Wednesday 3 February 2010

Random News

I have been far too distracted with Facebook to attend to the Beat Frequency blog of late. Mea culpa.

Here's the Beat Frequency Facebook page.

And here's a bunch of news. Firstly joining Facebook has led to a gig, which will be announced formally once they have a website in place for it. It's a themed charity fund raising party in aid of prostate cancer at Jamm in Brixton, on Saturday the 20th of March. The theme is "The Mad Hatter's Tea Party.

But before then, I'm going to another of Lydia Kavina's workshops in Oxford on Saturday. This one is sold out, but keep an eye on Theremin UK News for announcements of future ones.

And on Sunday week I'm joining in The Synth-Off, an improvisational synthesizer circle at The Foundry. Here's the Facebook event page.

And there's another Sonic Weekend coming up, and some other interesting things in progress, but they're not definite yet - you'll hear about them if and when.

And my next album is with White Label music and will be coming out on CD soonish.

Just to tease you, here's the track listing and some album art from the very marvellous Alex Bertram-Powell. A skilled thereminist and maker of wonderful drawings.

CD Title: Psilocyren

Dance Of The Flower Pot Men
Gently Drowning
Boundary Logic
Chikhai Bardo
Dark Lizard (ft. Another Mystic)
The New Consonance
Point Of Collapse (for Caché Vidja. vox: HK)
Night Shift
The Loss Of Small Things

On a similar theme, Hands Off 2009 was great! The first of THREE! albums recorded during the weekend is also with White Label for physical release. (The other two will probably be free releases, after the first is out.)

Oh, and I have a big upgrade figured out for the etherwave, with theremin electronics wizard Thierry Frenkel, but that's now going to have to wait until I can be sure I don't have any gigs for a while, and until Thierry has done preparatory work so that he can send the theremin back to me quickly. 

Sunday 8 November 2009

The Panic Box

The Configuration

The audio signal moves from the theremin to the amplifier from right to left, starting with a delay pedal in ping-pong configuration. The delay is, for the sake of argument, 1 second. A sound appears at both outputs (A and B) instantaneously, and is then repeated at A one second later, then again at B one second after that.

Both the signals from the delay are fed into the ring-mod where one amplitude modulates the other, and the resulting signal (C) exits the box at the centre of the right side. The knob at the centre on the left side controls its volume.

Signal C then passes through a low pass filter. The knob at the top in the centre controls the operating frequency of the filter, and the knob on the left side controls the filter's resonance.

Meanwhile copies of the signals from the delay pedal A and B exit the ring-modulator unaffected on the sides, and are mixed with the ring-modulated and low-passed signal C. The knobs at the sides of the top of the box control the volume of A and B.

The combined signals then pass through a reverb pedal.

The Ring Modulator

It is sufficient to consider the simple case of two sine waves being fed into the ring modulator.

A signal of frequency X amplitude modulated against a signal of frequency Y creates a new signal Z with two component sine waves which are the sum of X and Y and the difference of X and Y.

The pitch of the sum component Z(sum) is between the pitches of X and Y, but one octave higher. The exact relationship gives ring-modulation its characteristic and familiar sound.

Where X and Y are consonant with respect to each other, Z(sum) will be consonant with respect to both. Likewise, given a dissonant X and Y, Z will be dissonant with respect to both.

Where X and Y are in unison Z(sum) will be one octave higher. Z(diff) - the difference component - will be silent, zero.

When the difference between A and B is small, Z(diff) will be low in pitch. When it is larger Z(diff) will be higher in pitch. The same considerations about consonance and dissonance apply as with Z(sum).

In short, it augments consonance and dissonance alike.

Z(diff) becomes more interesting when it is fed via a ping-pong delay, giving a relationship between A and B over time.

The Delay

It is sufficient to consider the simple case of a signal going first to A and then to B one second later.

A slow sweep upwards through the pitch field, varying the frequency at a constant rate (note - not the pitch - in practice this means slowing down logarithmically as pitch increases if the field is linear with respect to pitch to maintain a constant rate of change) will create a Z(diff) of constant low pitch, while Z(sum) rises with A and B.

In short, the pitch of Z(sum) is dependant on the player's pitch hand's distances relative to the pitch rod, and Z(diff) is dependant on its velocity relative to the pitch rod.

In this configuration the panic box can be thought of in part as a simple audio "difference engine."


The piece Gently Drowning is an example of this configuration. On YouTube here. Very slow changes in pitch by overlapping notes or slow glissandi create very low sounds.

By inserting a pitch shift between the delay pedal and the ring-mod on one of the channels increases the frequency of Z(diff) by a constant amount throughout, giving higher pitches.

The piece Iron Sun is an example of this configuration. On YouTube here.

