Saturday, 10 October 2020

ARP 2500 - 1026 Preset Voltage Module

The 1026 is a rare module. I think only a few were produced and Ive never seen a original
though there are a few reproductions around.
Probably the year of production of the originals was about 1970 ???  
 


There are 16 preset voltages : 2 rows of control voltages 
each holding 8 individual CV values.
You set their value with the pots.
You trigger the CVs by pushing the associated momentary button
or with a 10V gate. (at lines 1 to 8).
The output voltages appear at lines 9 & 10.
Pretty simple.
The manual suggests using this with the 1027 sequencer or 1050 Mix-sequencer.
There is a socket at the rear of the unit to connect to a 1027 or 1050.
 
Specs:
Output voltages: 0 to +10V
Output impedances: 1K ohms
Input impedances : 100 K ohms
Power requirements: +/- 15V @ 20ma , regulated to +/-0.1%

 
 
 
 
 
 

It reminds me very much of the Serge programmer.
I have of course, rotated the pic to illustrate my idea.
I wonder which module came first?

The programmer has evolved into many forms today.
Think Makenoise pressure points & 0-control 
or Synthwerks 4x4












Friday, 9 October 2020

Online 808 . 303 emulation from Roland.

 There is no excuse not to add this to your bookmarks.

https://808303.studio/

 Its from Roland, sounds great & is free.
 
Roland and Yuri Suzuki have joined forces with the Design Museum to create 808303.studio.

  
A "Guy called Gerald" demos the emulation


Electronic: From Kraftwerk to The Chemical Brothers - The Design Museum

 If you're in London, don't miss this:

 


Hope the exhibition comes to Australia one day.

Wednesday, 7 October 2020

Akai Force - importing Abelton projects

 Importing and exporting abelton project files is a great feature in the AKAI force.
This is new in firmware 3.0.5

Firstly , the Force itself does have some limitations.

Up to 8 audio tracks, 8 plug-in instrument tracks, and 128 Drum, Keygroup, or MIDI program tracks may be added to a project. 
A project can have a maximum of 128 total tracks.
 
Importing abelton into the Force
You will need to first "save and collect all".
You can now import the ALS (Abelton Live Set) file to the Force and it’ll load the Session View & Arranger View with all audio and MIDI files.
 
It won’t import any third-party VSTs.
In this case you’ll have to bounce the tracks to audio before you export.
 
Abelton's  Impulse, Drum Racks, Simpler and Sampler instruments are compatible with the force.
 
Abelton's Impulse & Drum Racks looks like they are a great way to import your own custom drum racks into force.
 
 ------------------

Saturday, 3 October 2020

ARP 2500 - 1005 ModAMP Module - Ring Mods vs VCAs

The 1005 is a really interesting module.


 At first glance it seems simple... a ring-modulator (Balanced Modulator) connected to a VCA (Unbalanced Modulator). Actually ARP (and Tonus) often combined different components which would usually
be separated, into a single module. A good example is the filtamp 1006 -- it's a filter+VCA.

 The interesting bit about this module is how the two parts interact with one another, how you can control them and how they modulate the modulating VCOs ... but more about that later.

First, a brief description of Ring Modulators & VCAs.

Ring modulators & VCAs are of course related.
Both modules accept two signals and both multiply them together, but in different ways.
VCAs are also called Unbalanced Modulators & Amplitude Modulators.
Ring Modulators are also called Balanced Modulators.

VCAs


A VCA lets a signal pass. How that signal is passed is however controlled by the second signal (The control voltage).


Basically, it's multiplying the input signal by the modulation signal.
If the modulation strength (CV) is at full voltage, all the input signal will get through. In effect, the signal is multiplied by 1. (There is a switch to change the slope of the VCA between exponential & linear).

If CV = 0, out = 0.  That is, there is silence when there is no CV.

An important point to remember with a VCA is that the (audio) input signal can be bipolar (+ve & -ve), but the CV can only be +ve. (Any -ve modulation signals are ignored).
So it won't let any audio through if the modulation signal is zero or -ve.
(Because of this, most VCAs have added a DC offset at the modulation input which inverts any -ve voltages to +ve.)  

VCAs are classified as 2 quadrant multipliers because they handle bipolar signals on the audio input but allow only +ve multiplication. 


