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regarding tone controls

sarath azad
Prodigy 200 points
Other Parts Discussed in Thread: OPA2134

Hello,

Could you please help in building a pre amplifier with tone controls as optional feature?

I have looked for tone control circuits with opamps in web, but mostly found circuits with tone control opamp in inverting (negative feedback) stage, and use another inverting opamp buffer before or after it, to get the signal to original phase. 

For the preamp , I am looking for a buffer opamp stage followed by a switch which will be used to select to connect to output or to tone control opamp stage. So making the tone control optional, and only use it in signal path , when it is needed.

For this the first buffer opamp needs to be in non-inverting stage. But when we are switching on to use the tone control stage, if use inverting opamp tone control, then we need another output inverting buffer to make the single in phase again. So, while using tone controls can we avoid the output buffer stage which is needed only to invert the signal because of the inverting tone control stage? Can we have tone controls opamp in non-inverting stage?

thanks and regards

S Sarath

  • 0
    TI__Guru 57800 points

    Hi Sarath, 

    Could you please provide the part number of the devices you describe so we could have a better approach on how to help you?

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 200 points

    Hi Diego,


    Thanks for the reply,

    As of now didn't finalized the opamps , will be looking for any audio opamps like OPA2134 or similar ones.

    Basically looking for a preamp with volume control and optional tone controls, means only switch on tone controls when they are needed, and else bypass tone control stage from signal path to keep signal path simpler and cleaner with less components the signal passes through.

    input ==> buffer with volume control ==> switch ==> output

                                                                             switch  ==> tone control stage ==> output

    But the tone controls that i see are mostly inverting opamp type, thus require another inverting buffer after it to bring its phase back to original phase.

    Can we avoid this additional output buffer after tone controls to keep the signal path simpler and shorter?

    thanks and regards

    S Sarath

  • 0 in reply to sarath azad
    Prodigy 200 points
    Hello,

    For tone controls using opamps, are the circuits based on bandaxall tone control, the best way to go like given in below link:
    sound.westhost.com/project97.htm
    Or are there any other better options for tone controls?
    Searching in internet mostly only getting Bandaxall tone controls either passive or active (opamp based).

    Also could you please suggest regarding my previous post ?

    thank and regards
    S Sarath