massive propagator

Ok, now i am finished for the summer i can actually get started again.

I've slightly redesigned the headstock, does this look any better?

No, wavelengths and frequencies are not always the same. Remember I am talking about upper harmonics, not the fundamental. I was in error in an earlier post when I used the term "fundamental" and I did point that out

Think about how you tune from string to string at the 5th fret

On the 6th string the open string is E

At the 24th fret you have 1/4 of the string which is "E" (the second octave)

At the 12th fret you have 2/4 of the string which is "E" (the first octave)

At the 5th fret you have 3/4 of the string which is "A"

Each of these have a different fundamental wavelength but they all share the fundamental wavelength of the second octave E as an upper harmonic

(You could say 3 x E = A)

I don't know if that explains it well enough but I hope so,

cheers

Your post doesnt make any sense, they do correspond, for each and every harmonic. Whether it is the fundamental or a higher harmonic does not matter.

If the nodes dont change then there would be nothing special about the 24th fret position, this "reinforcement" of frequencies would have to happen everywhere on the string

I may need to clarify what I've said

When you play a fretted note, the new string length will have its own set of harmonic series. The wavelengths that are reinforced are the ones which both sides have in common

So when I put the cappo on really tightly, the string behind the fret is reinforcing a different wavelength which has different positions for nodes and antinodes, but they were always there

Also, different wavelengths have different lengths but no matter which fret you play on, (as shown in the diagram I put up) there will be a wavelength that both sides have in common and they have a node or an antinode at the 24th fret

So to clarify;

In a single sentence, am I right that your theory is that this 'sweet spot' at the 24th fret is because there is an unusually high concentration at that point of nodes and antinodes of the fundamental frequencies of all the frets?

Yes but I may have said "frequencies" when what I mean is 'wavelengths' or 'half-wavelengths'

Everyone seems to agree that the pickup on the 2nd octave node works for the open string but not for fretted notes. What I'm showing is there are always nodes or antinodes over that point

Btw thanks for that link, I'll have a look at it

In the past few days I've kept researching this 2nd octave node thing and found some surprising outcomes. But when you look at it a different way its quite obvious

First of all when playing the open string, if you take the 1st octave (12th fret) every harmonic has a node or an antinode over that point. Think about it, if you divide the string by an odd number you get an antinode over the 12th fret and if you divide it by an even number you get a node. And a string will only vibrate in whole numbers (so to speak) At the 2nd octave every harmonic has an node, antinode or half-way between node and antinode. So if you have a wavelength that is half way, then at double the frequency you get an antinode. When playing a fretted note, the "theory" I'm suggesting requires a wavelength that both sides have in common, so the rules for the open string will apply. Or in other words the fret is on a node

Now here's the killer. What if you use a slide? and you're half way between frets? Does the tone suddenly sound crap? Of course not...

Theoretically (mathematically) there is always a wavelength that both sides have in common. For example take 12mm of a 628.65mm scale (24 3/4")

12 divided by 628.65 = 80/4191 (btw I've got a scientific calculator which converts decimals to fractions)

This means the whole string is vibrating in 4191 half-wavelengths. The 12mm takes up 80 of them and the remaining string has 4111

The half-wavelengths are .15mm long so how many fit into 1/4 of the scale?

628.65/4 divided by .15 = 1047.75

The number ends in .75 which is half-way between a node and an antinode. So if you double the frequency you will get an antinode over the 2nd octave node

No matter which length you try, you end up with a whole number or one that ends in .25 .50 or .75

Now I don't know if its physically possible for a string to vibrate in such small increments but the in any case the theory is there

Also btw I tried the experiment with the cappo on another of my guitars and had the same result. Its not a huge difference because its not really a nut and theres no fret exactly in the right place so it takes a bit to notice the change in tone. What it sounds like to me is when the cappo is on, the note "rings like a bell" When it is off there are unwanted overtones

I am convinced about this idea and what it means is you can have a 24 fret guitar and still get a true neck pickup sound just by putting a cappo on in the right place. The way to do it is measure from the bridge to the pickup pole piece then multiply by 4 Then measure from the bridge to the closest fret to that length and put a cappo on, really tightly close behind the fret. You may need to re-tune though. And if you don't hear a difference then try it over and over again. Then try it the next day, the next week...

