GAGA - A New Kind of Tube Guitar Amplifier

Picture-Purefect™ — Purest possible tube performance, literally picture-perfect

Tubby 6L6's in a typical amp - No amp uses multiple audio output transformers all at once, for visible, audible and other reasons. Characteristics peculiar to audio output transformers are evident in this curve-tracer photograph which shows the response of a push-pull pair of triode-connected 6L6s. "This reveals real-world performance of typical tube amps using traditional audio output transformers of superb quality." The diagonal loopings of the grid-voltage lines are caused by magnetizing current (i.e., energy wasted in making the transformer transform) while the large horizontally oriented loop shows core saturation and hysteresis (i.e., magnetic inertia or lag), direct, visible and entirely audible causes of lost impact, detail and power. "Like inferior speakers, tube amp output transformers distort the low bass, muddying it and cutting the fundamental." » "Multiple output taps...are inherently a serious compromise in performance..." » Powerful, taught and deep low frequency performance, which typical tube amps struggle or fail to reproduce, is commonly cited as a major advantage of solid-state amps. Patented, all-tube GAGA uniquely delivers the full-bodied, rich warmth of tubes at uncommon speed and with total phase accuracy across all audible frequencies for solid, gutteral impact with extreme resolution and dynamics like you've probably never heard from a 'tube amp'.

Tubey 6L6's in GAGA - GAGA doesn't use any audio output transformer, for picture-perfect tube response: Dynamic, powerful, coherent, impactful, musical. Response of the same test amplifier and the same push-pull pair of triode-connected 6L6s but using ZOTL Technology. Response is faithful and musical as the tubes are operated ideally, as if driving a 4,000 Ohm speaker, while the speaker responds as if driven by a 0.6 Ohm triode. "ZOTL is designed to maximize tube characteristics: Actual performance is picture-perfect, resembling ideal response curves in tube manuals and datasheets. It can't get much tubier...ZOTL enables with tubes what was formerly impossible." Using ZOTL, GAGA responds smoothly and instantly recovers from overload on a per-note basis. The result is tube warmth with remarkable audible delicacy and nuance, full impact, sustain and slam when so driven, harshless alacrity, and addictive responsiveness — all bringing musicians closer to their true tone and musical ecstasy.

How GAGA will help you sound and perform your best

Light-weight, powerful, elegant, and unusually flexible, GAGA intensifies nuances, enhances "feel", increases dynamics, maximizes purity, heightens musical ecstasy, and brings musicians closer to their smiley, goose-bumpy tonal truth. Smart features fresh to the guitar world provide real world advantages for everyone.

• Ultimate in versatile: Completely control "the sound" — GAGA accepts and auto-biases any common octal audio output tubes, in any combination. Forget "matched" pairs (and types!), metering, tedious adjustments, bias drift, mismatch and aging —just plug and play, literally, with unprecedented control over the louder part of your instrument. Tweak the tone: Change a tube. Get a whole new sound: Change all four. Various input tubes may be swapped for an even larger palette of tone and feel. "The...technology is both complex and elegant. The auto-bias circuit alone is a technical tour de force." »
• Lighter than most guitars — Bring GAGA anywhere...arrive without one arm longer than the other...enjoy invaluably dependable performance...jam, shine, smile...and then actually leave the gig on time.
• No more batteries — Because GAGA includes a complete system of P3 Technology® (and Power-Chain™ cables), you don't need batteries or hazardous and noisy AC power for a "DC" brick up at your pedalboard. P3 works with all standard 9-volt pedals. It is the end to power problems — and talk about "green" technology: Never land-fill another 9-volt battery.
• Start with purity — Faithful, phase coherent, all-tube, pure power amplification across the audible spectrum. Why is this desirable? Many quotes uniformly implore 'start with purity':   Clean Tone = Wide Spectrum = Musically Rich. This is exactly the same old obvious truth that great meals are best made from pure ingredients. What's less intuitive, yet scientifically demonstrated, is that limited amplifier bandwidth results in reduced musical ecstasy and brain activity. GAGA's wide-bandwidth, accurate and full pure tube tone is intense, musical, natural and emotionally involving.

• Tremendous, taught lows — Coherent low frequencies give solid impact and powerful slam that extends all the way down without flub.
  
• Luscious tube warmth — Mids are warm and tubey but resolve without clutter for great tone all the time, without need for "scoop" or constant control twiddling.
  
• Harshless highs — Highs are wickedly fast, airy, natural, lively.
  
• No "loose ends" that are unterminated windings electrically flopping around, causing sonic mayhem inside traditional audio output transformers. See Luke Manley's comments: "Multiple output taps [present in audio output transformers as the ubiquitous 4, 8 and 16 Ohms] are inherently a serious compromise in performance. Inactive winding-segments are inevitable in a tapped transformer and result in additional leakage inductance that affects high-frequency response." GAGA completely avoids this.
• Elegant — Great tone and reliability. Few, large, single-purpose knobs. Auto-Everything. One output that optimally matches any speaker load, not 4-, 8-, or 16-Ohm taps that are always imperfect compromises. Literal plug and play. No nonsense, nothing to goof up or set wrong.
• Blow-Proof™ Auto Output — Drive any common cabinet or speaker combination, just plug it in. Blow-proof output sustains direct shorts or total opens. GAGA is robust and will drive any cable without damage: In a pinch, a "speaker" cable is not required.
• No distortion hangover — Instant, per-note response amidst any amount of overload, even the most severe output tube crunch. When you stop pushing GAGA it immediately stops being pushed - the sound never becomes bewildered, stalls out, blunders on, or "folds back over on itself". GAGA is made to provide continuously solid response and power, with smooth, rich overload and distortion when so driven, without fading off or collapsing: "lightning fast power without inertia, as responsive as no amp at all." Why is this important?
• Bottomless, pristine energy reserves — Supersonically recharged and regulated internal energy reserves provide for unsurpassed sensitivity, solid slam and lasting sustain. Typical amps store meager energy, loosely regulate if at all, and recharge at (audible as hum) line frequency. GAGA literally blows that all away. One manifestation is dramatic headroom and rich tone across audible spectrum, including bottomless bass. "[GAGA] is the first amp I've heard with headroom up top and down below." — Gary Smyers, audiophile, bassist, NAMM Jan 2011

Playing is believing. Measuring is proof.

