F Day

Posted Friday 22nd July, 2016 by Jamie Masters

 

F-day
F is for: Peter Frampton, 'Show me the way' (e.g.
https://www.youtube.com/watch?v=zLgeTtYwQ7o)
The Peter Frampton song I'm rather fond of – he's a likeable performer with a
good energy – but the main reason for playing it to Eddie was for the 'Talk box', a
guitar effect that basically involves pumping amplified guitar up a tube into your
mouth, and letting it be picked up by the vocal mike. A wah-pedal where you
literally go 'WAH'. A human-powered vocoder. I like it for its simplicity, its
crudeness. Eddie has challenged me to make one: maybe I will.
I like playing around with electronics. This is a fairly new thing for me: before
about three years ago I knew nothing about it – beyond what we all have to learn
at school, like, to make a light bulb shine the electricity has to go all the way
round the circuit kind of thing. But I wanted to build something fun for Eddie,
and thought I'd have a crack at something electronic, you know, a kind of
'Operation'-type thing, and got completely hooked. It speaks to some part of me
that loves to know how things work – maybe the same impulse that made me a
musician, too. I'm afraid Eddie's needs got swept away: now I'm too busy
conceiving and building electronic musical instruments.
It's something I didn't realise until I tried to make one, that the theory of how
filters work (such as the band-pass filter that you get in a wah-pedal, or the low-
pass filter that gives you a squelchy bass sound) is incredibly abstruse. The
components used are relatively humble, but the explanation of how they behave
mathematically goes far beyond my comfort zone – complex numbers (based on
the square root of minus one), Laplace transforms, and long, unwieldy equations
in multiple unknowns. I've long been familiar with a term like '4-pole low-pass
filter', but what's the '4-pole' about? Let me tell you! You start with representing
all frequencies, real and unreal – sort of the abstract idea of 'frequenciness' – on
a complex-number plane, then formulate an equation using the complex variable
's' to describe the effect of a filter on those frequencies. Then it is possible to plug
certain values of 's' into this equation so that something ends up being divided
by zero, which is mathematically undefined (it's either infinite, or negatively
infinite, or both): so the equation 'blows up'. Far from running away horrified,
we embrace these values, and call them 'poles'; and even though the poles only
exist in the theoretical two-dimensional plane that may not even be 'real'
frequencies, we use them as key indicators of how the filter is likely to perform.
There: now you know. A pole is where the filter equation blows up, like a
volcano. As long as they 'unreal', on the sidelines of the real frequencies, you are
safe. But even from there you can feel them, like being on the foothills of the
volcano. The more poles there are, and the closer they are, the more effect the
filter has.
(Or you could just pump the audio into your mouth and move your lipsF-day

F is for: Peter Frampton, 'Show me the way'

The Peter Frampton song I'm rather fond of – he's a likeable performer with a good energy – but the main reason for playing it to Eddie was for the 'Talk box', a guitar effect that basically involves pumping amplified guitar up a tube into your mouth, and letting it be picked up by the vocal mike. A wah-pedal where you literally go 'WAH'. A human-powered vocoder. I like it for its simplicity, its crudeness. Eddie has challenged me to make one: maybe I will.

I like playing around with electronics. This is a fairly new thing for me: before about three years ago I knew nothing about it – beyond what we all have to learn at school, like, to make a light bulb shine the electricity has to go all the way round the circuit kind of thing. But I wanted to build something fun for Eddie, and thought I'd have a crack at something electronic, you know, a kind of 'Operation'-type thing, and got completely hooked. It speaks to some part of me that loves to know how things work – maybe the same impulse that made me a musician, too. I'm afraid Eddie's needs got swept away: now I'm too busy conceiving and building electronic musical instruments.

It's something I didn't realise until I tried to make one, that the theory of how filters work (such as the band-pass filter that you get in a wah-pedal, or the low-pass filter that gives you a squelchy bass sound) is incredibly abstruse. The components used are relatively humble, but the explanation of how they behave mathematically goes far beyond my comfort zone – complex numbers (based on the square root of minus one), Laplace transforms, and long, unwieldy equations in multiple unknowns. I've long been familiar with a term like '4-pole low-pass filter', but what's the '4-pole' about? Let me tell you! You start with representing all frequencies, real and unreal – sort of the abstract idea of 'frequenciness' – on a complex-number plane, then formulate an equation using the complex variable 's' to describe the effect of a filter on those frequencies. Then it is possible to plug certain values of 's' into this equation so that something ends up being divided by zero, which is mathematically undefined (it's either infinite, or negatively infinite, or both): so the equation 'blows up'. Far from running away horrified, we embrace these values, and call them 'poles'; and even though the poles only exist in the theoretical two-dimensional plane that may not even be 'real' frequencies, we use them as key indicators of how the filter is likely to perform.

There: now you know. A pole is where the filter equation blows up, like a volcano. As long as they 'unreal', on the sidelines of the real frequencies, you are safe. But even from there you can feel them, like being on the foothills of the volcano. The more poles there are, and the closer they are, the more effect the filter has.

(Or you could just pump the audio into your mouth and move your lips).