GM Arts Home > Electric Guitar > More Info > Guitar FAQ
Problem is common to all, but attitude makes the difference. If you want to change your life, then change your mind.
  Home   Home 
  Electric Guitar   Electric Guitar 
  Guitar Amplifiers   Guitar Amplifiers 
  Guitar Effects   Guitar Effects 
  Guitar Pickups   Guitar Pickups 
  More Info   More Info 
 Guitar FAQ 
   Top Players & Guitars 
  Making Music   Making Music 
  Popular Science   Popular Science 
  Contact GM Arts   Contact GM Arts 
Site Map
Guitar Frequently Asked Questions

Mostly questions about pickups, but other topics also!

Fat Strat Sounds   top
How can I make my strat sound like a Les Paul?

Sell it and buy a Les Paul! Seriously, the 2 guitars have a different construction and use different types of woods. Changing the pickups will not transform a strat into a Les Paul (or vice versa). Most pickup replacement manufacturers make a range of pickups from close copies of the vintage originals to hotter variations, which will give your strat a fatter sound. Visit the manufacturers' web sites to read their pickup descriptions, and find out what pickups your favourite players use to get some ideas.

GM Arts

And a similar question:

GM Arts,
I have a 73 Strat and i want it to sound thicker and richer. I know that the year is terrible but i really want to use it and i think I am going to get it new pickups. I want something that still has that beautiful clean tone but i also want a fat thick distortion to it. Please help me i can’t decide!!!!!!!!!!!

Our rhythm player also has a 70's strat, and it is one of the heaviest strats I've ever held, but it also sounds great clean!

You can certainly fatten up the sound with some hotter pickups; have a look at the Seymour Duncan pages, which give some non-technical descriptions of what their pickups are trying to achieve. There are also some helpful user perceptions of pickups at (although I suspect some of these are written by the manufactures themselves!)

GM Arts

Addendum: I've recently installed a set of Kinman pickups on my strat, and they are sensational - rich clean tones and hum-cancelling! They lean towards vintage tones (with some hotter models), so they don't have that middley/fat 'traditional' humbucker sound.

Getting Rid of Noise   top
I recently purchased a Mexican Strat single coil guitar, a Fender Stage 100 head and a Kicks (offbrand) 212 cabinet.   It really sounds quite nice with a lot of power and headroom and is fairly compact. It is quite noisey however. What is the cheapest thing to do to at least cut down the noise by half. Do I need a noise gate effect or what.

Hi Dennis,
There are a few things to try that will minimise the hum, but getting rid of it entirely may not be cheap.

You don't say whether your noise problem his hiss from the amp, or buzz from the pickups. If you're not sure yourself, try turning down the guitar volume - if the noise goes away, then pickup interference is the problem. If the noise (hiss or even hum) remains with the guitar volume down, then it is almost certainly an amp problem.

Amp hiss and hum problems can be minimised by setting the volume and treble no higher than they need to be, and by turning off overdrive when you're not using it. If the noise is coming from the preamp, and your amp has a series effects send/return loop then you could use a professional noise gate there to help. Bear in mind that even with a noise gate, the noise is only muted when you're not playing - it comes back on when you start playing, but hopefully it's not too noticeable.

If the noise is hum or buzz from your pickups, you could use a noise gate stompbox to help, but best to try and minimise the problem first. Single coil pickups also pick up interference - it's just the way they work. I have Kinman pickups and find they really sound like single coils, have no hum, and don't need you to change to high impedance pots to keep the highs. Try to keep the guitar well away from electrical gear, such as the amp, computers, etc. Also, avoid light dimmers and flouro lights. You can minimise hum by facing the guitar in different directions as well; you should be able to find a position where the hum is least.

Lastly, there may be an earthing fault causing hum - if you have any reason to suspect an amp problem like this, I'd recommend you have your amp checked urgently.

hope this helps,
GM Arts

Humbucker pickup wire colours   top
I have red, green, white, black and silver wires coming from my pickup.  Which one gets wired where?

