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Would OPA1642 be suitable in the follwing CD player circuit?

Sam Mcdonald
Intellectual 330 points
Other Parts Discussed in Thread: OPA1642, LM833

Hello,

I have a Technics SL-PG440A cd player. I intend to change both of the opamps with the OPA1642.

Technics SL -PG440A
LM833M - differential
BA4560FT - L.P Filter

  • 0 in reply to Sam Mcdonald
    TI__Genius 15410 points

    Hello Sam,

    OPA1642 vs. LM833

    The OPA1642 is offered in both SOIC and VSSOP packages, while the LM833 is offered in SOIC, VSSOP and DIP packages. So as long as the LM833 that is currently on the board is not in a DIP package, it should be compatible. I looked over the specifications and these devices looked very similar in performance with a few notable differences that I have listed below.

                                                                 LM833                             OPA1642
    Aol                                                        110dB                                126dB
    Input voltage noise density                4.5nV/rt(Hz)                      5.1nV/rt(Hz)
    Input current noise density                700fA/rt(Hz)                       0.8fA/rt(Hz)
    Distortion                                              0.002%                              0.0003%

    OPA1642 vs. BA4560

    Can you please tell me which package the BA4560 is in? I looked in the datasheet and it doesn't list BA4560FT as an option so I can't tell which package the device is in. If the device packages are the same, it looks like these will be compatible.In fact, the OPA1642 looks to be lower noise, lower THD+N, and have lower supply current. Below shows some differences between the two devices.

                                                                  BA4560                           OPA1642
    Supply Current (Iq)                             7.5mA max                       4.6mA max
    Input voltage noise density                  8nV/rt(Hz)                       5.1nV/rt(Hz)
    Input current noise density                   Not Listed                       0.8fA/rt(Hz)
    Distortion                                                0.003%                           0.0003%

    While it may seem easy to swap out a device in a design, problems not related to device specifications can occur when a new device is used. One example would be issues with stability, the original amplifier might be stable but when a new amplifier is used in the design it may be unstable. Therefore, it is always recommended to verify the design when a new amplifier is used. One way to verify the design would be to use our free simulation tool, TINA-TI. I also recomend checking out our TI Precision Labs, the videos describe in detail specifications and applications that are important when designing with amplifiers.

    -Tim Claycomb

  • 0 in reply to Tim Claycomb
    Intellectual 330 points

    Hello Tim,

    Thank you for the help. Its a Technics cd player, and the  BA4560 is a SOIC package like the LM833.  From what you said the the specs the BA4560 would be the most compatible. I am currently downloading Tina. The LM833 just after the MASH DAC, might cause stability issues.  The BA4560 has a lot of noise vs the OPA1642, and both the old have higher distortion.  I had a look again at the BA4560, the F is just the package it's in.


    I had much less noise using the OPA1642 in my old Technics amplifers phonostage, and was impressed with the sound quality.

    Thanks again for the help.

    Regards

    Sam