Several things can cause tonal changes in the lowest strings, including –

If the string saddle is far back, due to intonation, it can cause the (stiff) low strings to round the front edge of the saddle poorly, which means that the string is not lying solid on the front part of the bridge, and can (in some cases) create a subtle muddiness (because the string length is changing very slightly as the string vibrates). Rare but can occur.

The action, height, can produce muddiness occasionally. Experimenting with higher or lower action by adjusting the height of the saddle may make a difference. (Be sure to adjust truss first to get flat fretboard if it has moved; see Megatar Owner’s Guide for correct trussrod adjustment procedure. Anyone can download a free copy in the documents section of the Megatar main website.)

Your playing, your touch, can make a difference, though it’s hard to specify.

Your particular amp or effects chain can make a difference. Try others at the guitar store to see if that’s it. Try removing all effects. Most likely problem effects would include chorus, and certain kinds of reverb. ‘Helpful’ effects would include the ‘aural exciter’ type of effect. And when your EQ kills all the highs, the ear cannot track low notes well, and can in some cases be perceived as muddiness.

If you’re tuning to something other than standard notes, then you may not get the best tone because the gauges and tension may not be optimum. If using a non-standard tuning, you may have to use non-standard gauges, to change the tension, to get the best sound. Careful experiment is the only way to find out.

Of course, do realize that all tapping instruments have a different sound than a plucked bass. If you ‘pluck’ your bass with a pick right next to the bridge saddle, you are triggering the string very similar to what tapping does. And this will not have the same soft pop as a bass plucked with vigor near the fretboard.

Other brands/kinds/gauges of strings — we’ve not experimented with other types. When designing, we wanted to use the most commonly available type of string, so that players could easily find strings that would work well. For this reason it’s difficult to say how other types of strings will work, and so cannot report much about that. If using other types of strings, you are the pioneer, and so you’ll need to experiment and compare.

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Experimentation is your friend. Here are some possibilities –

RECEIVING BROADCAST HUM

There is something in the environment which is “broadcasting” RFI in the room where your equipment is located. Common sources of Radio Frequency Interference include motors (vacuum cleaners, refrigerators, and automobile distributors), and transformers (high-intensity lamps, fluorescent lights), and from big magnets like speaker coils or television sets. The sound from autos are likely to vary in frequency. The sound from lamps and lights and refrigerators are likely to be be consistent, and at 60 cycles per second, which is what we normally call ‘hum.’

The RFI can be picked up either by strings (antennas) or by pickups (coils) as the signal is induced into the circuit created by the guitar and its parts, or into the cord (usually not possible if cord is properly shielded on both the guitar and the amp end), or into the amp.

The RFI is then *not* filtered by the humbucking pickups. Normal hum *is* filtered by humbucking pickups. In our shop, when we build the Mobius Megatar Tapping Basses, we do our lab work two feet under a fluorescent light, just to ‘hear’ if there is a problem, and this hum is normally filtered out.

So the best way I know to get an idea that strong RFI in the environment is some part of the culprit is to get the hum going, and then change the orientation of the instrument. If you hear hum while the instrument is flat on the table, but not when it’s upright, or if you hear hum while the instrument is upright facing east but not when it’s facing north, then probably there is a strong RFI source in your environment. Remember that it may be behind a wall or a ceiling or floor. Wood and sheetrock is no barrier to Radio Waves.

If the instrument seems the same in all orientations, then consider the cord and the amp. Try moving them to a different room or part of the room.

TOUCHING METAL

Sometimes you will hear hum, and then you touch the strings with your hand and the hum vanishes. Or you touch the (metal) tone/volume knobs, and the hum goes away. I’ve been told this has something to do with the ‘capacitance’ of the human body, and I think that means that the body soaks up alternating signals. But that’s too vague. It doesn’t get us anywhere. I suspect this is a meaningful clue; I just don’t know what it means.

A GROUND LOOP

Hum can be caused by something called a ‘ground loop.’