Firstly, it depends on who made your pickup. Different manufacturers use different schemes for their humbucker pickups.  Here are some common ones:

Manufacturer Coil #1 Hot Coil #1 Cold Coil #2 Hot Coil #2 Cold
Seymour Duncan Black White Red Green
Gibson Red White Green Black
DiMarzio Red Black White Green
Bill Lawrence Black Green White Red
Tom Anderson Red Green White Black
Jackson Green White Red Black
Schaller Green White Brown Yellow

In all cases, the silver (braided or foil cable shield) should be connected to the guitar earth, usually on the back of a volume control. For a standard humbucker sound:

  • use the coil 1 hot as the pickup's hot connection
  • connect coil 1 cold and coil 2 hot together (and tape them so they don't touch any other connection)
  • connect coil 2 cold to earth

If a pickup is out of phase with others on the guitar, reverse the hot and cold connections on both coil 1 and coil 2. If you want to switch between a humbucker and single coil sound, connect the coil 1 cold/coil 2 hot junction to a switch which connects them to earth. Here's a diagram with a simple on/off switch for the neck pickup, and a fancy on/off/on switch for the bridge pickup so you can tap either coil.

Just some ideas to get you started,
GM Arts

Difference Between Humbucker & Single Coil Pickups   top
GM Arts,
I have a question regarding pickups if you don't mine of course. I have a fender fat strat and I was looking on the fender web page and it said it had a "bridge position humbucking pickup" which I've heard isn't common on guitars. I was wondering what exactly this setup does which is different than a normal one. I've asked around and heard its for distortion but from your web page it appears you know more than the person I asked.


A bridge humbucker is only really uncommon in the sense that Fender Stratocasters have just about always used all single coil pickups, including at the bridge position.

In the 80's there were a large number of companies like Charvel/Jackson producing "super strats" which were hotted-up designs using the strat body shape and string length, but with sophisticated whammy bars, paint jobs, and hotted-up electronics. These designs just about always used a humbucker pickup in the bridge position.

Most humbuckers have the appearance of two single coil pickups placed side by side (sometimes placed under a cover), so it is a wider pickup. The easiest way to see the difference is to look at a Gibson Les Paul pickup, which is rectangular, and a traditional Fender Strat, which has thinner pickups with the 6 magnets showing.

There are other internal design differences, but the main difference for the player is the sound; here are some key features of each.

Single coil:
Bright, chunky, lots of character, conveys the natural sound of the guitar well, can sound thin clean, and a little "weedy" when overdriven hard. Picks up a lot of interference (hum, flouro lights, etc). Popular single coil sounds can be heard from Hendrix, Mark Knopfler, Buddy Guy, post-Cream Eric Clapton, Stevie Ray Vaughan. Good for blues, rock'n'roll, nice for country on a Telecaster.

Full, smooth, thick sounds. Can sound a little plain when used clean, but gives a really fat and creamy overdrive sound. Almost no interference. Popular humbucker sounds from Robben Ford, B B King, Slash, Santana. Good for rock and heavy sounds, nice for jazz on a semi-acoustic.

I think it makes a lot of sense to put a humbucker on a strat in the bridge position. It allows you to get the best of both worlds. It doesn't sound quite the same as a Gibson Les Paul bridge humbucker, because they are completely different guitars (different construction, woods, etc), but it will give you a lot of practical versatility. Many players find the standard strat single coil pickup to be too sharp and brittle to be really useful (often because they add a little extra treble on their amps to give some extra bite to the neck and middle pickups).

The standard 5 way switch can be wired so that you can still get the in-between sounds at positions 2 and 4, even if you use a humbucker at the bridge and/or neck. Here's a circuit diagram showing how it's done.

Circuit diagram - 2 x humbucker + single coil

Some of the new Fender Strat models now include a humbucker in the bridge position. I haven't used any of these new pickups, but I have read good reports on the Lone Star which uses two slightly hotter single coil pickups with a customised Seymour Duncan bridge humbucker.

Hope this helps,
GM Arts

5-way Switches   top
Am a novice when it comes to electric guitars, having recently picked 'em up. so was browsing the web for information on pickups and switch settings, since i have no idea how they work. I have a 3 pickup electric with a 5-way switch and i don't really know how to find out which switch setting does what, or activates what. Going thru your page i felt that you know what you are talking about, and, even though the information i need is elementary i would rather get it from somebody who knows what he's doing. You think you could help me out in this dilemma .

Hi Andy,

Nearly all 5 way switches are based on the Fender Stratocaster design. These switches started out as 3 way switches for each of the 3 strat pickups. So with the switch in the position nearest the neck, the neck pickup was on, middle position for the middle pickup, and towards the bridge for the bridge pickup.