 
Ring Modulators (Balanced Modulators)

It's basically an electronic multiplier. 
If there are 2 input signals, A & B, the output is the product.
A x B = output.
Actually, in the case of the ARP 1005 module, the output is really (A x B) / 10 .
This is to protect the synthesizer from overloads, where the product of A and B is greater than +/- 10V
 
In general, Ring Modulators differ from standard VCAs in that they allow both negative & positive multiplication of signals.

You may ask the question "where did the ring modulator get it's name?"


In the early days, the modules used diode rings to change the polarity of the modulation & carrier signals.
Most modern modules have done away with this old technology


So the ring modulator is just a VCA with a special bipolar (+/- ve) input.
Because of the difference , the Ring Modulator is also called a four quadrant multiplier

Convention, states that the audio input ("A" in the ARP 2500) is called the carrier & the modulating / multiplying input ("B" in the ARP 2500) is called the modulator.

The Modulator can be activated or disengaged from the audio signal by pushing the UNMOD/MOD buttons. You can also use gates & triggers to do this. 

The obvious modules to supply gates are the 1027 sequencer, or a pulse from a LFO/Oscillator.  However, the slow random CV outputs of the 1016 Random Voltage Generator  can also trigger these switches. The "internal clock out" of the ARP 2600 (Sample & Hold section) also works.

 
MOD = audio signals A & B modulate one another.
UNMOD = Audio signals are passed through the modulator unaffected.

The ring mod section of the 1005 possibly uses a potted module: the 4014 sub module (I'll check this one day).
This sub-module was used in the 2600.
Here is part of the schematic:


With a RingM you can create a wide range of new frequencies that have no relationship to either of the original inputs A or B. Inharmonic overtones can be produced. This brings us to the lower half of the module.


The 1005, in addition to the ring mod & VCA, contains additional circuits that produce two sets of "Inharmonic Preset Control Voltages". They are named CVa & CVb. 
 
These can be fed back to the two VCOs (which are supplying the inputted audio signals A & B) to detune them a preset amount when the ModAMP  is switched from its "Unmod" to its "Mod" function.

The preset detuning of the oscillators permits control over any apparent key change which could result from the modulation of the two signals, A & B.
 
 
 
The manual suggests using 1004 & 1023 VCOs.
The difference voltage (Va - Vb) controls the frequency ratio of CVa to CVb
The average voltage (Va + Vb)/2 controls the tuning of CVa to CVb

The output of the ring modulator is always passed through the VCA.
I understand that the VCA used in the 1005 is identical to the 1006 Filtamp. 

Electrical Specifications

 

Balanced MoD section:
Output : V out = (INa x INb)/10 +/- 1.0%
Audio Inputs : +/- 10V max (100 Kohms impedance)

VCA section:
(input attenuators fully clockwise)
Vout = (Vin x Vcontrol)/10, Linear Mode.
Vout = Vin10 (Vcontrol-10)/2. Exponential Mode.
Control input Impedance = 100 K

Power requirements: 
+/- 15 V @ 35 ma, regulated to +/-0.1 % 
+ 12 V to +15 V @ 20 ma, unregulated.


ARP was planning to make the 1035 Triple Modulator.

I have never seen one of these.
It offered balanced modulation without voltage controlled amplifiers.
The 1035 contained three balanced modulators and six microphone pre-amplifiers.

The inputs and outputs appear at the top and bottom of the module. For each ring modulator there are two audio inputs & one audio output. It looks like you can also plug in low level external instruments like mics and guitars.. you can select the gain (High: x 100 or low : x10).

A switch labelled "AC,DC" selects either AC or DC coupling for each of the 6 inputs. So you should be able to process control voltages as well as audio. I reckon (though of course I haven't tried this) you could mix audio with LFOs.. possibly creating a tremolo.

 The Mod/Mix switches
Mod = Normal Ring mod operation
Mix = simple 2 channel mixer  
These 3 switches allows a simple way to switch between a Ring Modulator or Mixer operation on the two input signals.
In the Mod setting, it can also be used as a VCA when one input is audio, and the other is a CV.

The 3 overload lamps indicate voltages over +/- 10V at the outputs of the modulators. If they are lit, the signals are most likely distorted & clipping... you should thus either reduce the amplitude of the inputs or reduce the gain of the amps.

