A great module for mixing, scaling, and processing Control Voltages. (the 257T can also be used with audio voltages)
There are 3 inputs: Va, Vb, Vc.
There are 3 knobs: K, M, Voffset
You can add, subtract, scale, invert & multiply voltages.
The above equation can be simplified to:
K + M + V = output
Va * K (Attenuverter): Inverts/attenuates and scales the voltage from input Va.... allows for -10 to zero to +10V control of whatever is plugged into Va
{[Vb*[1-M]] + [Vc*M]}: blends inputs "Vb" and "Vc" .
The voltages Vb & Vc can be crossfaded with the M knob
or a CV at the banana input between Va & Vc
There is a switch that when turned on, will apply +0.5-1V (depending on your calibration) directly to the Vb input
V(Offset): Adds a DC offset to the final output.
The V knob when increased will output 0-10V.
(with NOTHING plugged into the module, if you turn the V knob to 50% ,you
would have +5V show up at the output).
How I like to imagine this module is as a way to sum 3 voltages in creative ways.
Remember that you have two voltage processors. You can combine these.
For comparison see the Buchla 254v, Buchla 256 & 156.
The title :"How to Wreck a Nice Beach" is odd isn't it?
It's actually a vocoder distortion of the phrase "how to recognise speech".
The book follows the history of the vocoder from its invention by Homer Dudley (Bell Labs) in 1928 and its use in war, to its contribution to music today.
The word Vocoder is a combination of two words.
Voice + Code = Vocoder
Dudley invented it to reduce the cost and improve the distance of transmitting vocal signals across the Atlantic. Back in those days transatlantic copper cables were very expensive and distances were huge. Vocoded signals were essentially a form of data compression for voice........ like MP3 is for music today.
I have a few vocoders .. the Korg VC10, a EMS 1000 and the Roland VP-03. These are great, though if you really want to know how these things work you can't go past a modular. There aren't however many modular vocoders around these days. Doepfer used to produce one in their Eurorack A-100 series.
Sadly these are hard to find today.
These came under the code A-129. There were 5 modules in the series, though the 1st two (A-129/1 & A-129/2) are I think the most essential.
If you were back in 1928, you could imagine someone speaking into the A-129/1 in NYC and the A-129/2 being at the listening station in London.
The speech input is first chopped up, analysed & converted into 15 control voltage outputs by this VOC A-129/1 Vocoder Analysis Section module.
The A-129/1 uses 15 steeply sloping filters (13 bandpass, 1 LP & 1 HP). Attached to each filter is an envelope follower which produces the associated control voltage.
These control voltages are transmitted across the transatlantic cable to the A-129/2 module in London.
Here the 15 control voltages are decoded
The A129/2 basically has another 15 filters, but associated with each filter is a VCA.
The filter/VCA's job is to reconstruct the original voice.
The cool thing about this modular vocoder is that these 15 CVs can be modified between the 2 modules.
..... attenuators, slew limiters, LFOs, inverters, etc etc could be used to get interesting results.
The "instrument input" is where you would plug the "carrier" signal .... use something like a VCO.
For best results, the original voice & the carrier signal need to have a similar frequency spectra. ........something like a sawtooth is best as it has a dense audio spectrum. "A square wave has only half as many harmonics, and triangle and sinewaves are completely unsuitable" (A129 manual).
During WWII vocoding was used to encript voice transmissions. The control voltages could be sent over radio, The receiving unit had to have the same filter configuration to decode the messages correctly.
In 1968, Robert Moog developed one of the first solid-state musical vocoders for the electronic music studio of the University at Buffalo.
In 1979 , Moog Music released this vocoder
It does not have any internal
oscillators, so it is designed to be used as a signal processor for
external carrier & modulator wave sources. This 16-channel cross-matrix patching
system provides incredible flexibility, allowing for full external
patching between synth & vocoder sections.
Below is a pic of Kraftwerks vocoder... made around early 1970.
Buchla 296
Two 296s will give you a vocoder. The 296 has VCAs and envelope followers attached to each BP filter.
It's a lovely module.
In euro, Verbos has a similar module. The Bark Filter processor.
Like the 296, you will need two in order to perform vocoder effects.
Apologies for the poor sound on this instagram video, but it does sound really amazing.
I'll do a proper recording one of these days.
It started me wondering how many other "harmonic" related VCO modules there are out there.
Not may I think.
In Euro the The Verbos Harmonic Oscillator (HO), the Mutable instruments Plaits & Braids and the Make noise Telharmonic were some modules I could find. The HO looks related to the Buchla 148, 262v.
Do let me know if you know of any other modules that you think fall into this category.
The old Hammond organ with its drawbars is an example of this type of synthesis (additive synthesis).
