1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Phase cancellation with opposing and unequal audio frequencies.

  1. Dec 12, 2013 #1
    Greetings to ALL.

    tonequester here. I am re-doing my first, and LONG post. Concerning an electric guitar. Strings resonate at say, 800Hz. Wooden neck and body have their own resonant frequency, so I am told. No two guitars resonate at the same frequency, as no two, complex, combinations of the same wood could possibly be exactly the same physically. Will there occur any phase cancellation between the strings 800Hz vibration, and the resonance of the neck/body combination ? If not, why does adding considerable mass to the headstock(top of neck) or to the guitar's body, increase volume and sustain, if not by phase cancellation ?

    There is much hype and sales pitch involved in this regard for too long. I'm out for the truth.

    Example : Nitrocellulose finish makes for good tone because it lets the wood breath, and resonate.

    My Answer : Nitro plastic coats the wood. How can it breath. Hey ! Wood doesn't breath anyway, IT'S DEAD !

    All PHYSICS based comments are very welcome, and appreciated.

    Best Regards from tonequester.
     
  2. jcsd
  3. Dec 13, 2013 #2
    When you add signals with different frequences, at some moments of time their total amplitude will be greater and at some - smaller
    sumofsines.jpg

    When difference in the frequences is small, most of the time, total amplitude will be greater.

    When you add mass, you change the ressonant frequency and maybe the two frequences get near to each other and there is a greater total amplitude.

    http://music.columbia.edu/cmc/musicandcomputers/chapter3/03_03.php
     
  4. Dec 13, 2013 #3
    Greetings Malverin.

    Thanks very much for being the first to reply to my query. While the information you have given me does not give a quick and simple answer to my :problem", I now realize that this is more complex situation than I had thought originally. I printed off your reply, and the entire thread : The Frequency Domain..... As usual for me, a lack of higher math prevents me from understanding the article fully, I did get a general idea as to how sine waves affect each other.

    In the case of sine waves generated by guitar strings, as compared to the sine waves generated by an electric guitars resonance, I believe that the string frequency amplitude, would have to be much larger than even THE resonant frequency of a particular electric guitar's neck/body.

    I am now left to wonder how much the variation of an electric guitar's wooden components, structural design, and even finish, would affect the guitar's neck/body resonance. This especially in the sudden thought. that such construction parameter may very well affect the resonance of the guitar's strings as well.

    Thanks again for your help, which I see was much more rapid than I had expected. I had hoped for there to be some good late night posters, as I have much trouble during winter months, sleeping at night with regularity.

    Any further comments or opinions from you, or anybody else is appreciated "up front".

    Best Regards. tonequester.
     
  5. Dec 13, 2013 #4
    Adding mass etc to the headstock I think would keep the end of the string more fixed so less energy would be lost from the string in a given time, the string would be able to vibrate for longer so increasing sustain. Volume is more a function of the type of cavity and aperture. If the air in the cavity in free to move at the same frequency of the string with minimum damping you can get a good volume. Finally onto tone.... The final sound will incorporate not just the vibration of the string, but harmonic vibrations of the body (transmitted via the bridge). The body needs therefore to be rigid enough to allow decent volume (so not stuffed with wool) but also flexible enough to allow tonal quality. You can notice this very well when you apply a mute to the bridge of a violin. The sound is quieter but the tone is magical!
     
  6. Dec 13, 2013 #5

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Yes, this will be because of a mis-match between string and body impedances. A solid body gives long sustain because there is a mismatch at both ends. To get acoustic sound out, there needs to be a suitable match between string and bridge. Resonances in the body (air cavity, hole and table, mainly) will help to match further the string to the air. The wood for making stringed instruments must not be too lossy, or not enough sound gets out but needs to be lossy enough to flatten out resonances so the sound is not coloured. A semi acoustic will behave somewhere in between with a reasonable sustain but the body can interact with the strings and affect the sound. It depends on what you want.
     
