How Fender Stratocaster works
The guitar and amp affect the tone in different ways. We’ve said earlier that the amp and the speakers are the most important for what you hear, and we stick with this. Still, the amp can not produce a signal that was never there from the beginning (except harmonic frequencies due to clipping/distortion). It is therefore important to know how the guitar works and how to improve and shape its tone. We’ve tried to list the different tone factors in the Stratocaster, in an approximate order of relevance:
- Neck and fingerboard. Wood materials, thickness, density, tension, truss rod construction. Rosewood necks are usually darker sounding than maple necks. We have played maple necks that seem to have a wider and fuller tonal response compared to rosewood. Yes it can be brighter, but also something in the middle. Individual necks can be quite different, either good or bad. The thicker the neck profile, the more wood around the truss rod is allowed to resonate and give you a sustained tone. The purpose of the neck is both to steal (absorb) some frequencies and respond to other desired frequencies by resonating and sustaining. When the neck vibrates as the result of the initial pick attack and string vibrations, it will feed back some energy back to the strings which will force them to vibrate at other, different frequencies in addition to the initial vibration. The neck is acting like a frequency filter and working together with the strings to produce a complex blend of frequencies. Personally we find the necks on the current production (2010 and later) American standard Fender Stratocasters slightly too thin for our preferences. We feel there is simply not enough wood to give you a beefy tone and make the strings vibrate at the desired frequencies. We feel sustain and tone richness is improved with larger necks, also the spank and bass response is tightened up in big necks, mostly noticed in larger one-piece necks of maple, ebony or other hard wood. But one must be careful to suit the size of your hands and fingers. Remember that playability is more important than tone – great guitarists appear to sound great through most equipment.
- Strings. Weight, tension, distance to pickups, fret action. Thicker strings are darker and fuller sounding and have more sustain. New strings sound superior to older strings that are lubricated with fat and finger dirt. Change strings often if you care about tone and always wash your hands before playing your guitars. The closer the string vibrates to the pickup pole, the louder and more trebly the tone will be. Being to close may cause the magnetic field to prevent the string vibration, hence reduce sustain. The pitch may also change and the intonation gets false. Keep the distance! A very low fret action may cause the strings to collide with the highest frets while playing. This is very undesirable since the string will not vibrate freely after the initial pick attack. In stead you will hear the strings slam into the frets producing a high frequent metallic “snap” in stead of having a original, strong attack on the strings. Many players are not aware of this effect, or doesn’t seem to notice, and the result is a weak and thin sounding plink-ploink guitar.
- Pickups. The physical pickup nature or magnetic power, coil resistance and inductance. Pickups are heavily discussed elsewhere, and we dare not start a discussion here. One must make sure to select pickups that match the rest of your equipment. A dark sounding neck, body and pickups all together results in very little sparkle into the amp etc. On the other hand – a bright spanky body and neck might need the right trebly pickups to pass along the clarity and sparkle from the guitar that you want into the amp. And…, keep the string distance.
- Tremolo bridge. Saddles, spring tension, fixed one-way vs floating bridge. A quality tremolo bridge is important for the sustain. We find the sustain to be improved when tremolo springs are tightened so the bridge leans hard against the body. This allows only for frequency drop with the tremolo, but it is worth it due to increased sustain
- Electrical circuitry and components – explained below at high level.
- Body. Wood, density, weight. The force of the string vibrations is connected to the body via the tremolo bridge. The body must be resonant and vibrate nicely not absorbing this energy. Compared to the neck we find the body to play a less important role.
- Lacquering and paint. The paint must not prevent the string vibrations from being propagated between neck, tremolo bridge and body. All these are physical, mechanic connections where the metal and wood is in motion. Thick layers of paint and lacquer may reduce the resonance. Watch out below the tremolo bridge and in the neck pocket.
Circuitry explained In this section we’ll breefly explain how components inside the Stratocaster affects the tone. Below is the wiring diagram for the American standard stratocaster model. This is the most standard wiring – three single coil pickups, 5-way switch, 250k volume and tone pot, the lower tone pot coupled for both mid and bridge pickup and no treble bleed components/wiring. Search the Internet for more sources of in-depth information on how pickup works and the physical and magnetic interaction between strings and pickups.
The next figure whows the the equivalent electronic circuit schema. The schema is simplified here and does not show the internal pickup details – wiring dc-resistance, capcitance and, most important, the pickup inductance. The schema also shows the curcuit assuming the pickup switch is in position 1, 3 or 5, using only one pickup and one tone pot.
Before explained step-by-step, check the Internet or books for electronic basics regarding resistors, capcitors and inductors. We only touch the surface here and explain at a high level using non-academic terms.
Like water and other things in nature – current seeks to ground through the path of least “resistance”. A electric path that has little “resistance” will lead more current than a path with higher resistance.
Audio potmeters in guitar and resistors in amps have the same electric resistance for both dc(constant voltage, like a 9v battery) and ac currents(time-alternating, like 110/230V net current or an audio/guitar signal). They are simple and easy in this way.
Capacitors act different for signals of different frequencies. Cap’s are measured and specified by the term capacitance, with unit farad. The capacitance describes the cap’s ability to store electric potential – the bigger cap, the more electrical energy can be stored in it. Dc-current and low-frequency signals see a cap as a high electrical “resistance”. High-frequency signals see the same cap as a much smaller “resistance”. Caps are often used in circuits where it is desired to stop or pass the high- or low-frequency parts of the signal – often called high- and low-pass filters.