By replacing the delay pedal with a dual output pitch-shifter, with one output giving the dry signal, and the other a signal a fixed interval higher (or lower) than the dry signal, a new effect is created. Note that the interval is constant with respect to pitch. This means it varies with respect to frequency. The same interval will create a Z(diff) of low frequency when the dry signal is low pitched, and a higher frequency when it is high pitched.

The piece The New Consonance is an example of this configuration. On YouTube here. In this case the interval created by the pitch-shifter is very small - 30 cents, so Z(diff) is subsonic, and is audible as beats - low notes having slow beats and higher notes, faster beats. To add to the fun there is a delay after the panic box, so sounds can overlap.

Note that all three pieces have significant low frequency content, so are not well reproduced by small computer speakers.

Saturday 7 November 2009

My entry in the moog halloween theremin video contest.

Vote for it (Gently Drowning) here (registration required.)

Saturday 19 September 2009

two more Beat Frequency videos

Images by my good friend and photographer Mark Highton Ridley.

The LFOesque effect was done by passing the audio through a pitch shifter with two outs - one of which was detuned 25 cents sharp (an eighth note.) When the two slightly differing signals are combined it gives beats related to pitch - low notes get slow beats and high notes get fast beats. I combined them with a two input ring-mod to emphasise the effect. This added to the timbre, which I further modified by passing through a low pass filter and then mixing in some of the original signal, before going through an echo box. Post-production consisted of a bit of extra low pass, faux stereo and some reverb.

Sidebar: One of Theremin's other instruments - the rhythmicon - related pitch to rhythm, so this is, in a sense, a new take on an old idea.

The "bleep" sounds were made on my Kees Enkelaar theremin. (My etherwave power supply being on loan to one of Lydia Kavina's students while he was in the UK taking tuition from her.)

The "booster" sounds are from an iPod Touch app - Android FX.

Wednesday 26 August 2009

Friday 22 May 2009

Buy The Beat Frequency Method!

The Beat Frequency Method is now available in hard copy, and it includes a CD of Beat Frequency's first album, The Chordless Chord, for only £8.00 plus postage.

It's a sensibly priced CD with an oversized booklet, or it's an overpriced booklet with a free CD. Either way, it's essential reading and listening for the sonic explorer with a theremin!

Preview The Beat Frequency Method here as a Scribd document.

Preview some tracks from The Chordless Chord here:

Choose your location

(The word cloud image is the hundred most used words (not common ones) in The Beat Frequency Method, and was created using Wordle.)

Monday 20 April 2009

Sonic Weekend 4

Sonic Weekend 4 was excellent!

There was a bit of a downside - the bunks were underneath the recording room and were fitted with plastic mattress protectors and unfitted sheets. I could have slept better. But who cares! A great time was had and some fine tracks were laid down in a great big recording area - we had room to spread out. :-)

In addition to the usual White Label crew - always good to catch up with them - there were some of my friends from elsewhere - Tim - an old school chum, Chris and Fabio from Without Touch 2.0, and a good representation of theremins - Chris and Fabio with etherwave pros, Arthur with a Kees (mine!) and me with my etherwave. Also good to meet Heidi Kilpeläinen again - I met her at White Noise Festival the weekend before, and took the opportunity to borrow a good mike and record her saying the words for Point Of Collapse (and when Caché Vidja posted the Panic Box piece from the Festival on youTube I extracted the audio, cleaned it up and added the words to it. With that, Gently Drowning and Dance Of The Flower Pot Men I'm half-way to my next album.) And I made some new friends - Arthur's sister Astrid, Chris's wife Anja, and Vicki. There were some blokes too.

I didn't get to play with everyone I wanted to, but I'm already booked for Sonic Weekend 5, so no problem. I did get to play with Tim, who has wicked keyboard skills, and that was fun. Contrary to previous indications, we had a "four seasons" theme this time around, and Tim and I were drawn out of the hat to be on the Summer team. I suggested the closing chapter of Amerika - The Natural Theater of Oklahoma where Karl walks though sun-drenched fieldsthough the gateway surrounded by angels and demons on pedestals blaring their horns atonally (that was my bit!) and into a vast funfair. Although the funfair music was perhaps more vicarage fête than carny. But I think overall we got a good hot summer feel to the piece without being sugary or sentimental. [edit] I found a copy of the chapter here. I remembered most of it wrong, apart from the horns. Well, it was 27 years since I read it. [/edit]

The other piece I was instrumental in was a great big chunk of Noise that started out being a quartet but mysteriously turned into a seven piece, driven by Sam kicking a big wooden box at 20bpm!

The culinary highlights were (1) cooking up an almost endless vegetable curry with Tim and selling it at £2 a bowl. It paid for itself and provided the basis for the next meal! and (2) The local café, which was just excellent. I had a sweet chilli beef baguette from the lunch time menu on the Saturday, and on the Sunday evening Fabio, Chris, Anja and I went for an evening meal. The best steak I have ever had.