 
 
 
 
It's interesting to compare the 1035
 and the ring modulator of the ARP 2600.
They both have preamps, DC / AC coupling etc.

 

Links

+ ARP index
+ The ARP 2500 & the 1005 MODAMP module
+ Guitar fool
+ TTSH (ARP 2600 clone) build notes - Ring Modulator

PS: Please let me know if there are any mistakes or errors.
Cheers Jono

Pemberton WA - Fire Lookout Climbing Trees

 We in New South Wales are looked out of Western Australia until this virus is done.

So I can only dream for the moment.

I visited Pemberton many years ago. It's famous for it's great wine and super tall trees.
The climate is fairly cool, making it suitable for growing Pinot Noir, and Chardonnay grapes.
 

A series of fire lookouts were constructed in the top of a few very tall Karri trees during the 1930s and 1940s. These lookouts were a way of spotting fires in the tall Karri forest.  
....
 

Dave Evans Bicentennial Tree in the Warren National Park is a 15 minute drive from the Pemberton township, and off the Old Vasse Road. The Dave Evans Bicentennial Tree lookout was first pegged in 1988 as part of Australia’s bicentennial celebrations. 

...

At 75m above the ground, it is the tallest with a 360-degree view of old growth Karri forest.
 
 Karri trees live to about 350 years old
 
 They reach their full height after about 75 years. The three fire lookout trees are likely over 250 years.
 

--



All the trees are now pegged with metal pegs which are easier to grip. They are regularly checked for any faults. 



No one has died climbing the trees, however two people have suffered heart attacks. I find this incredible. It's a credit to whoever manages the park. If you are planning to do this climb beware that there is only one path of pegs going up and down. So you need to be patient and careful of climbers going in the opposite direction.
 

 
The Dave Evans Bicentennial Tree has 165 pegs.
 
It's a long way down. ;-)

Make Noise - 0-control / 0-coast Patches 3

 This is a continuation from patches 1 & 2

10. 


Strength to control ratcheting.
Interupt is on. 
Start the sequencer.

Use the O-control's inverter .. this  inverts the voltage making it speed up
as we press harder.
The inverter's LED should glow red when you touch a plate.
The 0-ctrls main time knob sets the number of ratchets.

Thanks to MakeNoise for their great videos

 

 


11. Overtones & envelop 1 control (of Time)


Strength is modulating overtones
Time is modulating MLTPL
Pressure is modulating Time ( of envelope1)
Set this envelope to self cycle


 

 

 

 

12. Subharmonics & analog quantizers

These are harmonics having frequencies below a fundamental frequency
You can think of them like suboscillators that play one or more octaves below the main oscillator.
This allows you to play notes in various frequency divisions

Connect the square output of the oscillator to the slope trigger.
Pitch modulates time.
(You can also modulate time with "strength" & "Time")
The EG 1 settings are impt. 
Rise (attack) @ 12 o'clock. 
Fall (decay) fully left. 
Exponential curve.

The big main pitch knob is @ 12 o'clock

Balance knob fully left

He describes it as an analog quantizer.


Of course you can use both envelopes
for double the fun.

Make sure the settings are exponential, a fastish attack, and decay is zero.

You can transpose the sequence by plugging a keyboard into the 1v/oct input of the 0-coast.









Thanks again to loopop for this patch
Creating a subharmonic oscillator.

The idea is to clock the 0 ctrl at audio rates by plugging an external oscillator.
You can use any square wave oscillator.
 
 We are using the dynamic gate outputs. They are modulated with "strength"

Turning these strength knobs up and down will change harmonics

Experiment with the Gate out/reset
 
 
 
 
 
 
 
 

This is another patch which will work also.
 
















Sunday, 27 September 2020

Makenoise 0-coast/0-control - Patches 2

The 0-Control is a very flexible controller.
I love it. Responsive, tactile & beautiful to behold.
It's good to remember these voltages when you're patching it into a modular
It can be clocked really easily. any rising edge trigger/gate above 2V.
The Clock Output is complex : it contains both internal and external clocks, and is affected by the Time parameter. You can of course use both internal & external clocks simultaneously to create really complex rhythms.
The Clock out consists of 0/8V gates.
 
The reset is unusual as it resets to the last touched plate (not the 1st step). 
 
