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DX7 - Basic - Play & Function Modes - getting started

October 26, 2019, 11:34 pm
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 There are 3 main modes of operation on the DX7

1. Edit (purple-blue)
2. Play (white)
3. Function (brown)


Everything is colour coded

Play Mode


Play Mode (white) is the simpliest and a good place to start.
Here you can access the sounds contained in the internal & external memory.


The green buttons above PLAY let you select between internal and external sounds.
Just press either green button to activate the 32 (white) switches. Then press the switch to select the preset.


External sounds can be either ROM or RAM.


ROM or Read only memory cartridges are non erasable.
You cannot write data to a ROM cartridge.
Each ROM cartridge contains 64 sounds or presets organised into 2 sides... sides A & B. (32 on each side).
Selecting the side (A or B) is accomplished with the select switch on the cartridge itself.

RAM =Random Access Memory .... this is very flexible ... you can both read and write data to it.
This contains 32 voices


Function Mode

Press the brown function  key to enter this mode.
It covers various effects you can apply while playing (like aftertouch & Modulation wheel) as well as things like voice data load/save operations and checking the battery.

Functions parameters cannot be saved to memory after the DX is turned off.

1.     Master Tune
2.     Poly/Mono
3/4.   Pitch Bend (range & Step)
5/6/7 Portamento (mode, Glissando, time)
9.        Edit recall
10.     Voice Initialize
11.      Cartridge formatting
14        Battery Check
15/16  Cartridge (save & Load)
17/18/19/20 Modulation Wheel - range, pitch, amplitude, EG Bias
21/22/23/24 Foot Control - range, pitch, amplitude, EG Bias
25/26/27/28 Breath Control - range, pitch, amplitude, EG Bias
29/30/31/32 After touch - range, pitch, amplitude, EG Bias

 -----------------------


1.     Master Tune
Adjusts the overall tuning ... 150% range. Use the data entry slider to adjust.

2.    Poly/Mono
Controls mono vs poly voice
Use Data Entry -1 for poly , and +1 for mono

3/4.   Pitch Bend (range & Step)
 Range: between 0 to 12.
              0 = no pitch bend.  12 = 2 oct range
Step : Between 0 to 12
           0 = smooth pitchbend with no steps.
           1 =  semitone steps
          12 = 1 octave steps.

5/6/7 Portamento (mode, Glissando, time)
Portamento effect depends on mono vs poly mode
eg: on mono use Data Entry -1 for fingered porta , and +1 for  full time porta
(see manual)
Glissando - adjusts speed of portamento
----------------------------------------


9.  Edit recall
Allows you to recall a voice that was previously being edited or created.
 Use the DATA ENTRY "yes key"

10.     Voice Initialize
This sets up a basic voice for you to edit and create new voices.
Press the DATA ENTRY "yes key "

11.      Cartridge formatting.
Interestingly this is not written on the DX7 itself. 
This formats your RAM cartridge
 Press the DATA ENTRY "yes key "

 14        Battery Check
Battery voltage should be between 2.2 to 3V.

15/16  Cartridge (save & Load)
Save= this saves the 32 internal memeory voices to a cartridge.
Load= This loads all 32 voices from a cartridge into internal memory.

--------------------------------------------------------------


17/18/19/20    Modulation Wheel
Used to control the amount of LFO modulation to range, pitch, amplitude, EG Bias
Range : 0 to 99
Pitch : on or off
Amplitude : on or off

 ----------------------------------


 21/22/23/24 Foot Control - range, pitch, amplitude, EG Bias

 ---------------------------------------


25/26/27/28 Breath Control - range, pitch, amplitude, EG Bias
29/30/31/32 After touch - range, pitch, amplitude, EG Bias


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FM Index
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Yamaha DX7 - FM & Timbre in a digital world

October 31, 2019, 1:20 am
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 I have recently been exploring the Yamaha DX7 and thinking about how it compares with standard analog subtractive synthesizers....... and contrasting Analog FM with Digital FM

There is something very special about the DX7 and how it produces sounds.
The Yamaha DX7 is of course digital and for many, the DX7 = FM synthesis.

However, FM isn't the sole domain of digital. FM existed in the analog world before the DX range was produced. Below is a pic of a Buchla oscillator... the 158. You can see that Don was very much into wave shaping & FM. This module dates from around 1968/69.



The pic below is of a Buchla 208 with its analog FM, dating from 1973.

Notice the word "timbre".