One day I showed my new guitar to a friend of mine. He couldn't tell the difference between the neck pu and the bridge. But after I explained it he goes "Ah yea, I can hear it now" In other words you sometimes need to "train your ear" to notice differences in tone

Frequencies and wavelengths are the same thing.

None of what you are saying here is really relevant. Either the effect you are hearing is due to a node, in which case moving the capo would move the location of certain pinch harmonics, or it is not due to a node, in which case the relative position of the pickup makes no difference (other than how it would without the capo).

May be an obvious question, but have you tried different strings?

Something just occured to me that could need more clarification. When I did my experiment on the white guitar with the cappo

If I play a fretted note, the nodes are going to be in the same place with or without the cappo on. And this is where I believe the string behind the fret must be having an effect

When the cappo is on, the frequencies of the string length behind the fret are related to those nodes/antinodes (which occur over the pickup) and will give them support

When the cappo is off, the string behind the fret is unrelated and will not re-inforce those frequencies (It is related to the frequencies which have nodes over the 24th fret)

If the nodes dont change then there would be nothing special about the 24th fret position, this "reinforcement" of frequencies would have to happen everywhere on the string.

Good to hear your input guys. I hope I will clarify what I'm saying a bit

First of all I'm pretty sure you'll find when you divide a string into two, there will always be wavelengths that will go into both parts. When I talk about vibrations from behind the fret I'm not talking about the sound, just the vibrations. And I'm suggesting these vibrations enhance the upper harmonics of the note being played. The first fret a little bit, the second a little bit more...and so on untill the 12th fret where its not just upper harmonics but where the wavelengths are the same as the note being played. (This is why I believe when playing on the neck pickup I find the sound gets better as you approach the 12th fret, then fades as you reach the 22nd fret)

The problem of course is when you fret a note you also press the string onto the fret behind the one you want. So how does this affect the vibrations? This is where I'm not sure but I'd say the string partially vibrates transversely and partly longitudinally

Now what I've found mathematically, the corresponding wavelengths on the pickup side always land on the 2nd octave node in antinodes, nodes or halfway between (I was previously saying nodes or antinodes) But consider this; in relation to the open string the 2nd octave node is not on a node or an antinode, its halfway between. Its on the antinode of the first harmonic, an octave higher

When I did the experiment of clamping a cappo tightly on the second fret, I was trying to simulate the nut to have the effect of making the scale shorter. I have to admit it was hard to tell the difference at first but after a few comparisons with it on and off I was convinced. I had effectively put the pickup on the 2nd octave and therefore it had a nicer tone

And this is what I did with the double bridge experiment;

The second bridge was positioned so the neck pickup was on the 2nd octave node of the "secondary scale"

The strings went lightly over the 1st bridge to simulate a fret

I was trying to see if the pickup would "see" the secondary scale but play the note of the first scale

And yes it did work, I got that creamy neck pickup sound...but with a kind of out-of-phase sound. Which is exactly what I'd say was happening

Of course the other thing I did was drop the first bridge and played to the longer scale and yes that distinctive neck pickup sound was totally there. It was really funny how well it played with the intonation being out so much!

I have to point out that I haven't got everything completely worked-out, but I know enough about physics and experience with the guitar to be sure there is something here

I dont really get what you are saying here, the vibrations ARE the sound. If the two effects i described above cannot be seen, then there is no physical way the vibrations from the two strings are interfering. Any other effects would be constant over the string, and so would not produce a 'special' pickup position (they would affect a pickup anywhere equally).

You talk about the 'perfect spot' where the sounds add together or cancel out in an opera house. These are exactly the nodes we have discussed earlier. If what you say about vibrations from the dead string is true, then these nodes must move along the string.

Its a weak analogy anyway, the multiple source points, full frequency range, reflection, cancellation and absorption (and probably other things only an acoustic architect understands) all play a part in sound acoustics, You may as well be comparing a skipping rope to the oceans currents.......

I dunno, i think it works as an analogy for standing waves, he wasnt bringing any complexities into it.

Ok, here are two tests to show that frequencies from the 'dead string length' dont affect the 'active' length.

To show that no new frequencies are added, take a string stopped from vibrating at a point between fret positions. The string length when fretted is the same as before, but the total length is no longer mathematically related to the fretted length, so the frequencies on this new string length will not be harmonically related to the fretted note. This would be heard as a new set of frequencies out of tune with the normal fretted note.

