bluesy

+++1 for Audacity - it's the default free audio software

Since I have just started building guitars, 3 in total so far, I am still learning a lot, and I read often about people struggling to set up guitars, just as I have at times. The last couple of guitars that I setup, one I made myself, and one commercial guitar, I used a method that worked well for me and wondered what people think.

I am mainly talking about bridge height, neck relief and low-action, starting with a neck, assuming the frets are level with no relief and the neck angle should be such that the bridge saddles are within range of adjustment and a straight edge used guitar string laid down the neck just contacts the saddles where the strings sit.

So, the bit I have started doing differently is this. I set the bridge height FIRST so that, with strings on the guitar and in tune (i.e. under correct tension), the notes in the top region (where neck relief has little effect), will just play with out buzzing. You have to retune the guitar after raising the bridge (if you do it with the strings under tension) because they will all go sharp, and you want the correct tension for setting the neck relief next. To me, this seems to be the lowest possible bridge height for the given neck angle.

After doing this, I usually find the action is a bit high, and, hopefully, there will be too much neck relief because the truss rod has not been tensioned yet (on a newly made neck). So, I next tighten the truss rod, measuring the relief in the usual way as it reduces. This happily, brings the action down nice and low at the same time. You need to retune again because the strings will be sharp due to the truss rod tension straightening the neck. Without to much mucking about, I end up with a guitar with pretty much the lowest action.

Seems fairly foolproof to me, and it avoids one mistake I was making. That was, I was trying to set action using the bridge height, while I had too much relief in the neck. This resulted in buzzing on the high frets, when playing above the octave, by the time I had the action low enough at the 12th fret (because by then, the bridge was too low for the neck angle)

If your neck is sloped back (that is, away from the strings), tightening the truss rod would exacerbate the problem. If this is what's happening, you'll want to loosen the truss rod to allow the strings to pull the neck straight.

Of course you are right, well picked up

alright well now that u mention it, the neck seems to be sloped back a tiny bit and most of the buzzing i think is coming from the first three frets, its hard to tell exactly.

so your saying if i tighten up the truss rod some more itll fix my problem?

I would try that.

Im plugging it in to the tuner. Its wierd, it shows the tuning a bit different depending on what pickup i select. I dont have anything to measure the string height with.

Sounds like the tuner is picking up on some weird harmonics maybe. Having pickups too close to the strings can cause problems if the magnetic pull on the strings is too great.

FWIW - I am never happy with a guitar's tuning just from an electronic tuner. I always need to tweak a few strings to get it sounding good. Some people here explained some reasons why on a thread where I was asking about the need for compromise tuning. The scale isn't perfect to start with and any real-world instrument, even less so.

I read 5 replies to this and backed up. You used an unfretted LMI board, "It was a pre slotted board from LMI", and fretted it but didnt touch the frets after that.

If I am interpreting this right then you need to take the strings off level and crown the frets?????

Had a discussion about this earlier. It is possible to get all the frets seated well enought to not really need levelling and crowning.

as long as the signals dont travel through the resistors anyways...

But the signal MUST travel through the resistors. When you say things like that, I get the feeling you don't understand the basics of electronics. The signal is applied as V2, V3, V4 etc as I said. Simple Ohms law tells you the signal must travel through the resistor to the (virtual) ground of the opamps inverting input. If it didn't, how would the opamp ever see it to amplify it?

For goodness sake yes - that's exactly what I said and provided the diagram for above. You are describing a mixer !!

But your diagram had resistors before the op amp. I'm saying if a resistor was after each parallel voltage follower. Surely they wouldn't act the same way.

V2, V3, V4 etc, are the outputs of your opamps. The diagram shows the resistors, R2, R3, R4 that mix the outputs into the following buffer (the op-amp shown in the diagram)

I don't think a signal can enter the output of a opamp.

Of course it can. Any voltage will try to produce a current through any non-infinite impedance it is connected to. If the "signal" voltage is different from the output voltage of the opamp, current will flow.

sorry but i still don't understand your "If you connect two zero impedance voltage sources that are different in voltage, the voltage difference divided by the impedance (zero) means it would try to deliver infinite current." Do you mean voltage follower A would try to deliver infinite current into the output of the voltage follower B?

now what if you put a resistor after each voltage follower, and THEN brought them together. Then the impedances would not be zero. Would that produce "A+B"?