We can think of an electrical power plug as have a left and a right prong, or we can think of a signal having a signal and a ground wire. If you’re not using two amps then the question of their having the same side (left or right) as the ‘ground’ should not be an issue, though it is *possible* that an input jack on your mixer *might* be reversed from the others ones *if* repair work was ever done on the mixer.

Likewise, if some of the inputs on the mixer are for ‘line level’ like synths, and others are specifically built for magnetic inputs like guitar, or others are specifically for mikes (and either with or without phantom power) then it is possible that all inputs are not equal. Sometimes there are switches associated with the inputs.

HUM SPECIFIC TO TAPPING GUITARS AND BASSES

On specialty tapping instruments, like the Chapman Stick, Warr Guitar, and Mobius Megatar, usually two outputs are provided. One for the bass pickup(s) and one for the melody pickup(s).

In Mobius Megatar and other instruments that I’ve seen, the bass and the melody have the same ground.

Normally, the ground is common throughout the guitar — The pickups cavity is grounded all around, the pots and pickups and outjack are all grounded to the same place. Even the strings are grounded to the same place. Therefore, the stereo cord goes into two mono cords, and the two mono plugs — one for bass, and the other for melody strings — have the same ground.

On Chapman Stick or a Mobius Megatar tapping bass, these output mono jacks, have signal on the metal tip, and ground on the metal sleeve of the jack, and it’s the same ground all the way back to the pickups and guitar components and the shielded cavity.

Therefore, unless one uses a mutant and miswired stereo cable, the sleeves of the two mono jacks should both be ground. A voltmeter connecting the two sleeves should show zero resistance.

HUM COMING FROM MIXER OR AMP WITH TWO MONO CABLES

But if a hum is coming from any mixer or amp when two common-ground mono cables are plugged into two inputs, it might be suggested that there is either (a) a 60-cycle induced hum that has been induced across the two signal tips; or (b) that the signal/ground is reversed on one of the mixer/amp signal paths relative to each other.

This article is not capable of analyzing or diagnosing the device you are using, but a fast way to find out if that’s the source of trouble is — carry your Megatar or Chapman Stick to Guitar Center. plug it into a bass amp, and plug it into a Guitar amp, and play it. No hum? Then there is nothing wrong with the guitar or the cable.

Get them to stop the kid playing Stairway to Heaven with his amp set to eleven while you do this test.

ELECTRICAL OUTLETS AT YOUR HOUSE OR ON THE GIG

The electrical outlets in the wall are ’spozed to have proper grounding. However … maybe they don’t. Even if they have three prongs, maybe somebody just stuck those part on the wall and maybe that third, grounding wire isn’t connected up to an actual ground.

If you have more than one amp or effects, best to plug them all into the same outlet. Or carry your own multi-outlet strip.

An easy way to create a ground loop in the power is to have two devices that have two prong plugs. Plug one in rightways and the other one reversed. Just about nearly always you’ll hear hum, and with the right equipment you can shock yourself seriously. Not even a joke.

Plugs these days are ’spozed to have one fat prong and one thin one, so they cannot be reversed, but it doesn’t always work. And remember … some human may have wired up that plug. Oops.

SINGLE COIL PICKUPS

Single-coil pickups are part of a radio-receiver circuit. Remember the coil of wire you made when you built a crystal radio in cub scouts? Signals can be induced into coils rather easily. They are natural ‘receivers.’ Any source of RFI is likely to sound through single-coil pickups. Darn.

Specialty touchstyle basses like the Chapman Stick, Warr Guitar, and Mobius Megatar, designed for two handed tapping, will usually have the instrument’s gain turned higher than a standard guitar, because we’re just tapping gently on the string instead of strumming like all get out.

Turning the gain up increases the signal, but also boosts the background noise, including hum, as well, so dealing with hum may require a bit more attention, if you want a quiet sound.