These 3 position switches were designed to be "make before break", meaning that as you move from one position to the next, there is a small area where two pickups are on at the same time. For example as you click from the neck pickup to the middle pickup position, you can actually balance the switch between the 2 positions to hear both the neck and middle pickups at the same time. This was good design, so you don't hear any sound cut-out when switching from one position to another.

Several players became deft at balancing the selector switch in these in-between positions; some even made it their trademark sound. It has commonly been called the "in-between" or "out-of-phase" sound, because it has a slightly nasal sound which is similar to a sound you get when connecting pickups out of phase. This is a myth; the pickups are really in phase.

Eventually Fender, and other manufacturers realised it would be a good idea to actually add proper clickable positions for these 2 extra sounds, so it really is a 3 way pickup selector with 5 different sounds.

Even later, manufacturers have produced selector switches which look like a standard strat switch, but which are true 5 way switches (with up to 4 banks!). These allow some far more sophisticated switching options at the whim of the manufacturer.

There is an easy way to tell what pickups are being used for each of your pickup selections:
(1) Turn your amp down to a fairly low volume.
(2) Tap something metal (such as a screwdriver) VERY GENTLY on your pickups (on each side of humbucking pickups)
You will hear a loud tap for the pickups which are on, and very little on those which are off.

GM Arts

Setting Pickup Heights   top
i find your page very interesting. I'm trying to learn the best i can to fix my dilemma! a lot of the info i read was understanding, but i need more experience with it. i tripped onto your page trying to find info about adjusting my pickup heights on my les paul studio light! i play mostly clean on my crate vintage club 50..5310 w/ 3 10in speakers).do you think this is not a good match up?
that maybe there is to much bass here and not enough color is getting through? it is driving me crazy! if you have any tips for me, it would be appreciated!!!!! should i change pickups? i play in a classic rock style and like colorful tones.

Hi Sean,

Thanks for the feedback.

I'm not familiar with your Crate amp, but they are a reputable brand, and of course your Gibson is also a reputable brand ;-) I wouldn't think you need to change equipment or pickups.

The way I set my pickups up is:

(1) Set the amp to give a clean tone close to what I want, by choosing each of the pickups individually (regardless of any volume mismatch at this stage)

(2) Adjust the bridge pickup to be fairly close to the strings, checking it's not too close to the strings when they're fretted at the top fret.

(3) Then adjust the middle (if you have one) and neck pickups for a good volume match between the bridge pickup.

The pickups would usually be level with the strings, but if you have any problems with strings "warbling" you would need to move them further from the strings. This problem is common with strats, and is usually solved by reducing the height on the bottom (low E) string side.

Classic rock usually is played with a moderate amount of overdrive, with "middley" tone settings.  You may want to keep the bass down on your amp, turn the middle up and set the treble (and presence if it has it) to set the amount of "bite" you want in your sound.  Check that the tone control on your guitar is set to 10 (maximum). If your amp does not have overdrive, try an overdrive pedal such as the BOSS overdrive pedal or Ibanez Tube Screamer.

One other thought - a faulty guitar cable can kill your treble also, so try another one to make sure.

Hope this helps,
GM Arts

Addendum: Here's some good information on setting pickup heights.

Building Pickups   top
Dear gmarts,
I've been playing the guitar for about two years know and though it would be kind of fun to try and make some pickups for an old guitar sitting around. However here’s were i ran into difficulty I've tried to find sources on the Internet and i have scrounged up the necessary materials to built a very basic pickup the problem was that when i hooked it up it wouldn't make any sound i was wonder if you could send me any basic info into building one


Interesting project!

I've never tried to build a pickup from scratch myself, and I suspect that not many people ever have. The pioneers like Les Paul and Mike McCarthy probably did, but nearly all of the replacement pickup manufactures all admit that their careers started by repairing existing pickups, and then modifying designs until they settled on some favourite variations, now sold as their customised pickup range.

I suggest you visit sites (which you've probably already done) like and read music trade magazines to get as much info as you can. Lollar Publications have a book with details on winding your own pickups.

The basics are that the guitar strings need to pass through the magnetic field of the pickup, and there needs to be a large number of coil windings also within the magnetic field. You need to be careful not to break the fine wire used for the coil; you can check this with a DC ohm-meter. You would usually expect to measure a DC coil resistance of 5K ohms to 10K ohms for a single coil pickup. If its really high (or unmeasurable) you have probably broken the wire in the coil somewhere. If its a lot lower you probably don't have enough winding. If all is OK, you should be able to hear something.