So in a non FM analog subtractive synth you usually start with harmonically rich wave forms like saw, square, etc. and you use filters to smooth the sound out a bit (technically we are subtracting overtones).
In analog FM synthesis, you start with a wave form and you then use other waves to distort it.... to create new tones & harmonics.


Timbre

We come across this term again and again. It is also called tone or colour. What exactly is it?
It's one of the 3 main parameters of sound. ...which are volume, pitch & timbre.

The Oxford dictionary says that
"timbre" describes those characteristics which allow the ear to distinguish sounds which have the same pitch and loudness.

For example a piano, a flute and a guitar may all play the same (frequency) note, at the same (amplitude) loudness, but we can still tell them apart. This is due to their different timbres.

The timbre of a sound depends on its wave form. Though the frequency & amplitude may stay the same what varies are the number of overtones, or harmonics, that are present, their frequencies, and their relative intensities. 

To elaborate further, the timbre of a tuning fork is clear and pure because the sound it produces is almost without overtones. It vibrates at 440Hz. This is known as it's fundamental frequency.
You can use this fork to tune our piano, flute or guitar to 440 Hz (Middle A), but each instrument will sound different because they have unique overtones which are related to the fundamental.

Harmonic          Frequency
First                   440 Hz
Second               880 Hz
Third                  1320Hz
Fourth                1760Hz
Fifth                   2200Hz

To calculate the next harmonic, you of course just add 440.

These relationships appear to be very important when using the Yamaha DX FM system.
What's important to remember is that when you hear any sound (in nature or music) you are hearing lots of different frequencies all mixed together.... fundamentals, harmonics of the fundamentals, 
dis-harmonics / en-harmonics of the fundamental, etc etc..... this is timbre.

More harmonics = more "musical" sounds
More dis-harmonics = more "non-musical" sounds

Digital synths generally produce sounds in two ways ... FM or additive
Additive digital synths like the Fairlight and the Synclavier can specify a fundamental frequency and add overtones (of harmonics & disharmonics) to create new sounds.  The Fairlight allows sampling where it will analyse a inputted sound, and recreate the sound using its additive synthesis ability.

Though the DX7 can do some additive, this is not it's main way of making new sounds.
It's method uses Digital FM
It's all accomplished in a virtual world consisting (not of waveforms distorting one another),. but of programs in a computer calculating what would have happened if these waveforms had really existed and were distorting one another.

The core of the DX7 is the operator.
Its not a physicial thing like a string on a guitar or an oscillating electrical signal.
It's a bit of software.
You can picture it something like this:
The Oscillator is the sound source.
It generates numbers.

The operator also has a digital amplifier and EG
The amplifier's job is to increase or decrease those numbers exiting the oscillator.
It may be changing volume (if the operator is a carrier).
The EG will send numbers (issuing software instructions) to effect the amplifier.... its changing volume over time in this example.

Note That the operators oscillator has two inputs:
1. pitch data
2. modulation data

When the output of one operator is patched into the input of another operator, the result is a complex waveform. This is the essence of FM synthesis.
By varying the ratio of the modulator & carrier frequencies, and by varying the envelope of the modulator, you can create some very complex waveforms.

They use DACs to convert those numbers to analog voltages which we can hear.

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FM Index
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Bega Synth Surfers Festival

November 1, 2019, 5:02 am
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Bega is about half way between Sydney & Melbourne ... about a 5-6 hour trip from Sydney.
It's a lovely neck of the woods.

Thanks to the Festival organisers  esp Scott, Chris & Carsten who made me feel so welcome.
It looks like the synth community on the far South Coast of NSW is in very healthy shape.

 Some video synths. Thanks Chris.


 This is the first time the Bega Synth Surfers Festival has been held


I hope this will become an annual event.




A TTSH & Deluge

 Medusa, Lyra,
Korg 770 --- that's a beauty !!!



 The AE Modular

Lots of fun.

Murrah Hall














 Videos to come.

Here is the official info
http://djjondent.blogspot.com/2019/09/synth-surfers-bega-valley-synth-festival.html

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Yamaha DX7 - Edit Mode

November 2, 2019, 3:36 am
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This is how we program new voices.

Though this is a long post, most of the basic concepts are repeated again and again, so once you have understood the first few edit procedures it is dead easy after that.
So don't be discouraged. And don't let anyone tell you that programming a DX7 requires a degree in rocket science. They have probably never owned a DX7 or tried to program one.

