Home (amp tone and effects placement)

The ADA MP-1 was the first unit to have both a vacuum tube and MIDI. I don't know if it had a DSP chip, but the 2101 had all these. Unfortunately, the tube was only a *preamp* tube, *not* a power tube, and the marketers glossed over that all-important distinction, and everyone hoodwinked themselves, out of wishful thinking, and pretended that preamp tubes and power tubes sound the same. Now that preamp tubes are everywhere, in many distortion boxes, yet distortion boxes still do not really sound like power tubes at the edge of saturation, we know that we're still not nearly there.

The technology in modelling amps is excellent, and they are attempting to reproduce the correct, specific, classic amps down to the various details, rather than just some generic amp. But the modelling approach, so far, lacks the dynamic, spongey, liquidy character of saturating power tubes, except perhaps when the modelling amp is played at full volume. From such an excellent starting point, getting saturated power-tube tone at headphone levels is almost trivial: the designers simply need to add a power tube and load in the correct spot in the default chain: compressor, preamp distortion, EQ, power tube and load, EQ, time-based effects. The load can be replaced by a miked speaker isolation cab.

I did my senior project for electrical engineering along these naive lines. If I could do it again, I would have used a 6V6 or EL84, and made *that* MIDI-controlled. While using a programmable 12AX7 was a good move, it wasn't nearly as revolutionary in terms of Tone as people and marketers wish and assert. Preamp tubes don't sound that much better than preamp transistors; any form of preamp distortion won't sound close to a tube power amp running at the edge of saturation. The MP-1 ultimately lead the entire industry into a dead-end. A preamp tube is of no significance compared to a power tube. Craig Anderton asserts that the preamp distortion *voicing* is more important than whether a tube or transistor is used, and I agree.

Though we've been lead into a dead end by the great preamp tube hoax, there *are* some actual power-tube saturation "pedals" such as the Lawbreaker, Crunch Master, Ampulator (preamp tube in a power tube configuration), Interstellar Overdrive, and Quadruplet which scream out, "put me between two MIDI-controlled DSP units or stages". The reviews of such devices are rave reviews; they report that these devices sound completely different and more amp-like than even the best non-power-tube distortion boxes.

Only when using such a combination of power tubes and DSP would I agree that we have a reasonably awesome cranked-tube-amp tone at arbitrarily low levels, thus preserving our hearing and generally attaining better electronic control and noise control in the home studio or apartment-based recording studio, as well as on stage. I doubt that certain sounds such as a cranked Marshall stack can be achieved to full satisfaction at headphone levels using very low-wattage power tubes, but combined with DSP and amp modelling, an equivalent, genuine power-tube-saturation tone will be available to everyone as soon as designers use this approach.

It is possible to cobble together a system today by combining small tube power amps with two DSP units such as between two modelling amps linked together via MIDI, but this can never be as ergonomic or good sounding as having a modelling amp that properly integrates a power tube from the start.

C. Kirbyengr wrote:

>There's no reason why any conceivable "tube tone" can't be achieved with tube amps of 10 watts or less.

I suspect that *many*, but not all, good power-tube saturation tones and speaker tones can be achieved at 10 watts or less.

Can "hard" sounding tubes such as the 6550 tubes can be reduced to such a low power level while retaining their dynamic response?

Is there a lower wattage tube that sounds like the 6550?

Supposing that guitar speakers must be driven hard for a supposed speaker-breakup tone, could this happen at just 10 watts or less?

>"Headroom" (i.e, increased dynamic range) can just as easily be achieved by pushing the noise floor down as by pushing power levels up. Just a matter of scaling the signal to suit the system.

Headroom can perhaps be preserved, but can Tone be preserved? Can the dynamic squashiness and character of a hard-driven power tube and a hard-driven speaker be preserved at such low levels as 10 watts or less? Not just in general, but for particular classic amp tones such as the Fender Twin tone, or the tone of a Marshall stack with 6550 power tubes?

Once you have the Tone by using a low-volume amp, you have much more flexibility by post-processing volume, EQ, and effects, and you have better mic-monitoring and overall control.

I have proposed using a very low wattage tube power amp with a large or small speaker isolation cabinet with a single speaker and a good mic or two inside, or using a power tube to drive a load and speaker cabinet simulator, all placed within two fx-and-eq stages. I have mentioned variations on these themes, such as the amp isolation booth or room, and at least one person has constructed an amp isolation closet for his full Marshall stack after reading my postings including those at my Amp Tone site. I have also proposed lots of variations on the theme of power-tube saturation pedals such as the Crunch Master, so that people can think of a tube amp as merely another pedal in a chain, and they can easily place it in the far sweeter spot *before* echo, rather than *after* the time-based fx as all the multifx industry currently forces you to do.

>The future of "tube sound" seems to lead in two directions: DSP (let's not get into that right now), and low-power (<10-15W) tube amps of very high quality.

My main proposal from the start has been to combine these two approaches, rather than treating them as competing alternatives. I am promoting this approach after to my essentially successful results with such a system, using this chain:

DigiTech 2101 high-end DSP preamp/multifx rack processor -- comp/dist stage
Home stereo equalizer, left channel
2101's FX out jack
Fender Pro Jr. 15 watt tube combo
Large, double-thick, homemade speaker isolation cabinet with Celestion Greenback 25 watt guitar speaker and Shure SM57 dynamic mic
Radio Shack XLR-to-1/4" adapter
2101's FX return jack
2101's EQ and then time-based effects (echo, reverb, chorus, flange, and related effects)
Solid-state amp and headphones or full-range monitor speakers

In case you try to hook this up, I don't recall if the 2101 eq is before or after the FX loop. You actually need a MIDI-controlled EQ on either side of the tube power amp.

Now, with the new modelling amps, I'm continuing to endorse that same strategy.

"Teleologist" wrote:

>Arsenio Novo wrote in article
>> the "even order" products are in effect "octaves' of the fundamental
>> Thus each individual harmonic is difficult to distinguish from the
>> fundamental since it is the same note after all. As such they blend into
>> the fundamental note giving it an apparent extra richness and character.
>> On the other hand, "odd" harmonics are much more easily audible since
>> form intervals which are not perfect like the octave and thus don't blend
>> with the fundamental tone.
>> The "beam" power tube also exhibits a distortion spectrum similar to the
>> transistor's. Additionally, the output transformer in a push-pull tube
>> amplifier inherently cancels "even" harmonics. The resulting harmonic
>> distortion products are then also predominantly "odd" just as in a
>> transistor amplifier.
>True a push/pull output tranny cancels even harmonics produced by the power
>amp, but even harmonics produced in the preamp stages pass right thru & you
>end up with both kinds in the final output. That said a single ended amp
>will produce more even harmonics than a push/pull amp.

>One thing not discussed so far is the preference of many musicians to feed
>that nice warm tube amp a signal distorted by a SS stomp box. IMHO the
>magic of tubes is the way they round off the edges of those square waves &
>the way they naturally compress.

You should be careful to specify "power tubes" to clue in the product developers that they should fall out of love with preamp tubes and get *serious* about tubes by making lots of innovative power-tube products.

For example, all full-featured guitar processors should have a power tube and inductive load (or speaker&mic loop).

You can get great tube amp tone using solid-state preamp distortion. Practically all the action happens in the power tubes. Preamp distortion tubes have been completely oversold.

Amptone.com ultra gear-search page

Home (amp tone and effects placement)