Hope this helps,
GM Arts

Jimmy Page Les Paul   top
Dear sirs, (there's actually ony one of me! - GMA)
I have read the useful hints in your pages, and found many helpful schematic diagrams for alternative pickup combinations on the Les Paul I have. I'm wondering how Jimmy Page had modified his Les Paul Standard, as Gibson decided to implement the same electric wiring in the reissue signature model. They put on their web site only the standard schematics...... Is it possible to get this schematic diagram ? The switches used there to get out-of-phase wiring are push-pull axial in the potentiometers (a good idea). Thanks in any case for yr attention

Hi Roberto

Thanks for the feedback.

Jimmy Page's LP I believe uses a push-pull switch on all 4 controls. I don't know which switch is on which control, but from a review I read, the switches are:

  • 2 x pickup humbucker/single coil
  • parallel/series
  • in phase/out of phase

This gives access to just about every sensible sound (and a few useless sounds) you could get out of these humbuckers. It is tremendously versatile for home/recording work, but I really don't like this approach for live work. As I've promoted in my pages, I favour a simple switching system that gives quick and easy access to the good sounds. For example, to go from a solo bridge humbucker sound to a both-pickups single coil sound, Jimmy would have to pull out 2 knobs (possibly more if the others are not left in the right position) and move the pickup selector. This is just not practical live. On my switching arrangement, it's one mini-toggle switch and the pickup selector.

I also don't favour push-pull knobs for live work; I find them pretty fiddly compared to toggle switches aligned to switch in the natural direction your hand moves. Of course, if you're not into live work, ignore all of this. The switches should be easy to work out: the parallel/single switches work on each pickup alone, the phase switch reverses the hot and 'cold' of one pickup (either one), while the series/parallel probably bypasses the selector switch to connect the pickups in series (I'm not so sure about this one). All of this can be done with standard DPDT switches.

GM Arts

Thanks for your exhaustive explanation !
You've really depicted a clear picture of your modification reasons.
Regards from rainy Milano

Standard Wiring   top
Hey GMA!
I was trying some different wiring in my strat and somehow screwed it up. I'm gigging tonight and you have to help me get it back together. Where does the white wire go?
(too many of you!)

It is a really bad idea to experiment on critical gear so close to a gig, but I guess you know that now! Anyway, here are some diagrams from the excellent Seymour Duncan site. Click on the following links for standard dual-humbucker wiring, and standard strat 3 x single-coil wiring.

Guitar Woods   top
First of all, Kudos to you for your endeavours and thanks a million for sharing with the rest of us.
One thing I did not see, that I would like to see from you is a discussion of the differences in tone inherent to different woods. I've seen guitars made out of basswood/mahogany, mahogany/maple, etc... What difference does the wood of the neck make to the sound? And the fretboard? (Rosewood, Maple, Ebony...)

Hi Steve,

I've left out detail on woods, because I'm really not all that knowledgeable here. I do know that heavier and denser woods giver a brighter, crisper and punchier sound. The neck and body are the prime contributors to overall sound, with fretboard material making a smaller contribution. But here's my stab at it (with the help of some info from the Fender Frontline catalogue).

  • Maple is bright (being dense & heavy), and is commonly used for Les Paul body caps, and strat necks. Maple can be highly decorative with "flame" and "quilted" grain patterns, also making it a popluar body cap for clear finish or sunburst guitars
  • Mahogany varies in weight and density. Heavy weight mahogany has a full and dark sound, common for Les Paul-style bodies & neck
  • Poplar and Basswood are light weight, giving a warm and punchy sound, often used for "super strats"
  • Alder is medium weight, with sweet and mellow tone that is also clear and precise
  • Ash varies in weight and density. A hard wood giving "an airy smooth tone favoured by Telecaster enthusiasts"
  • Spruce has a sweet sound, used for acoustic tops
  • Cedar has a softer sound than spruce, also used for acoustic tops
  • Rosewood is a darker sounding wood used mainly for strat fretboards
  • Ebony is also darker sounding, and used for Les Paul-style fretboards

Of course, woods dry out over many years, and most people think this improves tone with age.

How Much Difference a Pickup Makes   top
I can't find the original email, but it went something like this:

A friend told me that the neck wood only makes up 5% of the sound of a guitar, but the pickups make up 50%. Is he right?