The take home concept to know is that by varying the pitch frequency, modulation, and envelope data , it is possible to edit pre-programmed voices or to create entirely new voices.

Press the purple Edit/compare Function button on the extreme left  to enter EDIT MODE


Setting and modifying parameters is done with the DATA slider


A small dot will appear next to the voice number if any data is modified.



-------------------------------------------------
Operator On/Off
There are 6 operators - numbers 1 to 6
In edit mode pressing these keys will turn them on and off,


Voice 4, 5 & 6 have been turned off in the pic above

aLL the voices have been turned off in the above pic

-----------------------------------------------------
EG copy
This copys the envelope data from one operator to another.


Use the store key

---------------------------------------------

Algorithm
Press Key 7

 Use the Data entry key +1 & -1 or the slider to increase/decrease value to select one of the 32 algorithms.

--------------------------------
Feedback
Press Key 8

Choose an algorithm with a feedback loop.
eg:

The range of feedback : 0 to 7.

Use the Data slider to change the amt of feedback.

--------------------------------------

LFO

Use Keys 9,10,11,12,13.14.to set the LFO parameters.

Once the paramets are set, you can use the mod wheel, a breath controller, aftertouch etc
to apply the LFO effect.

9. Wave
 There are 6 waveforms
You use the data slider  to select the waveform.

10. Speed
This sets the frequency of the LFO
 Range: 0 to 99
You use the data slider  to select the frequency

11. Delay 
Sets a delay between the pressing of a key and onset of LFO modulation.
0 = no delay
99= longest delay
You use the data slider  to select

12. PMD -
Pitch modulation depth
The depth of LFO modulation applied to pitch
This is independent of the controller settings
0= no pitch mod
99 = max pitch mod
You use the data slider  to select

13. AMD
Amplitude modulation depth
0=  no amp mod
99 = max amp mod
This is independent of the controller settings
You use the data slider  to select

14. Sync
Either on or off
Pressing the sync button
alternately will turn it on or off.
on= modulation begins when key is pressed
off = the LFO is free running and modulation commencement is random.

---------------------------------
Mod Sensitivity
15. Pitch
16. Sensitivity
This adjusts the depth of pitch and amplitude modulation
Pitch:  range 0 to 7
It sets the modulation sensitivity to all operators

Amplitude : range 0 to 3
Amp modulation is independent for each operator.
It creates "wow effects for modulator operators.
It creates tremolo effects for carrier operators,
You can select the operator using the operator select key
Pressing the key successively selects the operator - 1 to 6.
Only active operators will be displayed. The ones that are turned off will be skipped.

-----------------------------
Oscillator

17. Mode/Sync
18. Frequency Coarse
19 Frequency Fine
20. Detune


17. Mode / Sync
Pressing button 17 will cycle between mode & sync

Frequency Ratio -- operator pitch is scaled to the keyboard was you'd expect.

Fixed Freq - a fixed freq is produced no matter which key is pressed.
                      (frequency is set using buttons 18/19)

Sync -
ON = oscillators begin at phase 0

18. Frequency Coarse
19 Frequency Fine


...



 20. Detune

------------------------------------------------------------------

EG - The envelope generator
Buttons 21 & 22
For more detailed info see here
The EG controls volume and/or timbre - depends if its effecting a modulator or a carrier.
Modulator -- timbre
carrier - volume

The shape of the envelope is controlled by levels & rates
Pressing button 21 will cycle through each rate (1 - 4)
Use the slider to set the amount of rate.

Pressing button 22 will cycle through each level (L1-L4) 
Use the slider to set the amount of level

The envelope can be set individually to each operator.
Use the z button to choose operators

---------------------------------------------------------
Keyboard Level Scaling
Buttons 23, 24, 25
Allows you to choose a keyboard break point and make a envelope to the left & right of this point.
You have control of the envelope shape (curve & depth).

For more detailed info chick here

The Breakpoint can be anywhere between A1 and C8
There are 4 different curves available:+/- exponential and +/- linear.


Depth varies between 0 and 99
0=flat

-----------------------------------------------------------------------
Keyboard Rate Scaling
Button 26
Range is 0 to 7
0 = short treble decay link an acoustic piano
7 = long bass decay
-----------------------------------------------------------------------
Operator
Buttons 27, 28.

Sets the output levels & touch response levels of each operator.
(each operator has its own envelope) 
Output level range: 0 to 99
Use the z button to choose the operator.