SORRY INSTRUMENT DESIGN

Cheap instruments, in some cases imported strat knockoffs, sometimes do things so sloppily that they do not have any shielding around the electronics. The cavity around the electronics and pickups should have a solid conductive material all around these components. It’s called a ‘Faraday Cage’ after Michael Faraday I suppose, and it keeps those nasty vibes from annoying the components.

I have heard, but don’t know whether it is true, that the basic Fender Stratocaster design has ground-loop errors in the basic design. I am dubious. Not Leo! But for certain, a guitar maker could make a blunder, I suppose. If it’s on one guitar but not another, take it to a whiz guy.

SORRY CABLES

The teeny signal is running on a wire across (to the signal) a vast distance to get to the amp. Lots of signals in the air could disturb it, but it is ’spozed to have a big fat woven wire all around it — again a Faraday Cage — protecting it from bad vibes. And this big fat woven wire would optimally be connected to ground on the tapping guitar, and to ground at the amp.

But is it?

A fancy name and expensive price tag may not be the best cable. However, again, a trip to Guitar Center with the noisy guitar and cable, and if you try some of their cables and the noise goes away … it’s a definite clue.

[This post adapted with permission from the Reducing Hum article at the Two-Handed Tapping website.]

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(1) First, it is a fact that little tiny strings wiggling in a magnetic field create a smaller signal than great big ‘ol strings wiggling in a magnetic field. The mass of tiny strings is smaller and so it disrupts/alters the magnetic field less. Also the swinging of a big string is somewhat larger than a smaller string, I think, so its wiggling is both further and more mass.

(2) So the first line of approach on the instrument is to see if you can get the magnetic field to be closer to the small string, because as the magnetic field grows closer, within certain boundaries, the magnetic field reacts to the wiggling string more.

The general way you do this is either to (a) raise pole pieces under tiny strings, if you have pickups like the gold-case pickups on the Dragon instruments, or if you have pickups like on the Chapman Stick, or (b) if you have rail or solid pickups then you adjust the mount screws so that the end of the pickup under the small strings is closer to the string.

How close?

One good way to do it is to bring the pickup high until the string strikes it when playing at fret 25. Then back it off. Now when the string is very close, the magnets will pull on the string, and it will have a slight distorted sound. (Depending on your rig, this may be subtle.) Back the pickup away until the distorted sound just diminishes.

The other way to approach this is to move the other end of the pickup away from the fatter strings. Because it’s the difference in closeness that makes for a difference in volume output from the thinner and fatter strings.

In the Mobius factory shop when prepping instruments to go out, we test the relative loudness of bass strings at fret 3-4, and the relative loudness of melody strings at fret 13-14, as a good general overall test.

(3) The other part of the equation is — what are you playing the instrument into? If you run it into a bass amp, the nature of a bass amp is to be very kind to bass strings, but it will absolutely eat up your highs, and tiny strings have very little sound t offer other than highs, so their volume is naturally diminished.

Likewise the tone control, if your instrument has one, if it’s rolled off will kill more sound on your highest strings. The Chapman Stick instruments don’t normally have tone controls, but Warr Guitar and Megatar instruments do, of course, because it gives you more control over your sound during the gig.

In a similar fashion, on any amp, your EQ settings create a large difference in what frequencies come out. In our factory shop when we set up instruments, we use an unusually flat-response P.A. type amp (Barbetta) with no boosts nor cuts in the EQ. We don’t want to hear the sound sweetened or colored in any way when we’re setting it up. But of course, for your music, you will choose the amp and effects which best present the music you are creating.

And also, some effects (even when not labled EQ) change EQ in order to accomplish their effect. Phasers and chorusers can cause phase cancellation, and some distortion effects boost mids (at the expense of highs).

Try carrying your instrument into Guitar Center and try other amps. They will all present different sounds, including a difference in the relative volume between high strings and low strings.

One favorite sound, for many of us, is a ‘jazz guitar.’ But it’s also a fact that this distinctive sound is created by rolling off highs, and so to compensate, your fingers have to be lighter on big strings, and heavier on little strings.