  7. Dec 13, 2013 #6
    Greetings Jilang, glad to make your aquaintance.
    Some of what you say is helpful for my needs. However, I think that you speak about acoustic guitars("volume is more a function of CAVITY and aperture"). I am posting about solid body electrics, with no cavities, like Stratocasters and Les Pauls. Acoustically speaking, as I did in my post, I meant only to eliminate the concern of amplification. A solid bodies acoustic qualities(and they have them), are a completely different "animal", compared to an acoustic that relies COMPLETELY on design, including volume of the body, the size of the aperture, the wood used, and perhaps even the finish, unlike my belief in what matters acoustically with solid body electrics.

    Thanks very much for your input, it is always welcome. I appreciate your time in posting. Best Regards....tonequester.
     
  8. Dec 13, 2013 #7
    Reply to sophiecentaur.

    Yes, what you say about mass of solid body guitar is true. The perfect design for volume and sustain would be one that has equal mass at headstock and body. However, that would be a nightmare to play, heavy and unwieldy. I am not so sure about so about wood type influence. I don't know exactly what you mean by "lossy" woods. If you could clarify this for me I would appreciate it. Anyway, I appreciate your reply and your time involved.

    Thanks, and Best Regards....tonequester.
     
  9. Dec 14, 2013 #8

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    By "lossy" I mean a material which dissipates energy when deformed. A steel frame would not be as lossy as there is low hysteresis. Resonances in a steel frame would be sharper.

    I have yet to be convinced that symmetry would make for a better sustain, in principle, but I would think that stiffness and not mass would be a possible reason.

    Interestingly, there seems to be little talk of plectrum design or fret stopping technique than on sound quality. Even the way a guitar is held will affect the sustain and tone, but you can't spend your way out of those problems, haha.
     
  10. Dec 14, 2013 #9
    Greetings sophiecentaur.

    Thanks for the ongoing help, and now I know what lossy means. I am in agreement with you that perhaps stiffness might be more of a defining quality here, rather than mass. I have spent years trying to achieve MY best tone, and have found that adding .25 lbs. brass plate to the back of my Strats headstock increases sustain, and somewhat brightens my tone. I don't yet know for sure what the underlying reason for this is. This is strange because I read a scientific study done by the University if Illinois, that determined that a guitars neck, while covering most of the length of the strings, does not contribute much to amplitude and fq response, even though it does transfer energy to the bridge/body, which does affect fq response and amplitude. This conclusion, again goes against traditional thought concerning necks and tone.

    I do not think that symmetry in body design amounts to anything worthy of mention. As to plectrum design, there is some activity out there to modify traditional flat picks, both in design and in the materials used. I have tried a good 2 dozen types, but so for, I am committed to my own design. I use bell brass plate(1/16" thick) which I cut into a pretty much traditional shape, but perhaps 10-15% larger overall. I have always struggled just a little, in trying to keep the pick "in position" during a performance situations. So, in addition to a slightly larger size, I score the bottom 2/3 of the blank with fine, but deep "cross-checking" which I don't polish out too much. This greatly increases my ability to grip the pick, even when my hands are sweaty. I bevel the edge of the pick, both sides of the edge, to about a 30 degree angle, only leaving the back edge without bevel. I polish the beveled edges and the tip end surfaces(1/3 of the pick) with a fine diamond flat hone, and then finish up with medium and fine "Fret Erasers" which I get from Stewart-MacDonald. The fine one is 1000 grit. I have had to stick with it for quite a while, to get used to, and to be able to cope with complete non-flexibility. However, I now believe that this design is superior(at least for me) to any other pick that I have tried. I would never go back to plastic, as the bright, ringing sustain that I get(increased perceived volume as well) now, suite the blues/blues rock that I especially like to play. It helps get a wicked twang, playing country music as well. One really has to get used to it though. It's nice to have a pick last many months, with only an occasional touch up with hone and fret eraser. I wish that I could tolerate finger picks, as I would make them out of the same brass, which is also not as hard on strings as one might think. It might not be suited for any string under .010" though, and I use .011"(first string of course).

    Anyway, I truly appreciate your replies to my posts, and I value your insight. I am printing all of this kind of info, for future reference. I am now, gong to "look up" hysteresis, instead of trying to further turn you into my own personal dictionary. I have at least heard this term, and may even have known it's meaning at one time. Too much partying in my youth may have robbed me of needed brain cells, maybe it's just age, but it seems that both definitions and spelling "ain't" what they used to be !

