What do input capacitors provide on amplifiers?

December 15, 2021
 by Paul McGowan

2 comments on “What do input capacitors provide on amplifiers?”

  1. Decades ago I built a Hafler DH200 amplifier kit. I recall a standard change was to use a larger value, higher quality input cap and that simple change noticeably improved the sound. Later my friend, Muray Zeligman built a DH200 for himself. But Murray was capable of designing an amp from scratch. Instead of a new input cap he designed a servo circuit to control DC like Paul mentioned. He built one for my amp also and the sound improved beyond the simple cap change.

  2. I understand the input capacitor thing.
    But when I was both designing and building tube amps from the ground up, I went in a slightly different direction.
    All depending on what kind of a sound I wanted the amp to have, and whatever kind of an application I wanted to use it in.
    This is what I did.
    I would put line level transformers on the inputs.
    But, if there was a chance that somebody mite use a preamp that outputs DC, I would put the blocking capacitors between the input jacks and the transformers.
    But for the ones that I wanted to make some what cheaply, I’d skip the input transformers, and put the blocking caps there.

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