Yamaha A-S2100 XLR attenuation

Discussion in 'Audio Hardware' started by sojer2005, Sep 11, 2019.

  1. sojer2005

    sojer2005 Member Thread Starter


    I have a question about XLR ATTENUATOR selector settings (on the rear panel of the AS2100).
    Will setting this parameter in the -6db position somehow adversely affect the sound quality?
  2. harby

    harby Forum Resident

    Portland, OR, USA
    You would use the attenuator function when using true pro gear XLR, instead of "fake" XLR found on consumer gear, which is often the same voltage per pin as RCA, and sometimes not even balanced. It should have little affect on the sound if used appropriately. I would leave it in the attenuate position unless you are connecting "fake, unbalanced" XLR devices or are using an RCA-to-XLR cable.

    In fact, this input is not exactly "pro" either. It is the same 200mV sensitivity as RCA inputs, only increasing to ~400mV with the attenuator. Max input level is 5.6V RMS with the attenuator (perhaps, after correcting a spec sheet mistake). Pro XLR (+4dBu vs -10dBv) is instead +11.8dB voltage difference.

    The actual attenuation of the switch is 6.48dB, and happens after the first JFET input buffer stage. The service manual lets you see the sensitivity is actually per-polarity-line, each "balanced" side having the same input stage and 47k loading as a CD input, so true balanced inputs should give +6dB volume increase vs CD/line inputs of the same voltage, and then pro gear (like my UAD DAC with +20.7dBu max output) would blow the doors off this input.
    Last edited: Sep 11, 2019

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