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comparing OP amp TLV2461 to LME49710TI

Duane Kinjerski
Prodigy 50 points
Other Parts Discussed in Thread: TLV2461, LME49721

Can anyone help me with this question? I Modified a guitar pedal using a TI OP amp TLV2461 and had good results. I am considering using another TI OP amp, LME49710TI. Are the gain characteristics the same? I need the input to output signal strength/volume to remain the same. Can I use a feedback circuit to cut down any gain if I need to?

I would really like to try the LME49710TI Op amp. I like the hifi and low noise/distortion specs.

Thak you for the help,

Duane

  • 0
    TI__Guru**** 189399 points

    Hi, Duane,

    You might want to read this most excellent Design Note by Bruce Trump, who's been working on op amps since I've been in middle school...

    http://e2e.ti.com/support/amplifiers/precision_amplifiers/w/design_notes/upgrading-op-amps-in-audio-equipment.aspx

    -d2

  • 0
    TI__Prodigy 385 points

    Hello,

    The gain characteristics are similar in that the "gain" is set by external components.  More fundamental differences exist in that the 2461 is a 6V amp made for portable applications.  This is very important if you are running off batteries as the 2461 has very low supply current and shutdown.  The 49710 typically runs at higher voltages.  Although it will run at low voltage it is not rail-to-rail.  Translation, you will not get as much voltage swing at 5V on the 49710.  However, if you want a high-fidelity part, this is where the 49710 shines.  It is best used on split supplies.

    Jeff,

  • 0 in reply to Don Dapkus
    Prodigy 50 points

    Thank you for the info. I understand what you are saying. First of all this is an extra guitar pedal I have and I am willing to give it a try. I fully  understand if it doesn't  work that it is was not designed for this purpose(the LME49710TI OP amp). I guess I am willing to try it for the benefit of a better sound. I compared the specs and the pinout and don't believe it will harm the component. I will be careful and not blame the OP amp if it doesn't work.

    Thanks again,

    Duane

  • 0 in reply to Jeffrey Bridges
    Prodigy 50 points

    Thank you for the reply. First of all I understand what Don was saying. This Op amp wasn't designed for this and may not work. I am willing to try it because I believe it will be a better sound without harming anything.

    You said I won't get much of a voltage swing with the LME49710TI. That should keep the gain in line for me as gain is the difference in the voltage swing. Am I correct in this?

    I am going to operate this on a power supply so voltage supply shouldn't be an issue. Yes the hifi with the low noise specs are what I'm after.

    Can you explain what rail to rail means?

    Thank you for your help,

    Duane

  • 0 in reply to Duane Kinjerski
    TI__Expert 3840 points

    Hi Duane,

    I can help out a little here. Rail-to-rail generally refers to the ability of the amplifier to process signals either at the input or output (RRIO) with signal swings very closely approaching the supply voltage. The word "rail" refers to the supply voltage.

    In the datasheet there is generally a Output Voltage vs Supply Voltage curve that represents the dropout voltage (voltage loss or saturation voltage) of the amplifier such that the signal will come within xV of the supply voltage.  For the LME49710 this voltage is around 2V (depending upon load impedance and measure of THD) which is not great, especially for low-voltage portable applications.

    If you are running a low supply voltage and single-supply voltage (ie +5V), then the LME49721 would be a better choice; it has low noise, low THD and runs closer to the rails. Otherwise, the LME49710 is a very good part; enjoy.

    JD

  • 0 in reply to John De Celles
    Prodigy 50 points

    Thank you for the info John,

    I checked the power supply and it is rated at 9.6VDC at 200mA. It's a standard 9V transformer used for guitar pedals. Knowing this would you still recommend LME49721 over LME49710?

    Thank you very much!,

    Duane

  • 0 in reply to Duane Kinjerski
    TI__Expert 3840 points

    Hi Duane,

    Unfortunately the LME49721 has a maximum operating supply voltage of 5.5V, so this won't work. the LME49710 would then be the part.

    Best Regards,

    JD

  • 0 in reply to John De Celles
    Prodigy 50 points

    Hi john,

    I did a little more checking into the supply voltage on the guitar pedal. I found out the power supply is internally regulated to supply a consistant 5VDC to the OP amp. It looks like I will go with the LME9721 after all.

    Thank you and everyone here for your time and input on this. You have a great support team here!

    Thank you,

    Duane

    I will let you know the results in a few weeks.

  • 0 in reply to Duane Kinjerski
    TI__Expert 3840 points

    Hi Duane,

    You are very welcome; we're glad that you have what you need and thank you for the kind words.

    Best Regards,

    JD