So where are these "Dead Spots" I keep hearing about?

Discussion in 'Electric Instruments' started by sergiodeblanc, Jan 15, 2013.

  1. sundog964

    sundog964 New Member

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    The dead spots are "caused" by parasitic modes of the guitar which damp out the mode of the string. You can change the parasitic modes by adding mass, or stiffness, or damping to the system. But that will simply just move it to another frequency. Which may or may not interfere with a note.
     
  2. PRS-user

    PRS-user New Member

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    These scientific reasons mean nothing to me, as I wanted a good guitar from a reputable company... I thought that company was PRS but I was wrong! How can PRS sell guitars with such problems, and at their expensive prices? Surely, I would understand if this would be a $300 guitar, this is not just a matter of poor quality control as I read many more guitars of the same league are being sold out there.

    I do have several guitars in my possession of much lower price which do not have such a problem, if there are less sustained notes, these are not enough noticeable to me. I did not buy this musical instrument to be only playing short notes, the contrary is true, PRS pride themselves for their guitar sustain, what is the point of selling a guitar with one or several dead spots? I do understand that all makes can be affected by it but my point is that at that price league it is not acceptable! It is not for the customer to find out the the problem, it should have been labelled as second quality or scrapped!
     
  3. Audie

    Audie New Member

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    I have not seen any recommendations, or resolve from a qualified guitar tech to come to the conclusion it is the guitar. Let a tech look at it, and not a weedhead from GC. Someone who has a reputation for knowing their discipline. While I appreciate peoples ability and experience with their instruments. A good tech knows much more and will likely find the problem and a solution. Please consider you may be overlooking the forest for the trees. These PRS are that good, and it it is more likely a fixable problem than a faulty guitar. I know the latter is a always a possibility with anything, just give it a try. Take care.
     
  4. Chrisk-K

    Chrisk-K New Member

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    You cannot fix a dead spot. You can only move it. Every string instrument has one or more dead spots if the neck is made of wood. It's just the law of nature. The real question is whether a dead spot is pronounced, and there is no way to predict it during the guitar building stage.
     
  5. Rider1260

    Rider1260 New Member

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    All I can say to this thread is I am happy to not have this problem of dead spots never really have, if a guitar was flat or some notes didn't ring as I liked a good setup always fixed the issue for me.
    I would love to HEAR some of these dead spots and wolf tone if possible.
    I am not convinced this HAS to happen on all wood guitars, I have been able to make Squires to our beloved PRS play well over 30 some years.
    I have a theory on trouble shooting problems that has always served me well, start with the cheap/small things first cables, strings, setup and so on more often than not the issue is something simple, a slight change can transform an instrument there are so many places on a guitar that can reduce sustain everything from the nut to your own fingers.
     
  6. veinbuster

    veinbuster In the cards

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    I'm with you 100%.
     
  7. Cjs570lp

    Cjs570lp New Member

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    I’ve bought and returned 3 Core Santanas due to dead spots on the G string between 13th to 15th fret. Even drove out to a store that had an additional two, they both also had it. It’s not a set up thing but the wood resonating out of phase with the fretted note. Pretty dissapointing that so many of that model had the problem. I really liked the smaller body style. ☹️
     
  8. Rider1260

    Rider1260 New Member

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    Funny I have a Santana 2 and had a KL-33 and have played dozens of Santanas and like I have said before and even more so on 24 fret guitars the littlest set up change can work wonders
    The smallest change in relief or in this above case a small adjustment in the saddle height ( or checking that the saddle screws are both firmly touching down )
    I have also found many guitars as delivered have dead or dying strings.
    Lastly on the Santana in particular with its short scale and 24 frets " for me " playing above the 12 fret requires a bit of extra attention to accuracy and finger placement ( Fat fingers small space )
    For me 95% of all guitars come alive after I do a full clean and set up , Rarely do I truly LOVE a guitar until I have my brand of Strings and action set to my preference.
    If I am not "head over heals" with a guitar on first play I will always try a string change real quick and that usually does the trick.
     
  9. Cjs570lp

    Cjs570lp New Member

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    Without going into background, let’s say I am well schooled in set up. I forgot to add previously that all had self regenerating oscillation at the same frequency on the B string.
     
  10. Base6

    Base6 Guitar Addict

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    I have experienced a deadspot on one of my GOTM 594s. 14th fret, G string (B flat) or after tweaking the setup on the 12th fret, B string. And that was not because of my technique or a setup issue! I sold it and got another which is fine.

    I called customer service and they acknowledged it happens and nothing can be done unless you significantly change mass or shape. And even then, it will shift, who knows where. Eigen frequencies or resonance as a result of material properties and geometrics can cancel out a note (frequency) more quickly than another. It is science, not myth.

    I only dicovered it after owning the guitar for several months. It did not make the guitar unusable, but the sustain drop-off was abrupt and different from any other note. It wouldn’t be noticable when you play normally, but did annoy me once I knew and I ended up selling it. I had the same thing, on a different position, on a Custom 24.

