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Who’s on First Bass? Making of the The Doctor Who Bass line

by Phil Taylor

I don’t know… but it’s a good question. Delia Derbyshire’s interpretation of Ron Grainer’s score for the ‘Doctor Who’ theme was one of those pivotal moments in electronic music. According to BBC Radiophonic Workshop technician Dick Mills, Grainer met with Derbyshire just once at the Workshop with a music score written on one sheet of A4 paper. The score contained the essence of the famous bass line and the soaring melody along with expressive descriptions of “sweeps”, “swoops”… beautiful words… “wind cloud”, “wind bubble”. Delia immediately got to work and put it together and when Grainer heard the results two weeks later after returning from holiday, “he was tickled pink!”. Derbyshire’s Radiophonic Workshop collegue and friend, Brian Hodgson said, “Doctor Who was the big milestone. Suddenly they became aware that it wasn’t just funny noises, that you could actually make music with it as well.” – the ‘Doctor Who’ theme was proof that electronic and sampled real sounds could be used to create a ‘proper’ piece of music, but what sound was really used to create the bass line?

19" rack panels

Take your pick – 1.6mm steel, 3mm aluminium or 2mm steel 19″ rackpanels. Possible candidates for the sound of the ‘Doctor Who’ theme bass line?

There are a couple of different explanations both given by Dick Mills. In a Sound on Sound interview in 2008 Mills, who helped Derbyshire (in a techincal capacity) create the piece, says, “We started with the bass line. You know those 19″ jack-bay panels? You could get blank panels too, to fill in between them. They were slightly flexible, so Delia found one that made a good musical twang and played it with her thumb. We recorded it then vari-speeded up and down to different pitches, copied them across to another tape recorder, then made hundreds of measured tape edits to give it the rhythm.”. Sounds plausible as steel is stiff and elastic, causing the panel to vibrate for a long time and just like a guitar string, but then there’s another BBC interview with Mills describing to Mark Ayres (BBC Radiophonic Worksop archivist) how Derbyshire plucked a single guitar string, ‘on a piece of metal channelling that Delia twanged’, whatever that means.

Lost Knowledge

These interviews are frustratingly (and disappointingly) light on those all important, significant details and consistency! For an ‘anorak’ such as myself, it’s fascinating to gain insight into the creative process of something so iconic and it would be tragic if this knowledge were to become lost and forgotten. At first glance both stories sound plausible, but which of these found objects were used to create that hard-edged, metallic sound for the bass line – rack panel, a simple string or was it something else? I suspect Mills wasn’t entirely sure what Delia Derbyshire was up to whilst she was working late into the night and the early hours when she captured the initial sound sample of the ‘plucked object’ on magnetic tape. After all, this happened over half a century ago, Mills can be forgiven for not being able to accurately recall, what at the time, wouldn’t have been a significant event – in 1963 Dr Who was just a new TV drama that looked like it would only run a few episodes and Mills and Derbyshire were still very young engineers getting a job done – he simply wasn’t aware that Doctor Who was destined to become legend. Derbyshire certainly knew what she was doing was cutting edge, however I don’t think anyone could have known how big Doctor Who would become – there was no motivation to keep a detailed diary of the recording process. So, given that Mills seems unable to recall the complete story, the only option is to wheel out the scientific method and undetake an investigation – do some reverse engineering to see if we can uncover the answers.

Reverse Engineering

Below is a sound sample of what a single note (E) from the Dr Who bass line sounds like.

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It’s not easy to determine if this sound is close to the original pitch or a vari-speed copy which has been substantially slowed down. Derbyshire and Mills sped it up and slowed it down to get the different notes, and these were cut to give it an extra sharp attack and decay for each note making an exceptionally clean and tight bass performance. Experiments in arbitrarily shifting the pitch upwards alter the sound so it sounds reminiscent of some kind of plucked string, but it’s not recognisable as an acoustic (nylon or steel strung) or an electric guitar or bass.

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Subjectively, it has a ‘cheap’ quality to it like ukulele but with the overtones reminiscent of strings plucked in unison as with a twelve string guitar or vibrating in sympathy as in a sitar. A small amount of reverb can be heard on the sound, again it’s not possible to tell if this is the natural reverb of the Radiophonic Workshop – assuming the sound was recorded with an acoustic microphone rather than a contact mic – or it was added artificially later on. Given that Delia Derbyshire was deliberately truncating the bass notes to increase attack and remove sustain, it’s difficult to imagine she would add reverb deliberately to the sound.


