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I have several audio devices built 40 years ago I am upgrading that used 748 and 558 8pin dip op-amps. I have used 833s to replace the 558 but can't find a cheap low noise replacement for the 748. Any suggestions?An externally hosted image should be here but it was not working when we last tested it.
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The 748 uses external frequency compensation. Does the intended use have any components attached to pins 1, 8 or 5 ?
If not, then you could simply be looking at something like a TL071 which even though it is a FET input device, could offer a big improvement.
As always, it would help to see the actual circuit they are used in.
Edit... and what is the supply voltage. The 748 can withstand 40 volts.
If not, then you could simply be looking at something like a TL071 which even though it is a FET input device, could offer a big improvement.
As always, it would help to see the actual circuit they are used in.
Edit... and what is the supply voltage. The 748 can withstand 40 volts.
Wow, that's a chip that I haven't come across since about 1980.
Also watch out for use of the offset null, this was a low offset part in its day.
The NE5534 might work if you move the compensation capacitor
Also watch out for use of the offset null, this was a low offset part in its day.
The NE5534 might work if you move the compensation capacitor
i goofed up adding schematics so re posting:
I have several audio devices built 40 years ago I am upgrading using 748 and 558 8pin dip op-amps. I have used 833s to replace the 558 but can't find a cheap low noise replacement for the 748. Any suggestions?
I have several audio devices built 40 years ago I am upgrading using 748 and 558 8pin dip op-amps. I have used 833s to replace the 558 but can't find a cheap low noise replacement for the 748. Any suggestions?
Low noise 748 op amp replacement?
The voltage supply for the amp +-15 and the mixer; +-12
An externally hosted image should be here but it was not working when we last tested it.
The voltage supply for the amp +-15 and the mixer; +-12
The 748's all seem to be used in highish gain configurations which means you have a lot of choice.
The 5534 David mentions could be a real contender but it can be slightly fussy on implementation and so I would only perhaps recommend that if you can verify with a scope that its stable. It should be at those gains but always best to verify.
Edit... another thought on the 5534. As your circuit (as drawn) is DC coupled, the relatively high input bias currents could be a problem, particularly for the 'mic' input.
What else... OPA604 (terrific performer) and OPA134 come to mind. LME49710 (single version of the LM4562... are they still available ?)
Whichever you fit, you need to remove the small 3pf caps shown on the diagram and also very important measure the supply voltage feeding the 748's. With the exception of the OPA604 (which can handle a high supply voltage), the others are limited to around -/+18 volts
The 5534 David mentions could be a real contender but it can be slightly fussy on implementation and so I would only perhaps recommend that if you can verify with a scope that its stable. It should be at those gains but always best to verify.
Edit... another thought on the 5534. As your circuit (as drawn) is DC coupled, the relatively high input bias currents could be a problem, particularly for the 'mic' input.
What else... OPA604 (terrific performer) and OPA134 come to mind. LME49710 (single version of the LM4562... are they still available ?)
Whichever you fit, you need to remove the small 3pf caps shown on the diagram and also very important measure the supply voltage feeding the 748's. With the exception of the OPA604 (which can handle a high supply voltage), the others are limited to around -/+18 volts
Wow, thanks for the great suggestions. I kinda like the idea of using the "same" line for both singles and duals But... I found the LME49710 still available (officially "End of Life") at Mouser in single quantities @ $2.50, but not the 4562. Digi-Key has the OPA604 for $2.89 but not the 2604. So much for that idea. THEN I checked out the OPA134 and 2134; Digi-Key has both, $2.78 & $3.90. Mouser also both. Yea!!
I'll get a couple of each and stock up on 5534s and 5532s. Again thanks for the help.
I'll get a couple of each and stock up on 5534s and 5532s. Again thanks for the help.
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