And my answer was something like this:

Yes I would agree, in a way. But I don't like the idea of using percentages, even though I think we all get the basic idea. For example, if I said strings accounted for 30% of the sound, does that mean it would still sound 70% good without strings? ;-) Maybe if I listed the things that I think affect overall guitar sound, it might be clearer:

  • Neck and fretboard wood - makes a small difference to brightness. Compare identical guitars with different neck in a music shop, and see if you can tell the difference.
  • Guitar body wood and construction - I think makes a bigger difference than neck material. For example, a heavy maple and mahogany Les Paul with a glued in neck sounds quite different acoustically than a strat-style guitar with bolt on neck.
  • Strings and setup - Replacing old strings that are corroded or have a build up of grime with new strings makes a huge difference to richness of tone, brightness, sustain, and the note play in tune up the neck. Using old strings is a false economy - this is the cheapest and most effective thing you can do to improve your tone. Heavy guage strings and a high action improves richness and fullness of tone, but you need to find a compromise that is playable.
  • Pickups and wiring - can make a big difference between extreme pickup designs. Vintage pickup styles have less middle, good note clarity and are generally suitable for rhythm and clean styles. Hot versions of these have more middle, and are better suited to solo work, and still retain the basic vibe of the guitar. Very hot pickups usually have a pokey and middley sound that stays smooth with heavy overdrive, but does not convey the character of the guitar so well. See other questions on this page about single coil vs humbucking designs. Wiring is a cheap way to get some entirely different sounds, but some experimentation is usually required to find the practical sounds, and some good design to make them easily switchable.
  • Technique - makes probably more difference to your sound than anything else. How hard you pluck the strings, whether you use picks or not, where you play the strings, how cleanly you fret, and so on, all affect tone, timbre, clarity and sustain.
  • Cables and effects - Obviously a faulty cable will destroy any sound, but I would recommend not using really cheap cables. The mid-price cables are fine for short to medium lengths, but high quality cables are essential for long cable runs. Good cables don't restrict highs, and prevent electrical interference. As for effects, these can alter your sound dramatically, or may be hardly noticeable, depending on where you set the dials!
  • Amplifiers and speakers - You can read lots more on this topic on other pages here, but generally, a good amplifier will have a richer tone and better sustain. Closed back speakers usually have a tighter bass sound, and less spread of sound.

The Ultimate Amp?   top
Hi GM Arts,
I just bought a Marshall, and I thought it would guarantee me great tone, but it doesn't sound any good until its way too loud to use! Why are guitars so fickle when it comes to getting a good tone? What amp would you recommend?
Steve H

Hi Steve,

Sorry to hear you're not getting what you want from your Marshall, they ARE great amps, but you're correct in noting that they excel at medium to high levels of overdrive, and this means they're loud! My recommendation is that you use an overdrive pedal at lower levels to get similar sounds at household levels.

I agree that guitarists are fickle when it comes to getting a single "ultimate" tone you have in your head. If you're fortunate enough to be playing in a constant band and a consistent style of music, it would be possible to buy a single amp to give you the sound you crave. You would buy the correct amp power rating that allows you to drive the amp as hard (or soft) as you need to get the volume you need in the band. And you would buy the style of amp that suits your music. For example, if you need great clean tones and slightly overdriven sounds, start with Fender designs and their copies. If you're looking for medium to heavy saturated lead sounds, look at Marshall and their copies, or if you're looking for harder edged metal sounds, start with Mesa Boogie. This is a gross generalisation of course, start here and shop around.

But many of us play in several bands (or unstable bands!), and in many different venues from outside to restaurants. The common solution to the need to get good to great tones at any volume is to have a medium to high power amp (50 to 100 watts), and when you can't wind it up to the volume you like, to use a clean amp tone with an overdrive pedal for similar, but less satisfying tones. Another possibility is to use a speaker load, such as the Marshall Power Brake. These allow you to still overdrive the power amp of your Marshall, where the good overdrive sounds are. For some reason, these devices aren't terribly popular; I'm not sure if its the loss of that Marshall "thump in the chest", or the loss of feedback induced sustain that is perceived as a loss of tone. Whether you go down the stompbox or speaker load path, I suggest you try before you buy.

