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The Tone Engine concept
A whole system built around the Tone Engine
Problems solved by various aspects of the Tone Engine system
The Tone Engine approach
Systems that are Simpler than the Tone Engine approach

The Tone Engine concept

A Tone Engine consists of:
- eq/level a - required to shape power tube saturation character
- tube power amp - required for power tube saturation dynamics
- speaker isolation cabinet - required for dynamic, complex speaker
tone in a contained loud space
- eq/level b - required to control the effective frequency response of
the guitar speaker and cabinet

The speaker can be a traditional open-front cabinet in an isolation room, a
basement, or an isolation closet... or even open-air. But the "engine"
concept fits best with a speaker isolation cabinet.

You can use a manual bank of tone knobs or equalizer to quickly dial in
tones. Or you can use a MIDI processor to program your input and
output eq curves for the Tone Engine. Picture the Tone Engine as the
Ampulator in a footpedal, with pre and post power tube tone knobs, and
containing a small guitar speaker and mic, rather than an inductive load.
Someone should offer MIDI eq's that have physical sliders for adjusting
the eq curve, and then a "store" capability to retain the curve.

Tube amp tone is heavily shaped by the eq before the power tubes, and
the eq after the power tubes (including speaker tone, cabinet tone, mic
tone and placement, room reverberation, and mixer eq settings). "Tube
amp" tone doesn't require preamp tubes, so much as it requires power
tubes and hard-driven speakers, matched in power with the tubes such
that the saturated tubes directly drive the speakers at about 2/3 of the
speakers' rated capacity. For example, a 15 watt tube amp should be
connected to a 25 watt guitar speaker. Attenuators and inductive loads
degrade the final tone audibly. A speaker isolation cabinet degrades the
tone very little -- it sounds very similar to a traditional open-front guitar speaker cabinet.

A whole system built around the Tone Engine


o effects a
o tube amp
o speaker isolation cabinet
o effects b

o power amp
o monitor


o Pre-amp effects (wah, compression, dynamic envelope filter,
distortion, phaser)
o Tone Engine
- eq/level a - required to shape power tube saturation character
- tube power amp - required for power tube sat.
- speaker isolation cabinet - req'd for dynamic, complex spk tone
- eq/level b - required to control and enhance final speaker and
cabinet frequency response
o Post-speaker fx (heavy time-based effects for use with heavy power
tube saturation)
o Solid state power amp
o Full-range monitor speaker

Notice how "eq and level" are broken out from the "effects" stages, as
separate modules. When bracketing a tube amp, MIDI is just as powerful
for shaping Basic Tone as for controlling special effects, because you
can program input and output eq curves, to control which input
frequencies dominate the power tube saturation, and to control the
cabinet and speaker tone.

You can also add a basic mixer to support:
o A/B switching to compare and emulate album tones, and jam along
with albums using headphones
o A/B switching to compare a loud traditional mic'd tube amp to the Tone

The power amp and monitor speaker should be considered an inherent
part of the complete Tone Engine system, while a mixer is merely
supplemental tool. However, if someone designs an integrated Tone
Engine, it would be nice if such a specialized mixer were provided.
Half-speed album phrase sampling could be patched in this way, too. It's
helpful to hear a finished guitar tone when you are learning a song from
an album. You shouldn't have to listen through a buzzy distortion box
while you use a half-speed phrase sampler. You should *never* have to
put up with an inferior, "practice amplifier" tone. Bad guitar tone can
stunt your playing. Good tone and good playing go together, and that of
course applies to practice amps as well as performance amps.

Problems solved by various aspects of the Tone Engine system

This system or architecture is the simplest way to get the following:

1. Genuine cranked-speaker tone as well as genuine cranked
power-tube tone, at headphone level - with almost no room noise!!
2. Programmable eq for the guitar speaker cabinet, as well as
programmable eq for the power amp input
3. Clear power tube saturation as well as clear time-based effects,

This approach solves three major problems:

1. Problem: Getting actual cranked tube amp tone at *low* room noise
Solution: Low-wattage tube amp directly driving a guitar speaker in a
speaker isolation cabinet.

2. Problem: Getting full tonal control over a tube amp, enough to sound
great and emulate the Tone of other great tube amps.
Solution: Put an eq before the power tubes and after the mic on the

3. Problem: You can use strong effects such as echo, but only when
the guitar amp is turned down. When you turn the amp up, the effects
make the amp sound muddy.
Solution: Place some effects after the mic on the speaker, rather than
before the amp.

Problem: solve all these problems together:
Solution: use the processing chain:
o effects
o tube amp
o speaker isolation cabinet
o effects

These are 3 major problems, solved independently. Each of these 3
problems also benefits from the other two solutions; the solutions work
well together. Or, you can use just 1 or 2 of these solutions, or none. It's not necessarily a monolithic system.

The Tone Engine approach is elegant, for its features

It is the most elegant way to get:

o Actual cranked tube amp and actual cranked speaker tone, at
headphone levels, with almost no room noise.
o Programmable eq before the amp
o Programmable eq after the speaker cabinet
o Convenient ability to place effects before or after the amp

Systems that are Simpler than the Tone Engine approach

These are just a few of the simpler approaches to power tube
saturation, simpler than the complete Tone Engine approach. These
simpler solutions have pros and cons.

System A:
o Tube amp with distortion and tone controls
o Speaker isolation cabinet
o Manual eq
o Power amp
o Monitor

System B:
o Manual eq
o Ampulator (power tube + inductive load + eq)
o Power amp
o Monitor

System C:
o Manual eq
o Ampulator
o Headphones

System D:
o 5 watt tube amp, cranked up to the level of a trumpet

System E:
o effects
o Marshall stack, mic'd into mixer channel 1
o Marshall Power Brake power attenuator
o effects tapped off the amp's line-level speaker tap or the line-level
output of the attenuator, into mixer channel 2

One of my goals of the "tone engine" approach, as opposed to the conventional guitar amp approach, is to make the final volume level independent of the type of tone. With a conventional, single guitar amp, clean sounds always are at a certain volume level, while power-amp-distortion tone always happens at a differnt, particular level. Clean sounds are always quieter than saturated (power-tube) sounds, thus putting certain restrictions on expressivity. With conventional amps, the entire band has to be quiet when the guitarist wants a clean tone, and the entire band plays loud when the guitarist wants a dirty tone. If your mixer man rides the guitar level in the PA mix, this supports more combinations of volume and tone; the Tone Engine accomplishes the same thing, but all under direct control of the guitarist. I want to be able to control sound level independently of Tone; I want to be able to have a clean sound that is louder than a saturated power-tube (and saturated speaker) sound. The Tone Engine concept permits this. (In a conventional concert setting, you can achieve this same effect by preventing the audience from hearing the guitar amp directly, but controlling the level through the mixing board.)

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