The pickup and controller circuit explained step-by-step
- As a result of the guitar strings movement near the pickup’s magnetic field, the pickup produces a corresponding current being able to flow out from the pickups
- The pickup current is divided in two paths – one is through the tone pot R2 and tone cap C1 and the other through the volume pot R1
- Tone-Pot: Set at max, fully clockwise seen from the guitarist, the resulting resistance R2 for the current is 250 K ohms. This is a certain resistance resulting in most of the current flowing to the volume-pot. At fully counter-clockwise position the resistance R2 is 0 (zero) ohms, which kind of invites the current to leak through here. Next in line is the capacitor C1. It passes the treble/higher frequencies to ground – the treble-part of the signal is lost for the volume pot. The bass/lower frequencies will see the capacitor as a much higher “resistance”, less bass-frequencies will flow here but rather continue to the volume potmeter. The result: the tone gets darker when turning the tone knob. The treble is leaked to ground while the bass continues to the volume pot. The bigger the tone cap, the more of the high and medium frequencies it will pass and ground, with the result that only the darker signal parts flows to the volume pot. Many people describe this as a muddy tone, like a carpet in front of your speaker. To small tone cap results in the tone knob not taking away the treble as much as you want – even at minimum tone you find the tone too bright
- Volume-Pot: from the circuit you see how the output jack (hot tip) is wired into the circuit at the middle leg of the pot. Setting the volume pot at minimum, results in 0(zero) ohm between ground and the output jack hot tip – the volume pot at minimum grounds the signal. Setting the volume at max results in 250kohm between ground and the ouput, meaning a higher voltage applied over this 250k resistance and a stronger signal going out.
Depending on the pots and cap values in your guitar, they affect the porpotions of the pickup signal leaked to ground and therefore how bright the signal will be.
What can we possibly draw from this? Which components affect the tone in what way?
The most important thing to remember is that the resulting tone that you and your glad audience hear, is a result of all the significant factors in the signal chain – neck, body, frets, bridge, strings, pickups, controller circuit, guitar cable(!), your pedals and your amp and speakers. All this must be considered together to give you what you like. Therefore there is no “correct” or “better” choice of component values.
- A little current will always leak through the tone cap even if the tone pot fully open. This means the tone cap does affect the tone a little bit even when the tone knob is fully open. Like us, you can try to experiment with loose cables hanging out from under your pickguard and swap different caps while you play – there is now significant change in sound as long as tone pot is set at max. After 2-3 beers, I don’t think we heard any difference. But in theory – a smaller tone pot resistance R2 and/or a bigger tone cap C1 -> the more treble frequencies will leak to ground. The signal to the amp will be darker and have less sparkle.
- If you want more sparkle and brightness in your tone, go for lower cap value C1 (i.e. 0.01uF) and/or a bigger tone pot R2 (i.e. 500Kohm). This will also make the tone control “slower” and you have to turn it more to get an effect.
- If you want to reduce the brightness in you tone, go for bigger cap value C1 (i.e. 0.1uF). This will also change the potmeter behaviour making the tone quickly go darker as you turn the wheel. The vintage 50′s strats had 0.1uF. Fender themselves changed this to 0.022uF later since many players thought the tone knob was too drastic.
- The tone cap is shared between all pickups (in vintage wiring, the bridge is not wired to the tone pot). You may install a separate tone cap for the mid/bridge pickups allowing you to tune them individually.
- If you want a less or more sensitive volume knob, you may change this value. 250K and 500K are the most common values. The vintage 50′s strats had 500 K, while newer have 250 K.
At fenderguru.com we believe that 250k tone and volume pot is a good choice of clear fendery tone with just the right amount of sparkle and low-end. Also a 250K tone pot makes your guitar less sensitive to “bad” or long guitar cables with high capacitance that kill some treble and clarity. We also believe that 0,022 uF or 0,047uF makes a proper tone cap, well suited for most pickups, guitars and amps. 0,1uF is too big, it makes the tone knob less useful since the tone too early in the controller-rotation gets too dark and muddy, regardless of your other equipment.
Treble bleeder kit
You may have noticed that the tone gets a little darker when you turn down the volume on a Fender Stratocaster. This is an effect of the original strat circuitry – some like it, some don’t.
The treble bleeder is a well known and used solution for those who don’t like that the tone gets darker when reducing volume. It consist of a cap and resistor wired in parallel over the volume pot – from the top leg of the volume pot to the middle leg and hot tip output.
The mod will allow for the treble frequencies to bypass the volume pot and directly to the amp. When playing at reduced volume levels you’ll notice a more sparkling tone which is nice if you play with effect pedals such as gain and wah wah. You will be able to utilize the effects better when all frequencies are present. We recommend to experiment yourself whether this mod suits you. You may easily enable and disable this mod by clipping or unsoldering one side of it attached to the lug and just leave it there, it will be out of the circuit.
We will soon also describe another wiring to address this point with reduced treble, sometimes referred to Vintage 50′s Gibson wiring or the “Fez Parka” mod, named after a discussion board member that posted the wiring schema on one of the Internet’s many and great discussion forums.