 
1.

  Master clock : clock 0-coast.
  Time controlling multiply .
 
If the speed knob is fully to the left, then the time knobs will have little effect on tempo/speed.  
(but it seems to add  tiny bit of slide between notes ???)
This frees up CVs from "time" to control other parameters such as "multiply"

The strength knobs effect the envelope ... 
(left = 0 strength, fully right = full strength)




2.
Rather than using the dynamic envelope out of the 0contrl, use the dynamic gate.
 
The 0-control's 2nd envelope has more controls allowing  for greater variety of envelope shapes.






2a

 
Connect strength to either  (not both) normal gate or dynamic gate

I prefer using the normal gate since it triggers env 2

 

 

 

 

 

 

 

3.


Random controls direction.

Random can also be used with overtones, etc









4.



Square wave triggers envelope 1 , which modulates the balance (0-coast mixer)

The "strength" modulates "time" of envelope 1

 
 
 
 
 
 
 
 
 
 
 
 
5a

Balance
Time modulates balance 
or
Dynamic envelope modulates balance
 
Of course, balance can be modulated by random, EG 1 , etc

 
 
 
 
 
 
 
 
 
 
 
5b. 

Balance #2

A variation of patch 5a
Using the mixer to blend between random and the dynamic envelope.
With a stackable cable you could also add in CVs from the O-control's time section. 

Or you could modulate overtones/MLTPL on the O-coast
with CV from the 0-ctrl or random, Envelope 1 or 2.
So many options 

 
 
 
 
 
 
 
6. Direction

The 8 gate outputs are really useful.
Use them to trigger envelopes, clock other sequencers,
 change sequencer directions (use a stacking cable)



7. adding rests


The main strength knob needs to just be open enough to let 8V in.
This eg adds rests on step 2 & 6.










 
8. 

Resetting from different gates


 
 
 
 9a.

One Shot sequences

 Turn interrupt on.
You can play different length sequences on the fly.
Experiment with changing direction
 
 
 
 
 
 
 
 
9b. 

One shot #2
Gate 8 --> stop
Pressure gate  ---> reset
 
 
 
 
 
 
 
 
 
 
 
 
 
9c .

One shot #3
By patching the pressure CV to time we can  
slow down the sequences by pressing harder
 
 
 
 
 
 
 
 
 
 
 
Links
+ 0-control / 0-coast Patches 3

Saturday, 26 September 2020

Arp 2500 - 50th anniversary virtual symposium

 Wow 50 years


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Looks good
Here is the event link in Facebook
 
Sep 27 at 2 AM UTC+10 – Sep 27 at 4:30 AM UTC+10
Australian Eastern Standard Time is 10 hours ahead of Universal Time Coordinated.
 

Saturday, 19 September 2020

How to Program a Roland TR-808 - Quick start guide


Roland TR 808 - Quick Start

The 808 is a pretty basic machine that isn't too complicated to program, though it has a few odd quirks that are good to know. Before, you write any new patterns, it's important to clear the old ones.

How to clear old patterns 




1. Turn on with the top left power switch
2. Turn the MODE knob all the way to the left, to "Pattern Clear".
3. Choose which memory location you wish to erase by pressing one of the
    16 step buttons.
4. The "Basic Variation" switch needs to be in the AB position.
5. Press the Red "Pattern Clear" Button

yOU will see the AB LEDs flash really fast



 


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

How to program a simple pattern (1st Part rhythms)

 
 
 
 
 
1. Clear any existing patterns (See above)
2. Turn the MODE knob to the "first part"
3. The LED should be blinking in time with the tempo.
    (If it's not blinking, check the sync switch at the back of the 808.
     It should be set to internal sync)
4. set the Basic variation to A. The A LED will light up.
5. Hit START.
   The LED should be running across the 16 steps
6. Set the scale (I mostly use the 3rd row which is 4/4 time)
 
 7. Use the "instrument select" rotary switch to choose your instrument.

8. Program your beats by pressing the step buttons (step mode) or the TAP button
   (Tap mode)

9. If you flick the Basic variation to B you can program the steps 17 to 32.
   The B LED will light up. (Keep the MODE Knob on "first Part")
   Setting the variation to A/B will play steps 1 to 32.


