| My passion for the sound of the electric guitar started when I heard the albums 'Balls To the Wall' and 'Metal Heart' of the then popular German band 'Accept', which I still like very much. The sound of electric guitars I heard on these albums was pleasantly shocking, since it was powerful and aggressive, but at the same time it was not the sharp and shapeless-at-low-frequencies sound of many other guitar heroes of that time. And that very sound of middle frequencies evolved into my own standard of the guitar sound.
Speaking about the aesthetical side of this band's music I would like to note the guitarist Wolf Hoffmann's performance, whose execution of the famous Beethoven's etude 'Fur Elise' in a song titled 'Metal Heart' made a strong impression on me. I did not expect that the famous musical composition, which is usually ment to sound calmly, could be executed so expressively producing a storm of energy. As the time went by, 'Accept' split and UDO's new solo albums started to appear, this time with other guitarists invited. However, the guitar sound was still very good though it definitely was not the same. In spite of this fact, the sound was remarkable for its drive and definiteness when, due to German pedantry, every single note in every guitar part could be heard. At the same time, the overall sound remained very transparent, though Udo's vocal could not be called pop-sounding.
The sound of the German heavy-metal was very inspiring, making my life more rich emotionally, but then I did not even think to start learning to play the guitar, not to mention the idea to start producing guitar effects of my own construction.
So, it all started by pure accident. In 1989 (if I am not mistaken), a friend of mine who knew that my job was connected with electonics brought me an electric guitar asking to construct a distortion pedal for him that posessed unique characteristics. Before that moment, I had never had an experience of constructing the devices of such kind since I mainly repaired audio- and video equipment. The very moment I first took an electric guitar in my hands was the moment I entered the magic world of the guitar sound.
Armed with all the necessary electronic instruments, I was studying the frequency characteristics of my favourive guitar tracks containing only the guitar sound. Out of mere curiosity I tried about 500 various electric schemes found in all kinds of technical sources, at the same time copying the schemes of the famous models of effects and amplifiers. However, I still was not satisfied with the sound of the standard mass-produced devices as well as with the sound of the effects constructed by me.
My inborn curiosity stimulated me to continue stydying the peculiarities of the sound of the guitar effects, which was just a hobby. I experimented a lot, constructing single-copy guitar effects for my friends, adjusting the effect pedals they'd already had according to their requests and repairing guitar amplifiers. I continued to search for my own formula of sound, which would enable the guitarist to feel a feedback from the emotions he is putting into the music while playing the guitar at any volume of the guitar amplifier.
 I liked the sound with an unpronounced attack since I wanted to get close to the sound of soloing bow-instruments. After a time I managed to develop my own scheme, which did not have any analogues. That was a device assembled on 6 chips. The compressor placed before the limiter made the attack (the sound in the moment the string is being plucked) smoother, gradually raising the level of each note, which in some way resembled the violin. The active filters placed before the limiter formed the main tembre, while the filters placed after the limiter emulated the frequency characteristics of the guitar speaker. It was then when I invented my own sound. That stomp-box sounded good through any amplifiers, while its sound differed from distortion pedals of traditional schematics. In 1995, quite suddenly, my hobby turned into my main occupation. By that time about 3000 stomp-boxes of my own construction described above had already been produced.
As the time went by, my musical preferences changed and due to this I started to dislike my guitar sound. I wanted to make it alive and breathing; I also wanted to make the attack on the moment the string is being plucked with a pick more pronounced. So I started experimenting once again. This time I, already being an experienced developer, decided to make the scheme quite simple. As it is well-known, the less the sound is proccessed, the more lively it seems. At the same time I started developing schemes on vacuum tubes and modern chips, since the use of chips is more preferable in terms of easiness of production and copying.
But chips, unlike tubes, act differently in the overdrive phase and even the famous tube-emulating schemes on chips does not produce the same effect in the overdrive phase as does a simple tube limiter. The difference can be easily noticed not only aurally. The signal obtained can be broken down to its constituent parts and the difference between a tube limiter and the transistor or the chip can be visually observed. Tube limiting amplifiers produce both even and odd harmonics depending on the degree of overdrive, enriching the guitar sound at the low level of limiting. Semi-conducting limiting amplifiers always produce only uneven harmonics (without emulating the operation of the tube). The sound signal consists not only of the main tone since there are always both even and odd harmonics present in it. The even harmonics add fullness and warmth to the signal, while the uneven ones add rigidness and typical metallic side-tones at high frequencies. That is why I was not going to reinvent the bicycle, having decided to develop a scheme entirely assembled on tubes, i.e. using the scheme proved by a score of years.
So, a painstaiking research started accompanied by tests with various modes of tube operation. To choose the type of filter and the cutoff frequency for both low and high frequencies was the most difficult task. This is a very important point because it depends on these very parameters whether the sound of the guitar will cut through the mix, not losing its unique character when overdriven. The point is that many manufacturers, when trying to reduce the level of the background noise of a product to the minimum, are paying much attention first of all to the noise characteristics of the product's scheme; it seems quite natural that manufacturers take into account the fact that the devices produced will be used by guitarists posessing guitars of different quality with different pickups installed. Thus, it is impossible to predict beforehand what noise level a certain customer will have when he will use a serially produced device, since all the pickups differ. That is why the manufacturers, to make sure that nobody would be able to say that a device has a high noise level, prefer to strongly reduce the high frequency component of the guitar signal. There are various ways to suppress this high frequency signal component, starting with the use of a simple condenser connected in parralel to the input of the tube/chip and ending with the use of active filters and frequency dependent circuits with degenerative feedback. This is at the same time another method of fighting positive feedback, which may occur when the volume is increased on a guitar equipped with low-quality pickups. In practice, this effect manifests itself through an uncontrolled squeal (generation) when the guitarist tries to increase the volume on the amplifier. The active use of the degenerative feedback in the distortion-type effects suppresses the high harmonics of the guitar itself, this being a sort of compromise between a vivid and open sound of the guitar and the acceptable noise level of the electromagnetic pickups. Developing my scheme, I was lucky enough to avoid such kind of compromise and get a good noise to signal ratio. A passive high frequency filter was used only in the third cascade (third triode) in order to supress new harmonics of the previous cascade produced as a result of overdriving the signal.
 By using the trial-and-error approach the present scheme was gradually adjusted and tested during many gigs and studio sessions. 1,5 years later a pilot lot of the all-tube T-324 distortion was produced. Though the scheme of this device turned to be quite simple, the ratings of all the electronic components were carefully selected. I decided not to use any equalization since additional equalization brings phase petrubations of its own. A passive filter with the 3 kHz cutoff frequency is only used to control the tone in the T-324 distortion. Despite the fact that ceramic condensers are so widely used, only high quality paper-film condensers with high dielectric resistance were used to provide for a stable operation of the device.
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The T-324 distortion was in the first place intended for the experienced guitarists who have already tried a lot of amplifiers and who have not only learned how to play the guitar well, but have also developed a good taste for the guitar sound. The high demand for these pedals has demonstrated the neccessity to start developing separate all-tube distortion pedals, which would enable the guitarist to obtain a natural and transparent sound of the electric guitar with the distortion effect, at the same time not bringing the cascades of the final amlifier's tubes to the limit and providing a good classic sound even at a low volume.
Now I am developing tube devices of this very kind and also constructing custom-made tube preamps according to different sound, switching and design requirements. |