Dr Who bass note frequency analysis

The graph on the right shows a fast Fourier frequency analysis of this single note. It can be seen that the note is composed of the fundamental at 83Hz – the same pitch as the bottom E string of a guitar – as expected but is also very rich with additional harmonic overtones – 2nd (166Hz), 3rd (246Hz), 4th (332Hz), etc. All these lower harmonics are very strong and the 8th harmonic at 664Hz is practically of the same amplitude as the fundamental. There also two very strong higher order harmonics between 1.2KHz and 1.5KHz making a very interesting sound with a great deal of texture. But was this sound generated by a 19″ rack panel?

In the SOS interview Dick Mills described how Derbyshire played a rack panel with her thumb and discovered that it gave a satisfying “twang” upon plucking it. Undoubtedly she would have rummaged around the workshop looking for anything close at hand that might be a source of useable sounds and considered a rack was a suitable candidate for the job. The equipment and panels are secured via four bolts – two at either end – which allows the panel to vibrate in a similar manner to a guitar string. Rack mount equipment comes in standard heights of 1U, 2U, 3U, etc where 1U is just under 1¾” high. It seems reasonable to begin experimenting with the 1U panels as they will vibrate more freely than the taller panels. The graph below shows a frequency analysis of 1.6mm steel panel being plucked.

It can be seen that the sound has an entirely different signature to the original Dr Who bass sound. The sound is a less complex, much sparser with only two recognisable harmonics – with the fundamental right down at around 30Hz and a 4th harmonic at 120Hz. Although the panel is shorter than a guitar string, it is much thicker and not under any tension giving it this lower tone. The thicker 3mm aluminium and 2mm steel panels produce even less encouraging results. The lack of flexibility in the aluminium panel makes it difficult to get a good “twang” out it and it is effectively “dead” and incapable of producing anything that might be sonically interesting. It’s simply not possible to generate the frequency signature of the original Dr Who bass from a rack panel by plucking it as Mills describes. It might be possible to generate the additional harmonics with a stiffer and thinner panel that can support the additional harmonic overtones, but such panels have never been manufactured – stiff and thin panels would be more expensive to manufacture as they would not be made from readily available, inexpensive mild steel.

Another possibility is to strike the panel with a hammer rather than plucking it. This method of exciting the panel can impart the additional energy required to cause it to vibrate at higher order harmonics. A panel with a finite boundary will vibrate at a fundamental frequency (and at mathematically related harmonics of the fundamental). The resonant frequencies (Hz) of the panel can be calculated with the following formula:

Fr = 0.45 × vl × t × ((r/w)² + (r/h)²)

where, vl is the longitudinal velocity of sound in the partition = 5960m/s for steel, t is the panel thickness = 1.5mm (0.0015m), w and h are panel’s width (0.483m) and height (0.044m) and r is harmonic number (1 gives the fundamental frequency).

Fr = 0.45 × 5960 × 0.0015 × ((1/0.483)² + (1/0.044)²) = 2095Hz

This calculated fundamental frequency of just over 2KHz is much higher than what was measured by plucking the panel. Experimentation confirms that the calculations are not unreasonably inaccurate and the graph on the right shows the frequency analysis for the same panel being hit sharply with a nylon-faced mallet. The panel emits an almost completely pure tone in the region of 2.3KHz but nothing else – not the rich series of strong partials that were observed in the sound sample of the Dr Who bass line. It wasn’t possible to even get close to recreating this signature sound with it’s unique harmonics by plucking or hammering a selection of panels. All the evidence weighs heavily against a 19″ rack panel being the source sound for the Doctor Who bass line.


This leaves open Mills’ other scenario of Derbyshire utlising a plucked string. Amongst all it’s sound making paraphernalia the Radiophonic Workshop did possess a lap steel guitar, zither and even an old upright piano – there were plenty of stringed instruments to choose from. Fundamentally (forgive the pun) all strings vibrate according to the same laws of physics, however the sounding boards of these instruments will emphasise harmonics to colour the sound and give each instrument its unique character. A frequency analysis of a plucked bottom E string of an electric guitar reveals a fundamental with a lovely rich set of harmonic overtones, much more interesting than than the boring old rack panel. These additional overtones occur because the string is much freer to vibrate and has less damping than the panel – it can support modes of vibration that the panel cannot, that is the higher partials.

The higher order harmonics do appear weaker relative to the lower ones though, unlike the Dr Who bass sample where energy is more evenly distributed between the lower 8 harmonics. It is possible increase the amplitude of higher order harmonics by plucking the string closer to the bridge and harder so that it slaps against the frets of the guitar as shown in the graph. Now this frequency signature has much more in common with the original Dr Who bass sound indicating that it is highly likely she used a plucked string. Also it ties in nicely with Dick Mills’ description of Derbyshire plucking a single guitar string, ‘on a piece of metal channelling’. – the string could have bounced off the side of the metal channelling to emphasise the higher harmonics.

