KVG Sound

The Sensations Of Tone

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Counterpoise Audio Output Transformer (click here for more information).
KVG Laboratories is pleased to announce our new Counterpoise Single-Ended Output Transformer, the product of ten year's intensive research into the design and quality of single-ended amplifiers. The Counterpoise is be standard equipment in many of our models. Typical single-ended transformers have an core made with an air gap to prevent the core from becoming saturated because of the unbalanced current flowing through the transformer primary windings. While many manufacturers boast of the design and materials used in their transformer core's air gaps, they nevertheless do have an air gap.

The Counterpoise has no air gap, unlike all other single-ended transformers. How is this possible? The Counterpoise incorporates a proprietary core degaussing coil that neutralizes the DC-induced magnetic field that would otherwise saturate the core and lead to distortion. The thematic diagram to the right shows the basic design of a Counterpoise.

The Counterpoise offers many advantages over traditional single-ended output transformers.

  1. Variable voicing: can be adjusted to sound very clean with late distortion, or very dirty with early distortion, all at the twist of a knob This unique feature offers unparalleled tonal variation in music instrument amplifiers, or optimized performance in audiophile amplifiers.
  2. The Counterpoise eliminates the air gap found in all other single-ended transformers.
  3. A Counterpoise transformer is more compact than traditional designs.
  4. A Counterpoise transformer is less expensive than traditional designs.
  5. The bass response of a Counterpoise transformer is superior to traditional designs because the degaussing coil reduces core saturation, allowing the Counterpoise to handle greater magnetic flux densities than traditional designs.
  6. A Counterpoise transformer can be made in power levels up to 200-Watts or greater. High power output capability is practical with the Counterpoise, whereas traditional designs seldom are capable of more than 20 Watts or so.

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Varipoise Audio Output Transformers (click here for more information).
KVG Laboratories is pleased to announce our new Varipoise Push-Pull Output Transformer, the product of ten year's intensive research into the design and quality of push-pull amplifiers. The Varipoise is standard equipment in many of our guitar amplifiers. Typical push-pull transformers are designed with the assumption that equal current flows in each half of the primary winding. The Varipoise can operate with severely unbalanced DC in both halves of its primary, allowing for more reliable operation and lower costs than traditional boutique-quality guitar amplifier output transformers. Better yet, the Varipoise allows the push-pull output valves to be deliberately unbalanced, creating new and unusual tones unavailable form any other guitar amplifiers.

The Varipoise offers many advantages over traditional push-pull output transformers.

  1. Variable voicing: can be adjusted to sound very clean with late distortion, or very dirty with early distortion, all at the twist of a knob. This unique feature offers unparalleled tonal variation in music instrument amplifiers, or optimized performance in audiophile amplifiers.
  2. The Varipoise is more reliable than most other push-pull transformers.
  3. The Varipoise transformer sounds great even with severely unbalanced output valves -- if one output tube fails, the amplifier will still make excellent sound with reduced output power. Your amplifier will be more reliable as a result.
  4. A Varipoise transformer lets the designer create new amplifier tones and unique-sounding guitar amplifiers.
  5. Amplifiers made with Varipoise transformers can operate in a balanced push-pull mode, a single-ended mode, a reverse-phase single-ended mode, or a continuously-variable unbalanced push-pull mode. This gives you a nearly-infinite variety of unusual tones and a sound like no other guitarist has.

Discrete Audio Opamps (click here for more information).
Designed as the basis for a many of our products, our A8500, A8700, A8800 and A8900 Discrete Audio Opamps offer the clarity and musicality of traditional transistor circuitry with the high common-mode rejection and easy versatility of integrated circuit opamps. Moroever, our Discrete Audio Opamps are optimized for a specific purpose in ways no integrated circuit can. Discrete opamps such as the Opamp Labs 425 and the John Hardy 990 have been the secret behind many of the finest-sounding audio equipment. Building on this tradition, our discrete opamps are made with silicon, point contact or germanium bipolar transistors, Darlington transistors, FETs, MOSFETs or IGBTs for a nearly unlimited palette of sounds.

Typical Features and Specifications:

  • Gain Product Badwidth of 3 MHz to 3.5 MHz.
  • Wide dynamic range.
  • Low noise floor - Equivalent Input Noise of better than -125 dB at 50 dB of gain.
  • Wide frequency response, at least DC - 100 kHz +/- 0.1 dB at 50 dB of gain.
  • Excellent transient response with minimum overshoot thanks to flexible compensation ports.
  • Versatile, easy to implement; design as with any monolithic opamp.
  • High reliability because they may be repaired in the field. Unlike IC opamps, damaged Discrete Audio Opamps don't need to be thrown away.
  • Designed for several standard power supply voltages: +/-1.5V, +/-5V, +/-9V, +/-18V, +/-24V, and +/-36V,

CNC Gantry Mill (click here for more information).
An important part of our production facility is a small footprint CNC (computer numerically controlled) gantry mill designed for industrial cutting in wood, acrylic and metas. CNC machines are powerful tools controlled from a computer software program which enable the operator to make everything from simple cut-out shapes to intricate 3D carvings, and everything in between.