 

I generally use pre-scale 3 which is a standard 4/4.
If you want to go double time, use pre-scale 4
 
 
 
 
 
 

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

How to Play existing patterns


Now that you have programmed lots of patterns, this is how you play them back. You can jump from one pattern to another.

1. Turn on with the top left power switch
2. Turn the MODE knob all the way to the left, to "MANUAL PLAY".
3. Choose which rhythm you wish to play by pressing one of the
    16 step buttons.
4. You will notice that the LED above the step button will flash.
5. The "Basic Variation" switch has 3 modes (A, B, and A/B) which gives you a total of 32 sixteen step patterns.
5a. Set the Basic variation to A. The A LED will flash.
6. Adjust tempo
7. Press the START/STOP Button

8. If you set the variation to B, steps 17 to 32 will play.
    Setting the variation to A/B will play steps 1 to 32.

9. Pressing a new step button will tell the 808 to play the rhythm stored in that memory slot.
 

aLWAYS check the sync switch at the back 
The 808 in this pic is the master, and is sending DinSync (clock info) to a TB 303.




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

The Second Part

I don't use this very often, but it's good to know what it does.
The 808 allows you to program a total of 32 different patterns (16x2). 
Each memory has a 1st & second part that can be used for even more rhythm patterns.   

This second part is used to allow for rhythms other than 16 or 32 steps.
Use it if want 12 steps, or 18 or 24 steps. 
It allows you add the difference that you are missing from the first part to the second part.
For example, if you want to make a 24 step pattern, you can make the 1st part 16 steps long and
the second part, 8 steps long. Or you can make the 1st and second part 12 steps.

Below is an example of how to use the second part. 
 
This is how you add a second part to an existing 1st part.
 
1. Program your 1st part rhythm as shown above.
2. While it it playing turn the program knob to "second part".
3.  Hold the red button down & press the last step you wish the 2nd part to have.
    eg to add an extra 8 steps to your existing 16 step pattern, press the 
    8th step button. You now have a 24 step pattern.
4. When you that step button you will instantly hear the tempo 
    of your existing pattern change (it's slower).
5. Add your extra beats as above.
6. While the drum is playing you can add new sounds to each part 
    by switching the program knob between the two parts

   If the mode selector is on the 2nd part, then the LEDs will indicate
   the 2nd part only.
   If the mode selector is on the 1st part, then the LEDs will indicate 
   the 1st part only.

7. Press the START/STOP button when programming is finished.
 

How to program two 12 step patterns

 ie 12 steps in part A & 12 in part B

1. Choose a free Memory slot (steps 1 - 16)
2. Set mode to Pattern Clear. (set Basic Variation to A/B). 
    Clear patterns as above.
3. Set the Basic variation to A. The A LED will flash.
4. Set Mode to 1st Part Pattern Write
5. Press Start. 
    (The sequencer must be running for this to work).
6. set PreScale to 4

7. Press CLEAR  + step 12
    You can add some drum beats if you wish for the 1st part, or leave it empty for now.
8. Set Mode to 2nd Part Pattern Write
   (the LEDs for each step will go off)
9. Press CLEAR + STEP12
 
 
 

9a. Program some drumbeats for the second part.
   You have now set up a 24 step pattern and the flow of LEDs will change from the 1st part
   to the second part. (Note, the number of steps in the 1st & second parts don't need to be the same).
10. Set the mode selector to Part 1 to program new beats or exit that part if there are existing beats present.
    Likewise for part 2

   If the mode selector is on the 2nd part, then the LEDs will indicate the 2nd part only.
   If the mode selector is on the 1st part, then the LEDs will indicate the 1st part only.
11. Press the START/STOP button when programming is finished.

After you have done all this put the 808 into pattern play mode.
Now you can jump between  patterns in real time.


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

I/F Variation Switch


I/F Variation = Intro or Fill-in Variation A or B
This performs the same function as the BASIC VARIATION switch, except it is only used for INTROs and FILL INs and relates to the last four white STEP buttons.
Intros and fill ins are additional rhythms separate from your basic rhythms. You add an intro at the beginning of your main rhythm, and a fill-ins between different basic rhythms.

