{"id":8372,"date":"2021-06-04T14:17:20","date_gmt":"2021-06-04T13:17:20","guid":{"rendered":"https:\/\/origineffects.com\/?p=8372"},"modified":"2022-01-21T15:42:48","modified_gmt":"2022-01-21T15:42:48","slug":"tech-tips-the-more-pres-control-what-is-negative-feedback-why-should-i-care","status":"publish","type":"post","link":"https:\/\/origineffects.com\/2021\/06\/04\/tech-tips-the-more-pres-control-what-is-negative-feedback-why-should-i-care\/","title":{"rendered":"TECH TIPS: The MORE PRES Control – What Is Negative Feedback & Why Should I Care?"},"content":{"rendered":"
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So, what is negative feedback \u2013 other than what I receive on school reports, first dates and job interviews? By clicking the link to read this article you have admitted that, to some extent, you are a guitar gear nerd, so you\u2019ll have almost certainly heard of negative feedback in relation to amplifier design, and with good reason. It has a huge impact on the character of an amp and can affect the clean headroom, dynamic response and the all-important transition into breakup (no, we\u2019re not talking about my dating life again). We all know these clich\u00e9s from reading the guitar press \u2013 \u201ctight, percussive and articulate\u201d or \u201ctouch-sensitive, natural compression\u201d \u2013 but it\u2019s useful to understand the electronics behind the marketing and, more importantly, how the Origin Effects RevivalDRIVE range of pedals can offer a whole spectrum of amp-tone personalities (spoiler alert: it\u2019s the MORE PRES control).<\/span>\u00a0<\/span><\/p>\n <\/a><\/p>\n <\/p>\n Negative feedback is a simple concept that can have a big effect on an amp\u2019s behaviour.\u00a0In basic terms,\u00a0an amp\u00a0takes\u00a0some signal from the speaker output and feeds it back to an earlier part of the circuit.\u00a0The important part is that the signal is fed back\u00a0<\/span>out of phase<\/span><\/i>.\u00a0\u201cOut of phase\u201d means that polarity of the signal is reversed \u2013 imagine a sound wave with positive peaks and negative troughs.\u00a0Inverting the phase means the peaks become troughs and the troughs become peaks.\u00a0It\u2019s\u00a0exact same sound wave, just upside down.\u00a0If we add this\u00a0out-of-phase signal to our original signal, they cancel each other out and we\u00a0are left with nothing. If, however, we add\u00a0just\u00a0a small amount of the out-of-phase\u00a0signal, the level of our original signal is\u00a0merely\u00a0reduced. Still with me?<\/span>\u00a0<\/span><\/p>\n This is where I hope it gets interesting. By taking the out-of-phase signal from\u00a0<\/span>later<\/span><\/i>\u00a0in the circuit\u00a0\u2013\u00a0the speaker output and feeding it to an earlier part\u00a0(before the power amp)\u00a0we can change the power amp\u2019s behaviour.\u00a0More output from the speaker = more signal fed back =\u00a0more level reduction = more clean headroom\u2026until the output section finally distorts. This is when\u00a0we hear a\u00a0sudden transition into overdrive, like\u00a0you\u2019d\u00a0expect\u00a0from a Fender Twin Reverb or a Marshall Plexi.\u00a0This is a trick from the\u00a0good\u00a0ol\u2019 days, when clean headroom was the goal, but it\u2019s just as desirable in the world of\u00a0rock distortion.<\/span>\u00a0<\/span><\/p>\n This type of circuit will typically\u00a0<\/span>feel<\/span><\/i>\u00a0percussive,\u00a0stiff\u00a0or aggressive to the player. It will usually\u00a0have excellent definition and a huge dynamic range, as well as being much more stable.\u00a0You\u2019ll\u00a0also notice quite an abrupt transition between clean and distorted\u00a0sounds,\u00a0for the reasons described above. To a great many players, these are all desirable traits, especially if you like your guitar to have a loud, clear, authoritative voice. But what if you lean the other way?…<\/span>\u00a0<\/span><\/p>\n Amps with\u00a0little or no\u00a0negative\u00a0feedback have a very different character altogether.\u00a0The Vox AC30 and the Fender Tweed Deluxe are both great examples of this.\u00a0Instead of a\u00a0clean, clear amp which suddenly distorts,\u00a0you get a very gradual transition into overdrive\u00a0that can be wonderfully expressive, especially if\u00a0you\u2019re\u00a0a player who lives on the edge of\u00a0breakup.\u00a0Once you push these\u00a0amps over the edge, they can become quite raucous and unhinged\u00a0\u2013\u00a0almost to the point of your guitar\u00a0tone completely falling apart. Let me be clear:\u00a0<\/span>all<\/span><\/i>\u00a0of these are good things!<\/span>\u00a0<\/span><\/p>\n