In the software world Native Instruments Razor is a good example.
This brings up the topic of additive vs subtractive synthesis.
and begs the question why are there so few Synth modules that do additive synthesis?
The other euro module that I think can be loosley added to this list is the Make Noise Echophon.
The Echophon's depth control of the pitch shifter can be used to roughly approximate the harmonic series of the imputed audio .. these are the frequencies that are multiples of the fundamental. To do this the large black pitch control knob must be set to max.
Every musical sound has these harmonics.A sine wave has only the fundamental or first harmonic, a saw tooth contains all harmonics in
inverse proportion to their number. A square wave has all the odd harmonics
in the same ratio, etc etc. So with the Echophon, we can for example, just use a sine wave which has only the fundamental harmonic, and then add more harmonics by turning the depth control knob (the blue one).
Maybe this is use of pitch shifting modules to obtain spectral shifting is worth further investigation.
I understand that shifting the pitch of signal components retains their
harmonic relationships.
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Other modules worth exploring are clock dividers & multipliers .
Eurorack modules in this category include the SSSR Labs VC Divider, the 4MS Atoner, the quad clock distributor, the RCD (rotating clock divider) and SCM (shuffling clock multiplier). Use audio-rate input sources instead of LFOs with the clock dividers & multipliers to get harmonically related outputs.
The Doepfer A-137 is worth a look at.
The basic
idea of a wave multiplier is to multiply the waveform of an incoming signal
(e.g. triangle/saw/sine from a VCO) within one period of the waveform. This
leads to additional harmonics of the incoming signal. The period and
consequently the pitch of the signals remains unchanged. The A-137 works as a kind of "inverse low pass filter", i.e. it
adds a lot of harmonics to a signal that contains none or only a few harmonics
(e.g. sine or triangle waveform). In contrast to that a low pass filter (e.g. A-120)
removes harmonics from a signal that contains a lot of harmonics (e.g. saw or
rectangle waveform). ------------------------- Ladik make a Harmonic Generator in 8 HP The H-020 ------------------------
A little bit more off this topic, but still loosley related are filter bank style modules.
I think the Verbos Bark Filter, and the Frap Tools Fumana are worth investigating.
The
Bark/Fumana seem to be inspired by the Buchla 296/295/294.
Also worth a google are the 4MS Spectral Multiband Resonator (SMR) and the Serge Resonant Equalizer.
Re the Buchla 294/295/296, the Verbos Bark, the Fumana, the 4MS SMR and the Serge Res Eq. ... maybe they can be better described as "spectral processors"..... they are much much more than fixed-filter banks.
The 294 comb filter is on the extreme left.
The 295 filter
The first two, the Buchla 294 & 295, Don called comb filters, but their evolution into the amazing 296 seems plain to see.
The 296, the Fumana and the Bark are 16-band filter/spectral analyzers. Amazing tilt-like
controls, you can address odd and even bands. They also have a row of
envelope followers -- one per band.
Mark Verbos has chosen to use the "Bark scale".
It is named after Heinrich Barkhausen who proposed the first subjective measurements of loudness.
The scale ranges from 1 to 24 and corresponds to the first 24 critical bands of hearing.
The Frap Tools Fumana - Dual16 Band Spectral Editor
The outward style of each of these modules is very similar ... the upper section provides access to each filter's main output at the chosen fixed frequencies.
The Buchla 294 uses the scale:
<250/ 1K / 4K / >4K
The Buchla 295 uses the scale:
<100/ 200/ 350/ 500/ 700/ 1K/ 1.4K/ 2K/ 3.5K/ >7K
The Verbos Bark filter uses the scale :
<100/ 300/ 510/ 770/ 1.08K/ 1.48K/ 2K/ 2.7K/ 3.7K/ 5.3/ 7.7K/ >10.5K
The published Bark
band edges are given in Hertz as [0, 100, 200, 300, 400, 510, 630,
770, 920, 1080, 1270, 1480, 1720, 2000, 2320, 2700, 3150, 3700, 4400,
5300, 6400, 7700, 9500, 12000, 15500].
So the Verbos Bark uses every second Bark band. Looks like the Frap Tools has more evenly spaced
bands following something like a graphic EQ, whereas the Verbos
focuses on frequencies that are more recognised by the ears. The Fumana might be better for shaping bass sounds as it has 3 bands below 100Hz, but the Bark may be better for singling out harmonics that the human ear can distinguish ???
Quote: Fumana manual. "Each of the two filter array is based on 16 parallel analog bandpass
filters. The main filter bands from 2 to 15 are mainly based on Bessel
calculation, while bands 1 and 16 are respectively a lowpass and
highpass with a custom method to obtain better musical results. All
bands on the main filter array use an 8th order slope (48dB/oct)."
