Technology, Techniques, History

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Roberto Gerhard’s Electronic Music Studio

Roberto Gerhard’s home electronic music studio grew over time between 1954 and 1960. In its final state Gerhard had access to five tape machines, a mixer, and a microphone. Playback was limited to the inbuilt speakers in the machines themselves. The tape machines in question consisted of:

2x EMI TR50 – Introduced to the market in 1951 by EMI, this robust machine was employed in many professional studios in the early days of tape music. Advertised as being “Used by the experts in the world’s leading recording and broadcasting organisations” it was a transportable, high fidelity tape recorder designed for professional use. It recorded in only one direction (known as full-track format), was capable of tape speeds of 7.5 and 15 i.p.s., and provided separate inputs for microphone and line inputs. There was also a model on the market that operated at 3.75 and 7.5 i.p.s. but this did not form part of Gerhard’s studio equipment. Notably, the machine minimised print-through by rotating the take-up reel clockwise, winding the tape with the oxide coating facing outwards, rather than inwards, a feature not employed by other contemporary machines.

1x Vortexion WVA – Introduced to the market circa 1951-52 by Wearite (later changing their name to Ferrograph in 1959). Wearite made both full and half-track versions of this model of Ferrograph tape machine, and the WVA model, owned by Gerhard, utilised a design which integrated two tape heads but did not provide off-tape monitoring, a feature only available in the WVB models. The tape machine came with an inbuilt speaker of 7×4 inches, and one of two selectable sets of tape speeds – 1, 3.75 and 7.5 i.p.s. or 3.75, 7.5 and 15 i.p.s.

1x Ferrograph Series 66 – Introduced to the market in 1957, the Ferrograph series 66 chassis model is a mono half-track recorder which came with two selectable sets of speeds – either 7.5 and 15 i.p.s. or 3.75 and 7.5 i.p.s. The design was based on the standard Ferrograph series 3-deck mechanism. This model was aimed at the semi-professional Hi-Fi enthusiast and designed to be integrated into a home Hi-Fi system. As such, it did not include a power output stage, instead needing to be connected to an external amplifier. Notably, controls (including start and stop) were set by a series of knobs rather than the more familiar push buttons.

1x Ferrograph Series 4 – Likely the newest of Gerhard’s tape machines, the Ferrograph Series 4 was introduced to the market in 1959. The machine operated primarily in half-track mono but was adaptable to a stereo format as a response to the rise of other stereo reel-to-reel tape machines on the market at the time. The Series 4 came with two selectable sets of speeds – either 7.5 and 15 i.p.s. or 3.5 and 7.5 i.p.s. A successor to the Series 3 model, the main differences between the two were those of function, not feature, with the Series 4 utilising a more ergonomically designed control knob and a new head cover design which allowed for playheads to be inserted interchangeably.

Roberto Gerhard with tape machines in his home studio

Gerhard’s studio also featured a range of other equipment for the purposes of making electronic music with tape materials.

1x 5-channel mixer – Gerhard’s mixer was probably a Vortexion valve mixer, which were produced with between three and twelve channels. This mixer was used to combine materials from two or more tape machines or acoustic sources, allowing him to create his unique assemblages of sound.

Splicing block – The splicing block is used to slice magnetic tape at a number of different angles and to provide a surface to combine two splices of tape together. The splicing block usually contains guide notches for 45˚ and 90˚ cuts, ensuring a uniform cut across the tape. Splicing tape at 90˚ allowed for a hard cut between two pieces of magnetic tape, while a 45˚ splice created a small crossfade. Some splicing blocks also came with a 30˚ guide notch to allow for a longer crossfade.

Single edge razor – Due to the fragility of magnetic tape, razor blades were used to physically cut the magnetic tape. Their sharp but thin edges ensured a clean cut, suitable for splicing.