The Key velocity = key touch response.
This can be applied to carriers and modulators ... so it effects more than just volume.
You can effect timbre !
Range : 0 to 7
-----------------------------------
Pitch EG
Buttons 29, 30

Just like the other DX7 envelopes you have Rate & Level settings
Pressing the RATE button successively will scroll through rate settings R1 , R2, R3, R4.
The same idea applies to the LEVEL button

------------------------------------------
Key Transpose & Voice Name
Buttons 31, 32

31. Key Transpose -- transposes pitch over a +/- 2 octave range.
(Semitone steps) with C3 as standard.
For example, to transpose up one octave hit KEY TRANSPOSE and then press C4.

32 Voice Name
Max of 10 characters.

To edit a name:
a) Press VOICE NAME
b) Hold the Character button and scroll through the letters/numbers
 You move along the LCD with the +/- buttons.

c) Use the 32 green membrane buttons to enter the name. Numbers 0-9 and letters A to V.

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FM Index
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Yamaha DX5 - initial pics

November 3, 2019, 1:07 am
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Just arrived.
Some fun times ahead.








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DX 5 - Getting started - 1. Play Mode

November 3, 2019, 3:01 am
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The DX5 has the same 3 modes: Play, Function & Edit that you find in the DX7.
It's also colour coded like the DX7.

1. Play (white)
2. Function (green)
3. Edit (purple-blue)

 Play Mode

Play Mode (white) is the simpliest and a good place to start.
Here you can access the sounds contained in the internal & external memory.

These are the internal/cartridge  voice memory selection switches, along with switches
to set the keyboard assignment ... single, dual, split.



The DX 5 is often described as two DX7s ... though its also a bit like a DX21
(but with 6 operators , not 4).
(If I understand the DX21 manual correctly, it actually has two completely separate 4 operator ,8 algorithm FM synths)

You can split the keyboard between two different sounds, and even split the sounds to left and right outputs. There is 32 note polyphony in single and split modes. You can specify hard splits on the keyboard. The keyboard ranges from E0 to F7 with full velocity and after touch.



Individual voices are selected using the two groups  (bank & voice).
The white labeling indicates the voice selection... arranged in two groups of 2 rows.
There are 4 banks. Each bank has 8 voices.
The upper row of switches is for channel A.
The lower row of switches is for channel B. 

Performance Memory Selection



The DX7 has 64 performance memories.
These are selected using these two rows of 8 switches.
The top row selects Performance memory banks (B1 to B8). 
The Lower row selects Performance & Voice Data  (P1 to P8) 

Each performance combination can can be given a name.
The performance name can be recalled by pressing the currently selected bank switch a second time.

Data for Performance Memories is stored on Cartridges.
So you must plug in the cartridges before you can retrive any performance memory data.

To be continued..........
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DX 5 - 3. Edit Mode

November 3, 2019, 3:03 am
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The DX5 has the same 3 modes: Play, Function & Edit that you find in the DX7.
It's also colour coded like the DX7.

1. Play (white)
2. Function (green)
3. Edit (violet)

Edit Mode  

Edit Mode is where we edit the voices and can also create new voices.
Notice the colour .. the violet colour indicates its part of the edit mode.

Entering Edit Mode is done here: EDIT/COMPARE
 You can switch between channel A and Channel B voices by pressing the violet EDIT A & EDIT B switch
Individual voice parameters are selected by pressing the appropriate violet labeled switches & programmed using the data entry slider / switches. These are identical to the DX7.


In some instances, you will want to compare the original sound to an edited one.
Do this by pressing the edit/compare switch again.
To save edited voices, you need to enter the store mode


Operator Select

There are six operator select switches. OP1 to OP6 ... just press the one you wish to work on.
Only one operator can be worked on at a time.
The operator on/off switches are below.

Working from left to right these are the next set of switches;


Algorithm.
Permits selection of any of the 32 algorithms.
Use the Data slider / switches.

Feedback Level
Feedback can be applied to one operator in any algorithm.
This controls the level only.  Range : 0 to 7
Use the Data slider.

Operator Output Level.
You can control the output level of a selected operator.
range; 0 to 99
If the operator is a carrier you will effect the volume.
If the operator is a modulator you will effect the harmonic spectrum & timbre.


EG select EG/Pitch EG
This is linked to the Envelope Generator Switches: R1- R4 & L1 - L4



To be continued....................