You talk about the 'perfect spot' where the sounds add together or cancel out in an opera house. These are exactly the nodes we have discussed earlier. If what you say about vibrations from the dead string is true, then these nodes must move along the string. This is easily tested, as the nodes are where you touch the string to get a particular pinch harmonic. So if you capo at a fret behind where you are fretting (like in your test above) the place you touch for a pinch harmonic must move significantly (by a few frets difference. Its probably best to test this with a pinch harmonic over the fretboard, so you can judge exactly where you are touching easier. Obviously, make sure you are playing the same harmonic.

If neither of these occur then the dead length has no effect relating to pickup position. Id be really interested if people could consistantly produce either result.

No comments? Do I have to pick on my own argument? (Or are you guys just getting sick of it?) I can easily poke holes in it!

What if you move the nut to the first fret? Or made the scale one fret longer? All the same vibrations will occur, the pickup is still the same distance from the bridge, its just a bunch of mathematics!

I just did the maths if you moved the nut to the 1st fret position. The nodes/antinodes are all on 148.46mm However what we want is the stronger vibrations (ie. the longer wavelengths) but even though the ones I’ve put up are directly related to the position of frets, they still aren’t very long. So I keep getting back round to the full string length having something to do with it

I’m still convinced that although you play a fretted note, the true 2nd octave node still exists even if its very weak (This is where the "railway track" idea comes in) My theory is, because the other nodes are close to it they would re-inforce each other resulting in the strongest nodal/antinodal point in the pickup region

Let me explain what I meant about railway tracks, what I had in mind was this. If someone hits a track with a sledge hammer, a person 5 miles away wouldn’t hear it unless they put their ear to the track. I’m theorising two things; (1) These types of sound waves exist in a string (and will have nodes) and, (2) The pickup will “hear” like putting your ear to the track

I’m at my wits end to think of ways of proving anything really but there has to be a scientific reason for the sound you get from having a pickup on the 2nd octave node to sound the way it does

Also I wanted to point out when I bought my first Les Paul in 1977 I don’t know if there were any 24 fret guitars around. I was just a 15yo kid who knew nothing and chose it purely by its shape. I wasn’t co-erced into buying it for any reason. I just pointed at a picture in a brochure and said “I want one of those” It was about 2 months later that I asked about 24 frets and it was explained to me that it wouldn’t sound as good

The first time I heard the argument about neck pickup position is maybe a year or two later when there were lots of 24 fret guitars on the market. To me the “sales talk” is the other way round to what you guys are saying. I remember hearing (to the effect) “the sweet spot is a myth” These things evolve though and what I’m thinking is salesmen started saying that there were 24 fret guitars with the pickup on the sweet spot - Like some magician has found a place where you can get the same sound as it being on the 2nd octave node!

I hope I've made sense in this post but one thing's for sure, if I make another guitar it will have the neck pickup on the "magic position"

cheers

Doug

How would the pickup detect longitudinal waves? How would they cause the magnetic field to change?

What is the difference between a good and bad spokeshave? Is it mostly in the blade?

I don't see anything "falling down" If by "other variables" you are talking about the fact that some guitars have a lot more string between bridge and tailpiece and others have none -

I'm sure the string length beyond the nut and behind the bridge would have a very marginal effect on the sound (in regard to the concept I am talking about) The length between the bridge and the nut is much longer and therefore have the most effect. It seems to me that Gibson have gone "all the way" with this concept - which may or may not be necessarry

The angle of the headstock etc plays an important role here too. If the nut, and the pressure on it was just like a fret, then the string length between bridge and tuning pegs would play a much more important role in the theory I am putting forward

Has it ever occured to you that standard pickup positions sound best cause that is what the pickups are wound for? Its not like much effort was put into choosing those 'original' pickup positions, but a lot more effort has gone into optimising the pickups to fit those positions.

Well after 3 nights in a row of drinking I should be right to make comments again!

Yeah the humbucker vs sc is an issue always on my mind too, but I think as long as one coil is over the right spot the other just adds to the sound. It would be interesting to hear what it sounds like if the inner coil was over the node

Anyway, on the theory that the full length of the string always has an effect on the nodes. Think about railway lines, they don't visibly move (vibrate) but sound will travel through them for miles even though they are nailed to chunks of wood all along the way (isnt that like frets?)