 

 

 

 

 


The step buttons 1 to 16 are divided into two groups:
a) BASIC RHYTHMS (buttons numbered 1 to 12)
b) INTROS / FILL INs 
   (white buttons numbered 1 to 4)



 

 

 

 

 


Drum-fills will play automatically. This is based on the 'AUTOFILL-IN' knob selection.
The AutoFill-In knob can be set to 16, 12, 8, 4 and 2.
The selected "White Pattern" will automatically play every 16 or 8 or 4 measures etc
If the AUTOFILL-IN is set to 'Manual ' then the 'TAP" button will function as a 'FILL-IN' trigger... but only while the unit is playing.


You can turn the Intro/fill function on and off by pressing the TAP button.
When you first turn the mode to "play" you will see two LEDs lit:
a) One from the 1 -12 group  (flashing LED)
b) one from the 1 - 4 group (solid LED)
Pressing the start button will play the rhythm as standard.
BUT
If you press the TAP button first, the 1-4 LED will start to flash.
Now press the START button and the selected intro rhythm will play before the basic rhythm.
To disable this function just press the TAP button again, and the LED will stop flashing.


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


Setting the Pre-Scale.

Pre scale is the number of steps for each beat.
The prescale must always be chosen to match the minimum division of the note to be used in the rhythm pattern.
 
Matching the pre-scale on each of the recorded rhythms is really important. Though the switch may not change, each track can still run at different tempos. This was the case when I bought this drum second hand, all those years ago... I couldn't understand why each rhythm played at a different speed.
 

If you are playing a pattern and decide to change the pres-cale switch, don't forget to also press the red Pres-cale button.
 
 
 
 
 
 
 Example 1
To program a rhythm in 3/4 time.... uses a 12 step measure and the number 3 Pre Scale.

1. STOP the Rhythm
2. Set MODE to PATTERN CLEAR
3. Press a BASIC rhythm button (1 to 12)
    The LED should light up but not flash.
4. Set the Basic Variation switch to A
5. Press CLEAR button
6. Set MODE to PATTERN WRITE 1st PART
7. press START/STOP button
8. Set the Pre Scale selector switch to #3
9. Hold the CLEAR button down & press switch 12 at the same time.
10. Release the CLEAR button
 You have just set a 12 step pattern using a #3 Pre Scale.

Example 2: (basic 4/4 beat)
Create a 16 step pattern using the #3 pre scale 

1. Clear the memory as above (in A/B mode)
2. Set variation to A
3. Set MODE to PATTERN WRITE 1st PART
4. press START button
5. Set the Pre Scale selector switch to #3
6. Hold the CLEAR button down & press switch 16 at the same time.
7. Release the CLEAR button


Example 3.
You can change the time signature of existing rhythms without erasing them.
1. STOP the Rhythm
2. Select a BASIC rhythm button (1 to 12) to edit
    The LED should light up but not flash.
3. Set the Basic Variation switch to A
4. Set MODE to PATTERN WRITE 1st PART
5. press START button
    Your rhythm will play.
6. Set the Pre Scale selector switch to #3 (for example)
7. Hold the CLEAR button down & press switch one of the step switches (1 - 16)
   at the same time.
8. Release the CLEAR button

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

Composing the Rhythm Track


Play/Compose/Track Clear

There is memory for 12 Rhythm Tracks .
It's labeled in orange and uses the instrument select dial.

This is how we sequence a entire performance.
It's done live.
 
1. STOP the Rhythm pattern.
2. Set the MODE to COMPOSE
3. You will see a Step LED flash. 
4. Set the instrument select to #1
    (to compose in bank 1)
5. Press TRACK CLEAR
6. Set both variation switches to A
7. Press START. 
    While in this mode every change of rhythm 
    patterns will be memorized.
8. Play your desired patterns in whatever order you wish.
9. Press STOP
    The exact time you press STOP is critical .... it must be exactly when the measure ends.
10. Set the MODE to PLAY to listen to your performance.
 
Each of the 12 tracks will memorize up to 64 measures.
These can be used separately or together for a max of 768 measures (12x64)

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

It's important to note that both Variation switches are "play" function only.
The 808 doesn't memorise the setting of either switch.
When the drum plays rhythm #5, you can control if part A, part B or part AB is finally played.
I think this is a pretty neat performance feature.
 
+ TR 808 Drum links
           + Repairing a Roland TR-808 - Part 1 - Opening the Machine           
           + Roland Drum Machine Timeline