Ghosting and Ghost Notes

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers T' started by gtrfinder, Apr 12, 2007.

  1. gtrfinder

    gtrfinder Supporting Member

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    What exactly is a "ghost note".
    I have heard this term associated with 2 types of phenomena here at TGP. One appears to be positive, while the other is negative.
    The first (negative) instance is associated with preamp tube problems, and is described as annoying and undesirable.
    The second ("ghosting") comes from some descriptions of vintage Marshalls that are dimed, and appears to be a desirable aspect of these amps.
    What is up with ghost notes and can anyone give some explanation of these 2 instances and how they are related.
    Thanks
     
  2. 57tele

    57tele Member

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    To confuse things further, there's actually a third meaning that I've come across, usually from inexperienced players. In a fingerstyle piece when there is a defined melody played over a quieter obligato, those quieter obligato tones are often referred to as 'ghost notes.'
     
  3. billyguitar

    billyguitar Member

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    Ghost notes are never good but usually you can't hear them when the band's playing. A ghost note is a lower dark toned note that follows what you play but is not as loud and worse is always out of tune.
     
  4. Madsman

    Madsman Member

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    Well, the term "Ghost Note" predates the cone cry sound etc. Ghost notes are notes that take up space (have rhythmic function) but are either very quiet or are even absent entirely.

    The amp/speaker phenomenon we refer to as ghost notes are also called "double noting" or "cone cry." The preamp tube problem you're referring to... I've heard of microphonic preamp tubes, but I have never heard of "ghost notes" as a result of preamp tubes. The "positive" effect you mention... is not something that most people consider positive. When you play a note (usually most evident on higher notes) at a very loud volume, your speaker may exhibit a second pitch, owing to the resonance of the speaker itself, or some other vibration. This sound is typically horrendously out of tune with what you're playing, and in my experience, it can stand out like a sore thumb even with the band. Certain speakers seem more prone to this sound than others... V30s for example. Greenbacks much less so. The only cure that definitely works is turning down. On the bright side, usually the sound is occurring when you're playing at levels much louder than are required for band rehearsals or performances.

    I've also been told that the "speaker goop" you see on some speakers can help with this problem.
     
  5. Jackie Treehorn

    Jackie Treehorn Supporting Member

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    Generally, I believe the ghost noting is caused by the power supply modulating the signal a bit. I think ghost noting is great! It's an integral part of the my-amplifier-is-about-to-blow-up sound, IMO. It gives you some swirl and seems to fill in the middle with some extra harmonics.

    You have to use small filter capacitances. Of course, you might make them big enough so there's no motorboating/oscillations.
     
  6. billyguitar

    billyguitar Member

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    Cone cry or edge yowl is a bit different than ghost notes. It's usually louder and more erratic. It always startles and distracts me so I stay away from Celestions in general.
    My Dr Z Route 66 has very apparent ghost notes but I can't hear them when the band plays. I haven't tried rebiasing the amp, that may help. This amp design is rather known for this. It can be reduced by using speakers with less lows and low mids. My favorite cab is the Z 2x10. Unfortunately it is very strong in these frequencies and accentuates the problem with the Route 66 head. But that's exactly the sound I want in a cab, along with the small size and light weight, so I ignore it. None of my other Z amps do it.
     
  7. AdmiralB

    AdmiralB Silver Supporting Member

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    There are two versions of the 66 - the first version has less filtering and more bass in the preamp. The current version has, well, more filtering and less bass in the preamp - an attempt to address the ghost issue, I understand.
     
  8. jakob

    jakob Member

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    I read everything but I'm still confused....
    Maybe that says alot about me...:jo
     
  9. tremolux

    tremolux Member

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    Madsman is correct about "ghost note" re: guitar tablature and as billyguitar said, cone cry from a speaker is a different animal, tho they often get mistaken for the other in the use of the general term "ghost notes". I havent come across the term 57tele refers to, but it sounds like another use of the term (to add to the confusion.)

    Ghost notes ride shotgun "on top" of the guitar note and are'nt usually in tune harmonically with the note being played, tho some people are more inclined to say a ghost note "follows" shortly behind the desired note.... and in certain amp designs they can be a real pain the butt and in others more tolerable....what AdmiralB is saying about the Dr Z Rt66 amp speaks to the ghost note thats usually caused by an underfiltered power supply.... and thats the type of ghost notes amp builders deal with and use the phrase in reference to. Most of the time the problem can be partially or fully remedied by increasing the filtering in the power supply.

