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preamp + TPA3123D2 amplifier design questions

Keith Kropf
Prodigy 85 points
Other Parts Discussed in Thread: TPA3123D2, TPA3106D1, TPA3130D2, TPA3118D2, TPA3116D2

I am attempting, after many years of not working in electronics, to design a preamp + amp system for an audio product.  The product is simply amplifying voice from a dynamic microphone and driving a 4 ohm custom speaker, using portable battery power ( 24V with 20 AA Ni-mH cells).  We need as much power output to the speaker as possible without causing feedback.  Our microphone outputs 300mV peak-peak max. under normal speech. We have tested a prototype, put together by another engineer, that worked acceptable using a preamp with a gain Vo/Vi = 40 (+32db), fed into a TPA3123D2 eval board, using only the left channel (not bridge tied), with it's gain set to +32db. As the TPA3123 spec sheet shows an absolute max. rating for Vin = 7V, and the preamp output had peak -peak voltages greater than 7V, we were getting clipped output to the speaker.

I would like to design another preamp/amp setup, and would like any suggestions for the power amp (would like to use an eval board if possible).  Also, our preamp uses two OP07 op-amps with a common ground input and output, and I'd like any suggestions on a better circuit to consider for that.  

I was considering the TPA3106D1, as it is a mono amp, or the TPA3123 in a bridge tied I/O.

Any other suggestions or direction is appreciated.

K2

  • 0
    TI__Mastermind 37045 points

    Hi Keith,

    I would recommend TPA3116D2/TPA3118D2/TPA3130D2 series. They are our new analog input Class D products and have excellent performance improve over the previous gen. All the 3 parts are pin to pin compatible and are rated for 15Wx2, 30Wx2, and 50Wx2. They can also be configured to PBTL (mono) mode for higher power output. The input voltage should be less than 6.3V for these parts.

     

    reg,

    Paul Chen

    Applications Engineer

    Dallas TX

  • 0 in reply to user5276421
    Prodigy 85 points

    Paul,

    Thank you.  I'll check out these amps.  In the bridge tied mode, how can I use an input that has one side tied to ground?  

    Keith

    Key Largo, FL

  • 0 in reply to Keith Kropf
    TI__Mastermind 37045 points

    Hi Keith,

    For single-ended input, you can tied the unused input AC coupled to ground. Differential input config will have the advantage of common mode noise rejection though.

    reg,

    Paul.