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Guitar distortion and tone factors not really available through traditional multieffects units -- factors for cranked amp tone:

Preamp factors:
o guitar body type, string gauge and age, and pickup response
o distortion voicing (eq before, between, and after distortion stages)

Power amp factors:
o power tube distortion
o output transformer tone
o speaker size and response
o speaker wattage and breakup
o cabinet response
o number of speakers
o feedback from speaker to power tubes, and from speaker to guitar strings

Control-room factors:
o number and placement of mics
o type of mic
o room response
o mixer settings and tape saturation


The reference, authentic, pro-studio approach to a genuine, authoritative rock tone uses the following sequence of processing stages:

o Eq-related effects
o Preamp distortion
o Eq and non echo-related effects
o Hard-driven power tubes, output transformer
o Hard-driven speaker, traditional cabinet -- guitar placed near the speakers
o Mics
o Post-processing at the board: eq, echo-derived effects, reverb

It's important to understand the basic stages that are used in a pro rock studio, in order to try to reproduce these stages as closely as feasible, whatever your equipment situation.

Many guitar tracks were recorded with echo before the power tubes, but almost always, the amp is not cranked, because the beats are unmusical and scramble and weaken the basic Tone. The only way to combine *cranked* amp Tone with echo-derived effects is to place those effects after the amp.

Now, if you want to attempt genuine pro rock studio tone with low room-noise levels, you know what's important, what the reference setup is that you're trying to emulate, and what shortcuts you might be able to get away with while retaining as many genuine cranked-amp elements as you can.

The speaker isolation cabinet, with perhaps a small speaker, driven directly by a 5-watt amp, *might* be able to perfectly reproduce all elements of the Reference Setup and Reference Tone except for room reverberation and feedback through the guitar. You could then fake (or improvise) those two elements by reverb and by putting the guitar close to a monitor or using the Sustainiac.

Amp Summit - Guitar Player, Mar & Apr issues, 1996. This is a big gathering of amp gurus and amp corporate reps.

Output Transformer Distortion

http://www.firebottle.com/ampage/bbs/amps/, 8/17/2000, Joe at ObsoleteElectronics.com wrote:

>There's a consensus on the 'net that IMHO is equally flawed regarding OT saturation and tone. But hey, everyone thinks it's a reasonable guess at what's going on, nevermind no one has really taken a hard look. I don't think OT saturation sounds good, or is a good and necessary part of tone. Real OT saturation sounds lousy. What many people attribute to OT saturation is something else entirely - but they never bothered to really examine what it was they were hearing. It becomes "fact" because no one knows any better and no one questions it. [He wonders if it could be BH curve non-linearity effects in the core]. Our OEI OT's do not saturate at full output (65W typically at 430V B+) and seem to sound OK to most folks.

Speaker Distortion

http://www.firebottle.com/ampage/bbs/amps/, 8/17/2000, Joe at ObsoleteElectronics.com wrote:

>Wattage ratings of speakers have little or nothing to do with distortion levels at output. They have to do (as most limits in engineering seem to) with heat and the dissipation of same. How hard can I drive my speaker before the coil melts, deforms, goes open or is otherwise damaged. 25W RMS through the coil is all the manufacturer feels is safely tolerable before damage will occur, not a limit on where the distortions of the cone and motor will become objectionable. To some degree, power ratings are just marketing. People want to buy 25W Celestions, so they label them as 25W speakers [though] they can take much more power.

>You can design a speaker to clip all over the place while never getting to it's full power rating - simple mess with the coil geometry.. A sine input translates to forward and reverse motion.. and if the cone cannot move far enough to recreate that wave form you have clipping. AFA low power levels sounding weak and buzzy, that could have as much to do with the work of Mssrs Fletcher & Munson as anything else.. (everything sounds heavy in the high mids at low levels. It's nature.)

>I've heard these speaker distortion views all over the place and I personally think it's dead wrong. I would welcome someone to actually do some measurements and show some facts one way or the other.

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