Harmonically rich cleans.........

Discussion in 'Amps and Cabs' started by The Captain, Oct 19, 2008.

  1. The Captain

    The Captain Supporting Member

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    I've seen this phrase a lot lately, but I'm confused by it.
    Now I was under the impression that a clean tone is the primary note, with the harmonics not audible, because they are overwhelmed by teh clean note.
    As an amp hit it's ceiling, the primary note "clips" meaning the top of the wave-form flattens out. The harmonics are still able to get loude though, and as they do, they become audible progressively, the first harmonic first, followed by the others.
    Thus, high-gain sounds are naturally compressed, as all the sounds being produced by the various segments of vibrating string become equally loud.

    A piano has no harmonics, with only the primary note being heard, whereas a violin sound has all the harmonics audible, like a high gain giuitar sound. The lack of an attack by the bow is probably a large contributor to this, and we are all familiar with the similarity between a high-gain volume swell and a violin tone.

    So, unless my understanding of this is fatally flawed, how do you really get "harmonically-rich cleans" ???
     
  2. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    When discussing the originally engineered intent of vacuum tubes (to amplify a signal with as little change as possible), there are several kinds of distortion. One kind is overdrive clipping. When not clipping, a signal can be distorted by the addition of harmonic "noise," which can be very musical to those of us who are so inclined. Engineers still call it distortion.

    In my experience with preamp tubes, for instance, I've compared Philips style short-plate 12AX7A tubes with other short-plate 12AX7 of the same time period ('60s-'70s). Philips tubes, such as Mullard, Siemens, Miniwatt/Amperex, and Valvo, all have much more harmonic content, even when not clipping, than most others of the era. The least amount of harmonic content in my testing came from the '60s RCA short-plate 12AX7A, which is nearly pure fundamental.

    There is a difference in harmonic content, and it is another kind of distortion.

    - Thom
     
  3. jumpnblues

    jumpnblues Member

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    Yeah, in my mind "harmonically rich cleans" is sort of an oxymoron because harmonics (depending on the definition) is a sort of distortion. But the overall note still sounds clean. It's a kind of barely audible mid range and top end distortion many orders above the root note that for many players, myself included, sounds pleasing to the ear. Tough to define and describe in words. You can hear it (some people can't) but it's hard to describe. To me it adds a richness to the overall tone. Some will be able to hear harmonics with the guitar and amp used in the clip below, but in this case it's not exactly a completely clean tone. That's my 2 cents worth on the subject.


    Tom
     
  4. Stratofuzz

    Stratofuzz Supporting Member

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    I have used descriptions incorrectly before, so this may be the case again...
    When I use this to describe a guitar or amp, it's referring to a lush/full tone with many overtones being heard in addition to the fundamental note.
     
  5. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Harmonic content is what primarily contributes to the timbre of an instrument. This is what allows you to distinguish a note played on a guitar from the same note on a piano, a violin, an accordian, a bell, etc. The other main contributer to timbre is the attack/decay envelope.

    - T
     
  6. Bryan T

    Bryan T Guitar Owner Silver Supporting Member

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    Not fatally flawed, but it should probably see a doctor.

    http://en.wikipedia.org/wiki/Vibrating_string

    A vibrating string has a lot of harmonics (even on a piano). If the pickup picks up those harmonics and the amplifier can reproduce them, then you can have a harmonically rich clean sound. Now, a lot of time the amplifier does distort (as in alter) the signal, often while still sounding 'clean.'

    Bryan
     
  7. ben_allison

    ben_allison Member

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    Play an open A string.

    Hit record.

    With an EQ, do a sharp high-pass at 440... what do you hear? Tons. I'd think anything besides a pure sine/square/sawtooth-wave would have harmonics. Harmonically rich cleans... there are harmonically rich pianos, and harmonically vacant pianos... it's all about distortion, but I guess you do (in the case of a guitar amp) arrive at this kind of richness via distortion... but we need to understand the difference between distortion and distortion.

    I'd defy anyone to describe a Twin as being an "unclean" amp... but, it's a bit different than recording straight to digital through clean, transformerless pres.
     
  8. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    An engineer's concept of distortion is different from an electric guitarists. We (guitarists) are influenced by the parlance of pedal and amp manufacturers to expect distortion to be some kind of signal clipping. The engineer will note many types of signal distortion, including production of harmonics.

    - T
     
  9. ben_allison

    ben_allison Member

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    Exactly! Well said.
     
  10. riffmeister

    riffmeister Gold Supporting Member

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    Correct. Any vibrating string has an associated overtone series, the relative volumes of which in relation to the fundamental depend on many things.

    Pickups, amplifiers, speakers will have an influence on the relative volume of the fundamental and overtones as well.
     

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