Comments on Profile Post by AdvanTech

  1. Marvey
    Marvey
    Whatever amount s necessary to make the circuit stable, gain usable, and distortion/Zout acceptable.
    Jul 7, 2021
    Cryptowolf likes this.
  2. AdvanTech
    AdvanTech
    @Marvey im reading about a 300B SE amp with 6dB of feedback. I don’t really have any experience with how that amount might affect the engagement-factor of what’s coming out of the amp.
    Jul 7, 2021
    Cryptowolf likes this.
  3. Marvey
    Marvey
    That's nothing. And probably even a good idea. It will affect engagement factor. Heck, even the 1.5db of feedback on EC amps that have them do affect a bit of engagement - but with much better bass quality. Tradeoffs.
    Jul 7, 2021
    Cryptowolf and AdvanTech like this.
  4. AdvanTech
    AdvanTech
    That’s helpful. Thanks!
    Jul 7, 2021
  5. schiit
    schiit
    It's really all over the map. And are you talking overall or local? Low gain tube amps may only be capable of 10dB or so. Low gain discrete (like Magni 3+) maybe 30db. Op-amps can be 100db+ easily. This is just what they're capable of, though.
    Jul 7, 2021
  6. schiit
    schiit
    Optimal? Old Sumo amps used 26dB overall, and about 10dB locally. These were a typical voltage feedback design with reasonable degeneration and resistive loads on the front end, so not super high gain. When I went to 0dB overall, with 26dB local and error correction in the output stage, it sounded better.
    Jul 7, 2021
    Cryptowolf likes this.
  7. schiit
    schiit
    But like Marv said, it's about trade-offs. Magni 3+ uses pretty much all it's got in one loop, because that's what it has and what it needs. Some of our other stuff doesn't have any overall, or is degenerated on the VAS to lower gain and thus feedback. This is part of the tweaky fun stuff.
    Jul 7, 2021
    Cryptowolf and AdvanTech like this.
  8. Priidik
    Priidik
    There is only one general rule: When possible, do not use any!
    This is the key to get SS amp to extract from music what used to be totl tubes territory. For better bass, increase parallel devices.
    Jul 7, 2021