Saturday, 7 March 2015

EMS Synthi - The Envelope Generator

In the EMS world what we normally refer to as the Envelope Generator is called a "Envelope Shaper". There is a good reason for this as it's definitely not your usual ADSR. 

The envelope can take the shape of a trapeziod, so is often referred to as a "Trapezoidal Envelope Generator."



It's actually a Envelope Generator + a VCA rolled into one.
The Shaper operates by generating a CV & using it to control a VCA.

The Synthi's Shaper has 6 knobs (4 red & 2 silver) & 2 outputs (Trapezoid Out & Signal Out).

The last two silver knobs (5 & 6) are called Trapezoid & Signal.
These set the level (amplitude) of the two outputs.(more about this later).

The first four red knobs are the Envelope Gen itself.
They are named: Attack, On, Decay, Off.

1. Attack is what you'd expect.(2ms to 1sec)
2. On = the time the envelope stays at the top level reached during the attack phase.(0-2.5secs)
3. Decay - again what you'd expect (3ms - 15secs)
4. Off = This is like having a built-in LFO. The length of time the envelope is off (between the end      of  the last envelope & the start of the next env)


The knob associated with this "off section" (see picture below) is unusual as it has two ranges/stages.
4a. While in the range of 0-6 we have an automatic retrigger ---
    it will lengthen the automatic off time between 0.5ms to 5 secs


4b. After about level 6 the cycle starts go into manual mode.... to trigger
    the envelope we can use the trigger button that sits next to the joystick.

Dials 5 & 6 control the
5. Trapezoid Level: This is just the CV level - what you'd expect from a standard Env Gen.
6. Signal level: This uses the Synthi's built in VCA.
   The useful thing about this is you can just patch a oscillator into the Env Gen and obtain a sculptured output without the need to patch a VCA

The two envelope shaper outputs : Trapezoid (row 11) & Env. Signal (row 12)

Voltage control options for the envelope shaper is limited to the decay. 
To do this place a pin in row L.
 

The synthi E also has a trapezoidal EG. 
The shapes are displayed  on the synth itself.
 

Links:
2. Video (Youtube)
3. Muffs
4. Sound On Sound

EMS Synthi - The Battle Patch.

The EMS Battle Patch is a classic EMS "preset".

Here is the patch:
Once you hear this patch you will come to understand why the name "battle" is so fitting.
The unedited video is here.
http://youtu.be/WTDsh43Uzws
The dial settings for the 3 Oscillators, noise, filter, Reverb, etc etc.


So what's inside the prestopatch card?
I couldn't believe how simple it all is.

This is all so familiar.
Doesn't it remind you of the Buchla Music Easel's program/preset card. 
Buchla Music Easel - The Program Card Evolution



Buchla 223e - Multi-Dimensional Kinesthetic Input / Tactile Input Port

A short video of Paul playing a 223e.
Always amazes me as to how responsive this is.



Some pics of the patch:

The unedited version of the video is here:
http://youtu.be/R02sXnVprvA






Wednesday, 4 March 2015

EMS Synthi - Tweaking the filter

I'm just playing around with the EMS Synthi filter today.
When I saw it for the first time, it looked unfamiliar until I realized that RESPONSE is the EMS version of RESONANCE. Sadly there is no voltage control for resonance.
As you can see, it resonates in the higher ranges so can be used as an extra oscillator. The Synthi & VSC3 are not as famous for their filters as say the Korg MS-20 LP or the Moog ladder, though I still like the sound.
The unedited video is here:
 http://youtu.be/Xhvb8RD2KW8

Before 1974, the EMS Synthi filter was officially described as a 3-pole diode ladder with a frequency response of  18dB/octave. In '74, EMS changed their design to a 4 pole 24dB/Oct response. (There is still much debate as to whether the pre-74 design is actually a 4-pole and the post 74 a 5 pole design). Anyway, I'm not sure why, though many say the pre 74 version sounded better. My filter is I believe a post 1974 design.

 This schemo is of the pre-'74 four-pole diode filter

Schematically, the Synthi ladder filter is very similar to the Moog ladder, except that Moog used transistors, and EMS used diodes. Another famous diode latter filter was made by Roland for their TB-303.

The audio enters via the matched pair of 2N5172 transistors at the base and exits via the two lines
above the group of 8 diodes.