Particularly if you play in a cover band, where you need to get a wide variety of tones (in addition to different overdrive levels at any volume), you might like to consider one of the new amp modelling offerings, such as the Line 6 Flextone. Popular opinion is that while these amps have no sounds that are as good as that single ultimate tone, they offer enormous flexibility, with many different sounds that are nearly as good as the real thing.

Hope this helps,
GM Arts

"Treble Bleed" Circuits   top
Is there a good source on the web (maybe you) that could give me some wiring diagrams and capacitor/resistor values to install across volume controls to minimize loss of highs? I assume this condition is due to impedance loading on the pickup by the volume control when it is turned down. This almost always happens on my humbucker-equipped guitars.

I tried a .o1 mf cap - it did minimize the loss of highs, but also took alot of the other frequencies ("beef") out of the sound. A friend of mine told me to use a cap/resistor combo, but I'm having a hard time finding the cap resist. values. Would values vary depending on pickup ohm rating (say an early 70's number-stickered Gibson, vs. a SD Jeff Beck humbucker)?

Thanks much in advance,

Hi Geoff,

Good question, and unfortunately one that doesn't have a single correct answer.

The values to use depend on just about everything - the impedance of your pickups, the value of your volume pot (and the actual reduced levels you want to use), the length and quality of your guitar lead, and the impedance of the amp or effect you plug into.

So the way to work it out is to experiment. Usually you will want a resistor in series with a capacitor connected across the volume pot "hot" and wiper connections. The resistor would typically be a value between zero (ie no resistor) and about 270K, while typical capacitor values would be from 100pF to about 2.7nF (ie .0027uF).

Larger capacitor values have more effect on high-mids in addition to the highs. Larger resistor values reduce the overall effect of the treble bleed circuit. Maybe a starting point is 120K and .001uF for a 250K volume pot or 180K and .001uF for a 500K volume pot

Hope this helps,
GM Arts


Thank you very much for the reply....yes, I do see that some experimentation will be required. I'll have to go to my college Electrical Engineering 101 textbook to the filter chapter, and do the math.

I'm sure you'll agree that this is all related to one's personal taste in tone - a (subjective) art by definition, rather than a science.

Thanks again!
- Geoff

String Action vs Tone   top
I have just purchased a second hand fender, and I noticed the strings were very high off the fret board. I tried making it lower by adjusting it with an allen key but now it is rattling on the pick ups. i tried to lower the pick ups, but it makes it sound horrible. Help!!!!!

Hi Nick,

I wouldn't expect lowered pickups to sound worse than strings hitting the pickups. If your action is too low, the strings will rattle on the frets which kills the lower harmonics (they're the ones with the biggest string vibration, so they go first if the strings vibrate against things they shouldn't). This destroys the richness and sustain, giving you a thin, weedy sound.

Unfortunately, a high action and heavy strings gives the best tone, but most players find a compromise between this and what's comfortable to play. For me, I set it so there's no audible string rattle ACOUSTICALLY when played with medium picking strength. You can get away with a lower action by setting it for no audible string rattle when played ELECTRICALLY, but this is where you start to lose tone.

If you can't get a comfortable playing action, your guitar may need a professional set up, or even some minor repair work. You would normally adjust your bridge pickup to about 1.5 -2 mm below the strings when they're fretted at the top fret, then set the other pickup(s) for roughly equal volume when played through an amp with a clean sound, using "even" tone settings.

GM Arts

Valve Power vs Solid State   top
Hello -
I have heard that a tube amplifier will be louder than a solid state amplifier of the same wattage. Is this true? Any additional info you have on this topic would be appreciated.

Hi Chris,

Yes, it is true that a valve amp is louder than a solid-state amp with the same RMS power rating. Of course, 100W RMS is 100W RMS whether its valve, solid-state or steam powered, but there is a difference in the way these amplifiers work with typical plucked guitar signals, and in the way these amplifiers are rated.

A solid-state amp is usually rated at it maximum power at a very low % total harmonic distortion (THD) which means it is really clean up to its maximum power. What the ratings don't say, is that it turns really dirty very abruptly just over its maximum power rating. The abruptness of this increase in distortion is quite unsuitable for percussive sounds (such as a plucked guitar string), because when you get near the maximum power, the plucked portion of the sound produces a dirty "spitting" type of distortion whith then decays into a super clean sound (quite unnatural).