(4) The action of strings does absolutely have an effect on relative loudness. If you have a relatively low action, and you have the gain up, usually a good balance is available.

Sometimes overlooked is that, if you have a high action, then you have to hit all strings hard, and this gives you very little control over dynamics. So how could you create, with your fingers, more volume from the high strings? You can’t.

With a nice low action, and the gain turned up a little higher than seems reasonable, then you can play lightly, and your fingers will have far more control over how loud the strings sound.

Although tiny strings absolutely make less sound than fat strings, and that continues to be true for any guitar or bass, all these other things will affect the volume that you hear.

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TWO AMPS

Because the instrument has bass and melody outputs, some people simply use a bass amp for the bass sound and a guitar amp for the melody sound. If you were gigging, this can be a lot of stuff to haul, but at home it’s not all that difficult.

Of course two amps cost more than one amp, but it is a fact that bass amps are built so as to be very *kind* to the sound from bass strings, and guitar amps are built so as to be very *kind* to the sound from guitar strings. So this two-amp plan does work pretty well for getting a great sound.

ONE AMP

Tapper Teed Rockwell, for one, uses a Fender Twin Reverb. He plugs both the bass and the melody leads into the single amp. His reasoning is that the instrument is *one* instrument, and so he wants to have *one* amp. Now Teed is also a guy who uses very little in the way of effects.

He says his fingers are his effects. And he gets a great sound from the single amp.

If you’re selecting a single amp, the thing to beware of is this — Some bass amps will produce rather a muffled sound for the guitar strings, and some guitar amps will produce rather a weak bass sound. However, other bass amps and guitar amps can produce excellent results.

Your ears must be your teacher. And most any guitar store will let you try amps, as much as you like. (Just don’t play ‘Stairway to Heaven,’ OK?)

ONE KEYBOARD-TYPE AMP WITH EFFECTS

Some use this particular method, because it allows them to have a rather light-weight amp which can handle very low and very high sounds. Keyboard amps or PA-type amps are made to handle both very low and very high sounds.

Now, bear in mind that keyboard or PA amps are *not* designed to be *kind* to the sound of bass or guitar like bass and guitar amps are made to do, and also anybody playing loud rock and roll should be aware that over-driving a keyboard amp doesn’t get a great sound but can damage the amp instead, because they’re built differently from guitar and bass amps.

Also, most everybody who uses a PA-amp uses *something* to condition the bass and melody sound before it goes into the keyboard amp. Some folks use two direct boxes, and sometimes these direct boxes have amp modelling built in, so it sounds like your melody is a guitar amp and your bass is a bass amp.

Other folks use guitar stomp boxes on the floor. Other folks (including me) have experimented with floor-type keyboard effects which can then produce a wide range of lush and exotic sounds.

We’ve also had good results with amp-emulating and effects units like the Johnson J-Station or the Line Six units. And I’ve also had totally great results with the Guitar Rig software from Native Instruments. It runs on your computer, and lets you choose amps and effects, and has great sound. (The videos I’ll mention below were done using the Guitar Rig software, but with very minimal effects, as I wanted a very clean and bare sound.)

We cannot really recommend a particular amp or effects chain. For one thing, they change every year, and so who can be up to date? But, more importantly, your own ears will tell you the answers fast, and we could never guess those answers, just because we’re all different guys and different musicians. I (Traktor) play ‘elevator music’, and I like jazz harmonies and ‘beautiful music’ mixes, used in standard, Beatles tunes, and bossa novas. Your music will be different, and even if you played the same songs, you’d treat them differently, and you’d best enjoy some different
sound.

However, though we don’t know the answer, we know where the answer can easily be found — Go to any music store, and plug in and try the things. Your ears and your budget will tell you the answer quickly.

Also, remember that you can *start* with almost anything, because your earliest practice will be getting the feel of it. Luckily, your past training will transfer quickly, and the process is a lot of fun. And after a couple of weeks playing through *anything*, you’ll probably be in a better position to specify what you’d prefer more exactly.

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