Archive for the Amplifier Basics Category

Research Blog Note

Posted in Amplifier Basics, History: Marshall Amplifiers, NPD: Guitar Amplifiers on June 15, 2008 by ivancheung

This research blog was kept up until 3rd May. This is because the research process started to slow down and the creative process began.

For more information on how my work was formulated please see the research dossiers and module reports. (Note, the majority of New Product Development research has been worked into the presentation).


Amp Types: Full Stack

Posted in Amplifier Basics with tags , , on April 23, 2008 by ivancheung

Images for this post taken from

A full stack amplifier is a Marshall design and a signature.
This is the stack amp (or half stack), stacked onto an additional speaker cabinet. Each cabinet houses four 12″ speakers.
The full stack grew out of Pete Townshends request for a single speaker cabinet with eight 12″ speakers. Although this was built, Townshend’s roadies soon complained about the difficulty of transporting such a large unit. Jim Marshall’s solution was to cut it in half!
No other amp screams Rock n Roll more than a Marshall full stack!

Here are some images of the Full Stack.



Amp Types: Stack Amp

Posted in Amplifier Basics with tags , , , , on April 23, 2008 by ivancheung

Images for this post taken from

A stack amp is the term used to refer the use of an amplifier head and a speaker cabinet (with the head stacked on top of the cab).
Sometimes this unit is referred to as the ‘Half Stack’ to distinguish it from the ‘Full Stack’

Here are some images of the stack amp (or half stack).

Amp Types: Combo

Posted in Amplifier Basics with tags , , , , on April 23, 2008 by ivancheung

Images for this post taken from

A combo is the term used to describe a unit that contains both the amplfier head and the speaker cabinet together.

Here are some images of combos


Amp Types: Speaker Cabinet (aka Cab)

Posted in Amplifier Basics with tags , , on April 23, 2008 by ivancheung

Images for this post taken from

A speaker cabinet is a (usually wooden) cabinet that houses speakers inside it.
Depending on the type, there may be a single speaker, two speakers, four speakers or even eight speakers inside it.
The enclosure of the cabinet also effects the tone. A cabinet with an open back (with no panel on the back of the cabinet) gives a more airier and warmer tone – a Fender style (also referred to as American). While a cabinet with a closed back (with a panel fitted on the back, thus making a box) gives a tighter and punchier tone – a Marshall style (also referred to as British).

A speaker cabinet is often referred to as a ‘cab’ for short. Here are images of some speaker cabinets.

Amp Types: Amplifier (aka The Head)

Posted in Amplifier Basics with tags , , , , on April 23, 2008 by ivancheung

Images for this post taken from

Although we use the word amplifier (or amp) as an all encompassing word for the units which produce the sound of a guitar, it actually refers to the unit which amplifies the signal.
An amplifier consists of a preamp and a poweramp. A preamp to recieve a low level signal like a guitar signal, and the poweramp to power the preamp signal so it can drive speakers.

When the amplifier is on its own, it is usually referred to as ‘The Head’. Here are images of some amp heads.

History Of The Amp: Digital

Posted in Amplifier Basics with tags , , , , , on April 7, 2008 by ivancheung

The history of digital is more complex than valve and solid state.

Digital refers to the software rather than hardware, and as a result most digital amps are actually solid state amps with digital software.
Digital technology has been used in other musical instruments for a long time, such as keyboards and synthesizers. In the realm of guitars, digital was used in the effects pedal market around the late 80s; here is where it gets confusing as digital is not really an amplifier at all but an effect. When digital was used in effects pedals, it was to create sonic effects such as a delayed sound, reverb, clipping of the signal, etc.
It was only until the mid 90s where digital technology became part of the amplifier market. Here digital signal processing (DSP) was the method used. DSP is the study of audio signals, and how they can be emulated by digital processors. As a result, digital ceased creating sonic effects, but began emulating sound (this has since been known as digital modeling).

One of the first digital modeling equipment was the Roland VG8, introduced around 1995. The VG8 was a unit (approx. 30cm x 12cm x 15 cm) which would capture the output of an electric guitar, analyze the signal’s wavelength, which is processed and reassembled into a new signal. The user had a number of options as to how the VG8 would process the guitar signal, all of which were emulations of particular pieces of guitar equipment, such as different amp sounds. The VG8 retailed for around £2000 and was definitely aimed at the professional market. It should be noted that the VG8 was not an amplifier, it is a processor which created a new signal which would then need to be amplified.

Digital modeling was not an instant success due to its rarity amongst the average guitar player. Those who could afford it felt that digital was astonishing, but its sound quality was not the same as the amps it was emulating. As the years went by, digital modeling would improve in all aspects.

Around 1999 digital modeling began to renew interests with the introduction of Line 6’s POD. the POD was a unit the size of two hands, and not only was it a DSP unit, it was designed to take the place of the preamp.
<Quick lesson: An amplifier consists of two circuit stages, the preamp and the poweramp. The preamp essentially takes a low level signal (the type produced by a  electric guitar) and amplifies it to a level that can be handled by the poweramp. It is also the preamp stage where the majority of tonal shaping of the signal takes place. The poweramp stage takes the signal from the preamp, and literally powers it so that it can accepted by speakers thus producing a sound.> 
The POD could be used in conjunction with a poweramp/speakers, or the player could bypass that stage by using headphones (to play alone), or plug straight into a mixing desk.
The POD provided more emulations that any other digital gear, and it also allowed more flexibility as to how the signals were produced (the user could match certain amps with certain speakers). The best characteristic about the POD was the quality of sound, if you asked the POD to emulate a vintage Marshall stack amp, it actually sounded like it!
The new incarnation of digital modeling posessed fantastic sound quality, portability and versatility. Best of all, it retailed for around £150 – affordable.

The fact is, digital modeling provided everyone a chance to play with the same equipment that professional used, and it also provided many practical advantages. However the POD was not perfect, and many felt it the sound it produced was cold and sterile in live situations, a problem which is being solved as we speak.

Today, digital modeling can be bought in individual forms like the POD (or the latest incarnation, the Pocket POD which is essentially the same except it will fit in your pocket), and it can also be bought in amplifier forms (where the digital processor is built into where the preamp would usually sit).
It is a piece of equipment used by the beginning guitarist, and the professional musician. All the major amplifier brands have realised it’s advantages and have released their own versions. Some have even developed hybrid amplifiers which combine digital with either solid state or valve or both.
Another notable form of digital modeling is in the form of software only. There are products where the user installs the software onto their computer, and the computer becomes the central medium. 

Below: Revalver, a digital modelling software.

As someone who owned the original POD, I agreed with the sonic criticisms it received. However recently I bought a new version of the POD and all I can say is it has improved vastly – the good just got better!
It is my belief that digital would fulfil most players practical needs, but the popularity of valve is that it fulfils an emotional desire.