    Still love PRSi though! Can happen on any guitar.
     
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  11. Michael_DK

    Michael_DK New Member

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    Yeah, I'm pretty sure all my PRSi also have dead notes. Often around the 12-14th fret, on B or G string.
     
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  12. Dirty_Boogie

    Dirty_Boogie GasX - No cure for PRS!

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    Just a thought... Maybe the highly resonant woods (and other components) that PRS uses can be a contributing factor to this (occasional) issue. If the instrument just naturally "rings", physics says that certain frequencies will naturally occur at certain locations on the instrument and cancel out desirable notes.

    And the converse... perhaps a $200 Squire with dull wood and thick poly coating, while not resonant at all, probably is less likely to have any "dead" spots?
     
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  13. Guitarsan

    Guitarsan "I floor it. That’s technical talk." SRV

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    THIS.

    ANY guitar of any brand, electric or acoustic might exhibit this symptom. Any.

    Why? Because each and every guitar has a natural resonant frequency. Take 10 exact models of the same guitar and that natural resonant frequency of the "constructed guitar system" will vary. Different stresspoints, different densities, amounts of glue or pressure, inconsistencies of hardware or wood weight, etc. etc. etc. will cause the variance. So take 10 random exact models and 0 or 1 may exhibit a dead spot. And it could be at different "spots".

    [​IMG]

    "Dead spot" really throws some people off. It's not the spot per se, it's the fundamental note played at the fret in question. If it matches the guitar's natural resonant frequency and is out of phase with that resonant frequency, the guitar will steal energy (out of phase will cancel the note) and that note will decay faster than others. If it exactly matches the resonant frequency, and is completely out of phase, the effect is the most exaggerated. As some have noted, if it's exactly in phase, you get a wolf note, not a dead spot. OK, carry on......

    http://acoustics.org/pressroom/httpdocs/137th/fleischer.html
     
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  14. Ovibos

    Ovibos No, YOU'RE a New Member!

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    Since 'deadspots' are largely about irregularities and inconsistency, I think the best way to minimize deadspots may be to buy a carbon fiber or graphite instrument. Might not be as pretty and you may not gibe with the tones tho...
     
  15. Guitarsan

    Guitarsan "I floor it. That’s technical talk." SRV

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    Um, no. Wrong premise/assumption - dead spots are not largely about irregularities and inconsistency. That part is simply to explain why some guitars have them and some don't.

    Dead spots are about phase cancellation and each individual guitar's natural resonant frequency relative to fretted notes. A carbon fiber or graphite guitar also has a natural resonant frequency. Theoretically they may vary less, but the opportunity for "dead spots" remains.

    Again, calling them "dead spots" tends to mislead what is really happening (see my post above), but it's easier to say and remember than "inter modal phase cancellation at resonant frequency".
     
  16. Michael_DK

    Michael_DK New Member

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    I disagree with the thingy in the red above :)

    The instruments I have with dead spots are indeed spots - a certain string at a certain fret. When I play a unison note on another string, there isn't a dead spot at that location too.
    I assume this is because the guitar body/neck vibrate at different frequencies at different places - and that a dead SPOT is a place where that body/neck resonant frequency matches the frequency of the note played when fretting the string exactly there.

    I can't remember how the instrument reacts if I tune up or down from E standard - changes in instrument resonances and their locations due to altered string pull notwithstanding, I would assume that dead spot would be gone. Maybe another one would pop up.
     
  17. Michael_DK

    Michael_DK New Member

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    I think he meant that such materials may be easier to predict and thus design dead notes out, as compared to an instrument made of wood.

    A thing I've noticed, by the way, is that for the dead spots I've encountered, the fundamental dies out quickly, but the overtones don't die out as rapidly. I'm sure they're not sustaining LONGER, they just become more apparant quicklier.
     
  18. Guitarsan

    Guitarsan "I floor it. That’s technical talk." SRV

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    Yeah, I think you're right technically. But per your post above (my bolding) "if I tune up or down from E standard - changes in instrument resonances and their locations due to altered string pull notwithstanding, I would assume that dead spot would be gone. Maybe another one would pop up."

    It doesn't "pop up".... the spot ... moves! Ironically that "spot" will move if you tune that string up or down. It will not remain stationary. And it may be more or less pronounced when it moves, including disappearing. So it's a bit of conundrum. So when is a spot not a spot? When it moves? ;) At the end of the day it's mostly about frequency, but to your point it's also about positional frequency. Now my head hurts.
     
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  19. Guitarsan

    Guitarsan "I floor it. That’s technical talk." SRV

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    By the way, my personal anecdotal experience having owned roughly 12 to 14 electric and acoustic guitars over the course of many years is only one of my acoustics ever exhibited a noticeable "dead spot". I remember it was quite annoying and I don't have that guitar any more.
     
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  20. BWV548

    BWV548 New Member

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    Solutions from our bowing brethren

     

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