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Audio: You can hear some opamp difference
  • Different operational amplifier topologies are frequently thought to play a significant role in the sonic character of analog audio equipment. This paper explores whether common audio operational amplifiers are capable of producing distortion characteristics within their normal operational range that can be detected by listeners and alter listener perception of character and quality. Differences in frequency response and noise are carefully controlled while the distortion characteristics of the op-amps are amplified. Listening tests are performed in order to determine what differences listeners perceive. Listening tests also examine listener preference for different op-amps for the purpose of exploring what physical measurements best predict differences in perceived audio character and quality.

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    http://www.aes.org/e-lib/browse.cfm?elib=16029

    Note that it was double blind tests.

  • 3 Replies sorted by
  • We have known this for at least 20 years--back when it was more common to have discrete circuits in both mics and preamps, we routinely added sockets to the boards so we could swap opamps in and out for testing. In some cases, before the advent of widespread surface mount stuff (ick), many of these components came with easy sockets already in place. The difference was slight but fairly clear, and in most cases a question of taste, i.e., open, clear, bright, muddy, covered, transparent, etc. Emphasis on slight. Typically, we would make a recording of the same material with several different types of opamps, then leave the ones we liked in the sockets.

  • @DrDave

    This is extremely muddy topic. As some of properly made blind tests I saw proved that people can't tell difference between cheapest and top cost opamps. Each of cases of difference must be observed by engineer and with all measurements provided.

  • Well, it isn't a big difference. Years ago, I spend many hours socketing ICs to test them. Now I just use whatever came with the preamp/recorder/whatever. Actually, some of the newer stuff sounds just fine with no mods.....
    It's a small difference.