These guidelines are the surest way to get good tone, which is inherently richer and more interesting than mediocre tone.
Try various blends of preamp distortion and power-stage saturation, for a full tonal palette. Whether an amp has a tube power amp or a solid-state power amp, turn the amp up loud enough to produce some degree of power-stage saturation. This brings out the power-stage saturation and engages the guitar speakers. To play quieter, use a lower-power tube amp such as 5 watts. Strive to bring out the physical, real, tangible tone of saturating power tubes and hard-driven speakers. This includes using feedback, room noise, room reverberation, and hum and buzz. Clinically sterile tones such as a guitar effects processor and "speaker simulator" (treble-cut) recorded straight into the mixer sound cheap and too convenient and easily reproducible.
Some power tubes have a hard, sudden breakup, and some have a soft, squashy breakup that comes on gradually.
Power tube saturation sounds and feels spongy; it has some dynamic depth and greater tonal richness. The saturation comes on by degrees, fluctuating along with the volume. Try using slight preamp tube clipping with heavy power tube saturation using soft-breakup power tubes. This is a distinctly tubey tone that solid-state amps and direct-to-console approaches can't produce.
Amps without effects sound good. Effects without amps sound bad. Amps with effects can sound good if the gear is connected according to certain principles. Playing through a loud tube amp is a prerequisite for getting the most impressive tone out of effects. If you have no gear and have to choose between a tube amp and effects, buy the tube amp first, and make arrangements to play it loud at least a couple times a week. That will set the right foundation for effects, which are not as important as good tube amp Tone. When buying effects, remember that the sound of the effect when used with a loud tube amp is better and rounder than the sound of the effect in isolation.
Combining effects and amps in certain sequences sounds bad -- harsh, unmusical, vague, muddy. Placing time-based effects before distortion or before power tube saturation sounds muddy. The safest placement for time-based effects is after the mic'd guitar speaker.
Connecting a guitar preamp unit directly to the mixer is safe, easy, and fake-sounding. Rock listeners want to hear the real, physical tone of a stressed speaker wrestling with power tubes.
Effects sound better when combined optimally with a tube amp than when used directly into the mixer. You can connect effects and amps in many ways. But the default, optimal way of connecting them in the recording studio is to place time-based effects after, rather than before, any heavily overdriven stage. This prevents beats and preserves a clear Basic Tone. When using a saturated power tube tone, reverb and echo are clearer when placed after the mic'd speaker, rather than before the power tubes. When playing clean, the order of effects and amps is more flexible. To study the placement of time-based effects and overdriven stages, place an echo before a distortion box, and then after. Slowly bend a note, listening for beats. The resulting behavior applies to saturating power tubes as well as a distortion pedal. As far as placement, think of a loud tube amp as a big distortion pedal, and don't hesitate to place echo, chorus, flanging, pitch shifting, or reverb *after* the mic'd speaker.
Speaker simulators, reactive loads, and power attenuators should not be used for final recording. They all degrade the tone. The best rock tone is from saturated power tubes directly driving a guitar speaker hard, with no load or attenuator getting in the way. The only really satisfactory way to get actual cranked tube amp and speaker tone with almost no room noise is to use a speaker isolation cabinet and its attendant gear.
Eq *before* distortion or saturation sounds different than eq *after* distortion. Think of all the tone knobs and frequency response curves of gear placed before a distortion pedal as the first equalizer. Think of all tone knobs and response curves between the distortion pedal and saturating power tubes as the second equalizer. Think of all the tone knobs and response curves between the speaker and recording tape as the third equalizer. Shaping your amp tone is controlled by adjusting, one way or another, one of these three effective-equalizers. To study how eq alternates with distortion, use the chain: eq->dist->eq. The resulting behavior applies to saturating power tubes as well as each individual stage of preamp distortion. Bass boost before saturation causes a dry, rough, crusty breakup tone. Treble boost before saturation causes a liquidy, glassy breakup tone.
Smaller guitar speakers tend to sound brighter than larger guitar speakers. Some guitar speakers sound very warm -- they have little treble response. Others sound bright -- like full-range speakers.
A powerful way of connecting effects and tube amps is the chain: effects->tube amp->speaker (isolation) cabinet->effects. This approach requires a final amp and a full-range monitor speaker.