On the other hand, valve power amps have a very gradual increase in THD before and after the amp reaches its rated power. Valve guitar amps are usually quoted as watts RMS at something like 5% THD. This means they produce less power a little cleaner, and more power with a little more overdrive. This is the real reason valve amps sound louder, because they can produce more power without an apparent transition beyond its rated "maximum" power.

Finally, (abruptness aside), the "quality" of the overdrive (the THD you hear) is quite different between the designs. Most guitarists prefer the smoother sound of valve overdrive to the harsher sound of solid-state overdrive, although solid-state distortion is preferred by some thrash and metal styles.

Hope this answers the question without being too technical.

GM Arts

Class A vs Class B   top
I enjoyed reading your discussion regarding guitar amps.

I'm not electronics expert, but I have a fundamental understanding of how guitar amps work (which is almost a necessity when you use a Mesa Boogie Mark IV). I wonder if you could briefly explain or direct me to an explanation of the basic difference between class A and class B power stages. As you know, my amp uses both.
Dave Anderson

Hi Dave,

Technically its the way the output tubes are biased. The output valves (being analogue and not digital) vary between fully on (almost like a short circuit), and fully off (like an open circuit).

For the sake of this explanation, consider a power amp with just 2 output valves. In Class B, each valve handles one half of the waveform (one handles the positive half, the other, the negative half). The advantage of this is that with no signal, both valves are off. Here's a diagram showing how each valve handles a sine-wave:

Class B

In Class A, the valve(s) are already half-on at rest. When you play, each valve cycles between off and on; here's a diagram of Class A:

Class A

True Class B causes a lot of crossover distortion (roughness during the changeover from one valve to the other), so most amps use class AB, which is nearly Class B, but with both valves turned slightly on at rest. Doing this, and including electronic negative feedback smooths out this crossover distortion.

Here are some differences:

  • With Class AB, valves run "cooler" at rest, and therefore last longer
  • Class A has no changeover between valves, so no crossover distortion, and sounds smoother
  • Class A doesn't need as much (if any) electronic feedback, giving a softer, more organic sound

High power Fenders and Marshalls use Class AB. Fenders traditionally use 6L6 power valves for a gutsy, clean sound. Marshalls generally use EL34s which give a smoother overdrive sound.

Vox AC30s, and many boutique amps use EL84 valves in Class A for classy clean and overdrive sounds, at lower power levels. Boogies and a few other amps give you choices to reconfigure the output stages, although bear in mind that choices can be offered anywhere along the path from Class A to Class AB. Boogies (as you know) also offer flexible preamp overdrive, before the signal even gets to the output stage.

I think you would be most likely to hear the difference in sound using a clean sound, played at a level where the power amp is just starting to break up. Chances are that the Class A setting will have a wider "sweet spot", but less volume.

I hope this explains the difference,
GM Arts

Fender Mustang Switch Mods   top
There are 2 three position switches on my Fender Mustang. I found out that they are On-Off-Phase. I also found out that phase lowers the frequency on the guitar single so it sounds really brittle and single coily. There is a volume control and tone knob. Mustangs have two single coils. I want to find new ways to wire the guitars. I don't like the phase setting at all and I would like to get rid of it.
Joseph P

Hi Joseph,

I found a great site on Fender Mustang guitars - history, schematic and suggested modifications!

Anyway, it is crazy that there are 9 possible switching combinations, and only 4 different sounds (plus both off). If you want to preserve the original appearance, I'd recommend changing one of the 3-way switches to work as a pickup selector, and use the other switch to give you:

  • control bypass (ie full volume and tone)
  • volume control only
  • volume + tone control (normal)

GM Arts

Click here for my modified schematic
Click here for the original schematic drawn by Seymour Duncan.

Thanks!   top

By far, the most common email I get is from people writing just to say thanks. I appreciate all my email, but these especially are what makes it worthwhile for me to maintain my site. It is a wonderful way to stay in touch with people all over the world with similar interests, even though I choose to do it anonymously.

I also value the questions and constructive criticism received, because it usually means I can improve something on my site with additions, updates or plain clarification.

So thanks to all of you who take time to read my site. I'd like to add more pictures and sound clips, but I have many other priorities, so I'll do what I can when I can. The upside is that while I'm earning elsewhere, I intend to keep this site advertisement free (that means I don't make any money) and still manage to answer some emails.

Rock on!
GM Arts

Home > Electric Guitar > More Info > Guitar FAQ More Info < back back       ^ top top       next next > Top Players & Guitars