    Best Regards Always.....tonequester.
     
  11. Dec 14, 2013 #10

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    There's not a lot of money in selling picks - so you wouldn't expect a lot of research to go into them. Ha It all has to be 'personal'.
    Look up Hysteresis on Wiki. There's a lot about it, in various contexts

    There's a make of guitar that has no headstock; I can't remember the name. The strings go back down the neck to tuners on the body. I wonder what the sustain is like in those. The mass would be less in that design but the back tension on the strings could increase stiffness. [Edit: That's nonsense, of course - the strings are just mounted the other way round - just the mass is affected ]
     
  12. Dec 14, 2013 #11
    Hi sophiecentaur.

    The guitar without a headstock, at least the original ,was the Steinberger(Ned). He started with basses. The original L series(guitars) was made entirely from a proprietary blend of graphite and carbon fiber. It was said to have a smooth sound, immediate note attack, and even tonal response(I hope so !). Some liked the fact that it was sonically clean, others thought it too unnatural/synthetic sounding. Gibson bought him out, and still retains the right to use his name, while Ned Steinberger cannot(shades of Leo Fender). They stopped production in the mid 90's, but by then wood was being used in the bodies, and the\ necks were made of graphite. Gibson is now making a new version, in Korea, called the Synapse. Again wood body/graphite neck. The original Steinberger had 40 : 1 tuners ! I would think that the original Steinberger, with graphite/carbon fiber blend would be very stiff, compared with all wood construction, but I could very well be wrong on this point. Especially when I don't understand how one would "blend" graphite and carbon fiber. I would think that perhaps ultra fine graphite powder would be added to carbon fiber during a liquid phase, at some point. The process surely could not be comparable to making a metal alloy, where there is crystallization involved, with tempering and annealing.

    Chasing tone is a never ending pursuit to some(like me). I have sustain down pat, and need no pedals, or active circuitry for that. However, what I still seem to be chasing is that complex harmonic content, that performers like Leslie West and Clapton got, especially early on. This is why most of my time is devoted to tube amp design(keeping it simple), and ways to best push power tubes just beyond spec. Then there is the issue of attenuation, so I can play without the cops showing up every time. This is a daunting task itself, as I have yet to hear any attenuators out there that don't "cop my tone" to a noticeable degree.

    Hey....catch ya later here. I'll be looking for YOUR posts, although I can't claim to be able to give you anything but my opinions, and support. Best Regards....tonequester.

    P.S. I have wondered about using carbon fiber for picks, but have not found any out there, and I truly don't know enough about it's properties to pop for the materials needed to experiment .
     
  13. Dec 14, 2013 #12

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    @tonequester
    Your name reveals your quest!
    I have just one (classical) guitar and borrow my son's old Samic for messing around on - so I have no experience, just some Engineering 'nowse'.
    You seem to have covered a lot of this in your investigations. Now all you need to do is to look at your fingering technique and investigate what treatments you can give the fingers on your left hand. There are a million different hand creams and whatnot that will / could affect the stopping of the strings. That could be a marketing idea, even. (You will tell me it's already been done.)
     
  14. Dec 14, 2013 #13
    I can't speak to that particular finish, but surely dfifferent finishes result in different absorption of the wood underneath...a sponge absorbs, but doesn't have to be 'alive'.....
    ....I could tell different paints were more or less moisture resistant over many years of wood boat finishing.....also, the stiffness of finish, even the thickness potentially, could affect resonant frequencies...and possibly tonal qualities as discussed in posts above.

    I'm pretty sure there was a special finish used by Antonio Stradivari for violins and such.....
    lets see........ok, I did not originally read it in wiki but found a quick mention:

    Anotnio Stradivari:

    This seems closer to what I recall....
    http://en.wikipedia.org/wiki/Stradivarius

    Having worked with wood for many years [in non musical applications] I can also testify that wood often becomes 'harder' as it ages....maybe because it 'dries out', but is sure gets stiffer...less flexible. The stiffness in wood is likely dependent on the lignin cell walls, likely their structure, maybe by the sequences of groqwing seasons and can be affected by the environment.
     
