30 years of basic research and product innovation. Industry leading physical modeling technology underlies the strength of K’s Lab.
We met the one-of-a-kind sound research group, K’s Lab, in two preceding articles: “How the discovery of a 1977 thesis led to a breakthrough at the Yamaha K’s Lab research division 30 years ago,” and “Rupert Neve designs from the 60s and 70s realistically recreated by the Yamaha K’s Lab research team.” In this, the third and final installment of the K’s Lab series, we will take a look at some of the processors and guitar amplifiers that have been created using their VCM (Virtual Circuitry Modeling) technology.
Rather than recreations of classic equipment, the products discussed in this installment are new designs based on the results of K’s Lab research. We interviewed the researchers who developed the MBC4 multiband compressor and Dynamic EQ4 four-band equalizer included in the RIVAGE PM series digital mixing system, and the extremely popular THR series compact guitar amplifiers, and will focus on those products in this article.
As mentioned in previous installments, K’s Lab is a research group led by Yamaha research fellow Dr. Toshifumi Kunimoto, located at Yamaha headquarters in Hamamatsu, Japan. The group spearheaded the new field of virtual acoustic technology in its early years, and later teamed up with audio legend Rupert Neve to digitally recreate some of his most famous and sought-after designs from the past using modeling technology. K’s Lab has been engaged in research and development at the forefront of sound technology for approximately 30 years.
The first person we spoke to for this article was Mr. Hayato Ohshita, the researcher who was in charge of MBC4 development. At university Mr. Ohshita was involved in research aimed at developing technology that could differentiate between the sounds of musical instruments, automatically transcribe music, and more. After joining Yamaha he was assigned to VOCALOID research and development, and became a member of the K’s Lab team in 2010. Mr.Ohshita started work on the MBC4 in around 2013.
Mr. Ohshita begins: “The use of multiband compression in digital mixers for music production and live sound reinforcement was not unusual, but many users were confused and even intimidated by the extensive array of controls that such devices involved. Even using a basic compressor can be daunting. We wanted to solve the problem, and began work on the MBC4.”
The generic diagram below shows how multiband compression works. The input signal is divided into multiple frequency bands that are then fed to independent compressors, the outputs of which are mixed to produce the final output signal. Multiband compression can help blend and unify multiple sounds, making it ideal for natural-sounding mastering. But it is also ideal for processing individual sounds when a natural result is desired. For example, it can be used to achieve a smoother, more balanced overall sound by separately processing the vowels and consonants in a vocal track, the attack and body resonance of a guitar or bass, or the low and high frequency components of a drum set.
The difficulty is in the sheer number of controls and/or parameters that must be understood and adjusted, and in monitoring the current state of operation. To resolve these issues, the GUI was refined and VCM technology was employed to provide a set of parameters that would be easy to use.
Mr. Ohshita adds: “We really wanted to make it easy to “read,” so we adopted a graph type display with color coded frequency bands. We also tweaked the size, color, and contrast of the on-screen text and controls until we were totally satisfied. To make adjustment easier, we added FLAVOUR (VCA and OPTO) and HARMO switches that help users achieve the sound they’re after.”
The switches mentioned are located in the lower right corner of the interface. The VCA “flavor” results in solid compression with clear level control, and is ideal for situations that require tightly controlled compression. The OPTO setting has slower attack and release response, so you don’t hear the compressor working. OPTO is a good choice when a natural sound is desired. The HARMO switch can also be engaged to add warmth and depth as well as sparkle, improving the way sounds blend.
Ohshita: “All of these parameters are based on VCM know-how accumulated by K’s Lab through years of research. They are not VCM emulations of any specific existing equipment, but entirely new features created using VCM technology. A number of live sound and recording engineers actually used the processor during development, and we made adjustments based on their feedback to ensure that it would be easy to use.”
Like the MBC4, the four-band Dynamic EQ4 equalizer included in the RIVAGE PM10 is a new processor built on VCM technology.
Kenji Ishizuka, the researcher who was in charge of Dynamic EQ4 development, explains: “CL series digital mixing consoles include two-band Dynamic EQ that is easy to use and very highly regarded. The only problem is that two bands aren’t enough in some cases. Development of the four-band Dynamic EQ4 was initiated with the goal of providing four bands while retaining the sound quality and operability of the original two-band version.”
As shown in the diagram below, the Dynamic EQ4 equalizer distributes the input signal to two filters, one of which feeds a level detector and EQ gain calculator that controls the gain of the remaining filter. The main benefit of this configuration is that it allows targeted control of very narrow frequency bands. Mr. Ishizuka surprised us by demonstrating an unusual way of using the equalizer.
Mr. Ishizuka continues: “The ability to target specific frequency bands makes it possible to control sibilance (“s” and “sh” sounds), a job that would normally be handled with a de-esser. Unlike a de-esser, the Dynamic EQ4 effect can also be used to control plosives (“t”, “k”, “p”, “d”, “g”, and “b” sounds). It can be very effective in suppressing excessively prominent elements of a vocal track. It is also great for organizing frequencies. For example, overlapping kick drum and bass guitar frequencies can result in muddy sound. Dynamic EQ4 can be used to reduce the level of the bass guitar only when it overlaps the kick drum.”
It seems that the Dynamic EQ4 equalizer can function as a type of sidechain effect when used to control overlapping frequencies as described above by Mr. Ishizuka. ABOVE and BELOW mode switches are provided for each band, and these can be used in conjunction with the RATIO control to produce a level boost when a specified level is exceeded, gate-like operation in which the signal is allowed to pass only when a preset level is reached, as well as compressor-like level reduction when the set level is exceeded.
Mr. Ishizuka: “The selectable shelving response of the Dynamic EQ4 effect is a characteristic that has been made possible by VCM technology. When the shelving mode is selected, frequencies beyond the shelf are not simply attenuated, they are attenuated in a very musical way that has been derived from our vast library of VCM research data.”
A quick note about Mr. Ishizuka’s background. In university he was in the control systems department, and could engage in just about any field of research that interested him, so he began working on ways to control speakers digitally. That, and his interest in guitars, led to employment at Yamaha where he received his dream assignment to K’s Lab after working on the RIVAGE PM series user interface and other projects.
While much of the VCM technology that emerges from K’s Lab ends up in professional equipment, some has reached a wider spectrum of users. THR series guitar amplifiers are one example. K’s Lab researcher Takashi Mori was responsible for the development of the THR series. Although Mr. Mori was primarily occupied with research on simulating the physical properties of semiconductors in university, a subject that is fundamentally unrelated to sound, his first major assignment after joining Yamaha was the THR series.
Mr. Mori recalls: “I started out working on firmware for the THR amplifiers, but was later assigned to K’s Lab where I began working on the signal processing. Unlike other products that include VCM technology, there was no plan to use VCM in the THR amplifiers when the project was initiated. The original idea was to create a unique guitar amplifier that would stand out amongst the innumerable amps that already existed. Our discussions led to the concept of a guitar amplifier that would not be out of place on a desktop. These days many guitarists play while watching YouTube or while using a DAW program like Cubase, so a small amplifier that could be placed on a desktop and yet still deliver authentic big-amp sound seemed like a good idea.”
Mr. Mori: “It was eventually decided that the full force of Yamaha technology was to be applied to the THR amplifiers, and an original DSP LSI manufacture in-house by Yamaha was selected for the job. That chip embodies large variations of audio processing technology, plus USB communication functionality, which was an advantage both in terms of computer connectivity and cost. We also adopted Hi-Fi audio technology from the Yamaha audio division for the amplifier’s speaker section. And then when it came time to actually create the amp’s sound, we chose amp simulators, flangers, chorus, and other effects based on VCM technology developed by K’s Lab.”
Development proceeded in accordance with catchphrases like “Your Sound, Anywhere” and “An Amp that Delivers Serious Offstage Sound,” and when VCM was incorporated, evaluating artists began making comments like “this is an amp I can play seriously” and “this is the real thing.” At that point the development team knew they had more than just a compact desktop guitar amp. They had an amp that players could really use.
In reality, the THR guitar amplifiers were not the first to include K’s Lab modeling technology. The DG1000, released in 1997, included digital vacuum tube amp modeling and was generally based on a similar concept, but advances in signal processing technology made it possible to take the concept to a much higher level in the THR amps.
This graph shows the point at which a vacuum tube amplifier model begins distorting. The blue line represents a previous tube amp model, and the red line is a new THR model.
Mr. Mori continues: “This graph illustrates how much the modeling has improved. It shows the point at which a tube amp model begins to distort, and by using that as an indication of how the sound will change the difference becomes clear. The blue line, representing an earlier model, is essentially straight up to a certain point, and shows clipping. The red line representing a THR model, on the other hand, curves gently past the bias point, indicating a smoother, rounder sound. The difference may appear slight on the graph, but the difference in sound is quite significant.”
Of course, modeling is not limited to Yamaha or K’s Lab. It is actively applied by many manufacturers throughout the world. VCM modeling developed by K’s Lab is distinguished by the fact that it is based on measurements of each and every vacuum tube involved, and detailed modeling at the component level. Even subtleties like the slight variations between individual components that add up an amplifier’s “character” become part of K’s Lab models.
Mr. Mori: “The seven guitar amplifiers, four effects, and compressor included in the THR10 are all VCM models. The delay doesn’t use VCM, but one of the reverbs is a VCM model. And it is not just circuit modeling. Six physical cabinet models are included as well. The cabinet models aren’t new though. Basic models that existed in the K’s Lab library were specially tuned for the THR amp.”
One of the strengths of VCM is that it is not simply a collection of “presets.” It provides frameworks that can be easily tuned to achieve the desired sound, and that is why it is possible to create a unique, character-rich amp like the THR in a relatively short period of time.
Mr. Mori: “Each amp has different points of appeal that need to be modeled, and the way each knob affects the sound changes too. During development we had professional guitarists use the product, and we made changes on the fly based on their feedback. The fact that we were able to make adjustments that went much deeper than simple EQ tweaks when the product was basically finished is undoubtedly one of the reasons for its success.”
Mr. Mori concludes: “Many users have commented that it is a very analog-like, serious amplifier, but inside it is all digital. These days, extremely high-level digital technology is essential to the creation of analog-like sound. The fact that you can connect a THR amp to a computer for detailed editing is also an important feature. In that sense THR amps are ideal for DTM recording, and we expect users to find new ways of using them that suit their individual working style.”
The compact THR10 and its variations are not the only models in the THR series. There is also the larger THR100 with separate head and cabinet that is a favorite of many guitarists.
That completes our three-part series in which we introduced the Yamaha K’s Lab research group and some of the technology that has grown from their basic research. We have learned that long years of basic and applied research have given birth to many products that are now held in high regard throughout the world. We have also seen some of the difficulty, but also the fascination, of developing digital models through VCM technology.
It is often said that basic research is not one of Japan’s strengths. In reality, Yamaha has been carrying out industry-leading basic research for more than 30 years. The K’s Lab legacy is being passed on to younger researchers, and there is no doubt that even more fascinating technology and epoch-making innovations will be forthcoming.