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Yamaha DX5 - 2. Function Mode

November 3, 2019, 4:04 am
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The Function Mode
This concerns the programmable parameters that are not concerned with voice programming.
Everything on the DX5 is colour coded.
The colour for the Function Mode is Green.

To access the Function Mode you need to press this GREEN FUNCTION BUTTON


Below are the Function Job Tables. (you won't see this on a DX7).

tHESE are on the front panel of the DX5 itself.

It shows the various jobs that can be done by using the performance memory / function switches.
(B1 to B8 & P1 to P8)
These switches are dual use (we are using the green function bit)
The Job groups are further divided into 4 sections:
a) Tune (B1)
b) Performance Memory Parameter (B2 to P3)
c) Memory Management (P4 to P7)
d) MIDI (P8)

To Be continued................
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bty

November 3, 2019, 4:07 am
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Top 40 Synth Blogs for 2019

November 7, 2019, 3:18 am
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Thanks to Feedspot for their rankings.
FEEDSPOT has selected the top 40 blogs / websites from thousands of synthesizer blogs in 2019.
This site has reached #22 for the 2nd year in a row.






Thanks to my viewers who helped put the site on this list.
It's a great honor.


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Jasper-Wasp build pics

November 7, 2019, 3:59 pm
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Jasper Build notes. I'm building this for a friend.
These aren't official notes and I'm not a professional Synth Technician..
Just my personal thoughts to help me trouble shoot if I encounter any probs.

The official website where you can buy a kit is here:
jaspersynth.co.uk

There are lots and lots of CMOS ICs. This is almost a Lunetta synth. Here is my page on CMOS &  Lunetta synths


Anyway, the integrated circuits used in this build are mostly CMOS (with a smattering of the occasional op-amp). I've got a few old vintage WASPs and I love how they sound .esp considering the simple components.
This is the main Jasper PCB. The keyboard is attached.
I like how the colour of the keys is reversed.

 iT should be a fun build. This is a rev 2.2 , July 2017 PCB.


Here is a list of the ICs used.
LM386 or NJM386D
555
CMOS 555 like TLC555CP recommended
LM3900

CD4006 - shift register
CD4013 - dual flip flop
CD4016 -- analog bilateral switch
CD4019
CD4024 - shift register
CD4028
CD4040-- counter .. binary,ripple
CD4046 .. PLL phased locked loop... probably the VCO
CD4052 .... multiplexer.. dual 4 channel
CD4069UBE... its an inverter ... I think this is part of the wasp filter ???
CD4070... XOR gate
CD4071....quad two input OR gate
CD4081... quad 2 input AND gate
CD4503
LM13700
CD40103
CD40174

There are many ways to build this but I like to put the IC sockets on first.

Then caps, resistors, etc. All the simple non polarized stuff.


Electro caps are polarized. Insert thus: Long lead in square hole.


The link port cable on the underside of the main board.
 The switched pots.


Fix everything into place then solder.

The rotary switches. You need 6 of these.
These are 2 pole, single level/
 You need to cut the shaft to the right length.


You can set the number of positions with the key washer:
In the pic below, it's set to 4.


To be continued.................

Links:
+ Jaspersynth
+ BOM
+ Build notes
+ DSL man.de
+ Knobs
+ Muffs

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Wasp filter Vintage and AE modular

November 8, 2019, 2:26 pm
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I'm just getting into the AE modular.
The lovely small format is esp useful for live performance.
I can carry a whole modular in a small suitcase.
And its battery powered.

A friend asked me to do a video comparing WASP filters.
I hope this helps the community.


The Tangible Waves / Abused Electronics modular
https://www.tangiblewaves.com/


The WASP filter is based around a simple CMOS chip.
The 4069.... its an inverter.
If you're going to build one the CMOS ic has to be unbuffered  ... use CD4069UB
The circuit also uses the CA3080 ... a OTA...Operational Transconductance Amplifier..
An OPAMP is a Voltage to Voltage amplifier.
The OTA is like a op-amp but the output is a current source instead of a voltage source.
Also the OTA has 3 inputs (unlike a op-amp with 2)
The 3rd input sets the gain with a current.






Links
+ Elby/kenstone
+ https://www.tangiblewaves.com/
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Yamaha TX81z

November 9, 2019, 5:40 am
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Some pics of this Yamaha Tone Generator.


Though its only 4 operators , it sounds great.


Maybe a new classic??
It can be configured to act as 8 independent instruments.  .... each controlled on a different midi channel.