When thinking about Tone, consider the song to be a servant of the amp tone; music exists to enable us to listen to amp tone.
Use guitars which ring true on almost all frets and strings. Play guitars through heavy distortion using a single note at various spots on the neck. Listen for unmusical overtones caused by rattling in the guitar.
Spin your guitar around to find the angle with minimal hum.
Playing single notes distorts differently than playing multiple notes. Power chords distort more clearly than complex chords. Power chords have muliple notes, but really only two notes, repeated in multiple octaves. Some power chords distort more clearly than others, depending on the interval between the two main notes.
A good chain is: wah->compression->distortion->time-fx->loud tube amp A clearer chain is: wah->compression->distortion->loud tube amp->time-fx
The Eddie Van Halen tone uses a bridge humbucker pickup. The Stevie Ray Vaughan tone uses a neck single-coil pickup.
These principles are known by almost all rock guitarists and producers, who record rock guitar through loud, mic'd tube amps with no loads or power attenuators getting in the way, and only a few effects.
There's a general consensus on the Net that speaker distortion is an important factor in amp Tone. Also, what I call "speaker smoothing" is important.
The worst, thinnest, grainiest sound is when the speaker is barely moving - say, 20 mW.
Then around perhaps 1W you start getting some speaker smoothing.
Then around perhaps 20 watts with a 25-watt speaker, you get speaker distortion.
Consensus about tone is like a statistical bell curve. There are shared and dominant ideas. Sure, a small fraction of people have very different ideas, but there is some concensus or some groupings of opinions into which most people fall.
There are recognizable standards for what sounds good -- that is not to say there is no divergence of views, opinions, or preferences. There is no need to throw up our arms and say that no agreement can be reached - that would be an unwarranted extreme relativism.
I have recently identified key units of Tone. When you cut out or simulate any major component in a classic amp rig, something is lost. You can lose a degree of dynamic depth or lose a distortion component such as preamp distortion, power-tube saturation, or speaker distortion. As you move time effects from post-mic toward the front of the amp, you introduce increasing degrees of "intermodulation distortion", as the delayed signal conflicts with the immediate signal in a distortion bottleneck. The best Tone (or a rig for the widest tonal palette) has:
o All 4 degrees of distortion: preamp distortion, power-tube saturation, output transformer distortion, and speaker distortion.
o Minimal intermodulation distortion (the most would be time fx before the amp, introducing a degree of I.M.D. at each distortion stage).
o Full dynamic depth. Requires transparent preamp distortion that allows all notes of a chord to come through. Requires power-tube saturation response. Requires a hard-driven speaker. Requires direct power-tube/speaker interaction with no dummy load in between.
I am not a relativist and do not say that all ideas about Tone are equally valid. There is an evident concensus, or predominant groups of concensus, about what sounds good.
There are guidelines, principles, and common ideas about Tone. One missing component for concensus is amp tone MP3s. Having these will not create universal concensus, but will help tremendously toward presenting evidence publically, just like we can all critique the amp tone on a standard Hendrix album.
When I first started a comprehensive online research pass about the pros and cons of power attenuators, I felt that there was a radical divergence of opinions on whether they suck Tone or work well. But now that I've mulled over the various postings and mentions from Web pages, I think there is a clear consensus, with minor variations in opinions about the degree of Tone-suck contributed by various aspects. I summarized this concensus about Tone and power attenuators in the Power Attenuator FAQ.
The consensus is that power attenuators suck some degree of Tone, and that this is partly due to the speakers being under-driven, and partly due to the lack of direct dynamic interaction between speaker and power tubes. The "debate" becomes merely about degrees: how *much* Tone is sucked, and how much of that suckage is due to under-driving the speakers, and how much is due to changing the load from a speaker to a dummy load.
Another statement of concensus about Tone is the "Single Coil Manifesto" at the bottom of the Harmony Central Guitar Forum FAQ.
There is definitely a consensus, and standards -- this doesn't mean that there is an absolute and narrow concensus. One important standard is the traditional studio chain: preamp distortion, power-tube saturation, speaker distortion, mics, mixer, time fx. When trying to get good sound at low volume, people often try to deviate from that standard and it's certain that Tone is sacrificed; it's only a matter of how many degrees of Tone are sacrificed.
Harmony Central pages about "amp tone"
Newsgroup postings about "amp tone"
Amptone.com ultra gear-search page