Splicing tape – Splicing tape was specifically designed to be stronger, thinner and cleaner than regular sticky tape, providing a strong adhesive bond between two splices of tape that is able to resist the stress of being suspended between the two tape reels during playback. The splicing tape is applied to the side of tape not making contact with the tape head and should cover the entirety of the tape splice.

Tape leader – Tape leader is non-magnetic tape, paper or plastic used at the beginning and/or end of a magnetic tape reel. It might also be used in-between tape splices so as to separate sections of magnetic tape on a single reel. In the Roberto Gerhard Tape Archive, we have also found that Gerhard was fond of making notes on the tape leader that provides important clues as to the context and content of the tape contents.

Roberto Gerhard working in his home studio c.1959

A software analogue of Roberto Gerhard’s electronic music studio has been created for the Roberto Gerhard Digital Archive. Download The Gerhard Machine from our educational resources page to experiment with the kinds of sounds and technology Gerhard used in the creation of his electronic music.


Roberto Gerhard’s Electronic Music Techniques

There are a wide range of musical techniques available through the manipulation of magnetic tape. These techniques were frequently used by Roberto Gerhard in the creation of his electronic music.

1. Record and playback a sound. Perhaps the most obvious technique in evidence throughout the Roberto Gerhard Digital Archive, the use of tape recording allowed Gerhard to record a wide range of sounds and instruments, including piano, cello, percussion and accordion.

2. Play a sound backwards. By inverting the direction of the magnetic tape allowed Roberto Gerhard to reproduce a sound in reverse.

3. Change the speed of playback, to transpose a sound. Roberto Gerhard frequently made use of changes to the speed of tape playback, often to the point where at times it’s difficult to ascertain the intended speed some tapes in his archive were intended to be heard at. His tape machines varied between playback speeds of 3.75, 7.5 and 15 i.p.s. By recording a sound at 7.5 i.p.s. and playing it back at either of the other two speeds, the sound could be transposed up or down an octave by playing it back at half or twice the original speed. This can then be compounded by re-recording and re-transposing sounds multiple times.

4. Splicing. Unlike recordings made to acetate discs, the relative fragility of magnetic tape offered composers the opportunity cut and splice recordings together in different physical combinations. Many of Gerhard’s tapes demonstrate his use of this technique to cut and splice different recordings and treatments of sound together to create different assemblages.

5. Mixed sounds. Gerhard’s studio him to not only splice recordings together, but to combine different sound sources onto a single recording. This is evident throughout the archive, as Gerhard would often combine different processes of the same materials together to create an ‘assemblage’ of material with a rich, contrapuntal activity.

6. Looping. One of the most striking elements of composing with magnetic tape was the ability to splice together two ends of tape, creating a circular loop that would run repeatedly across the tape machine playhead. This allowed for composers to create rhythmic sequences or cycles of entire sequences of material. There is some evidence that Gerhard explored the looping of materials in some of his earlier theatrical soundtracks, although physical tape loops have not been found in his tape archive.

Roberto Gerhard working with magnetic tape in his home studio


History of tape and electronic music

By Matthew A. Bardin

Following the development of magnetic tape in the 1930s its popularity soon skyrocketed as an effective way to store and playback various data. Many audio recordings and eventually films were stored on variations of the original tape because it allowed for a relatively large amount of data storage in a relatively small and inexpensive format. Many early pieces of tape music were developed at various national radio stations because these places had the materials, equipment, funding, and means of distribution for the relatively new art form. Pierre Schaeffer and Karlheinz Stockhausen, both mentioned in the following section, did a large portion of their work in Radiodiffusion Française (RDF) and the West German Broadcasting Station (WDR) respectively.

As technology began to develop, and Europe began to recover from the effects of World War II, Tape composition began to develop into a new art form in the mid-late 1940s. Understanding some of the key distinctions between previous acoustic and tape compositions are fundamental to understanding exactly what tape composition is and the processes utilized in the writing of these pieces. One large difference is that acoustic music is traditionally written as a series of instructions to be given to a performer, whereas tape music is “concrete”. Tape composers create a physical collection of sounds that is exactly the same every time it is reproduced, and rather than focusing on time passing as a series of musical measures, are building their materials out of mathematical relations based on lengths of tape.