For goodness sake yes - that's exactly what I said and provided the diagram for above. You are describing a mixer !!

You really can't connect ideal voltage sources together. There needs to be some resistance, otherwise interaction due to loading will occur.

hmm i'm not sure i'm understanding your explaination here. What is "interaction due to loading" referring to? What is loading what?

You have 2 low impedance sources in parallel, why would the 2 voltages not just average each other?

Let's try it this way. An "ideal" voltage source has zero impedance. If you connect two zero impedance voltage sources that are different in voltage, the voltage difference divided by the impedance (zero) means it would try to deliver infinite current. In the real world, this is not a good thing. They will NOT "average each other". They MIGHT try to destroy each other :-) except that built in protection in opamps and the fact that they are less than ideal voltage sources, might save them. They will both try to control the voltage to the value they want, and as that is different - they cannot both succeed. How's that for interaction?

I will say, after using cloth wire (it came with an amp kit I built once) the push-back properties of it are a peach to work with - no stripping, no heat shrink if you want an extra bit of protection against shorts, and often you can pull it right up over the tabs of the pots. Makes working much quicker. That said, seeing the condition of ancient cotton wire in the telephone lines in my house makes me understand why it was phased out.

There's another old solution you can use. It's called spaghetti. Usually made of cloth, and comes in various sizes, and can be pulled over solder joints. It's main use is in point to point wiring, where lots of long, uninsulated component leads might come into contact with each other.

An Op Amp Voltage Buffer, a.k.a. Voltage Follower, is when you connect the output of an op amp directly to the inverting input. The voltage at the noninverting input is copied directly to the output. But there is infinitely high input impedance and infinitely low output impedance. Google it for more info.

So here's the Question:

Say you've got a voltage source, "A", before the Voltage Follower. In parallel with all of that, you've got another voltage source, "B". How does B affect the operation of the voltage buffer? Would the 2 voltages just be added? Would the total output just be equal to B or A? Would B invade the inverting input and get saturated?

I ask because I am considering using op amps in some active circuitry in my guitar.

You really can't connect ideal voltage sources together. There needs to be some resistance, otherwise interaction due to loading will occur. This is how a basic mixing circuit works. Each voltage source is "mixed" together by feeding it to the common point via a relatively large resistor. The result is then usually further buffered by a gain stage (another opamp if you like), and it is A + B although, as these are complex waveforms of various frequencies, sometimes peaks coincide, sometimes they don't and the result is not twice A or B alone, unless your voltage sources are identical (which they are not if they are coming from different pickups for example)

Could I use a large screw embedded into the body of the guitar?

No, it needs to make electrical contact with metal that contacts the strings. i.e. the bridge or tailpiece

I recently finished a custom body witha redish pinkish stain on a maple body. I put about 10 layers of clear lacquer on it and let dry for quite some time, but it now scratches very easily, i can take a guitar pick and scratch of the clear coats.

What kind of clear paint/lacquer can I use that will be relatively cheap?

Or could I have screwed up some where else?

How long did you leave it? For some coatings it can take weeks to cure fully.

thanks,

i had actually read that exact article a long time ago, but i forgot what it said and I couldnt find it again

so basically my body is an electrical shield and by grounding it, the EMI that i'm picking up gets sent to ground

It acts as as shield, only after it is grounded, before that, a more correct term would be antenna.

hehehe...you guys are just getting crazy now...you know when you see those valves in effects units they are largely token...you can tell because they require an LED behind them to even light them up. The risk of damage to any tube in a guitar is pretty great, but hey, they might make an interesting talking point.

I'd leave the valves to amps or at best something on the floor...to get tube warmth, valves have to run pretty hot and that means a lot of power...not something that you really want or need to have running inside a guitar!

Well, you are right, sometimes they are just for appearance - but, for example, some of the BEST microphones use tube preamps inside them. I design and build valve amps as a sideline/hobby by the way. Not all valves run that hot, especially the miniature ones designed for battery and/or low voltage use. Besides the "Control Cover" for the compartment where the valve is installed, can easily be ventilated. All that said, I can use a FET to do virtually the same thing, and I'll bet most people could never tell the difference.