Piecing it Together

The bass line is the backbone of the Doctor Who theme, driving it headlong like a runaway steam locomotive into an unknown tunnel. For detailed look on the music score itself it’s worth taking a look at “The Definitive Guide to the Dr Who Theme Music”. The theme is built up from the bass line and several other tracks.

  1. The plucked string bass-line
  2. The plucked bass is emphasised on the beat with an electronic oscillator slide tone
  3. Filtered white noise swishes and swirls that sound like steam
  4. The main melody played on a sinewave oscillator with a lot of reverb
  5. This is augmented with some higher harmonics

The original composition is 2 minutes and 19 seconds duration and is constructed from hundreds and hundreds of tape splices. The bass line itself is made up of pitch-shifted samples of the original plucked string recorded on small loops of magnetic tape. These would have been made in bulk, probably by Mills, and then hung on the walls of the workshop so they were ready for use later. It was very challenging to keep count of all the tape splices and when it came to mixing the final composition Mills and Derbyshire noticed a timing descrepancy between tracks. Mills describes this, “Eventually, after some pre-mixing, the elements of the entire composition existed on three separate reels of tape, which had to be run somehow together in sync. we had a bum note somewhere and couldn’t find it! It wasn’t that a note was out of tune – there was just one little piece of tape too many, and it made the whole thing go out of sync. Eventually, after trying for ages, we completely unwound the three rolls of tape and ran them all side by side for miles – all the way down the big, long corridor in Maida Vale. We compared all three, matching the edits, and eventually found the point where one tape got a bit longer. When we took that splice out it was back in sync, so we could mix it all down.”

The Workshop did own a Leevers-Rich multi-track machine, however Derbsyhire deemed it to be of lousy sound quality, so all recording and mixing was performed on the three Philips EL-3503 machines, “Crash-sync’ing the tape recorders was Delia’s speciality,” says Mills. “We had three big Phillips machines and she could get them all to run exactly together. She’d do: one, two, three, go! — start all three machines, then tweak until they were exactly in sync, just like multitrack.”

Sum of Parts

The theme for Dr Who has a certain visceral and dark quality to it – as if it were some kind of live performance played with an odd or perculiar musicianship on unknown instruments – it just doesn’t seem possible that the final recording was the result of painstakingly and meticulously piecing together magnetic tape fragments in a purely electronic environment. Even fifty years later the original theme still sounds cutting-edge, haunting and even terrifying. Derbyshire had created something timeless and unique – a soundscape that had never existed before. It’s worn much better than the numerous rehashed versions made by successive producers of the show – manufactured in an effort to make the music sound ‘fresh’ (a term often used by these kind of people) and exciting they had felt compelled to stamp their mark by “tarting-up” (Derbyshire’s own words) the theme by pasting layers of the latest synth pads or heavy-handed orchestrations on top of the original recording. At best these versions sound dated and cheesy, adding nothing of value to the work and at worst, bury a beautiful masterpiece beneath layers of gaudy tinsel and glitter.

Very Pricey Art

Ron Grainer was so impressed with Delia Derbyshire’s interpretation of his score he attempted to obtain her a co-composer credit. However despite his efforts he was thwarted by the BBC pen-pushers, whose policy was that any creative output from Radiophonic Workshop staff should remain anonymous – Delia never received any royalties for her work on the Doctor Who score. In Radiophonic Ladies Interview in 2000 she recalls, “I was just on an assistant studio manager’s salary and that was it… and we got a free Radio Times.” In hindsight this seems terribly unjust, especially in light of a more recent interview (January 2013) with Kara Blake where she tacitly mentions that performance rights for Derbyshire’s work were “Not easily or inexpensively” obtained – Blake wanted to include a sample of the Doctor Who theme in her Film Board of Canada-sponsored film “The Delian Mode”, the BBC quoted her the outrageous sum of $1000 per second. At 15 i.p.s. that’s $1000 for 15 inches of 1/4″ magnetic tape! For Delia, her the work was a labour of love and she often worked late into the night for weeks at a time to complete compositions – it’s very saddening that she didn’t receive the recognition she wanted and deserved during her time with the BBC Radiophonic Workshop; she was an asset to the BBC; an incredible creative talent.

Derbyshire resolutely pursued her own path – often against the mainstream – to create unique art that has proved far-reaching and influential. The Doctor Who music is one of the most recognisable themes in television and has stood the test of time to become one of the longest continually used pieces of theme music. Along with her other work it has inspired and influenced electronic dance avante garde musicians such at “Orbital”, “The Chemical Brothers” and “Pink Floyd” – “One of These Days”, the opening track on Floyd’s 1971 album “Meddle”, echoes the theme about three minutes into the track. She elevated the art of music concrete, breathing life into common everyday sounds to create something magical… out of almost nothing. Before Delia, electronic music had a reputation for sounding harsh; even ugly – she proved beyond all doubt that it could also be flawlessly beautiful.