It's a 1-unit rackmount module ...basically a key-less version of the DX-11.
The sounds are similar to the DX-21 and DX-27. 

 The TX81Z has 5 banks of 32 voices. Banks A-D contain factory preset voices.
Use the PARAMETER keys to select banks I, A, B, C, D. Use the DATA ENTRY keys to select voices 1-32 in each bank.

 




...jUST 8 algorithms 




 A pull-out card lists the main operations of the TX81Z.
 --------------------------------------

You can edit your own voices... In single mode , press the edit-compare button.


 Use the PARAMETER keys tomove through the parameters, Use the DATA ENTRY keys to change the datavalue. When the LCD shows several parameters at once, use the CURSOR keys to move the blinking cursor to the parameter you want to set.

..
While editing a voice, you can compare it with the original voice. Press EDIT/COMPARE. The LED will begin blinking, and the LCD will show a “c” in theupper left corner, indicating “Compare”.Use the PARAMETER keys to lookthrough the parameters. 


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FM Index
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Synth shops in tokyo

November 9, 2019, 6:14 am
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Echigoya Music
Japan, 〒150-0041 Tokyo, Shibuya City, Jinnan, 1 Ch
Shibuya, Tokyo, Japan
http://www.echigoyamusic.com/index.html

Mostly 2nd hand stuff.
Tiny shop on 6th floor.
Opposite Tower records


----------------------------------------------------

Otaku Tokyo
Shibuyaku, Japan
Reverb address
https://reverb.com/au/shop/otaku-tokyo?locale=en-AU

Shop website:
https://otakutokyo.com/

-------------------------------------------

Five G - Music technology
http://fiveg.net/

---------------------------
Ishibashi Music
Ishibashi Music Shibuya
150-0042 2F Shibuya-BEAM Bldg. 31-2, 31 Udagawa

Website
https://www.ishibashi.co.jp/eng/


Google maps
https://goo.gl/maps/drdTRGv6tn1e9tZF9

--------------------------------------------
Hard off
Its part of a department store chain
Japan, 〒180-0002 Tokyo, Musashino, Kichijoji Higashic

Website
https://www.hardoff.co.jp/shop/kanto/tokyo/hardoff/101079/ 


Map:


--------------------------------------------------------------------

Akihabara Electric Town

Radio Centre    

Japan, 〒101-0021 Tokyo, Chiyoda City,


Sotokanda, 1 Chome

Akihabara ( Akiba)
10, Tōkyō-to 101-0021

 Japan Guide

Look for the electronics shops (one man operations to department stores)
Larger stores: Sofmap and Laox

  -------------------------------------------------------------------

Recycling Garden Yoyogi shop

3 Chome-38-10 Yoyogi, Shibuya City, Tokyo 151-0053, J

recycle-garden.net 

-------------------------------------------

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OTA - Operational Transconductance Amplifiers

November 10, 2019, 6:13 pm
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I've been building a Jasper wasp lately and been wondering why the filter sounds so darn good.
I never really studied the circuit till recently so always assumed it was a completely digital design.
It uses a cmos 4069.... its an inverter... but the other part of the circuit is a
CA3080 ... a OTA...Operational Transconductance Amplifier. This is used instead of your standard Op-amp.
I'm sure this is a big part of the sound.

So what is a OTA?
It's a amplifier unlike your standard Op-amp.

What the OTA  shares with your common Op-Amp is:
1. a single output.
2. They both have inverting & non-inverting inputs.
3. They both have power lines (V+ & V-)


What makes the OTA different is that it has 2 extra inputs (Ibias & Iabc)
and it's output is a current not a voltage.
So, to put it another way, a OTA is a voltage to current amplifier or a voltage controlled current source.

The OTAcan also be viewed as an ideal transistor. 



Like a transistor,it has three terminals—
a high impedance input(base)
a low-impedance input/output (emitter)
a current output (collector). 

There are loads of circuits that use the OTAs like VCOs, filters, VCAs, waveshapers. 