Along the lines of the tube idea - you could try using these tiny 6021 tubes that are a feature of the ZVex Nano Heads.

mini-tubes

Yes they would work well, although, with the 2" thickness of a guitar, I could easily fit a 12AX7 sideways.

Build the Tillman preamp with a 6.8uf or 10uF bypass cap on the FET, you'll pummel the input of your amp.

http://www.till.com/articles/GuitarPreamp/

I like the idea of a FET preamp too. I'd even go further, and try a tube preamp. Maybe power it via phantom power as used for microphones. The interaction of tube microphonics and guitar vibrations might lead to interesting effects.

May I ask if the finish lets the natural texture and pores of the wood show through? Or does it fill the pores with such few coats?

In my experiments with it, it doesn't fill open grain. You need to use a grain filler first, unless you want to be able to see the grain. Of course with enough coats and sanding, it must eventually fill, at least some of, the grain.

If we were talking about a radical departure in design perhaps I would be less adamant about this kind of thing, but with a tele there are so many options in the premade or complete guitars to start with, it does warrant some real soul searching as to whether it is worth it...especially when reduced to costs like this and what you will end up with in the end if you make it through successfully.

just an opinion, feel free to modify or disagree...welcome to PG...as I say, this could be a very valuable discussion to many here with a host of different perspectives...

pete

I'd just like to say that, for me, it was never about the cost. I set out to overcome my fear of woodworking and lack of skills in that area - and, most importantly, to be able to say "I built that myself from scratch". But what is "from scratch", because I purchased ready made hardware like bridges, tuners etc.

Building a neck myself was mandatory, because I wanted to develop the skills of fret replacement, fret levelling, nut building, etc.

It sounds like he's gonna put a cheap acoustic top on there. $20 is about right for that.

I see. Never thought of that - does it work well? Certainly no way to carve it because it's thin, but for a flat top with binding (which I kinda like on a Tele) ...

"top cap $20.00 LMI "

That seems cheap, looking at their site, I see top caps - but not many are less than $100, and none as low as $20 (but then I probably missed something)

I played around with the nut. I think that when I originally made the nut, I may have cut the nut slot at the same angle as the headstock.

I did two things:

1- Changed the angle of the nut slot so that it is not as angled

2- Deepened the slot ever so slightly as a result of the above.

The fretted notes in the first couple of frets are much better. They only seem to go off by 5 cents with moderate pressure. Still not prefect but much better.

Does that sound reasonable?

I have read that an angle about half of the headstock angle is about right. I don't think it is critical, but it's important that the string is sitting flat in the bottom of the slot. I used to try to adjust nut slots with all sorts of implements, and had problems, until I bit the bullet and purchased a set of 8 nut files. Expensive but worth it. (of course if you are already using nut files, ignore me )

So, making the slot deeper helped? Then that begs the question, how much lower can you go? I forget the figures quoted, but one rule of thumb was that you should barely be able to get a piece of paper under the string over the 1st fret, when you are holding the string down at the 3rd fret.

i know what a high pass filter is, but there are two ways to make it, either with a series cap or a parallel inductor

oops i accidentally said "variable cap" but i meant "variable resistor"

A volume control actually does have an effect on the signal at 10, though. Just like a tone control bleeds off some highs at 10, volume control bleeds off volume. Because it's impossible for the volume pot to have infinite resistance (unless its a no load pot). A series pot would be able to have 0 resistance and therefore you wouldnt lose any signal.

OK, you asked what they usually do - and the answer is, series capacitor.

The Volume pot should be a large enough value, compared to the other impedances in the circuit - like pickup impedance and amplifier input impedance, that is has no appreciable effect when set to it's maximum. Most other impedances in the circuit are 10's of k (like the 50k input on a guitar amp), hence volume pots are 250k or 500k. Being an order of magnitude bigger, it's effect should be small. So small, that the small loss is swamped by variations in gain in all sorts of other places in the guitar pedals and amplifier.

A series pot would indeed let 100% through at full volume, but it would have another serious problem. At zero, there would still be some sound because it cannot have infinite impedance. In fact, for a 500k pot into a 50k amp input, you'd get approx. 10% of the signal voltage still coming through. The design decision is that it is better to be able to turn it all the way down.