
Regards Karl

synap2012 · 7th May 2008, 03:57 AM

Thanks ALOT!!!

can you upgrade transistors aswell? they have some "A970 BLo" Transistors in them.

also I have come to the understanding that the power supply has a lot to do with the performance of the components, how true is that and what would be a good power supply and power transformer to use to power the modules . How does powering multiple modules affect the power supply? I want to power 4 - 8 modules with one power supply.

I have seen these power supplies on Five fish studios called PSU-2448 how well would this work?

jaycee · 7th May 2008, 05:53 AM

Upgrading transistors isnt recommended as the specifics of the parts used will be relied upon. A970 will be 2SA970, which is a pretty good small signal transistor (you might find C2240 on there too).

Opamps - don't go overboard. Try either TL072 as suggested, or NE5532. Anything more pricey isn't warranted and might make the circuit unstable.

Mooly · 7th May 2008, 07:16 AM

How many are there in this thing ? Some Op Amps draw more current than others, the difference can add up if there are a lot.
4558 and TL072 draw little.
Regards Karl

5th May 2008, 04:25 AM	#1
synap2012 diyAudio Member Join Date: May 2008	question on upgrading old board Hello, newby question for everyone. WHat would be an upgrade in quality from a " JRC 4558dy" op amp I know very little about what I am looking for in compatibility between op-amps. the reason I ask is I have a old Yamaha MR1642 that needs work, I want to try to upgrade a few things on it to help my DIY skills, before I tackle something that I would care if I destroyed. anyone know where I can get schematics for such a board?

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5th May 2008, 04:56 PM	#2
Mooly diyAudio Member Join Date: Sep 2007	The 4558 is like a dual 741 type OpAmp. You can do much better, but I would not go overboard on something like this. Fit TL072 OpAmps, and see what you think. Use solderbraid to remove the old ones. Regards Karl

7th May 2008, 03:57 AM	#3
synap2012 diyAudio Member Join Date: May 2008	Thanks ALOT!!! can you upgrade transistors aswell? they have some "A970 BLo" Transistors in them. also I have come to the understanding that the power supply has a lot to do with the performance of the components, how true is that and what would be a good power supply and power transformer to use to power the modules . How does powering multiple modules affect the power supply? I want to power 4 - 8 modules with one power supply. I have seen these power supplies on Five fish studios called PSU-2448 how well would this work?

7th May 2008, 05:53 AM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Upgrading transistors isnt recommended as the specifics of the parts used will be relied upon. A970 will be 2SA970, which is a pretty good small signal transistor (you might find C2240 on there too). Opamps - don't go overboard. Try either TL072 as suggested, or NE5532. Anything more pricey isn't warranted and might make the circuit unstable.

7th May 2008, 07:16 AM	#5
Mooly diyAudio Member Join Date: Sep 2007	How many are there in this thing ? Some Op Amps draw more current than others, the difference can add up if there are a lot. 4558 and TL072 draw little. Regards Karl

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