If the 'dead length' of string made a difference to nodes, the nodes wouldn't be under the 24th fret for every guitar, and the whole 'magic position' disappears again.

Yes pickup height is very important especially when comparing different positions, you have to keep it consistant (I have to confess its one reason why I spent so long experimenting!)

Well I don't know why some people don't find "sweet spots" Dugg, what kind of guitars were you working on? Regular scale-length, baritones, bass guitars? And did you go past the 2nd octave node? (btw my name is Doug too lol) I haven't actually stated this yet, but I think the theories on regular scale-length guitars are out the window once you go past a certain length like baritone guitars and especially bass guitars (subject to further experimenting)

I've looked at what I've said so far and its like a bit here and a bit there so I want to go over it again and a maybe a few new things (probably should have said at first post!)

BRIDGE -I agree with what I read somewhere recently

The harmonic points are so weak around that area and they're so close together that its just a matter of preference. And I also agree with Wez- further from the bridge, the warmer the sound - and I don't like it too close to the bridge either. The 61 Re-issue SG bridge pu is too bright (which is probably why I find some of Angus Young's solos a bit ear-peircing)

MIDDLE (talking single coils here) - On a Strat is 100mm from the bridge which is not on a node, but move it too far off that point and you lose the unique Bridge+Middle sound

I tried it at 1/6 the scale length which produced a similar sound and also quite unique but only over a limited area of the fretboard, from about the 4th to the 9th fret. I also found this if I moved the Bridge and Middle together (keeping distance between them the same)

NECK - I haven't done extensive testing yet. But what strikes me is any guitar that has the pickup at 1/4 the scale length has a very distinct sound. And like my comments on the middle pickup if you move it you lose it (The area of the fretboard that gets that distint sound shrinks)

The biggest argument against the neck pu sweet spot is that when you fret a string its no longer at 1/4 of the sounding string length. But re-stating what was explained to me, the string still vibrates up to the nut and therefore still has an effect

I don't completely understand it myself and thats why I've done so much experimenting. But anyway let me put forward this theory;

Maybe the neck pickup has that distinct sound at the 2nd octave node because

- when playing open its at 1/4 the scale

- when playing at the 5th fret its 1/3 the length of the string being played

- when playing at the 12th fret its 1/2 the length of the string being played

- when playing at the 19th fret its 3/4 the length of the string being played

In other words no matter where you're playing its not far from a node

Well surely the same thing applies to a neck pickup shifted down by two frets for a 24 fret neck.

When playing 2nd its at 1/4 of the scale, 1/3 at the 7th....

It is always near nodes too, wherever you are on the neck.

Its pretty simple to prove that the 'node sweet spot' idea is nonsense.

Find a guitar where the distance between the neck pickup and the last fret is the same as the bridge pickup to the bridge. Fret any string here and play. Switching between the pickups should reveal they sound identical. The pickups need to be the same, obviously.

Only positon along the vibrating string matters. (the string is symmetrical, so in which direction the distance from the midpoint is measured is irrelevant)

hmm, trying to resize the headstock, I i cant really get it to either look good or for the tuners to line up well, think i'll just keep it at this size

wes, the strap button placement was just a relic of the original drawing i modified, i hadnt actually chosen it yet, i'll wait to see how it hangs before actually drilling for either position

I bought a hipshot 7 string bridge from wymore guitars, dunno if there are any better options, as importing from the US is far less favourable now.

Ok, been planning this for a while, must've read at least 1/3 of this forum by now!

Bubinga neck, alder wings, sd blackouts, hipshot hardtail bridge, 27" scale.

How does this headstock look? I've only got as far as glueing up the neck blank (and removing some waste) so i can still change this easily.

How much does the timber used on a fretboard affect sound?

In my experience it seems quite a lot, but I'd like to hear other people's opinions

I dont have the experience to know for myself, but the general idea seems to be that it has a large effect on the attack portion of the sound.

How do i go about making an ultra-flat glass sanding surface? I know i need float glass, but i dont really know where to go looking for this (im in the uk), or what type specifically i need.

Would buying a mirror be a good place to start? I assume even fairly thin glass will be ok mounted closely to a (very) flat piece of wood/metal?

Also are there any cheap alternatives i should consider?

I know its basic but i want to get it right.