OTA's include:
CA3080 (discontinued)
LM13600 - Texas Instruments (formerly National Semiconductor)
LM13700 - Texas Instruments (formerly National Semiconductor)
MAX435 (obsolete product)
MAX436  (obsolete product)
OPA860 -- Texas instruments (SOIC)
OPA861 -- texas instruments
NE5517 - ON Semiconductor
NJM13660 - New Japan Radio (JRC)
NJM13700  - New Japan Radio (JRC)
V13700 - CoolAudio
BA662A  Roland (manufactured by Rohm in the 1970s)*
BA 662B - Roland (manufactured by Rohm in the 1970s)
IR3109
BA6110  - Rohm

* The BA662A is the VCA used in the SH101, TB303, Juno-60, JX-3P, etc etc.
   It's used for portamento in the Jupiter 4.
------------------------------------------------
CA3080
Lots of old synths use the CA3080 which is obsolete and can be expensive to buy on the second hand market.

----------------------------------------------------------------------------

LM13700
The LM13700 is basically two CA3080s on one chip. You can also get these in a DIP (through hole) format. There are also conversion circuits that allow you to use a LM13700 in place of the CA3080.

There are lots of manufacturers still making this useful chip. They may have different part numbers, but the design is still the same one designed by Bill Gross & Don Sauer of  Texas Instruments (formerly National Semiconductor).

Here is the pinout for a LM13700

We basically have 2 identical op-amps.
This is really good for circuits that require matched pairs of amps.

Pin1
Amplifier Bias input
This sets the level of transconductance.
(the relation between the output & input current).

Pin2
Diode Bias A
Current applied here allows the chip to accept a higher differential input voltage.
This will improve linearity & distortion.

Pin3
Non-inverting input A

Pin4
Inverting Input A

Pin5
Output A
The output of the opamp as a current.
This equals the difference in input voltage  between pin 3 & 4 , multiplied by the transconductance.

Pin6
-V

Pin7
Buffer input A
Darlington pair buffer

Pin8
Buffer output A
Darlington pair buffer
 ----------------------------------------------------------------------------

Links
Comparing BA662A with BA6110 VCA chips in the x0xb0x 

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If there are any mistakes, omissions or if this is just BS please let me know.
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f56

November 12, 2019, 1:14 am
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Shibuya Crossing - Sat night 16th Nov 2019 - Tokyo Japan

November 21, 2019, 2:15 am
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I stayed in Shibuya during the recent TFOM (Tokyo Festival Of Modular).
Its a trendy suburb of Tokyo ... very much geared towards the youth & young at heart.




There are lots of nightclubs & designer shops.
Night time is when it really comes alive.




Ginza, in comparison has an older, more sophisticated feel. After the first night

The Shibuya  department store,109-2  has the best views (Mags Park) over the  crossing.
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National Art Center Tokyo - Roppongi

November 21, 2019, 2:15 am
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Roppongi is a suburb of Tokyo situated on a hilly area with great views of the Tokyo CBD.





You can see the Ginza district and the old Tokyo Tower from there.


If you have limited time in Tokyo, this is a great place to go to get your bearings.

Highly recommended are the National Art center (NACT) and the Mori building.







Address:
7 Chome-22-2 Roppongi, Minato City, Tokyo 106-8558, Japan.


Website:
https://www.nact.jp/english/

The NACT is probably Japan's largest museum


 The building is made up of seven enormous column-less display rooms. 





Architect: Kisho Kurokawa.
He is one of Japan's leading architects and is one of the founders of the Metabolist Movement (along with Kiyonori Kikutake,and Fumihiko Maki )which fuses architectural structures with organic biology.
 

Metabolism (/məˈtæbəlɪzəm/, from Greek: μεταβολήmetabolē, "change") is the set of life-sustaining chemical reactions in organisms..... leading to renewal & organic growth.

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ui

November 21, 2019, 2:15 am
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TFOM -Sat 16th - Sunday 17th Nov 2019

November 21, 2019, 2:16 am
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Some pics from the Tokyo Festival of Modular (2019).
This was held in the Suburb of SHIBUYA, Tokyo.
https://djjondent.blogspot.com/2019/08/tokyo-festival-of-modular-2019.html

 Tenderfoot Electronics

It's an annual event. Hopefully I'll return in 2020.


Address : B2F SHINTAISO BLDG No.4, 2-10-12 DOGENZAKA,
SHIBUYA-KU, Tokyo 150-0043 Japan
TEL : 03-6427-810
Directions: Go through the entrance of Shintaiso bldg parking lot located next to the Seven Eleven Dogenzaka Chuo Shop.



Tokyo Tape Music Center














WYWS - While You Were Sleeping  (Brisbane, Australia)

As well as the manufacturer's displays, there were electronic performances at night.
Videos of the performers to come.
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