I wonder whether this abundance of diode ladder filters is a direct response to Moog's dispute with ARP over their use of a transistor based ladder filter in their early 2600s.???

Beware ...the response knob is very sensitive -- before you know it you are into self oscillation mode.
The response/resonance also effects the audio level a lot. ... it (loudness) can fall quite dramatically
as you approach the Resonance/Response's upper limits



Patch variation 1

Basic Patch: 
Osc 1 + Osc 2 --->Filter + Osc2 ----> channel 2
Osc 1 + Osc 2 --->Filter ----->reverb ----> channel 1
The touching the keyboard triggers the Envelope which opens Channel 1's output.

Patch - Variation 2

EMS Synthi meets a Arturia BeatStep

A few experiments using the Arturia Beatstep as a sequencer instead of the Synthi's KS.

The standard un-modified Synthi uses a 0.32V/oct scale. My Synthi has been modified to 1V/oct.


The unedited videos are here:
http://youtu.be/IxRrzSAgvTA
and
http://youtu.be/IHtSnNXMl6w


The basic patch:
All osc outputs ---> Filter -----> Reverb -----> Channel 1(Out)
Osc 2 & Osc 3 ------> Ring Mod -----------> Ring Mod Out + Osc 2 ------> Channel 2 (Out)

Patch - variation 1

Tuesday, 3 March 2015

The Baby Taj - Agra - India

This site is the Tomb of I'timād-ud-Daula " the Treasurer of the Empire".
It's a Mughal mausoleum in the city of Agra (the Indian state of Uttar Pradesh).

Nur Jehan, the wife and queen of the Mughal Emperor Jahangir built this tomb for her father, Mirza Shiyath Beg. Soon after her marriage, Mirza was appointed Prime Minister & Treasurer.

Mirza must have done his job well as treasurer to have earn't this tribute.

It's a jewel that most tourists miss in their rush to see the Taj Mahal which is only 6km away.

The tomb was built between 1622 and 1628. In the history of Indian architecture this site is very important. It marks the transition from the old monumental style of red sandstone with marble decoration (seen in the Humayun's Tomb in Delhi and Akbar's tomb in Sikandra) to structures built completely from white marble and pietra dura inlay (the pinnacle being the Taj Mahal).

Pietra Dura or pietre dure is the art of stone inlay. The aim is to cut the stone so precisely that contacts between the edges are invisible. This art was made famous in Renaissance Italy, esp in Florence & Rome.
The walls of this site are completely constructed with white marble from Rajasthan.

Marble encrusted with semi-precious stones – agate, carnelian, garnet, jasper, lapis lazuli, onyx, and topaz.
This ornamentation is so beautiful. Floral, arabesque, geometrical - very stylised.- inspired by the plant studies of Ustad Mansur.
 These screens (called  jālī screens) are also carved from white marble. So delicate & beautiful.
 
Many of its design elements can be found in the later Taj Mahal. These Islamic mausoleums are of great architectural interest. Notice firstly that the main tomb stands on a plinth on red sandstone. 
The Tomb is square with octagonal towers.
They are both situated in the centre of a park which is then divided into 4 gardens (Char-Bagh). The gardens are formed of 4 raised avenues which have waterways running through them. We also see the usual enclosing walls & side buildings

There is also a multi-storied open pleasure pavilion on the western side which overlooks the river.
This is made of red sandstone, inlayed with white marble. The tomb is situated on the left bank of the river Yamuna.
Above is a view of the Western Pavilion which overlooks the river. Notice that it's built in the older "Monumental Style" of red sandstone/marble inlay.

This layout evokes the "Persian Paradise".... the fountain of life plays in the centre from which 4 holy rivers gush.... the deceased is in the centre of paradise for eternity.

The central room of the mausoleum (qubba) is a cube. In this case it is not covered with the usual domed ceiling. Here, the building is roofed with a square "Barahdari".


Above, we have the Northern Pavilion. It's identical to the Southern Pavilion. They have a single storeyed "Iwan" in the middle, and double storeyed wings on their sides. There are rooms and halls on the first floor of these pavilions. There are also stairways on the sides. The very top "crown" is called a "Chhatris".





This is the main entrance to the tomb (The Eastern Gate). Notice the use of red sandstone with white marble inlay.