Undertone when playing double stops on el-84 amps? Ghost notes, cone cry, what?

Discussion in 'Amps and Cabs' started by Paul S, Jun 27, 2006.


  1. Paul S

    Paul S Member

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    Background: I am the proud recipient of a brand new Hayseed 30, complete with green levant tolex and black diamond grill cloth. I love this amp, everything seems really solid, and there's a lot of tones I can just lose myself in (like when you get a setting you like, and then look up and it's 45 minutes later). Just getting lost in the tone is very inspiring.

    So I'm playing it a week ago, and I start hearing an undertone when I play double stop 3rds on the 1st and 2nd strings (also on the 2nd and 3rd strings) starting with D (--that is, D/F#, E/G, F#/A, etc. Gets really noticable when moving the 3rds chromatically, from F#/A to A/C. Like an slightly out of tune (to sometimes way out of tune) harmonizer a 3rd below the lowest pitched note in the double stop 3rd. Much more noticable in D (major, or mixolydian) than in other keys.

    Increased gain (from the amp) seems to accentuate it, but it happens on both the ef-86 channel, and the ax7 channel, and at fairly low volume (with the master at 9 o'clock, and the channel volume at 3 to 5 o'clock). I tried it with 3 different guitars--humbuckers, p-90's, and single (strat) coils.It is much less noticable with single coils, but that could be because of the lower volume and bass response. Increasing bass and/or gain definitely increases this phenomenon.

    So now I'm worried that my new custom amp is acting weird, so I hook up another speaker cabinet (to see if it's the redfang that is the problem), and the broken in celestion blue in that cab also has the same sound (albeit just a tad less noticable).

    Then I tried other el-84 amps I own--a Carvin Nomad, and a Traynor guitarmate. AND THEY ALL MAKE THE SAME SOUND! I guess I never noticed it before, or never happened to play that same double stop lick in that key on those amps?

    Anyway, what the heck is this called? Ghost notes (thought those were higher?), cone cry, what? If I've noticed it on 3 seperate el-84 amps,then some of you must have also? the filtering switch I have on my hayseed (traditional vs modern) doesn't change it a bit, which makes me think it's not ghost notes at all. Is this just part of the el-84 sound--what gives them that rich, complex, jangly sound we all love?

    Hoping to be enlightened by you el-84 guys on this board,

    Paul S
     
  2. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Sounds like ghost notes to me. Yes, lots of cathode-biased EL84 amps seem to produce ghost notes. I've owned numerous amps that do this in varying degrees. Matchless C30s, Jorgenson, Vox AC30s among others. But I believe it's due more to elements of circuit design than use of EL84s (or even cathode-biasing) per se. I've played a few EL84 amps that did very little if any ghosting (e.g., Mojave Coyote, Aiken Tomcat).
     
  3. Macaroni

    Macaroni Member

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    I had a similar situation with my Kingsley Deluxe 32, 4 x EL84 amp, so I asked Simon Jarrett, (who makes the amp) about it and here's what he wrote...

    "Ghost notes can quite often be caused by the amps power supply, especially in an amp with small or relatively small value filter capacitors. The sag that occurs when an amp is pushed (which manifests itself as a sort of compression - which we like!) causes a 120Hz signal from the power supply to modulate the actual guitar signal, resulting in ghost notes. Volume always makes it worse. While adding larger filter caps can help reduce it or eliminate it, you may not want to do this to an amp or may not be able to.

    If the amp uses a tube rectifier, the size of the first filter cap has to be kept under a maximum value that the rectifier can handle. This is around 50mF. The first filter in your amp is 47mF, so it is already at the limit. Also, adding more capacitance has an impact on the sound of the amp. While it can increase an amps ability to produce low frequencies, it will make the amp have less sag and may also make the amp sound more sterile. Having a tube rectifier increases sag also.

    A lot of amps will exhibit this to a greater or lesser extent. Old AC30s had very small value first capacitors and can really have this problem a lot, as do other class AB amps with tube rectifiers and small filter caps. You could use a solid state rectifier, which would allow you add more capacitance, although it would be an experiment, as obviously the sound would be affected.

    In your amp the power supply is very much part and parcel of the sound of the amp and an unfortunate by-product of this is ghost notes."
     
  4. wordsonyou

    wordsonyou Member

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    In short, if it is a Vox ac30 it will have the ghost notes. Some people have described this as a defect but the reality is it is part of the design. I have even seen some people who don't know better complain the CC line is defective because they heard a ghost note...never had an ac30 that did not have it...
     
  5. Rod

    Rod Tone is Paramount Silver Supporting Member

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    It's not the EL84's per se that are the problem, it is in the power supply design of the amp...I played through Top Hat amps for over 10 years back East, and Brian Gerhard and I had many conversations about power supply, versus feel...I nrecently sold a Carr Hammerhead II because the power supply had some very strange notes coming from it through my speakers...But to get the vibe right, Steve Carr designed the amp this way...If it really bothers you, sell the amp and buy one that doesn't have those tones...Bad Cat's and VHT's are pretty clean that way, as well as the Cornford Hellcat, all using EL84's
     
  6. esoteric pete

    esoteric pete Supporting Member

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    +12
     
  7. Unburst

    Unburst Member

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    Not necessarily, I've played some AC30's that had unbearable ghost notes, but my old '64 had none at all.
     
  8. hasserl

    hasserl Member

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    Hey, how are you liking the Carvin Nomad. If you're interested I can hep you out with that amp : http://www.geocities.com/rlhassebrock/nomaddioderemoval.html

    Feel free to use these mods as you like, hope they help your enjoyment of the amp. I've also got some additonal mods not listed, you can contact me if you're interested.

    Hasse
     
  9. Paul S

    Paul S Member

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    Thanhks everyone, for your replies.

    AS far as ghost notes, I always thought these happened at a much higher volume--I'm noticing these at bedroom levels...unless maybe having the amp volume low is making me notice them more? Also thought they happened when playing high up on the neck, like high E string above the 12th fret? I'm getting them around 3rd, 5th, 7th frets...

    Do any of you who have experienced this notice it being more noticable using double stop 3rds around "D", as noted in my 1st post? I don't really hear it on single notes, or chords much. I still love the amp, and am willing to chalk it up to class A, complex tone--I just haven't really noticed it before--but if all 3 of my el-84 amps do it, I guess it's pretty common.

    Thanks,

    Paul
     
  10. Sunstone Recordings

    Sunstone Recordings Supporting Member

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    I noticed it recently with my AD30, its not terrible by any means, but it never was this noticible before... could it be bad power tubes? what is the cause of ghosting?
     
  11. stratovarius

    stratovarius Supporting Member

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    Thanks Macaroni! That's one for the archives. :AOK
     

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