CV Expander: what does it do?
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doubleyouel
- Posts: 7
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CV Expander: what does it do?
i saw radiohead this month in mansfield, massachusetts (they were awesome!) and when they played "idioteque", guitarist johnny greenwood was playing with something that looked like a CV expander to produce these soft electronic bell sounds. i'm curious as to if this CV expander for the voyager works the same way in that one plugs cables in and out to produce different pitches and maybe different sounds?
As far as I know, Johnny Greenwood uses an Analogue Systems Integrator. Check out:
http://www.analoguesystems.co.uk/
This is not a "cv expander" but rather a modular synthesizer. Nothing in a modular synthesizer is fixed. When building a modular you can select any modules you like to build up your system: i.e. you choose your oscillators, filters, modulators, etc. Each module is essentially a circuit that produces and/or modulates electrical signals. Modules are then connected together to produce the requisite signal flow: each patch cable passes voltage from one module to another. These voltages are usually called control voltages (or CVs). There are (usuallly) no hardwired connections between modules.
The voyager OTOH is a normalised synth. There are predefined conenctions between most of its parts. However, the voyager on its own will accept CVs from some other source. So you could patch in an LFO from an Integrator, say, in place of the voyager's own or to complement it. These ins give you a much larger range of sound producing possibilities IF you have external gear capable of producing CVs.
The vx351 allows you to use the CVs produced by the voyager to control external gear (or you can route the voyager's own CVs back into it by patching the vx351 outs to the voyager's ins). So, on its own a voyager + vx351 won't allow you to do much more than you can with just the voyager. But a voyager + vx351 + external gear is a formidable combo.
http://www.analoguesystems.co.uk/
This is not a "cv expander" but rather a modular synthesizer. Nothing in a modular synthesizer is fixed. When building a modular you can select any modules you like to build up your system: i.e. you choose your oscillators, filters, modulators, etc. Each module is essentially a circuit that produces and/or modulates electrical signals. Modules are then connected together to produce the requisite signal flow: each patch cable passes voltage from one module to another. These voltages are usually called control voltages (or CVs). There are (usuallly) no hardwired connections between modules.
The voyager OTOH is a normalised synth. There are predefined conenctions between most of its parts. However, the voyager on its own will accept CVs from some other source. So you could patch in an LFO from an Integrator, say, in place of the voyager's own or to complement it. These ins give you a much larger range of sound producing possibilities IF you have external gear capable of producing CVs.
The vx351 allows you to use the CVs produced by the voyager to control external gear (or you can route the voyager's own CVs back into it by patching the vx351 outs to the voyager's ins). So, on its own a voyager + vx351 won't allow you to do much more than you can with just the voyager. But a voyager + vx351 + external gear is a formidable combo.
p.s. Bells are rich in enharmonic content so any form of modulation which produces sidebands will usually produce bell like sounds. The most obvious way is either linear FM (i.e. using the output of one oscillator to modulate the frequency of another) or ring modulation. For the former option, I have only just gotten my voyager so I don't know whether FM in the voyager will produce such sounds, but it should. For the latter option, check out the mf102.
If these terms are new to you, here's a (very) potted summary of FM. There are two main types of FM: exponential and linear. In both cases you have a modulation source (called the modulator) and a destination (called the carrier). The modulation is (basically) multiplicative and one of the results of this operation is that additional frequencies are produced both above and below the carrier frequency. These frequencies are called sidebands.
For the voyager, any CV from a frequency source that is patched into the voyager's Pitch In will produce exponential FM. Basically, the name stems from the fact that the pitch of the modulator (i.e. an oscillator) increases on an exponential basis: e.g. C2's frequency is twice that of C1. The downside to this approach is that the sidebands generated are also subject to exponentiation. Thus, the sidebands below the carrier frequency will fall in a frequency range approximately half that of those above the carrier frequency since the carrier is pushed up and down an equal musical interval (therefore more Hz up than down). Simply put, this means that as as the amount of modulation is increased so the pitch of the modulated sound increases relative to the actual scaling. This is the reason why exponential FM can produce such grinding, tearing lead sounds or such an unholy noise.
Linear FM is a form of synthesis created by John Chowning and patented by Yamaha for their DX series of synths. It's pretty tricky to understand (it's certainly beyond my limited maths knowledge) and I don't want to be any more verbose than I've already been but basically, the modulation is linear: the carrier is pushed an equal number of cycles per second above and below its center frequency. Thus, as modulation increases there is no perceived rising in pitch. Using the voyager's 3->1 FM switch results in linear FM.
Ring mod is a form of amplitude rather than frequency modulation. It takes two input frequencies and produces an ouput which contains both the sum and difference of those two frequencies. e.g. if your input frequencies are 100Hz and 500Hz, you will receive an ouput signal containing the frequencies 400Hz and 600Hz. The original frequencies are usually (but not always) excluded so only the sidebands remain. Moog have the manual for the mf102 online and this explains the concepts here quite well.
If these terms are new to you, here's a (very) potted summary of FM. There are two main types of FM: exponential and linear. In both cases you have a modulation source (called the modulator) and a destination (called the carrier). The modulation is (basically) multiplicative and one of the results of this operation is that additional frequencies are produced both above and below the carrier frequency. These frequencies are called sidebands.
For the voyager, any CV from a frequency source that is patched into the voyager's Pitch In will produce exponential FM. Basically, the name stems from the fact that the pitch of the modulator (i.e. an oscillator) increases on an exponential basis: e.g. C2's frequency is twice that of C1. The downside to this approach is that the sidebands generated are also subject to exponentiation. Thus, the sidebands below the carrier frequency will fall in a frequency range approximately half that of those above the carrier frequency since the carrier is pushed up and down an equal musical interval (therefore more Hz up than down). Simply put, this means that as as the amount of modulation is increased so the pitch of the modulated sound increases relative to the actual scaling. This is the reason why exponential FM can produce such grinding, tearing lead sounds or such an unholy noise.
Linear FM is a form of synthesis created by John Chowning and patented by Yamaha for their DX series of synths. It's pretty tricky to understand (it's certainly beyond my limited maths knowledge) and I don't want to be any more verbose than I've already been but basically, the modulation is linear: the carrier is pushed an equal number of cycles per second above and below its center frequency. Thus, as modulation increases there is no perceived rising in pitch. Using the voyager's 3->1 FM switch results in linear FM.
Ring mod is a form of amplitude rather than frequency modulation. It takes two input frequencies and produces an ouput which contains both the sum and difference of those two frequencies. e.g. if your input frequencies are 100Hz and 500Hz, you will receive an ouput signal containing the frequencies 400Hz and 600Hz. The original frequencies are usually (but not always) excluded so only the sidebands remain. Moog have the manual for the mf102 online and this explains the concepts here quite well.
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doubleyouel
- Posts: 7
- Joined: Fri Aug 29, 2003 6:26 pm
- Location: albany, new york
- Contact:
salute, suthnear!
holy cow and you didn't even break a sweat! i just wanted to let you know, suthnear, that your efforts are not overlooked. what an awesome compilation of information, thank you! i can hang with most of what you are saying; i took 2 electronic music classes at my school, SUNY Albany, and i have been reading into this stuff. i am planning on purchasing a voyager in november and the cv expander looks so cool, i was just wondering if it would be beneficiary for me. of course, you answered that question quite thoroughly, thanks again!