Our CNC machine has easy-to-use but versatile software to drive the machine to make precision components that can hold tolerances of better than 1/1000-inch, even in wood. The machine itself is built in the USA using materials and components primarily sourced from USA suppliers.

The easy programmability of the CNC machine allows us to quickly customize each product we make. This CNC machine is one of the secrets to our unique ability to produce one-of-a-kind custom products individually, yet achieve the same efficiency as other boutique equipment makers who produce only a few largely-standardized models. We can achieve this efficiency without compromise, in part thanks to our CNC machine.

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Vacuum Tubes Versus Transistors (click here for more information).
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KVG Laboratories builds equipment with both tube or transistor electronics. Most of our designs are vacuum tube, but not for the reason you may expect. Most writers assert that tube electronics lack the clarity and low distortion of transistors. This assertion is seemingly verified by the majority of commercially made equipment that is encountered, but to generalize that a commercial example of tube technology represents the ultimate capability of the technology is erroneous. Proprietary research of the causes of, and characteristics of, all forms of distortion and quality losses in vacuum tube and transistor technology has given us a unique perspective. KVG Laboratories has developed proprietary design techniques and circuit elements for vacuum tube electronics based on our research. Vacuum tubes are actually capable of the same level of clarity and low distortion as transistors, albeit with possibly greater cost. A tube won't overload with as great a magnitude of clipping, which is an advantage over transistors which clip a signal readily during transient overloads.

KVG Laboratories does build most of its electronics products with vacuum tubes because we can create any sound the customer requires more quickly and more easily with tubes than we could with transistors. Regardless of whether the customer wants extreme clarity, extreme distortion or anything in-between, KVG Laboratories can almost always satisfy the required sound using vacuum tubes. In those instances where portability or size are important requirements, or where we cannot satisfy sound requirements with vacuum tubes, we use a variety of transistor designs.

Engineers and musicians have long debated the question of tube sound compared to transistor sound. Measurements of the differences assume the tested amplifiers operate perfectly linearly, which in fact is never the case. Conventional methods of frequency response, distortion and noise usually show that no significant difference exists between tubes and transistors. Recording engineers often are directly involved with the controversy of tube sound versus transistor sound, especially in pop recording and in audiophile recording projects. Differences are quite noticeable now that solid-state consoles are commonplace. It's not uncommon during a recording session in studios notorious for bad sound that a visiting engineer will plug the microphones into vacuum tube mixers or preamplifiers instead of the regular console. The result is often a change in sound quality that is nothing short of incredible, surpassing even improvements made to the studio's acoustics.

Those who avidly listen to analog LP disc records can easily discern that tubes sound different from transistors. Defining the cause of the difference is a complex problem in psychoacoustics, that is further complicated by a wide variety of subtle phenomena. Musicians usually are more objective listeners than audiophiles or engineers. They don't express their observations in standard units, but the musician's "by ear" measuring technique seems quite valid because the human ear's response may be quite different than an oscilloscope's.

Common statements by musicians express their observations that:

  • Recordings made with transistor electronics tend to emphasize sibilance, especially at low levels.
  • Recordings made with transistor electronics tend to over-emphasize emphasize cymbals, especially at low levels.
  • Recordings made with transistor electronics are very clean yet lack the "air" of a recording made with vacuum tube electronics.
  • Recordings made with tube electronics have a tightly defined space between the instruments, even when they play loud
  • Recordings made with transistor electronics sound restricted, like they're under a blanket.
  • Recordings made with tube electronics "jump out of the speaker at you."
  • Recordings made with tube electronics have more bass.
  • Bass sounds like it is an octave lower with tube electronics.
  • The middle range of recordings made with tube electronics is very clear
  • Each instrument has presence with tube electronics, even at very low playback levels.
  • Vacuum tubes do not restrict the music's dynamics because they overload gently.
  • Transistors buzz.
  • Transistors add musically unrelated harmonics or white noise, especially on attack transients.
  • Transistors have a "shattered glass" sound that restricts the music's dynamics.
  • Transistors have highs and lows but there is no "punch" to the sound.

The major distortion characteristics of vacuum tube amplifiers are the presence of strong second and third harmonics, often in concert with, but greater than, the amplitudes of the fourth and fifth. Harmonics above the fifth harmonic are insignificant until the equipment's overload exceeds 12 deciBels.

At first, the vacuum tube was the only way to build audio equipment. The 1950s brought the transistor, which rapidly pushed vacuum tube-based electronics out of the market because advertisers in the late 1960s said that the solid-state electronics was the “wave of the future,” claiming it was always quieter, clearer and more accurate when compared to vacuum tube gear. That told only part of the story. Transistors are the best technology for many applications (computers being one excellent example), but they are not always the best way to build an audio circuit. Professional recording studios and many audiophiles have always prized tubes for the tone and quality of the sound they produce, seeking the very “coloration” that was criticized in Hi-Fi marketing literature. The recent rise of computer-based digital audio has increased the demand for tubes.