    When its bad and difficult to live with, its usually appears to be the most exaggerated on the D, G and B string above the 10th/ 12 fret, tho it can crop up about anywhere. Ghost notes caused by inadequate power supply filtering usually have a freq at around 120hz modulating the signal (60hz ripple in the supply supply X 2 based on full wave rectification = 120hz) and creating the ghosting. If youre in Europe it would be a 100hz freq since the standard is 50hz in the supply. Its also somewhat related to something called "intermodulation distortion" which occurs in all tube driven amplifiers being pushed hard at higher volumes, but is not nearly as noticeable as the out of tune ghost notes created by an underfiltered power supply (also more evdident when the amp is being pushed toward the max end of its output.)

    A poorly designed bias circuit can be an ingredient in the ghosting problem mix also, for the same reason (being underfiltered and allowing ripple in the supply to pass.) There are also proponents of bad grounding and lead dress, the way wires are routed and components are situated, adding to the problem with an underfiltered power supply. In some amps with triode/pentode switching, the problem can be so pronounced in the triode mode thats almost or is, unuseable without more filtering.

    In essence, in some amps it can be tolerable and be considered part of the overdrive/distortion mystique....some players tend to live with it better than others while its waaay annoying to others depending on a number of variables. If its a problem, as said...it can usually be helped with added filtering.
     
  10. kimock

    kimock Member

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    To further confuse things, you can hear them on an acoustic guitar.
    they're just easier to hear with a distorted amp.
    Any two tones in an overtonal relationship will sum to their tonic, you can see that with a guitar tuner when you play a double stop.
    They're only out of tune if you are. . .
    Combination tones.
     
  11. kimock

    kimock Member

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    http://users.rcn.com/dante.interport/winckel.html
     
  12. hasserl

    hasserl Member

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    This can also be a problem inherent in certain guitars, which is aggravated when the pickups are set too close to the strings. Most common among Strats and other single coil pickup guitars.
     
  13. Galo

    Galo Member

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    That would be a wolfe tone...I believed...
     
  14. vibroverbus

    vibroverbus Member

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    Well summarized Trem. Confusion comes from the same name being used for 3 different things.

    All I'd add is that PS driven Ghost Notes are intermodulation distortion, just IMD between the signal and ripple, whereas IMD alone usually refers to multiple audio signals inside the amp interacting. Ripple-ghost-notes ALWAYS sound terrible in my experience - although I'm sure there's some note where 120hz forms a melodious harmonic, I have yet to find it...
     
  15. tremolux

    tremolux Member

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    Good point vibroverbus, where one is interactive the other is more like interference, situated in between the signal and ripple in the line.

    If you ever find that "beautiful, rosy bloom of ultra-low midrange harmonics" that an underfiltered amp is supposed to be known for delivering (according to a fairly well known amp designer that under-designs filtering for that very response as he desribes it), let me know!!

    I've yet to hear 120hz sound harmonically "rosy" to other fundamentals in the signal either, I agree. Thats why I had to add that "some players tolerate it better".....:confused:
     
  16. Jackie Treehorn

    Jackie Treehorn Supporting Member

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    Ha ha! I love that quote! He's right, of course. Who said it?
     
  17. tremolux

    tremolux Member

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    In retrospect, I want to say that it was Mark S when the very first Matchless DC-30 hit the market in 91? I know that after hauling several to a guitar show and having various people try them out that he booted the mains filtering up by about 30/40uf. But I asked a friend about it and he thinks it was the Kendrick guy in an ad for a tweed deluxe knock-off in a mag in the mid-90s? It could be.........?? A good one wherever it came from! :D
     
  18. rmconner80

    rmconner80 Cantankerous Luddite Silver Supporting Member

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    I like the tone of smaller filters (within reason) over larger filters in the power supply in certain amps. I tried 100uFs, 50uFs, and 32uFs in a 50 watt marshall super lead clone and vastly prefered the midrange and low end of the 32uFs in that amp. I don't think it is all BS and marketing.

    Interestingly, most of Mark Sampsons amps, according to the schematics, are pretty stiffly filtered.

    In any case, if I recall correctly, you can hear a good example of recorded PS ghost notes on the big bends at the very end of Rush's "Working Man". If you listen closely, you'll hear an underlying descending howling note on each bend.
     
  19. tremolux

    tremolux Member

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    Yeah, the early DC30s were demo-ed long before he had schemos printed up and ready...I think he learned a lot from the Hellcasters at the Arlington show in 92 and redesigned his thinking on filtering after that, which probably followed on future Matchless amp designs.

    They (Hellcasters) used them for the Sat eve jam in 92 and sounded great, but none on them were too crazy about the out of tune harmonies they were playing......with themselves. Donahue ran over and grabbed a DR halfway thru the show and used it for the remainder while Ray and Jorgenson continued with the DC30s.
     
  20. tremolux

    tremolux Member

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    oooppppss....Arlington...Texas show in 92!
     

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