  15. Dec 14, 2013 #14
    I forgot to include:

    no question there are such effects.....some are alluded to in the Wikipedia articles....
     
  16. Dec 14, 2013 #15
    sophiecentaur;

    Your a classical man ! My first lessons were with a 60's rocker, turned classical. He was a great teacher, willing to spend extra time with me, figuring out how to play certain songs I'd take him on tape(that I wan't ready for yet). We tried and tried to get me going with finger style, but a couple of years prior to beginning with him, I had partially amputated the tips of my right hand index,ring, and pinkie fingers. I was lucky. that with plastic surgery my nail beds were saved, but the nails that grew back were, and are to this day deformed. The finger tips are also rather bulbous on the ends, so finger picks won't fit. By keeping those meat hooks filed back to the quick, I have over the years, been able to learn to hybrid pick, although it's not easy due to lack of sensitivity where they grafted skin on to finger tips. Hey, do you use naile or skin ? My teacher sure got great tone with long,perfectly manicured nails. it probably was a big help owning a $5000.00 custom ,hand built classical guitar. I was taking the lessons on a cheap Fender Squier, but my treacher always had a "rainy dsay" guitat, *** the custom model was finished with shellac, and he wouldn't take it out on bad weather days. Each year, he sold the rainy day guitar, often to students, and bought a new one. I bought one of these. It was a Takamine. I don't know if I ever knew what model it was, but i remember that there was a lable on the inside of the guitars back that was signed by the Japanese luthier that made it. My teacher said his asking price was always half of what he had paid new, and he was a man of integrity, so I believed him. I paid $750.00 in 1982 for that guitar. It too, has great tone, although even I could tell how rich that hand built model sounded in comparison. About ten years ago, my youngest son borrowed the Takamine and I've only seen it once since then. He showed it to me after he paid a Mars Music "tech" $100.00 to buff it out. so, I guess it's his now. KIDS....jeeez !

    I don't think I've run into any creams out there. The only music/guitar related cream that I have any interest is capitol C Cream.....Eric, Jack, and Ginger ! As for finger treatment , the one thing that I do, out of necessity, is to file my callouses down about every other month(unless I rip one off). I do lay my new strings out before i install them, and spray them with silicone lub. I just use the all-purpose kind you can get at Walmart. I also use a Q-tip to dab a bit if it into the nut slots, and on to the saddles. I haven't broken a string since I began doing this.
    Hey, who's your favorite classical guitarist(if that is indeed the music you play). I really like to listen to Andre Segovia. that's the great thing about YouTube. I just watched him play on a video there, with him alone, setting in a chair, in what looked like a Roman bath setting. I think that he was playing something by Mozart. I have tried and tried to SEE what brand of guitar he is playing, but it's impossible. he played Hauser's early on, and he did experiment of course, but it is kind of a mystery as to what he played in his later years.

    Well, I don't mean to "talk" your leg off, but it's nice to be able to talk shop here with folks like you who understand what I am trying to get across. I can't even talk to that guitar grabbing son of mine, as he just piddles,and can only talk on a very simple basis about music, guitars, and amps. I think that he is one of those folks who believe that if they just can get a hold of the right pedal.........................!

    Have a great day/night my friend. tonequester down, but not out.
     
  17. Dec 14, 2013 #16

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Not a Classical man - I have always been rubbish at reading music. I bought the guitar around 1970 and it tends to spend the odd couple of years in its case and then I take it out for a few months then put it back. I mainly play Jazz standards and other nonsense. It's a sort of 'piano' style and I play on my own. I must admit I'm in a bit of a rut (a 40 year rut!!!) I have just started trying for Blues style on my Son's semi acoustic with his Laney Amp. I don't give it long each day for the sake of the neighbours but it's fun.
    But this isn't Physics and we're probably boring the others.
    So many variables involved in musical instruments and I was just making the point that many important factors may be neglected and other things given more attention than they deserve.
     
