scratchy buzzing Marshall G12 Vintage / Recone?

Discussion in 'Cabinets & Speakers' started by headcrash, Jan 29, 2020.

  1. headcrash

    headcrash Active Member

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    I may have the possibility to buy a what seems to be defective Marshall branded Celestion G12 Vintage.
    Assuming the cone/coil unit might be the suspect of what the seller describes as scratchy or buzzing sound when hitting the strings harder:
    Would I just have a 444 cone reconed, or does that speaker need a somewhat special 444 cone (since they are said to be different from the standard Vintage 30)?

    Also, what I'm afraid of is, that the speaker basket has a mechanical damage (fell off somewhere e.g.), and thus the buzzing sound. Would that be typical for such a sound description?
     
  2. South Park

    South Park Well-Known Member

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    Let’s see some pics
     
  3. SkyMonkey

    SkyMonkey Well-Known Member

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  4. GIBSON67

    GIBSON67 Well-Known Member

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    Where are you located? I wouldn't buy a V30 just to have it reconed for exactly the reasons you mention.

    I have 2 Marshall V30's that i would let go fairly cheap that sound great! One has a bit of rust and one is clean but missing the label.
     
  5. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    The voice coil is probably melted.
    And- there is no guarantee that a blown speaker can be reconed. If the magnet is mis-aligned, then the speaker is probably junk.
     
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  6. headcrash

    headcrash Active Member

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    I am in Germany :-/ I happen to like those Marshall G12 Vintage speakers a lot.
    I have one, and I am one of those, who believe they are somewhat different from the standard Celestion labelled Vintage 30 (at least I do so until someone proves me wrong :) ).
    They're hard to come by here, and when they pop up, they usually go for too much here.

    But I think I#ll stay away from that offer, especially since the reconing plus the cost of what the seller still wants for it, will probably cost me more than buying one, even for not so cheap, when one pops up occasionally..
     
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  7. headcrash

    headcrash Active Member

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  8. BygoneTones

    BygoneTones Well-Known Member

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    I would not recommend buying a speaker that needs repairing. Just wait for a good one to come along instead. The amount of extra expense involved getting it reconed, and you will still only have a reconed speaker afterwards rather than an original one. Not worth it in my opinion.
     
  9. BygoneTones

    BygoneTones Well-Known Member

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    Poor method in my opinion. I agree with him that you need to move the voice coil slightly off its axis, rather than pressing directly down on the cone like most people do. However the speaker he concluded was good could still sound horrible when used.

    The best way to check for coil rub (in my opinion) is to lie the speaker on it's back, press the cone down at the edge a few times using a light pressure, then repeat that about 8 times all around the outer edge of the speaker cone until you come full circle back to where you started. Then do the same as best you can for the outward cone movement with fingers pressing underneath the cone. Moving the cone slightly off its axis.

    I came to that method after many years of trial and error testing and repairing god knows how many vintage speakers. Trust me, it works. It won't catch everything, ideally you need an audio generator but as a good basic test that anyone with hands, ears and eyes can do, then it should catch about 90% of problematic speakers. That is assuming you have checked everything else beforehand, loose parts, tears in the cone, damaged wires etc.
     
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  10. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    I agree with him that you need to move the voice coil slightly off its axis, rather than pressing directly down

    Pressing directly down in a straight line is the correct method, not off axis.
    It's supposed to be aligned straight, because it only moves in 2 directions (in and out).
    A blown speaker that scrapes when it moves is blown. There is no if or maybe about it.

    And if the speaker scrapes even slightly it's blown and should not be used in a tube amp.
     
  11. BygoneTones

    BygoneTones Well-Known Member

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    Disagree sorry.

    Don't ask me why, but the coil does seem to move horizontally slightly when in use. Like I said, I'm talking from experience here, and have seen it many times. Trial and error to find a testing method that works. I had some just before xmas actually, a really nice looking pair of Fane Crescendos, they looked mint but as soon as you turned up the volume they started rattling. You could only detect the rub by hand when the cones were moved slightly off center, moving the cones directly upwards and downwards didn't detect it. Just one example.

    Also disagree that "if a speaker scrapes even slightly it's blown". A scraping noise can be caused by many things. Dirt in the coil gap is one of them, and is common on vintage speakers, completely repairable and does not mean the speaker is blown.
     
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  12. shakti

    shakti Active Member

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    FWIW, it seems that the voice coil gap in Fanes is veeeery tight, which makes them susceptible to coil rub even from over-tightening mounting bolts. At least that has been my experience with Hiwatt and Sound City Fanes.
     
  13. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    Not worth the time, effort and money to recone one of those frames. If the voice coil moves sideways that means it's glue is either loose, the spider glue is loose, or the cone was deformed when it was built. I don't agree with the off axis pressing down of the cone, because that's not the way the cone/voice coil and spider are supposed to move, normally. But if it's built right and has no issues it might pass that test, but it's not conclusive

    Audio waveform generator with 30w of power applied to it in a sweep from 20hz to 20khz is what I do when testing speakers. Then you know how it will react under a load.

    If the glue is coming apart, though, it can leave debris in the voice coil gap, or under the spider. Fixing the debris is easy enough with careful removal of the dust cap, and cleaning out the gap with a thin piece of plastic ship with two pieces of tape wrapped around the edge. After it's cleaned, you can glue the dust cap back down with white/Elmer's glue, and weight it down with heavy washers to make the glue bond to the cone.

    That's been my experience with this situation, but if the magnet is misaligned, toss the frame. It would cost more to break the magnet's glue bond, re-center it, realign it, glue it and then have to recone it to be solid.

    I did that with a frame off eBay I bought...once. It cost more to fix it as a recone than it would have been to wait for a good one to buy.
     
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  14. headcrash

    headcrash Active Member

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    Like Dave Lee Roth / Van Halen said: I'll Wait...

    Thanks for all the tips and hints, guys, appreciate it!
     
  15. BygoneTones

    BygoneTones Well-Known Member

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    Yes the coil gap is thinner on Fanes, but I think it varies a bit depending on speaker model. They do tend to be more prone to coil rub than Celestion. Generally I dont like buying them, but if I find any Crescendo 12A's I'll have a punt on them. Great speakers and very rare with pulsonic cones (pre 1974). I got lucky before xmas and found a really nice sounding pair, no rub, but unfortunately a bit of an ugly repair at the cone edge. They still sounded great though. The other pair I found that were coil rubbing I sent back to the seller, shame as they were otherwise mint.
     
  16. BygoneTones

    BygoneTones Well-Known Member

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    The problem is most people do not have audio generators. All they have is their hands, eyes and ears.

    Pressing around the cone edge is a lot more conclusive than pressing directly down on the cone. Disagree with me all you like, I know from experience that it just is. I've even got videos on my website demonstrating this on a pair of greybacks - one good, one rubbing. The rubbing speaker does not rub when pressing directly down on the cone, but it does rub on the audio generator and when pressing around the outer edge of the cone.

    I'm only talking a microscopic amount of horizontal coil movement here. At least it's the only explanation I can think of why some speakers pass the pressing down on the cone test, yet still coil rub when tested with an audio generator, or when in use with guitar.
     
  17. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    Well, I've seen speakers rub on the bench, but as soon as they're mounted they are under tension from the bolts in the baffleboard and the rub goes away. I've seen them rub in one position, but you rotate it 90 degrees and it stops.

    There are all kinds of variables I've witnessed over the last 20 years, not all of them make sense logically or mechanically. That's why I test them on the bench with the waveform generator, and mount them in a 1x12 test cab to verify them. It takes more time, but it's pretty effective at determining what's working and what's not.
     
  18. eastsidecincy

    eastsidecincy Active Member

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    My old 80's SS Lead 12 amp had a buzzy sound...I thought it was the speaker....so...I have tried 2 other speakers hooked up to it....still buzzy sounding with both speakers...but still fun to play thru...oh well...:jam::jam:
     

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