Triodes and pentodes differ in the composition of their distortion components. When triode tube amplifiers distort, the second harmonic is dominant, followed closely by the third harmonic; the fourth harmonic's level rises 3 to 4 deciBels later; and the fifth, sixth, and seventh harmonics remain below 5% up to the equipment's 12 deciBel overload point. Clipping is asymmetrical and the waveform's duty cycle shifts prominently. When pentode and cascode amplifiers distort, the third harmonic is dominant and the second harmonic increases about 3 dB later, both the fourth and the fifth harmonics are prominent, the sixth and seventh harmonics remain under 5% up to the equipment's 12 dB overload point. Clipping is asymmetrical and the waveform's duty cycle shifts slightly.

Transistor electronics have different distortion characteristics, with their distortion being dominated almost entirely by the third harmonic, with all other harmonics present at a much lower amplitude than the third harmonic. As transistor electronics overload, the amplitudes of all the higher harmonics begin to increase simultaneously within 3 to 6 deciBels of the 1% third harmonic point. Overload waveforms of transistor amplifiers are the distinct square wave shapes, Clipping is symmetrical and the waveform's duty cycle is not altered.

Operational-amplifier, or opamp, electronics exhibit distortion similar to that of transistor electronics, of course, but the rate of the increase in the slope of distortion rises steeply because of the extreme amount of inverse feedback inherent to opamp-based circuits. The third harmonic is the dominant distortion component, but its slope increases steeply, occurring from Also rising very strongly from the same point as origin of the fifth and seventh harmonics. Opamps suppress all even-order harmonics completely. Even slight overloading results in a perfect square wave, limiting the opamp circuit's ability to reproduce transient overload cleanly.

In summary, the differences between tube and transistor sound is caused by the relative proportions of the harmonics that comprise the amplifier's distortion during the time the amplifier overloads. Transistor amplifier distortion is mainly comprised of the third harmonic, creating a "veiled" sound that gives recordings a restricted quality. When a vacuum tube amplifier overloads it generates a spectrum of harmonics comprised of a particularly strong second harmonic, with overtones from the third harmonic, fourth harmonic, and fifth harmonic, creating a full-bodied "brassy" quality to the sound. As the amplifier's overload increases, the magnitude of the seventh harmonic, eighth harmonic, and ninth harmonic greatly increase, adding an edginess to the sound which the human ear interprets and a sign of increasing loudness. When an opamp overloads, it produces harmonics with such extremely-fast rising slopes that they quickly become objectionable. Transistors extend the overload range, while vacuum tubes provide the greatest extension of overload range. This illustrates why vacuum tube amplifiers are considered excellent for music instrument amplifiers as well as high-end high fidelity amplifiers.

Musicians have determined how various harmonics relate to the timbre of a musical instrument.

  • The timbre of an instrument is determined by the magnitude of the first few harmonics.
  • Each lower harmonic produces its own effect on timbre when it dominates, and it modifies the effect of another dominant harmonic when it becomes prominent.
  • Odd-order harmonics (the third and fifth) produce a "blanketed" or "veiled" sound.
  • Even-order harmonics (the second, fourth, and sixth) produce "choral" or "singing" sounds.
  • Musically, the second harmonic occurs one octave above the fundamental tone and is therefore imperceptible on its own because of masking. Yet, the second harmonic adds fullness to an instrument's timbre.
  • The third harmonic is referred to by musicians as a "quint" or a "musical twelfth." Therefore, the third harmonic produces a softer timbre, creating the sound described by many musicians as "blanketed."
  • Adding a fifth harmonic to a strong third harmonic gives the instrument's timbre a metallic quality that becomes annoying or grating as its amplitude increases.
  • A strong second combined with a strong third harmonic tends to open the "veiled" sound.
  • Adding the fourth harmonic and the fifth harmonic to the combination of second and third harmonics changes an instrument's timbre to an "open horn" like character.
  • Higher harmonics, above the seventh, give "edge" or "bite" to an instrument's timbre. If the edge is balanced with the fundamental pitch, it reinforces the fundamental, giving the timbre a sharper attack.
  • The seventh harmonic, ninth harmonic, and eleventh harmonic are musically-unrelated.
  • The presence of too many "edge" harmonics produces a raspy, dissonant timbre.
  • The human ear seems very sensitive to the edge harmonics, so minimizing their amplitude is extremely important.
  • The effect of "edge" harmonics varies directly with loudness.
  • Playing the same note pianissimo or forte creates little difference between the amplitudes of the fundamental tone and its lower harmonics.
  • The amplitude of any harmonic above the sixth harmonic varies directly with changes in loudness.
  • The relative balance among "edge" harmonics is a critical cue for the ear to perceive changes in loudness.

As an aside, the second and third harmonics are those used when making electronic distortion measurements, which brings into question the validity of steady-state distortion measurements as a means of predicting the subjective quality of an amplifier.

© 2015 by Kermit Gray • Telephone (913) 422-0957 • Shipping address upon valid request. Contact