This is because tape music composers were working with pre-recorded material; whether they or some other person created the sounds that were originally recorded. Tape composers could define the characteristics of their music to extremely specific degrees in order to create a product that would sound identical every time it was performed, regardless of the time or venue. They could duplicate, edit, and re-record any sounds that had been previously recorded onto the tape they had; something that had previously been impossible. Because of a wide variety of new possibilities, composers tended to group into different schools of thought in relation to how to go approach tape composition. Of which, the most prevalent in Europe being Musique concrete and Elektronische Musik.

Musique Concrète

Musique concrète developed in France in the years following World War II. Pioneered by Pierre Schaeffer at RDF, the composer defined musique concrète as “music made from recorded natural and man-made sounds”. A slightly more in-depth definition by Andre Hodier defines musique concrète in the following way:

Composers of musique concrète begin by recording various sounds (either musical sounds or noises of indeterminate pitch) and then, by speeding them up, slowing them down, filtering or inverting them, metamorphose these sounds into “sound objects” (objets sonores) whose origin it is not always possible to distinguish.

The key aspect of musique concrète that defines it as something separate from Elektronische Musik is that the material utilized by these composers naturally occurring sounds, not tones generated through electronic means. For example, looking at Pierre Schaeffer’s Cinq études de bruits (1948), credited as the first piece of musique concrète, one can that each etude is comprised of a collection of sounds from various real work sources such as trains, persecution instruments, piano, and household objects. This aesthetic of taking recordings of items found in various everyday settings and manipulating so that they take on a new, unique, and at times unidentifiable characteristic is the core element of musique concrète and its objets sonores.

Elektronische Musik

In a different vein, we can see Elektronische Musik develop out of Germany at around the same time period as musique concrète. Compared to the French, the German development of electronic music was more gradual, which helped it develop its own, unique aesthetic. Two main parts of this aesthetic include the use of 12-tone serialism, and the use of recorded material that came from electronically produced means.

Contrasting the objets sonores utilized by musique concrète, German tape composers would often record tones generated via electronic means such as electronic tone generators and predecessors to modern synthesizer. This would result in material with a definite pitch (to contrast the real-world sounds utilized in Études de bruits) The Germans would then utilize the 12-tone system as a common way to organize these sounds. These elements gave Elektronische Musik its own timbre that was noticeably distinguishable from musique concrète. It allowed Elektronische Musik composers to be able to control the elements of their music with extreme precision, especially in the case of Karlheinz Stockhausen, whose total serialization allowed him to serialize all of the major aspects of his music.

In a specific work of Elektronische Musik, Karlheinz Stockhausen’s Elektronische Studie II (1954), a listener can hear how it is entirely composed of electronically synthesized sounds, created through Sine Tone generators. Looking at the score, of which Elektronische Studie II was the first piece of electronic music to have a complete score, it can be seen that Stockhausen was arranging his material in terms of frequency, timbre, and duration. By combining, splicing, re-recording, and adding other processes to his samples, Stockhausen was able to create the timbres heard in the piece.

Although they both utilized the manipulation of tape recordings, the two schools did not agree on the sounds and processes used by each other, and were vehemently opposed throughout the 20th century. This opposition was due in no small part due to social and political tensions between France and Germany following World War II.



Adkins, M., Duque, C., & Karman, G. (2012) “The Electronic Music of Roberto Gerhard” in The Proceedings from the 38th International Computer Music Conference (ICMC), 9-14 September 2012, Ljubljana, Slovenia.

Bardin, M. (2020) “Common Tape Manipulation Techniques and How They Relate to Modern Electronic Music” in The History of Electroacoustic Music, Spring 2020, Louisiana State University.

Chion, M. (2016) Michel Chion’s analog tape techniques. Published 20 July, 2016.

Reel-To-Reel (2021)