Left photo shows response curves of 6L6 tubes played through a superb audio output transformer. Magnetic bloat manifests audibly as lost power, muffled attack, dulled nuance, skewed timbre, or "munge", "flub", "smear".

Right photo shows response curves of the same 6L6 tubes in GAGA match their ideals shown in tube data sheets and technical literature. The resulting faithful tube amplification gives clarity of tone, leaping dynamics, immediacy, impact, body, warmth, and three-dimensional naturalness. Toward the goal of maximizing musical ecstasy, GAGA audibly and measurably provides the purest possible tube tone.

Quality ingredients vanquish compromise: How every part is a feature

Auto-Everything™ — Use Any Tube, Auto-Bias, Auto-Impedance, Auto-Power, Auto-Standby

• Any-Tube™ - Easily and completely change "the sound". Plug in any number or combination of octal output tubes for tone and power. Escape from "matched pairs" or even same types and choose your own voicing and tonality with whatever tubes you like. Insert 2, 3 or 4 tubes. Every tube inserted can be completely different. Any octal output tube (pentode, beam tetrode or kinkless triode) having RETMA standard 7AC style base and pinout will work.   "...a perfect studio amp."

  The output tubes operate in full-power, class AB1, linear push-pull manner at impedance higher than is possible with even the very best traditional audio output transformers, and without any of their attendant saturations, roll-offs, phase effects and hysteresis lags. GAGA delivers purest possible tube tone.

  6L6 family:	6L6, KT66, EL37, 5881, 7581, 6P1P-EV, 6P3S-E, 6P6S 6W6 6Y6 6146
  EL-34 family: (power pentodes)	EL34, KT77, 6CA7 6K6
  6550 family:	6550, KT88, KT90, KT120 » » »
  6V6 family:	6V6, 6EY6, 6EZ5, 6P6S, 6AY5, 587, 5871, 7184, 7408, 7EY6
  STR family:	STR- 417, 420, 425, 427, 430, 442, 447, 450, 454

  Members of the EL-34 family are true Power Pentodes. Many other types are "kinkless" tetrodes.

  

• Use any compatible pre-amp tube to tweak tone further. Plug in any compatible input tubes into any position in the pre-amp section. Combined with Any-Tube™, the available tonal palette presents what some have called an amplification instrument. GAGA ships with a standard tube complement; any of its tubes may be easily changed to attain any desired tone or feel. Compatible pre-amp tubes:

  12AX7 type:	12AX7, 12AX7A, 12AX7LPS, 12AX7WA, 12AX7WB, 12AX7WC, 12AX7EH, 12AX7C9, 5751, 5751WA, 6057, 6681, 7025, 7058, 7729, ECC83, ECC803, ECC803S, E83CC, 12AD7, 12DF7, 12DM7, 12DT7, B339, M8137, 12AK7, E283CC   »
  12AT7 type:	12AT7, 12AT7WA, 6201, 6679, 7728, ECC801, ECC801S   »
  12AU7 type:	12AU7, 12AU7A, 5814, 5814A, 5963, 6189, 6680, 7316, 7730, ECC82, ECC802, ECC802S, E80CC   »
  12AV7 type:	12AV7, 5965, 7062, E180CC
  12AY7 type:	12AY7, 6072, 6072A
  12AZ7 type:	12AZ7

  Generally, the AX and AY variants are higher gain, and the others are medium or lower gain but higher current. Higher gain tubes are geared for amplification; higher current tubes are useful as drivers. See wikipedia for more information and also Frank Philipse's Tube Data Archive.

  GAGA comes with one 12AX7 tube (input), three 12AT7 tubes (tone, loop, driver) and four 6L6 tubes; substitutions are welcome.

  "Everybody else sets a 'sound' and sells it to you; we figured you should be able to set your own sound, and change it whenever you wish by simply changing controls and tubes. Flexibility and individuality largely defines musicians, so why should your amp dictate your sound?" -- Michael Milbert

• Auto-Active-Bias™ - Never worry or adjust bias again. GAGA automatically actively biases any combination of output tubes for full performance.
• Auto-Standby™ - No "standby" switch - GAGA automatically keeps the output tubes ready to deliver full power and performance instantly, seamlessly. "Standby" is not necessary, because of how GAGA operates the output tubes (i.e., as they are supposed to be used, at high impedance, not at high current). See Extended Tube Lifetimes below: Years to a decade or more (expected) tube lifetimes, as is common in all our other products. GAGA does not stress, burn up or "eat" tubes and may even be able to use tubes weakened by other amps. There's no guarantee of this, but we've pulled tubes battered in traditional amps enough times, and had them perform well in GAGA, that we're confident in mentioning this fact. Power tube microphonics also virtually disappears.
• Universal Mains / World-Power-Ready™ - Plug in anywhere on Earth — no settings, no jumpers. Standards compliance 90-240VAC @ 50/60Hz, RoHS, CE. Hum practically vanishes; GAGA is eerily quiet at idle.
• Drive-Anything™ - Nothing to set, match, mismatch, or confuse: Single 1/4-inch output jack drives any reasonable combination of speakers or cabinets over any type of cable.
• Blow-Proof™ - Output sustains dead-shorts or no-load total-opens without self-destructing. No more fear (or awful reality) of blown output transformers. The days of shorted output transformers and problems due to complex reactive loads are gone.

GAGA Headroom Control

GAGA's Headroom control allows for adjustment of power tube overload versus volume. Turning Headroom down gives less headroom before overload: overload comes on sooner, at lower volume. Turning Headroom up gives more headroom before overload: overload comes on later, at higher volume.

Technically, GAGA's Headroom control sets the apparent transconductance of the output tubes, allowing power tube distortion to be fully realized at less than full volume levels without abusing output tubes or heating big resistors. The Headroom control does not directly attenuate the audio signal, nor is it a 'power soak' or 'hot plate'. Headroom is also not a "brown" technique of plate (voltage) or heater (current) starvation.

GAGA's Headroom control, Gain, Volume and Tone controls interact smoothly and intuitively with any playing style. Headroom is ultimately a subjective control, as each output tube and every combination thereof, coupled with whatever particular speaker(s) and cabinet, exhibits unique response, distortion, power output, character, feel and tone. The Headroom control gives the musician another important, direct and unique control over tonal coloration. Headroom intuitively yields much tonal variety in a single, simple, wonderful control.

GAGA Tone Stack & "Midrange"

"...it became apparent that more different tones were available [with the two knob Baxandall] bass/treble combination than [with an added midrange control]. Not believing that two knobs gave more variation than three, I double checked everything [to confirm it is true]." »

GAGA's tone stack is an improved, tube-buffered Baxandall circuit » », which is simple, proven and maintains great tone over wide, independent adjustment of bass and treble. GAGA allows variable 16dB of boost or cut with both bass and treble controls.

"The standard Fender midrange control does not really boost just the midrange — it boosts ALL frequencies. ... This is perceived as mid-boost because it does cancel some of the midrange cut, but it cannot be a true boost because there is no way for the mid control to elevate midrange levels any higher than bass or treble levels. In fact, increasing mid control will actually boost the bass and treble a bit." »

Midrange Scoop or Boost — Bass and Treble controls are "center flat" and offer 16dB of boost or cut. If desired midrange may be indirectly adjusted via the bass and treble controls: Turning both down gives a relative midrange boost, turning both up gives a relative midrange scoop.

"...I had the choice of the traditional Fender/Vox/Marshall tone stack using Bass/Mid/Treble controls, or using a passive version of the Baxandall Bass/Treble tone stack which is popular on hi-fi equipment. On the basis that 'the more knobs, the better', I started the design using the FVM tone stack. When SPICE modelling the effects of the stack, it became apparent that the tonal control was limited. Furthermore, the effect of the mid control on everything else was more than noticeable." »

We reached the same conclusion: Fewer knobs is and sounds better.

"...don't let the number of knobs...impress you. The important thing about an amp is how it sounds — and more specifically, how it sounds to you when you play your guitar through it. Some of the best amps in the world have very few knobs and look rather low tech. So make sure you check out an amp the way you would a guitar — by listening to it as well as playing through it..." — John Chappell, et al., "Guitar All-In-One For Dummies", p. 190 »

GAGA Auto-Everything™

Auto-Bias — GAGA automatically biases whatever output tubes are inserted. Insert four output tubes, in whatever flavor of tonal variety, for maximum power. Remove one or two output tubes and the sound continues, albeit at reducing power output; GAGA will continue playing without being damaged.

"The ... technology is both complex and elegant. The auto-bias circuit alone is a technical tour de force." —Charles Hansen, describing Berning's ZH270 amplifier, which lends technologies to GAGA, Glass Audio Magazine, February, 2000, page 38

Auto-Idle / Auto-Standby — Output tube lifetime is greatly increased in GAGA as whatever output tubes are inserted promptly settle to quiescent bias current, essentially providing automatic idle whenever playing ceases. When playing resumes the output tubes instantly fly seamlessly from standby to full power demand at the moment of the first note. There is no lag or delay.

Tube lifetimes vs operating temperature — Sometimes in traditional tube amps, tube bias and operating currents are elevated, presumably in attempt to reduce unpleasant crossover notch distortion and shorten overload recovery » Rarely if ever is bias turned down (and now it's clear why not). While examining several major brand tube amps we measured some tube temperatures consequently in blistering excess of 500 degrees Farenheit. None of this afflicts GAGA, whose tube temperatures do not exceed 275 degrees F at full power, conservative by any standard. Tube lifetimes in GAGA are expected to exceed several years, possibly a decade or more, similar to our other products.

Power Ratings & Distortion

Unlike consumer electronics, power ratings of guitar amplifiers face no federally mandated standards. As a result, actual performance varies considerably. For example, we measured one "100 Watt" amp that put out only 37 Watts when measured to consumer electronics standard, and even then with wild, 'never seen anything like it' response. Another "100 Watt" amp we measured shamefully mustered only 56 Watts when pressed to standard. In high-fidelity amplification, 1% THD is described as 'barely noticeable', 3% THD as 'barely objectionable', and "'clipping' is typically quantified by a THD measurement of 10%." » Although electric guitar amplification can be driven by different goals, without a measurement standard "output power" can (and apparently does) mean anything.

Total Harmonic Distortion (THD) "is one of the ways that amplifiers are rated, and in the hi-fi world, where people are quite conscious of total harmonic distortion, everybody goes for the lowest possible amount of distortion. In the guitar amp world, people tend to go for the most." -- Andy Marshall, THD Electronics

With GAGA we provide proper, standards-based power and performance ratings. Rated to standard, GAGA delivers 50 Watts of power at 1% THD (measured with 1kHz sine wave into 8 Ohm load) and up to 90 Watts at full power and distortion. In other words, when "comparing apples to apples" for reference in terms of power output, GAGA's standards-compliant 50 watts of power surpasses what others may call "100 watts", and that's not just in output power: Phase coherence at all power levels maintains naturalness and disarmingly full impact - the tone does not convolute into mush nor does it collapse over on itself in overload hangover, even at extreme power levels and full distortion. If you're so inclined, GAGA lets you explore and enjoy what power tubes pushed to their tonal extremes can do, without over-current damage to the tubes.

For reference, GAGA provides up to 90 Watts of power when using four 6L6 output tubes. Two 6L6s provide up to about 50 Watts, and three 6L6s provide maximum power somewhere around 70 Watts. The vagueness is unintentional and occurs because all tubes and all combinations therefrom are slightly different, depending on internal construction, resulting electrical characteristics, and power handling capabilities.

The highest (fully-distorted) power level we've measured is 128 Watts (at 1KHz into 8 Ohms) from four 6CA7 output tubes. GAGA is rated conservatively.

On the other hand, power output from GAGA may be intentionally reduced by removing power tubes and/or by using power tubes which provide less power output. For example, four 6W6 tubes provide about 35 Watts; two 6W6 tubes provide 22 Watts. Note that this is accomplished without forcing any tubes into high current, high stress, high heat, life-reducing service. The "H" (Headroom) knob can also losslessly step total power output down to below 1 Watt, perfect for achieving realistic "bedroom" levels with full power tube feel and overload distortion yet without stress, excess heat, wear or damage.

"Without deviation from the normal, progress is not possible." — Frank Zappa »

Because GAGA provides efficient ultrasonic power recharge and regulation (whereas many tube amps droop, fade or even collapse) it is somewhat difficult to compare against the actual performance of GAGA — several people have suggested GAGA applies "alien" technology. Remember, GAGA is not an attempt to clone or mimic but to instead present a clean-slate for purity and faithfulness in guitar and musical instrument amplification. We like to think of GAGA as Space-age tube amplification for guitar, bass and musical instruments.

"Just as audiophile product designers can learn from us music guys, it's time for vice-versa." — Howard Davis, Electro-Harmonix, Pigtronix »

Wattage, Power, Speaker Efficiency by Howard Davis

Audio Power on wikipedia

RMS: Root Mean Square on wikipedia

SPL Chart

"This is [a Strat] pickup with a 1 Meg ohm load. See that it has a classic overshoot with heavy ringing before becoming stable. The peaks are more than double the step size, and this explains why amplifier power ratings are basically meaningless in overload situations." --Malcolm Moore's fantastic guitar pickup research

Does an audio transformer affect "the sound" ?

"...while many manufacturers wind great transformers, there's no transformer like no transformer at all...The difference is not subtle."

An audio transformer is a huge, homogenizing filter. Research reveals serious measurable and audible drawbacks with what has, until now, been a necessary evil in tube amps. Custom-wound and/or heavier magnetics may arguably improve low-end power handling, but usually at the expense of high-end phase (manifesting as impact, "air" or "edge"), frequency roll-off and other factors, not least of which are cost and weight! Rightly regarded as a kind of black art, even superb audio transformers always present complex, inescapable trade-offs, explored below. Let's start with common knowledge:

"Output transformers also have a reputation for coloring the sound..." —Howard Davis, Electro-Harmonix, Pigtronix »

"...transformers can distort and color the sound...a change in the output transformer...can make a huge difference in tone..." »

"...it is the output transformer that can dramatically affect the tone of your amplifier since audio signal is actually passing through it." —John Chappell, et al., "Guitar All-In-One For Dummies" »

It's probably accurate that say that an audio output transformer largely (and often individually and uniquely) sets a characteristic 'sound' — a filter that can never be turned off. How desirable an inescapable effect may or may not be ultimately plays out in ears and minds. Some people may play an amp for its "sound", but not all "identical" amps sound the same because not all "identical" transformers sound the same because not all transformers (with their hundreds of laminations and tens of thousands of windings) end up being made the same. The situation is very much like cymbals. Or guitar bodies. Or diamonds. Uniqueness at every level (in metal alloys and hammer blows, or wood grain orientation and cuts, respectively) ensures unlimited, unique (and confounding) variety. This is also true of vacuum tubes; although, vacuum tubes are far easier to trade, borrow, and swap for tone, feel and flavor than are output transformers!

"...I was amazed at how different [transformers] sounded, even [those having identical] specifications..." »

"...it is not the tubes alone that account for the 'tube sound.' The large, heavy output transformer...introduces harmonic distortion, particularly at low frequencies...like the many pounds of transformer weight, this distortion cannot be eliminated when it is NOT desired." — Howard Davis, Electro-Harmonix, Pigtronix »

"I didn't realize that tone was so much a part of the amp." — Paul Reed Smith, Vintage Guitar Magazine, November 2011, pg. 26

Technically, parasitics skew phase and mangle impact », magnetizing current and core saturation rob power », and detail evaporates ». Inescapable magnetic bloat inherent to audio output transformers audibly and measurably manifests as distortion » : munge, flub, smear ». These are others' findings, experiences and words, not our assertions.

GAGA unveils and intensifies the character of whatever tubes are inserted by eliminating the audio transformer along with all transformer-specific magnetic peculiarities. The goal, of course, is to start with tube purity and let musicians select their sound by selecting which tubes they prefer to play. While four 6L6s may sound more "jangly" and "unruly" than four comparatively "smooth" and "warm" EL34s, the choice, mix and intensity of flavor GAGA now avails to each musician individually. In so doing, GAGA not only clarifies and intensifies the musical emotion it also highly personalizes it for each player.

We figured- why not circumvent the magnetic roulette and instead focus on great tube sound (that is repeatably attainable) and in the process eliminate weight, bulk and other serious problems? That's precisely what GAGA is designed to do: maximize tube purity, performance, reliability and musical ecstasy.

"...'the sound' of the amp is no longer coupled to the transformers." »

Advanced power supplies and patented ZOTL Technology in GAGA provide idealized impedance matching and power conversion (specifically not power amplification), without all the weight and limitations of traditional audio frequency output transformers and big, low-frequency power magnetics.

"... pure tube tone with no Iron to lug around." »

Freed from driving an homogenizing iron bulk, the output tubes really shine. It's shocking how different EL-34s and 6L6s actually sound, and the sonic benefits don't end with audibly unveiled nuance.

"Like inferior speakers, tube amp output transformers distort the low bass, muddying it and cutting the fundamental." — Howard Davis, Electro-Harmonix, Pigtronix »

"Transformers tend to smear the sound and limit the frequency response, and while many manufacturers wind great transformers, there's no transformer like no transformer at all -- something that becomes clear when you hear...bass as deep as that from a solid-state design, but with levels of detail and tunefulness that most solid-state amps miss. The difference is not subtle." »

"A preamp stage driven nonlinear produces clipping behavior with substantial asymmetry, meaning higher levels of even-order harmonics. Depending on the gain structure of the amp, it is possible that multiple preamp stages will clip. Because the common-cathode gain stages used in tube amps are inverting, a signal that is clipped in two successive stages may appear more symmetrical as a result of the clipping in the second stage. In that case, odd harmonics will be added to the signal. Power amp stages have much more complex reactions when driven into nonlinearity. Because the signal is coupled through a transformer, there is the possibility of core saturation. Additionally the power supply ("B+") DC voltage may begin to sag, causing a type of compression. The onset of nonlinearity is affected by the amount of negative feedback in the design. Zero-feedback designs enter nonlinearity earlier and more gradually, whereas designs with negative feedback tend to stay clean longer but clip more abruptly. A power stage driven into nonlinearity will often lose high frequency bandwidth as it is driven further into clipping, then recover the bandwidth as it comes out of clipping. This has a profound effect on the tonality and dynamics of single notes vs. chords." »

"... transformers epitomize...obstacles to high fidelity: Abruptly limited bandwidth [short-changes] both the ends of the frequency spectrum [with] smeared transients. Limited power bandwidth in particular [hampers] output transformers, resulting in compressed dynamics, masses of harmonic distortions from hysteresis(1), low-frequency saturation(2), phase distortions and more. ...the gross distortions of power output transformers... (1) Hysteresis, in this case, refers to the tendency of the magnetic flux in a transformer's core to not respond precisely to the magnetizing force of the current in primary coil. For instance, the predilection of the core to stay slightly magnetized even when the current in the primary coil has ceased. [In other words, "magnetic inertia."] (2) The upper limit of a transformer's core to contain magnetic flux is called saturation. Above saturation, additional magnetic force causes little increase in flux density. The flux density in a transformer's core is inversely proportional to frequency of the signa1 applied to the primary coil: Halve the frequency and the flux density doubles. [In other words, "magnetic compression."] ... (5) B is the notation for magnetic flux density and H is magnetic force. Plotted together, they graphically illustrate hysteresis. A large separation between the magnetizing and demagnetizing curves (a "fat" loop) shows much hysteresis and a small separation (a "narrow" loop) approaches the ideal of no hysteresis." [GAGA has no magnetic audio loop at all.] — Line-level transformers in High-End Audio, Mark J Medrud, Design Engineer, Jeff Rowland Design Group, Inc., 17 March 1995 »

We could keep adding to the list of examples, but by now it should be pretty clear what's been going on with audio power magnetics. Let's look at some research directed precisely at audio output transformers:

At the 118th convention of the Audio Engineering Society, Menno Van der Veen presented his paper ( PDF | archive ) detailing a universal audio output transformer system that "includes all possible [90+] variations in topologies." [excepting GAGA's ZOTL Technology, which was not included in the study] With good technical discussion it demonstrates how audio output transformers inescapably impose compromises. Compare that situation with GAGA's demonstrably picture perfect performance.

Summarily paraphrasing Menno van der Veen's Low Level Details in Output Transformers research paper (presented at AES 122, May 2007): Failing to accurately transfer fine details at low levels, audio output transformers inherently smear details and obscure natural fidelity. While the research shows this primarily involves fine details at low power levels some effect is always present, and it is equally true that fine details are where finest musicians and best performances really shine.Transformers, according to this research, impede excellence.

So even the dogged research is bearing out what ears can hear.

"Ideally, a transformer stores no energy - all energy is transferred instantaneously from input to output. In practice, all transformers do store some undesired energy: Leakage inductance represents energy stored in the non-magnetic regions between windings, caused by imperfect flux coupling. Leakage inductance delays the transfer of [energy]...the main cause of...problems... Mutual inductance represents energy stored in the finite permeability of the magnetic core and in small gaps...Mutual inductance and leakage inductance energy causes [arcing] voltage spikes...resulting in...damage or destruction..." — Texas Instruments »

The professional audio people know this, too.

"Phase distortion not only alters musical timbre, but it has potentially serious system headroom implications as well. ... Even ultrasonic phase distortions caused by undamped resonances can excite complex audible cross-modulation products in subsequent nonlinear (any real world) amplifier stages. Low-frequency phase distortions are often described as 'muddy' bass and high-frequency phase distortions as 'harshness' or mid-range 'smear'. The complex cross-modulation products are usually described as 'dirty' sounding and often are the cause of 'listener fatigue'." — Glen Ballou, Handbook for Sound Engineers, p. 605

"The downside with iron [audio transformers], and there is always a downside, is ... time smear ... with sounds that have lots of energy (and tightness)..." — Manley Labs

It may all boil down to this: Were audio output transformers truly beneficial, wouldn't at least one guitar tube amp maker — after so many decades — be using two, three, or even ten transformers all at once for killer tone thereby totally out of this world? That zero do so tells all.

Necessary evils until now, audio output transformers are not the source of good tone, nor requisite. Transformers cause quirky drawbacks and colorations, and unreliably so at that - meaning, no two "identical" transformers sound or even measure the same - too much variability amongst tens of thousands of windings, laminations, materials, assembly.

Were audio transformers truly more good than bad, then surely by now — decades into amplification — at least one amp maker would be using two, three or even ten transformers all at once for tone thereby totally out of this world. That zero do so tells all.

Tubes are the primary source of good tone, as GAGA emotively demonstrates. GAGA eliminates the audio transformer (and heavy power magnetics), obviates all the attendant shortcomings, and transcends the limitations inherent in all traditional tube amps. Every claim is supported by common experience and research linked below.

Left curve-tracer graph shows two 6L6 tubes playing through a superb audio output transformer, an inescapable, homogenizing filter. Parasitics roll-off accuracy, skew phase and mangle impact. Saturation and core losses hinder response and rob power. Accompanying bias collapse mires tone in awful crossover-notch distortion, drawn out by slow hangover recovery of vintage circuitry. AES papers investigate evaporating detail. Dynamics are compressed. Plainly visible magnetic bloat manifests as munge, flub, smear. Photo shows effects at one frequency at one moment in time; imagine what's happening to music.

Right curve-tracer graph shows the very same 6L6 tubes playing in GAGA. Tube response matches ideal graphs in original tube data sheets and technical literature. Pure tube tone and feel are dramatically unveiled. Response is fast, full and faithful to what's played.

GAGA's ZOTL Technology vs Audio Output Transformer

A major purpose of GAGA is to maximize the tone and response of tubes. With no physically and electromagnetically bulky, limiting and homogenizing audio output transformer, the purity of output tubes is unleashed.

"Previously, truly changing 'the sound' of an amp meant changing the amp. Now, GAGA gives a remarkable palette of tone by just changing a tube. In other words, the pure sound and response of the tubes is revealed."

GAGA does not attempt to clone or mimic but instead provides a solid foundation for any tone desired with the idea that starting from purity is musically advantageous.

"To sound musically rich, go for wide range, low distortion at high volume, and desirable tone qualities." —Howard Davis, long-time engineer at Electro-Harmonix, » »

"...before you attempt to use any effects or tone-shaping devices, you must dial in a flat-response clean tone on the amplifier...it's crucial to attain a pure, clean tone prior to adding other effects to your signal for better overall tonality. If you can find a clean-sounding amplifier...then anything that you add to the signal path...should accentuate what your natural [guitar] tone sounds like." — David M. Brewster, "Introduction to Guitar Tone and Effects", p. 14, »

Sometimes confusion arises regarding the importance of wide and accurate frequency response in guitar amplification. Malcolm Moore's extensive research into the magnetics and realities of guitar strings and electric pickups provides more than adequate technical evidence.

"For a guitar, the audio spectrum needs are wide. ...The lower open E string has a fundamental of about 128 Hz, and significant harmonics are the second, fourth, sixth and eighth meaning the spectrum here extends to 1024 Hz. On the twelfth fret on the upper E string the fundamental is about 1,024 Hz, and the spectrum extends to about 8.192 kHz. On the 21st fret the fundamental at C#'' is about 1,722 Hz, and the spectrum extends to almost 14 kHz! The transduced (string movement to electrical) frequency response needs to be virtually flat from less than 100 Hz to greater than 14 kHz to faithfully reproduce the vibrations from the guitar strings - before anybody starts to play with the audio spectrum, develop distortion, or introduce echo and / or reverberation." —Malcolm Moore »

As Rupert Neve and others have pointed out, many people can hear the difference between a sine and square wave at 15 kHz which means they are hearing at least the first harmonic of the square wave; at 30kHz, that's well above what is commonly considered the upper limit of hearing.

Tim de Paravicini notes the importance of frequencies outside the conventional 20Hz-20kHz range. He points out that one can sense the standing wave of a large cathedral which is below 5Hz. A body senses sound through more than the ears:

"This traditional notion of the hearing stopping below 20Hz is absolutely rubbish. We detect sound down to the resonant frequency of the body, about 3Hz. Deaf people certainly seem to hear through the body. Likewise, the high frequency notion of 20kHz is also rubbish. We detect audio up to about 45kHz, not as a tone but a certainty that something is going on. My method of demonstrating this was several years doing work on ultrasonic bath cleaners. Everybody in the room suffered the after-effects of tinnitus, aware of something going on. Moreover, playing a 20kHz tone through suitable speakers puts listeners in discomfort. So traditional myths have to be thrown out the window."

Noted amplifier designer Nelson Pass explains how ultrasonic anomalies carry audible effect:

"Although human hearing is generally very poor above 20,000 Hertz, ultrasonic frequency roll-offs produce phase and amplitude effects in the audible region; for example, a single pole (6dB/octave) roll-off at 30 kHz produces about 9 degrees of phase lag and 0.5 dB loss at 10 kHz."

Amplifiers that fail to reproduce accurately for any reason by definition come between musicians and their true tone. Moreover, such amplifiers lacking in high frequency reproduction have been demonstrated to result in lesser brain activity and lesser perceived sound quality.

In other words, limited amplifier bandwidth results in limited musical ecstasy:

More evidence supporting the importance of wideband amplification: Reproduction of high frequencies measurably and dramatically stimulates increased brain activity and "...[listeners] felt the sound containing [ultra sonic high frequencies] to be more pleasant than the same sound lacking... These results suggest the existence of a previously unrecognized response to complex sound containing particular types of high frequencies above the audible range. We term this phenomenon the 'hypersonic effect.'"

Transformer: High-frequency loss

Fig 1: Given a 5 kHz square wave and driven into no-load open-circuit, this test reveals dramatic high-frequency loss (triangular, not sharp rising edge) due to the audio output transformer's capacitance caused by its necessarily large number of windings. Even in superb transformers, this loss generally begins below 5 kHz and gets worse at higher frequencies. See Luke Manley's comments on audio output transformers concerning this loss and other complex factors degrading accurate reproduction in audio transformers. Supersonic roll-off (top leading edges) with ZOTL is due to capacitance inside the output tubes themselves and is above audio frequencies. Accurate high frequencies reproduced by GAGA translate into harshless airiness, presence, naturalness.

Transformer: Low frequency saturation, power loss

Fig 2: Given a 30 Hz square wave and driven into an 8 Ohm load, this test reveals transformer core saturation evidenced by variably sloping waveform levels. This loss begins well above 30 Hz and gets worse at lower frequencies. Deviation from perfect flatness with ZOTL is due entirely to lack of stiffness in the test power supply. Though GAGA can (optionally) suppress subsonic frequencies, ZOTL Technology amplifies all the way down to and including DC ( 0 Hz ), a technical feat formerly impossible with output tubes. The result is full power bandwidth phase accuracy that keeps all frequencies synchronized in time, for astounding impact and vivid naturalness. "Low frequencies don't turn to mush and muddy everything up. The bottom end maintains phase to deliver a thick, rock-solid feel...not thinned, collapsed or bent out, it remains true to what was played."

Transformer: High frequency slow response

Fig 3: Given a 10 kHz square wave and driven into an 8 Ohm load, this test reveals a significantly slower rise time caused by the transformer (soft rising edge) which also adds a low-frequency component to its overshoot. This is one way in which the "flub" or "munge" often experienced with traditional tube amps as tones which were never played are nevertheless created and injected into the music signal. "GAGA is extremely fast and faithful to any leading edge however sharp, full body however sustained, and trailing edge of every note however delicate, giving unprecedented feel, immediacy and impact, without audible overshoot or intermodulation."

"When you can measure what you are speaking about, and express it in numbers, you know something about it..." — Lord Kelvin

These claims are supported by measurements and numerous technology/product reviews noting, among other experiences, sustained periods bordering "on the spiritual". »

GAGA Lightning Response Without Collapse

GAGA is fast, always responsive, and does not mire on overload. Recovery from any amount of power tube overload is instantaneous, on a per-note basis. There is no bias collapse or consequent overload hangover. You can literally fly from the most overloaded scream to the most delicately nuanced pluck in a wink. Play a note and it's there, full-spectrum from head to toe, with an unsurpassed immediacy that audibly melds GAGA as an integral part of your instrument. GAGA's speed may be one of its most understated advantages - an analog might be a sports car that responds nimbly to every slightest wheel nudge or turn, versus the awful slop in a loose rack-and-pinion.

This extreme immediacy also figures into GAGA's automatic bias and automatic standby features. In GAGA, the power tubes are always operated as they were made to be, at high impedance. Optimally, bi-directionally and intimately coupled to the speaker load, power tube characteristics are maximized, and that translates directly as immediacy, impact, faithfulness and musical ecstasy. Those words are from reviewers' quotes.

Someone asked:

"By not having either the transformer losses, nor the bias shifts resultant from overdriving capacitively coupled stages are you not removing part of the very features that give some amps their classic sound? The brief sudden loss of all sound (even background hiss) as the electroncs scramble to recover after you've played that ultimate power chord is very much part and parcel of the sound." »

To which we responded:

"... people who've played GAGA haven't [noted absence of] this. I suppose it comes down to if you want to hear amplified music from the guitar or an amp that falls apart when pushed."

"It's apparently somewhat common to turn up tube bias in an AB output stage. This would directly affect bias upset (and also crossover notch) by reducing it. Who turns down their bias (to presumably increase the amount and length of bias upset)? [No one; it's practically unheard of, at least to us.] Also, R. G. Keen notes '...[amps] that sound good...recover from overdrive gracefully.' Both of these facts point favorably to minimal bias upset and faithfulness to what's played, not to how an amp might (mis)interpret it."

"Another thought: imagine if that ultimate power chord never ended or even faltered because of the amp."

Interesting and relevant, an innate drive to subdue awful crossover notch distortion may be the cause behind the general tendency to increase bias in traditional tube guitar amps. Of course this isn't good for the life of any tubes, pushing them to and even beyond their intended applications. GAGA operates power tubes at high impedances and proper bias, automatically maintaining optimum balance, reducing heat, and greatly extending tube lifetimes. GAGA essentially treats power tubes as the valuable, expensive (and sometimes irreplaceable) sonic gems they are. "The...technology is both complex and elegant. The auto-bias circuit alone is a technical tour de force." »

"Crossover distortion is a particularly onerous-sounding animal, and I've never met a guitarist who likes the sound of it. The biasing technique I use with tube amp output stages involves watching the output of the amp with a sine wave input on a scope and increasing the bias just past the point at which the crossover distortion cleans up. This gives you the lowest bias current - and therefore the greatest linear voltage swing and lowest idle power - consistent with no crossover distortion." »

One way to audibly demonstrate this might be to progressively turn down the bias on a conventional tube amp, as doing so would likely increase the unpleasant crossover notch distortion resulting from bias upset or collapse and widen the gap between push and pull. But who does this? Crossover notch distortion has never been prized. That any amps succumb to it is unfortunate.

Not made to clone or mimic specific peculiarities, GAGA provides the purest possible performance of tubes and faithfully amplifies what's played, towards the goal of true tone and musical ecstasy. Particular colorations of tone and feel in unlimited variety may be easily achieved by plugging in various combinations of power tubes. Ultrasonically recharged and tightly regulated, GAGA does not collapse, droop or fade out on its own; it will sustain notes as long as they are held on the instrument.

Is GAGA existing technology ?

No. GAGA is a new kind of amplifier. It is not solid state, hybrid, OTL, class D or "digital" anything.

GAGA uses only vacuum tubes (in preamp and power output stages) to perform 100% of audio power amplification, in analog, not digital manner, coupled with advanced power supply and conversion techniques and patented ZOTL™ Technology - a new name, for a new technology, in a new kind of amplifier.

"I just read their patents and tech descriptions...This really is fresh..." »

ZOTL Technology lets tubes operate more like tubes -- that is, at higher impedances and voltages, and with lower currents. Using advanced, patented radio-frequency power conversion techniques, ZOTL Technology provides automatic, ideal, bi-directional matching and power conversion between any power tubes and speakers, without any of the bulk, weight, compromises, or serious limitations of traditional audio output transformers.

Freed from the measurably and audibly degrading homogenizations of driving any bulky, traditional audio output transformer, the power output tubes really shine and convey their desirable tonality and characteristic response. Audible differences among tube types are magnified, naturalness and emotional appeal is heightened, and musicality is maximized.

New technology can be challenging and sometimes individuals assert ZOTL must be something which it isn't, such as class D, digital, hybrid, OTL or whatever. If any of that were true, the USPTO would have refused patent, citing prior art. Yet, although solid state, class D, hybrid, digital switching, OTL and myriad other techniques existed long before ZOTL, the USPTO affirmed ZOTL's novelty and granted patent. Examination of this page and all of its links reveals no references to ZOTL Technology, further confirming by absence its novelty. It is therefore accurate to describe GAGA as a new kind of amplifier and not as hybrid, solid state, OTL, class-D or other existing term or technique.

Why isn't GAGA a "hybrid" ?

Just as a transformer matches impedances and is not an amplifier, ZOTL Technology also matches impedances and also is not an amplifier (ZOTL patent: column 3, line 20). By definition » » » "hybrid" describes circuits in which some or all audio power amplification is performed by solid-state semiconductors with a tube or tubes present primarily for filtering, feedback or other control. GAGA performs all audio power amplification with only vacuum tubes in pre-amp and output stages, and GAGA performs no analog signal processing of any kind in any way with any solid-state devices (ZOTL patent: column 2, line 29). Therefore, by definition, GAGA is not "hybrid".

In The Absolute Sound Magazine (Feb, 2011), David Berning further clarified one technology used in GAGA: ZOTL emulates an ideal output transformer. It matches impedance just like a transformer, and it is a two-way communication between tubes and speaker as is a conventional transformer. However, ZOTL does not suffer from the frequency-dependence issues of [an audio] transformer that must handle orders of magnitude of frequencies. Its two-way communication separates ZOTL from a hybrid amplifier:

ZOTL "is not a tube amp followed by some other kind of output buffer. By having the two-way communication, the speaker is fully controlled by the output characteristics of the tubes, and that includes all-important damping. This is not the case with the hybrid amplifier that is simply tubes with an output buffer."

Why isn't GAGA "digital" or "Class D" ?

GAGA applies new technology not fully described by old terms: Its ultrasonics are entirely for power conversion and impedance matching (and specifically not power amplification). In contrast, by definition, digital or "class D" amps use the "switching mode of transistors to regulate power delivery" » (or, are those in which "all power devices...are operated as binary switches...the high-frequency [serving] no purpose other than to make the wave-form binary so it can be amplified by switching the power devices." »). GAGA does not do this. In fact, GAGA's tube output stage incorporates linear, class AB ("push-pull") operation (ZOTL patent: first line of abstract and colum 3, line 25), and GAGA uses only vacuum tubes for all audio power amplification in 100% analog fashion (ZOTL patent: column 5, line 54, and all diagrams). Therefore, by all definitions, GAGA is not "digital" or "class D".

Why isn't GAGA an "OTL" ?

"OTL" ( Output TransformerLess ) refers to a technique developed by Julius Futterman in the 1950s that applies numerous output tubes connected in parallel to drive speakers, attempting to overcome fundamental incompatibilities with brute force and purportedly suffering shortcomings including tube noise, unreliability, rather severe impedance mismatch, excessive heat, and inefficiency. GAGA uses patented ZOTL Technology which is entirely different from the Futterman OTL technique. Therefore, GAGA is not "OTL".

GAGA Phantom Power for Pedals and Active Pickups

GAGA is the first amplifier to include patented P3 Technology® as a standard feature.

Via any standard stereo (TRS) cable, when switched on P3 provides phantom power for effects pedals and/or active pickups: 9 Volts (supplied by GAGA) flows out to the pedals/pickups while the music signal flows back to GAGA over the same cable. Musicians aurally confirm its laboratory measurements: P3 has no negative effect on tone and in fact improves tone because supply voltage is regulated and no longer droops or fails as do batteries.

On the pedalboard, P3 redefines flexibility. P3 power may be distributed by a break-out box (via standard DC barrel connectors). Also, because any P3 pedal is also a break-out for P3 power, one P3 pedal in the chain (closest to GAGA) may send power out from its DC input jack. Moreover, this power is then daisy-chainable (or Power-Chainable) to all stock pedals. P3 is the end to dead batteries, power cables, ground loop hum, and power problems.

P3's many advantages:

• no more batteries
• no more ground loops
• no more power cables - number of cables cut by up to half — dramatically cleaner pedalboard
• no more AC power required
• no more wall warts
• no more droop or vanishing headroom
• no more D.O.A.
• no hassle setup and teardown
• no more land-filling spent batteries
• no more scrounging or running out for batteries before or during a gig
• high current — 1,500mA continuous, 4,000mA burst
• ultrasonically maintained, linearly-regulated, pristine power

GAGA's licensed and improved implementation of P3 Technology® includes overcurrent, overheat and custom short-circuit protection, pushbutton power on/off, and 1.5 amperes (13.5 Watts) continuous (4 amperes (36 Watts) burst) current of ultrasonically maintained, linearly-regulated, pristine power for all 9-volt pedals and active pickups.

GAGA Power, Weight, Tone and Feel

In its final, production form GAGA is six pounds of amp in about six pounds of chassis; powerful, flexible, and oozing pure tube tone.

The first (proof-of-concept) prototype GAGA weighed about three pounds and produced about 50 Watts of power. That prototype was without universal power and required a practical, sturdy chassis (see below).

Now, in a strong but lightweight aircraft-aluminum chassis with all features, GAGA can provide 50 Watts of clean (RMS) output power and (depending on power tube complement) up to 90 Watts of (highly distorted) output power. The maximum power output we've measured is 128 Watts into 8 Ohms using four 6CA7 power tubes. For reference, a typical power tube complement (four 6L6's) provides about 50 Watts (RMS) of clean, undistorted output power, and about 90 Watts of highly distorted output power.

GAGA will operate with four, three or two power tubes, with consequently diminshing output power. The onset of power tube overload can be adjusted (via the Headroom control) with any tube combination.

World Power Ready™ — Universal Power, Power Factor Correction (PFC), Power Consumption

GAGA may be plugged in anywhere on Earth without adjustment. Proper power design is intrinsic and was not an afterthought. GAGA is an efficient global power citizen.

POWER CONSUMPTION, MAINS POWER INPUT
Voltage range is 90 VAC to 240 VAC, from 50 Hz (thru 60 Hz) up to 440 Hz. Maximum power consumption is 200 Watts.

LINE FILTERING, SURGE SUPPRESSION
Safer and more adept than most "power conditioners", GAGA includes double surge suppression, a four-stage line filter, and proper isolation, shielding, layout and grounding.

POWER FACTOR CORRECTION (PFC)
GAGA is Power Factor Corrected (actively and automatically), meaning that although GAGA appears (at its mains input) as a negative resistance (i.e., whose current draw increases with decreasing voltage) its power consumption presents relatively synchronous ("corrected") current and voltage waveforms to the power mains, presenting a manageable load instead of one that's highly reactive and noisy.

REGULATED POWER vs VARIACS, DIMMERS, SAG and BROWN SOUND
GAGA's advanced power supplies maintain internal regulation by appropriately adjusting current draw from any standard line ("mains") supply. Dimmers and VARIACS, sometimes used to "sag" voltages and cause a "brown sound", will not work with GAGA because GAGA will draw more current as voltage drops to maintain power.

STANDARDS COMPLIANCE - CE, MIL-SPEC, ROHS
Above "mil-spec" in many ways, GAGA is also CE and RoHS compliant. Lead content is greatly reduced, no known toxic materials are present, and strong electromagnetic emissions are neither unduly accepted or emitted.

IDLE, EFFICIENCY NOTES, P3 DRAW
With four 6L6 tubes inserted, GAGA consumes 0.5A at 117VAC (60Hz), or about 60 Watts. Approximately 25 Watts is consumed by tube heaters. Approximately 20 Watts (2,400 mA) is available as 9-volt P3 power for pedals and active pickups. Excepting tube heaters, GAGA is otherwise highly efficient.

Everything about GAGA is on 3 main web pages Brief, Details, Technicals.

Preliminary information will change. Last updated 30 Dec 2011