  18. Dec 14, 2013 #17
    Greetings Naty1.

    The four most common professional solid body guitar finishes are nitrocellulose, polyurethane, polyester(all waterproof),and acrylic enamel, the most important type of which is automotive enamel(also considered waterproof. All of these will however, break down in time if in constant contact with "the elements". With any of these finishes, properly mixed and applied, one could leave a guitar so finished out in the rain for 24 hours, and not increase the water content of the wood by more than a miniscule amount, if any. Even the oil based acrylic would probably be considered to be truly waterproof, except when in constant contact with water. They are made with modified, polymerized oils such as Tung, Linseed, and Soybean oils. Thus the terminology of long oil, short oil. This refers to the polymer molecule, synthetically produced from the oil. At least, I would say "oil and water don't mix".

    I believe that you are correct in your feeling that wood gets stiffer with age, and that this is due to final drying of wood. I worked as a carpenter when young, and the company I worked for used kiln dried wood exclusively. It was still commonplace to cause moisture to"squirt" from the impact of a pneumatic nail gun at 120 p.s.i. I once cut a large Walnut blank from a tree that had blown over in a storm on my property. It measures 8" thick, by 13" wide,by 4 and 1/2 feet long. It took 7 years of indoor storage for it to dry out enough to make wood lathe turning bowl blanks that would not further dry, and warp. Now, when wood is truly dried, the commonly used finished for solid body guitars, if not absolutely waterproof, ARE water tight. Humidity changes could not affect tone enough to be noticeable.

    Stiffness would do as you said and affect string resonance. The less prone a wooden neck is to deformation, the more sustain a plucked string will have, and this effect will be more pronounced with heavy strings/lower fq, than with lighter strings/higher fq. A stiffer neck will not only sustain longer, but it will give an overall brighter tone. Still, I believe that all of this(stiffness of neck,mass, design symmetry, finish, etc.) does not add up to anywhere near the tone shaping capabilities of the electronic circuitry. In fact, I guarantee that for no more than $5.00, I can make any electric solid body sound brighter/more "treble", or darker/more "bass"). This would be the cost of changing guitars tone cap(s), or in the extreme case, using a small inductor instead.

    Therefore, my main argument is that all the big "to do" about"tone woods"(which are very expensive), which finish to use, how stiff a neck should be, completely PALE when compared what one can do electronically to get the tone that they desire. I am only talking about passive electronics.....caps,inductors,resistors,pots,pick ups, and modifying such circuitry that exists, from the factory, so to speak. Anyone that wishes to spend $300.00 dollars for a KOA body(that's from a guitar parts dealer like Allparts.com) can do so. I will save at least half of that to get the "Koa tone", and even more variation, by tweaking the electronics. I've been doing just that for the better part of 33 years of playing, repairing, modifying, and finishing guitars.

    Don't mean to get up on a soap box, However, I have just gotten tired of the hype by people who SELL "tone woods", or say that only maple necks are any good, or try to sell one on getting, or doing a nitro finish, when it yellows with age, can be damaged even by alcohol, and is highly toxic to work with, and on, and on, ad infinitum. What made the electric guitar great ? Electronics ! Electronics is a field that is based on pure science, and theories proven. Show me the thousands of pages of scientific literature that have been produced, to show that one species of wood is always going to sound in any manner, when compared to another species. Wood differs greatly within one tree, even one board. One could say" scientifically", that Swamp Ash has many different tones, but even so, there exists only a fraction of a percent of scientific fact to back that statement up, when compared to something about electronics like :" a .047 tone cap can give you a darker/"bassier" sound than a .022 cap can". That quote is a scientific fact, all other factors being the same.

    Thanks again for your input and time to do so, it's all valued by me, and makes one constantly re-think their position.This prevent stale thinking ! Best Regards......tonequester.
     
  19. Dec 14, 2013 #18
    sophiecentaur.

    Agreed and ditto. Good luck with the blues. you won't need it though with jazz experience behind you. We seem to think alike about stressing and over stressing tone factors.

    It's been a blast this time around. Hope to check in with you again sometime. I'm always searching for that which I lack the most.....knowledge ! Best Regards. tonequester.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook