Technical Brief

Looking at Solid State and Modelling Amplifiers

Tube amps have been the default choice for amplification of an electric guitars signal since Les Paul created the guitar that carries his name. Tube amps have remained the staple for discerning musicians since then. However, in the 1970s a challenger arrived, the transistor or solid state amplifier. While being more reliable, cheaper, less damage prone, and easier to work on than tube amps, they never quite caught on with more astute guitarists. Their complaints range from, They just dont sound good, to, They just dont feel alive man! Are these complaints justified? Are solid state amps inferior to their tube counterparts. How do solid state amps work? I will be discussing these questions in the paragraphs ahead.

How Do They Work?

All amplification equipment works on the same principle, we need to turn little sound waves into big sound waves. Tube amps achieve this by modulating and amplifying the input signal from a guitars pickup through a variety of different vacuum tubes to create a tone. Transistor amps perform the same job as the tube amps do, However, instead of using tubes to amplify the sound, the transistor uses digital circuits that behave in a similar way to perform the same task. Pretty much since the invention of the transistor, tube amps for just listening to music normally have been phased out. The reason being is that it is cheaper, more efficient, and can be much smaller. For replicating sounds from a recording and playing it through. Solid state and tube amps are virtually identical. The difference here is that we are talking about guitar amplification. Guitar amps need to interpret and distort the signal going into them in a different way than just standard sound amplification. Many people feel that tube amps create a more alive and warm sound. Of course, these subjective terms but there is truth to the matter. Early, and a lot of cheaper modern, solid state amps create very dry tones. That being said many high-end transistor amps and modelling amps can create tones that sound and behave in a way almost indistinguishable from tube amps. (Burnett)

Rise In Use

With increasingly powerful computers and modern technology, the line between tube and solid state becomes blurrier by the day. The transistor amp revolution was started in 1956 by Paul Penfield Jr. who published a paper titled Transistorized Guitar Amplifiers outlining the details of a transistor guitar amp. In 1962 Kay, a small company known for making cheap musical instruments, brought the first transistor amps to the market with their Vanguard line. After this happened larger companies like Gibson jumped on the bandwagon releasing their own transistor amplifiers. These first transistor amps however were not very reliable. Not much was known about transistors at the time so the first transistor amps used the same circuits that tube amps did only with the tubes swapped out for transistors. More development would be needed for the product to become a viable competitor to tube amps.
After these first failures, manufacturers began to spend more time and money on research to create circuits designed for transistor amps specifically. This lead to the release of products like the Fender Super Showdown, a large improvement over the original designs. In the 1970s transistor amps began to improve drastically. Roland released the JC 120, a legendary amp that is still popular and manufactured today.
In the 1980s transistor amps gained widespread success with products like the Peavey Bandit. Due to their low cost and reliability, solid state amps have become the norm for bedroom rockers and professional musicians alike. During the 1980s the next big breakthrough came along. This breakthrough was digital amp and effects modelling.

Amp Modelling

Unlike transistor amps which use transistors to act like tubes in an amp circuit, digital amps are on a chip exclusively. The computer then emulates the characteristics of amps via software. There are two distinct types of amp modelling. The first is hardware amp modelling. High end products like the AxeFx and Kemper have powerful processors that can emulate accurately the qualities of hundreds of different amps and effects. Among other features they can also learn to emulate new amps. These products can listen to a true tube or transistor amp and match that tone perfectly. These high end products blur the lines between their physical counterparts significantly. There is very little to no difference in the way these tools sound, play, and react to a guitars tone than a physical amp. This is thanks to powerful modern processors and years of trial and error.
The second type of modelling equipment is software modelling. These are programs that run inside a Digital Audio Workstation, or DAW, and process a clean guitar tone after it has been recorded. These programs require a powerful computer as the emulation is done by your own computer instead of a standalone unit. These are much less expensive than their hardware counterparts but do have their downsides. One of them is high latency. These programs require the use a digital audio interface to transmit the guitar signal to the computer via USB. This can lead to significant latency when trying to record guitars live along with a track. Another downside can be sound quality. (Wikipedia)

Current Market

As with many specialty products, the market for these products is very diverse. The market needs to be broken up into three spheres. The low end average user, the middle user (nonprofessional musicians and semiprofessional musicians), and Professional Musicians. For the low end or average user, the share of solid state and low end modelling hardware far outperforms traditional tube amps because of their high price. The middle market sees a shift away from solid state amps and towards more tube and high end modelling products like the AxeFx. Finally, the high end market is almost completely dominated by traditional tube amps. However, a large number of professional musicians have moved over to high end modelling systems like the AxeFx and Kemper due to their small size, ease of use, reliability, and portability. It also helps that these products can produce that is virtually indistinguishable from their counterparts. I think this trend will continue. (Fractal Audio)


Ever since the transistor amp was brought into the mainstream people have argued about the pros and cons of them. With modern computing power, however there has been a large shift in the way many people think. With the line between the two growing blurrier every day, it isnt hard to imagine how much farther the technology can go.

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