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PGA2310 application question

Lee Shaw
Prodigy 110 points

Other Parts Discussed in Thread: PGA2310, PCM5102

Hi,

Could the input stage of the PGA2310 (or similar) be used to interface directly with the speaker outputs of an amplifier?

It would be purely for attenuation purposes, as I want to convert the speaker output (potentially of a range of different amplifiers) to linein/out levels.

Or maybe there is a better way of achieving this?

Thanks in advance and apologies if it is a stupid question!

  • 0
    TI__Guru**** 189401 points

    Hi, Lee,

    Technically, this could work, just be careful not to exceed the maximum input voltage (which is the supply minus 1.5V according to the d/s).

    However, realistically, I don't know how you're going to adjust the volume in the PGA2310 to get a line-level output (assuming someone could adjust the master volume).

    You really need to grab the signal prior to the volume stage in the piece of equipment you're trying to use.

    For example, if you can access the I2S audio inside the box, you could tie that to our PCM5102 2Vrms DAC and get your line-out signal that way. It would be independent of the master volume setting. 

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 110 points

    Thanks for the reply Don,

    Unfortunately I can't access the signal prior to the amplification stage. I'm thinking of an after market product that can be fitted to any existing amplifier, but can use the existing amplifier remote control to adjust volume levels - hence the connection to the speaker terminals.

    With regards to adjusting the volume in the PGA2310 I'm thinking, rightly or wrongly, that the attenuation would need to be set so that maximum input levels to the PGA2310 (+/-13.5V) give an output that is equal to the maximum allowed levels for line in/out (whatever they are?). However i'm thinking this may not make the best use of the dynamic range if the user never has the volume anywhere near max. Maybe there is a clever way to handle this?

    Do many amplifiers have an output swing of more than +/-13.5V? If so, is there an appropriate way of reducing this without compromising audio quality? Maybe resistive dividers, op-amps, transformers or some other way.

    Does the input impeadance of the PGA2310 have any negative impact on an amplifier that I connect it to? i.e. the amplifier will be expecting to see low impeadance speakers, but will see high impeadance PGA2310 inputs.

    Thanks again,

    Lee.

  • 0 in reply to Lee Shaw
    TI__Guru**** 189401 points

    Hi, Lee,

    I don't see an obvious solution to your problem...

    +/-13.5V is not very much for a power amp.

    The high input impedance of the PGA2310 won't cause any issues with the amplifier.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 110 points

    Hi Don,

    Thanks for your answers and advice on this.

    Does anyone else maybe have any thoughts or ideas on how this can be done?

    Thanks.